@article {2206, title = {Analysis of the high cracking resistance of a Co Ni superalloy during laser additive manufacturing}, journal = {Scripta Materialia}, volume = {239}, year = {2024}, pages = {115770}, abstract = {

A newly developed CoNi-based superalloy is demonstrated to be tolerant of a wide range of laser powder bed fusion print conditions, with limited defect content and high relative densities. These promising traits motivated investigation of the structural uniformity in samples printed at the upper end of the scan velocity processing window (\>Image 1). A new misorientation metric, starting reference orientation deviation (SROD), was calculated from Image 2-scale 3D microstructure information to examine structure evolution during epitaxial growth of columnar grains. Misorientations of \>20\° were observed within the large columnar grains that grew through multiple build layers. The SROD observations highlight the CoNi superalloy\&$\#$39;s ability to plastically deform to high levels, as evidenced by misorientation gradients, across the range of temperatures experienced in laser additive manufacturing. Misorientation gradients within the columnar grain structure are high relative to Ni base superalloys, allowing for strengthening with high volume fractions of L12 precipitates.

}, keywords = {3D EBSD, Rapid solidification, Superalloy}, issn = {1359-6462}, doi = {https://doi.org/10.1016/j.scriptamat.2023.115770}, url = {https://www.sciencedirect.com/science/article/pii/S1359646223004918}, author = {James Lamb and Kira M. Pusch and Andrew T. Polonsky and St{\'e}phane A.J. Forsik and Ning Zhou and Austin D. Dicus and Remco Geurts and McLean P. Echlin and Tresa M. Pollock} } @article {2211, title = {Rapid Screening of Single Phase Refractory Alloys Under Laser Melting Conditions}, journal = {Materials \& Design}, year = {2024}, pages = {112726}, abstract = {

Refractory alloys can be difficult to fabricate by laser-based manufacturing methods due to their high melting temperatures, high interstitial solubility, and propensity for low temperature brittleness. Laser-based processes, such as welding and additive manufacturing (AM), yield similar populations of defects, including microsegregation and solidification and solid-state cracking. Given the extreme challenges and cost associated with the production of refractory powders, this research aimed to develop a rapid screening methodology that combines predictive defect formation metrics with single track melting experiments. A flexible single laser track melting platform was designed to perform screening experiments on conventional and multi-principal element refractory alloys across a wide range of laser energy inputs. The platform was employed to investigate laser melting on solid substrates, or on a substrate with a single layer of powder feedstock, and is demonstrated with the highly fabricable Nb-base alloy C103. Preliminary investigations are performed on refractory multi-principal element alloys in the Hf-Mo-Nb-Ta-Ti family, and significant differences in cracking resistance and solidification morphology are observed. Implications for future alloy design and processing strategies for defect-resistant refractory alloys for AM are discussed.

}, keywords = {Additive manufacturing, high entropy alloy, multi-principal element alloy, refractory alloys, solid-state cracking, solidification cracking}, issn = {0264-1275}, doi = {https://doi.org/10.1016/j.matdes.2024.112726}, url = {https://www.sciencedirect.com/science/article/pii/S0264127524000984}, author = {Kaitlyn M. Mullin and Carolina Frey and James Lamb and Sophia K. Wu and McLean P. Echlin and Tresa M. Pollock} } @article {1841, title = {Insights into Plastic Localization by Crystallographic Slip from Emerging Experimental and Numerical Approaches}, journal = {Annual Review of Materials Research}, volume = {53}, year = {2023}, month = {07}, pages = {275-317}, doi = {10.1146/annurev-matsci-080921-102621}, author = {Stinville, Jean-Charles and Charpagne, Marie-agathe and Maa{\ss}, Robert and Proudhon, Henry and Ludwig, W. and Callahan, P.G. and Wang, Fulin and Beyerlein, I.J. and Echlin, M.P. and Pollock, T.m.} } @article {1901, title = {Nondestructive quantification of single crystal elasticity for additively manufactured SB-CoNi-10C, IN625, and Ti64}, journal = {NDT \& E International}, volume = {135}, year = {2023}, month = {02}, pages = {102803}, doi = {10.1016/j.ndteint.2023.102803}, author = {Rossin, Jeff and Leser, Patrick and Benzing, Jake and Torbet, Chris and Dillon, Robert and Smith, Stephen and Daly, Samantha and Pollock, Tresa} } @article {1961, title = {Determination of peak ordering in the CrCoNi medium-entropy alloy via nanoindentation}, journal = {Acta Materialia}, volume = {241}, year = {2022}, month = {09}, pages = {118380}, doi = {10.1016/j.actamat.2022.118380}, author = {Zhang, Mingwei and Yu, Qin and Frey, Carolina and Walsh, Flynn and Payne, Madelyn and Kumar, Punit and Liu, Dongye and Pollock, Tresa and Asta, Mark and Ritchie, Robert and Minor, Andrew} } @article {2026, title = {Development of grain-scale slip activity and lattice rotation fields in Inconel 718}, journal = {Acta Materialia}, volume = {226}, year = {2022}, month = {01}, pages = {117627}, doi = {10.1016/j.actamat.2022.117627}, author = {Hestroffer, Jonathan and Latypov, Marat and Stinville, Jean-Charles and Charpagne, Marie-agathe and Valle, Valery and Miller, Matthew and Pollock, Tresa and Beyerlein, Irene} } @article {1971, title = {Merging Machine Learning and TriBeam Tomography for 3D Defect Detection in an AM CoNi-Based Superalloy}, journal = {Microscopy and Microanalysis}, volume = {28}, year = {2022}, month = {08}, pages = {862-863}, doi = {10.1017/S1431927622003828}, author = {Lamb, James and Echlin, Mclean and Polonsky, Andrew and Geurts, Remco and Pusch, Kira and Raeker, Evan and Botman, Aurelien and Torbet, Chris and Pollock, Tresa} } @article {1966, title = {Multi-modal Dataset of a Polycrystalline Metallic Material: 3D Microstructure and Deformation Fields}, journal = {Scientific Data}, volume = {9}, year = {2022}, month = {08}, doi = {10.1038/s41597-022-01525-w}, author = {Stinville, Jean-Charles and Hestroffer, Jonathan and Charpagne, Marie-agathe and Polonsky, Andrew and Echlin, M. and Torbet, Chris and Valle, Valery and Nygren, K. and Miller, M. and Klaas, Ottmar and Loghin, Adrian and Beyerlein, I. and Pollock, T.} } @article {2006, title = {Observation of bulk plasticity in a polycrystalline titanium alloy by diffraction contrast tomography and topotomography}, journal = {Materials Characterization}, volume = {188}, year = {2022}, month = {04}, pages = {111891}, doi = {10.1016/j.matchar.2022.111891}, author = {Stinville, Jean-Charles and Ludwig, Wolfgang and Callahan, P.G. and Echlin, M.P. and Valle, Valery and Pollock, T.m. and Proudhon, Henry} } @article {1976, title = {Observations of Damage, Defects, and Structuring in Femtosecond Laser Ablated Surfaces}, journal = {Microscopy and Microanalysis}, volume = {28}, year = {2022}, month = {08}, pages = {872-873}, doi = {10.1017/S1431927622003865}, author = {Echlin, Mclean and Polonsky, Andrew and Lenthe, Will and Titus, Mike and Geurts, Remco and Botman, Aurelien and Straw, Marcus and Gumbsch, Peter and Pollock, Tresa} } @article {1811, title = {Single crystal elastic constants of additively manufactured components determined by resonant ultrasound spectroscopy}, journal = {Materials Characterization}, volume = {192}, year = {2022}, pages = {112244}, abstract = {

Bayesian inference with Sequential Monte Carlo was used to determine the single crystal elastic constants of additively manufactured (AM) cobalt-nickel-based superalloy specimens from only the resonant frequencies and texture data. This novel framework enables the quantification of the single crystal elastic constants for AM and polycrystalline specimens using only electron backscatter diffraction (EBSD) and Resonant Ultrasound Spectroscopy (RUS), avoiding the expense of bulk single crystal fabrication or synchrotron experiments. A parallelizable and open-source Python package (SMCPy) was used to perform Bayesian inference of the single crystal elastic constants from resonant frequencies of AM specimens. The single crystal elastic constants determined from AM cobalt-nickel-base superalloy specimens were validated with measurements of the single crystal elastic constants on a bulk single crystal specimen. EBSD texture data was used to determine the single crystal elastic constants from the resonant frequencies of AM specimens, and validated with neutron diffraction data by considering the experimental uncertainty in both the EBSD and neutron diffraction data. The robustness of this framework for varied texture orientations relative to the build direction (BD) was demonstrated for AM specimens printed at 0\° and 20\° BD-inclinations.

}, issn = {1044-5803}, doi = {https://doi.org/10.1016/j.matchar.2022.112244}, url = {https://www.sciencedirect.com/science/article/pii/S1044580322005265}, author = {Jeff Rossin and Patrick Leser and Kira Pusch and Carolina Frey and Sven C. Vogel and Alec I. Saville and Chris Torbet and Amy J. Clarke and Samantha Daly and Tresa M. Pollock} } @article {1741, title = {Bayesian inference of elastic constants and texture coefficients in additively manufactured cobalt-nickel superalloys using resonant ultrasound spectroscopy}, journal = {Acta Materialia}, volume = {220}, year = {2021}, pages = {117287}, abstract = {

Bayesian inference with sequential Monte Carlo is used to quantify the orientation distribution function coefficients and to calculate the fully anisotropic elastic constants of additively manufactured specimens from only the experimentally-measured resonant frequencies. The parallelizable and open-source SMCPy Python package enabled Bayesian inference within this new modeling framework, resulting in an order of magnitude reduction of the computation time for an 8-core machine. Residual stress-induced shifts on the resonant frequencies were explicitly accounted for during the Bayesian inference, enabling the estimation of their effect on the resonant frequencies without a stress-relief heat treatment. Additively manufactured cobalt-nickel-base superalloy (SB-CoNi-10C) specimens were sectioned at multiple inclinations relative to the build direction and scanned with resonant ultrasound spectroscopy to demonstrate characterization of any arbitrarily textured cubic microstructure through the resonant frequencies. The orientation distribution function coefficients of the textured polycrystalline microstructure were estimated in tensorial form to calculate both the 2nd order Hashin-Shtrikman bounds and the self-consistent estimate of the elastic constants, enabling accurate determination of all 21 possible independent elastic constants through the convergence constraints of the texture. Pole figures generated directly from the calculated texture coefficients showed good agreement with experimentally measured textures.

}, keywords = {Additive manufacturing, Bayesian inference, Parallel computing, Residual stress, Resonance ultrasound spectroscopy, Sequential monte carlo, Texture characterization}, issn = {1359-6454}, doi = {https://doi.org/10.1016/j.actamat.2021.117287}, url = {https://www.sciencedirect.com/science/article/pii/S1359645421006674}, author = {Jeff Rossin and Patrick Leser and Kira Pusch and Carolina Frey and Sean P. Murray and Chris J. Torbet and Stephen Smith and Samantha Daly and Tresa M. Pollock} } @article {2101, title = {Corrigendum to {\textquotedblleft}Defects and 3D structural inhomogeneity in electron beam additively manufactured Inconel 718{\textquotedblright} [Materials Characterization 143 (2018) 171{\textendash}181]}, journal = {Materials Characterization}, volume = {176}, year = {2021}, month = {06}, pages = {111069}, doi = {10.1016/j.matchar.2021.111069}, author = {Polonsky, Andrew and Echlin, Mclean and Lenthe, William and Dehoff, Ryan and Kirka, M. and Pollock, Tresa} } @article {1686, title = {Electron backscattered diffraction using a new monolithic direct detector: High resolution and fast acquisition}, journal = {Ultramicroscopy}, volume = {220}, year = {2021}, pages = {113160}, abstract = {

A monolithic active pixel sensor based direct detector that is optimized for the primary beam energies in scanning electron microscopes is implemented for electron back-scattered diffraction (EBSD) applications. The high detection efficiency of the detector and its large array of pixels allow sensitive and accurate detection of Kikuchi bands arising from primary electron beam excitation energies of 4 keV to 28 keV, with the optimal contrast occurring in the range of 8\–16 keV. The diffraction pattern acquisition speed is substantially improved via a sparse sampling mode, resulting from the acquisition of a reduced number of pixels on the detector. Standard inpainting algorithms are implemented to effectively estimate the information in the skipped regions in the acquired diffraction pattern. For EBSD mapping, an acquisition speed as high as 5988 scan points per second is demonstrated, with a tolerable fraction of indexed points and accuracy. The collective capabilities spanning from high angular resolution EBSD patterns to high speed pattern acquisition are achieved on the same detector, facilitating simultaneous detection modalities that enable a multitude of advanced EBSD applications, including lattice strain mapping, structural refinement, low-dose characterization, 3D-EBSD and dynamic in situ EBSD.

}, keywords = {Direct detection, EBSD, Indexing, Inpainting, SEM, Sparse sampling}, issn = {18792723}, doi = {10.1016/j.ultramic.2020.113160}, url = {https://doi.org/10.1016/j.ultramic.2020.113160}, author = {Wang, Fulin and Echlin, Mclean P. and Taylor, Aidan A. and Shin, Jungho and Bammes, Benjamin and Levin, Barnaby D.A. and De Graef, Marc and Pollock, Tresa M. and Gianola, Daniel S.} } @article {1661, title = {Influence of plastic deformation on the magnetic properties of Heusler MnAu2Al}, journal = {Phys. Rev. Materials}, volume = {5}, year = {2021}, month = {01/2021}, chapter = {014408}, abstract = {

The Heulser intermetallic\ MnAu2Al\ is shown to undergo a dramatic change in net magnetization in response to plastic deformation. A mechanism is proposed involving antiferromagnetic interactions in the otherwise ferromagnetic compound (when ordered) that arise due to chemical changes at the antiphase boundaries created by the deformation. The coupling between chemical and magnetic order across antiphase boundaries is likely to occur in other ordered magnetic systems and may provide an explanation for otherwise anomalous magnetic behavior across several systems, including other Heusler intermetallics.

}, doi = {https://doi.org/10.1103/PhysRevMaterials.5.014408}, url = {https://journals.aps.org/prmaterials/abstract/10.1103/PhysRevMaterials.5.014408}, author = {Levin, Emily E. and Kitchaev, Daniil A. and Eggeler, Yolita M and Mayer, Justin A. and Behera, Piush and Gianola, Daniel S. and Van der Ven, Anton and Pollock, Tresa M. and Seshadri, Ram} } @article {1676, title = {Insight into microstructure-sensitive elastic strain concentrations from integrated computational modeling and digital image correlation}, journal = {Scripta Materialia}, volume = {192}, year = {2021}, pages = {78{\textendash}82}, abstract = {

The microstructural origins of highly localized elastic strain concentrations in polycrystalline microstructures under monotonic loading are studied using grain-scale, in situ digital image correlation and crystal plasticity finite element method. It is shown that the locations of exceptionally high elastic strain concentrations in the microstructure depend on particular crystallographic and morphological orientations of grains and less so on crystalline details of their local neighborhood. Based on these results, we discuss how topological and crystallographic features of annealing twin boundaries can increase the likelihood of slip band initiation throughout the microstructure of polycrystalline Ni-base superalloys.

}, keywords = {Elasticity, Micromechanics, Microstructure, Superalloys}, issn = {13596462}, doi = {10.1016/j.scriptamat.2020.10.001}, url = {https://doi.org/10.1016/j.scriptamat.2020.10.001}, author = {Latypov, Marat I. and Stinville, Jean Charles and Mayeur, Jason R. and Hestroffer, Jonathan M. and Pollock, Tresa M. and Beyerlein, Irene J.} } @article {2076, title = {Modeling lattice rotation fields from discrete crystallographic slip bands in superalloys}, journal = {Extreme Mechanics Letters}, volume = {49}, year = {2021}, month = {08}, pages = {101468}, doi = {10.1016/j.eml.2021.101468}, author = {Latypov, Marat and Hestroffer, Jonathan and Stinville, Jean-Charles and Mayeur, Jason and Pollock, Tresa and Beyerlein, Irene} } @article {2131, title = {Multimodal 3D Characterization of Voids in Shock-Loaded Tantalum: Implications for Ductile Spallation Mechanisms}, journal = {Acta Materialia}, volume = {215}, year = {2021}, month = {06}, pages = {117057}, doi = {10.1016/j.actamat.2021.117057}, author = {Francis, Toby and Rottmann, Paul and Polonsky, Andrew and Charpagne, Marie-agathe and Echlin, Mclean and Livescu, Veronica and Jones, David and Gray, G. and Graef, Marc and Pollock, Tresa} } @article {2046, title = {Recent Developments in Femtosecond Laser-Enabled TriBeam Systems}, journal = {JOM}, volume = {73}, year = {2021}, month = {11}, pages = {1-12}, doi = {10.1007/s11837-021-04919-0}, author = {Echlin, Mclean and Polonsky, Andrew and Lamb, James and Geurts, Remco and Randolph, Steven and Botman, Aurelien and Pollock, Tresa} } @article {2116, title = {TriBeam tomography and microstructure evolution in additively manufactured Alnico magnets}, journal = {Materials Today}, volume = {49}, year = {2021}, month = {06}, doi = {10.1016/j.mattod.2021.05.003}, author = {Rottmann, Paul and Polonsky, Andrew and Francis, Toby and Emigh, Megan and Krispin, Michael and Rieger, Gotthard and Echlin, Mclean and Levi, Carlos and Pollock, Tresa} } @article {1336, title = {Accelerated discovery of oxidation resistant CoNi-base γ/γ{\textquoteright} alloys with high L12 solvus and low density}, journal = {Materials and Design}, volume = {189}, year = {2020}, pages = {1{\textendash}12}, abstract = {

A systematic and accelerated methodology for alloy design is demonstrated by combining combinatorial synthesis, high-throughput oxide scale characterization, computational density functional theory, and CALPHAD database calculations. By applying this strategy to the senary Co-Ni-W-Al-Cr-Ta material system, a novel \γ/\γ\&$\#$39; alloy exhibiting a superior combination of properties has been identified. Properties include a \γ\&$\#$39; solvus near 1200 \°C, continuous \α-Al2O3 scale formation after 1 h in air at 1100 \°C, and comparable density to 2nd-generation commercial Ni-base superalloys. This novel alloy SB-CoNi-10 has a nominal composition of 39.8Co \– 36.5Ni \– 13.2Al \– 1.0W \– 6.0Cr \– 3.5Ta at.\%, and its properties are compared with other recently studied Co-, CoNi-, and Ni-base \γ/\γ\&$\#$39; alloys.

}, keywords = {Alloy design, Cobalt-base superalloys, Combinatorial synthesis, Oxidation, Superalloys}, issn = {18734197}, doi = {10.1016/j.matdes.2019.108445}, author = {Stewart, Colin A. and Murray, Sean P. and Suzuki, Akane and Pollock, Tresa M. and Levi, Carlos G.} } @inbook {1531, title = {Acquisition of 3D Data for Prediction of Monotonic and Cyclic Properties of Superalloys}, booktitle = {Integrated Computational Materials Engineering (ICME): Advancing Computational and Experimental Methods}, year = {2020}, pages = {1{\textendash}18}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, address = {Cham}, abstract = {

The component design and fatigue life prediction of turbine disk alloys are critically dependent on the thermomechanical properties of the material. The TriBeam microscope provides a pathway to capture large, targeted 3D microstructural data volumes from turbine disk alloys in order to instantiate models that are used to simulate mechanical loading and assess material properties. The TriBeam experiments used to capture the microstructure, the analysis methods, data requirements, and future needs for 3D infrastructure will be discussed.

}, isbn = {978-3-030-40562-5}, doi = {10.1007/978-3-030-40562-5_1}, url = {https://doi.org/10.1007/978-3-030-40562-5_1}, author = {Echlin, Mclean P. and Lenthe, William C. and Stinville, Jean-Charles and Pollock, Tresa M.}, editor = {Ghosh, Somnath and Woodward, Christopher and Przybyla, Craig} } @inbook {1536, title = {Multi-scale Microstructure and Property-Based Statistically Equivalent RVEs for Modeling Nickel-Based Superalloys}, booktitle = {Integrated Computational Materials Engineering (ICME): Advancing Computational and Experimental Methods}, year = {2020}, pages = {55{\textendash}90}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, address = {Cham}, abstract = {

This chapter discusses fundamental aspects of the development of statistically equivalent virtual microstructures (SEVMs) and microstructure and property-based statistically equivalent representative volume elements (M-SERVE and P-SERVE) of the Ni-based superalloy at multiple scales. The two specific scales considered for this development are the subgrain scale of intragranular \γ\thinspace\−\thinspace\γ\textasciiacutex microstructures and the polycrystalline scale of grain ensembles with annealing twins. A comprehensive suite of computational methods that can translate microstructural data in experimental methods to optimally defined representative volumes for effective micromechanical modeling is the objective of this study. The framework involves a sequence of tasks, viz., serial sectioning, image processing, feature extraction, and statistical characterization, followed by micromechanical analysis and convergence tests for statistical functions. A principal motivation behind this paper is to translate high-fidelity microstructural image data into statistics of parametric descriptors in constitutive laws governing material performance.

}, isbn = {978-3-030-40562-5}, doi = {10.1007/978-3-030-40562-5_3}, url = {https://doi.org/10.1007/978-3-030-40562-5_3}, author = {Ghosh, Somnath and Weber, George and Pinz, Maxwell and Bagri, Akbar and Pollock, Tresa M. and Lenthe, Will and Stinville, Jean-Charles and Uchic, Michael D. and Woodward, Christopher}, editor = {Ghosh, Somnath and Woodward, Christopher and Przybyla, Craig} } @article {1526, title = {Non-destructive evaluation of 3D microstructure evolution in strontium titanate}, journal = {Journal of Applied Crystallography}, volume = {53}, year = {2020}, pages = {1{\textendash}11}, abstract = {

Nondestructive X-ray diffraction contrast tomography imaging was used to characterize the microstructure evolution in a polycrystalline bulk strontium titanate specimen. Simultaneous acquisition of diffraction and absorption information allows for the reconstruction of shape and orientation of more than 800 grains in the specimen as well as porosity. Three-dimensional microstructure reconstructions of two coarsening states of the same specimen are presented alongside a detailed exploration of the crystallographic, topological and morphological characteristics of the evolving microstructure. The overall analysis of the 3D structure shows a clear signature of the grain boundary anisotropy, which can be correlated to surface energy anisotropy: the grain boundary plane distribution function shows an excess of {\textlangle}100{\textrangle}-oriented interfaces with respect to a random structure. The results are discussed in the context of interface property anisotropy effects.

}, keywords = {3d materials, contrast tomography, diffraction, grain growth, microstructure evolution, nondestructive x-ray diffraction contrast, science, strontium titanate, to, tomography imaging was used}, doi = {10.1107/S160057672000093X}, author = {Trenkle, Andreas and Syha, Melanie and Rheinheimer, Wolfgang and Callahan, Patrick and Nhuyen, Lily and Ludwig, Wolfgang and Lenthe, William and Echlin, Mclean and Pollock, Tresa and Weygand, Daniel and Hoffmann, Michael and Gumbsch, Peter} } @article {1406, title = {Solidification-driven orientation gradients in additively manufactured stainless steel}, journal = {Acta Materialia}, volume = {183}, year = {2020}, pages = {249{\textendash}260}, abstract = {

A sample of 304L stainless steel manufactured by Laser Engineered Net Shaping (LENS) was characterized in 3D using TriBeam tomography. The crystallographic, structural, and chemical properties of the as-deposited microstructure have been studied in detail. 3D characterization reveals complex grain morphologies and large orientation gradients, in excess of 10o, that are not easily interpreted from 2D cross-sections alone. Misorientations were calculated via a methodology that locates the initial location and orientation of grains that grow during the build process. For larger grains, misorientation increased along the direction of solidification. For grains with complex morphologies, K-means clustering in orientation space is demonstrated as a useful approach for determining the initial growth orientation. The gradients in misorientation directly tracked with gradients in chemistry predicted by a Scheil analysis. The accumulation of misorientation is linked to the solutal and thermal solidification path, offering potential design pathways for novel alloys more suited for additive manufacturing.

}, keywords = {Additive manufacturing, Microstructure, Solidification, Tomography, Tribeam}, issn = {13596454}, doi = {10.1016/j.actamat.2019.10.047}, author = {Polonsky, Andrew T. and Lenthe, William C. and Echlin, Mclean P. and Livescu, Veronica and Gray, George T. and Pollock, Tresa M.} } @article {1561, title = {Structural coupling and magnetic tuning in Mn$_{2}$$_{-}$ₓCoₓP magnetocalorics for thermomagnetic power generation}, journal = {APL Materials}, volume = {8}, year = {2020}, pages = {041106}, abstract = {

Promising materials for magnetic refrigeration and thermomagnetic power generation often display strong coupling between magnetism and structure. It has been previously proposed that MnCoP exhibits this strong coupling, contributing to its substantial magnetocaloric effect near TC = 578K. Here, we show from temperature-dependent synchrotron x-ray diffraction that MnCoP displays a discontinuity in the thermal expansion at TC, with spontaneous magnetostriction that is positive in the a direction and negative in the b direction, highlighting the anisotropic nature of the magnetostructural coupling. Varying the Mn:Co ratio of Mn2-xCoxP within the range of 0.6 \≤ x \≤ 1.4 allows the magnetic properties to be tuned. TC decreases as the composition deviates from stoichiometric MnCoP, as does the saturation magnetization. The magnitude of the magnetocaloric effect, |\ΔSM|, decreases as well, due to broadening of the magnetic transition. The large reversible change in magnetization \ΔM accessible over a small temperature range under moderate magnetic fields makes these materials promising for thermomagnetic power generation from waste heat.

}, issn = {2166532X}, doi = {10.1063/1.5142000}, url = {https://doi.org/10.1063/1.5142000}, author = {Levin, Emily E. and Bocarsly, Joshua D. and Grebenkemper, Jason H. and Issa, Ramsey and Wilson, Stephen D. and Pollock, Tresa M. and Seshadri, Ram} } @article {1586, title = {Twin related domain networks in Ren{\'e} 88DT}, journal = {Materials Characterization}, volume = {165}, year = {2020}, pages = {110365}, abstract = {

Annealing twins in wrought fcc materials have historically been characterized using simple 2D measures including morphology and volume fraction. Accurately describing twin related domain microstructure requires accounting for their complex 3D structure. A large microstructural volume of a nickel-base alloy Ren\é 88DT has been collected using TriBeam tomography for full characterization of a large number of complete twin related domains. A network based approach enables visualization of twin domain structures. Metrics adapted from graph theory enable the first quantitative 3D microstructure descriptions. The implications for fatigue properties in twinned nickel-base alloys are discussed.

}, keywords = {3D EBSD, Annealing twin boundaries, Graph theory, Nickel-base superalloy, Recrystallization, Tribeam, Twins}, issn = {10445803}, doi = {10.1016/j.matchar.2020.110365}, url = {https://doi.org/10.1016/j.matchar.2020.110365}, author = {Lenthe, William C. and Echlin, Mclean P. and Stinville, Jean C. and De Graef, Marc and Pollock, Tresa M.} } @article {1506, title = {Alloy Design and Processing Design of Magnesium Alloys Using 2nd Phases}, journal = {JOM}, volume = {71}, year = {2019}, pages = {2219{\textendash}2226}, abstract = {

Two phases dominate the performance of commercial Mg alloys: (1) \β Mg17Al12 and (2) porosity. Alloy design and process design to optimize the morphology of the first and to minimize the second are discussed. Second phase \β can be designed to improve tensile strength, fatigue strength, toughness, texture, formability and corrosion resistance of Mg alloys. Processing is applied to refine the grain size, to array this phase in micron sizes at grain boundaries, and to further precipitate this phase in nanometer arrays within the grains. Therein, the 2nd phase \β plays the following roles: (1) retarding grain growth, (2) randomizing texture, (3) Hall\–Petch hardening, (4) Orowan hardening, and (5) moderating corrosion. Porosity is a detrimental 2nd phase common to cast Mg alloys in the form of gas or voids; its control being essential to engineering applications. Porosity can be diminished by sub-liquidus molding with high-velocity/high-pressure injection and then eliminated by subsequent hot deformation.

}, issn = {15431851}, doi = {10.1007/s11837-019-03482-z}, url = {https://doi.org/10.1007/s11837-019-03482-z}, author = {Decker, R. F. and Berman, T. D. and Miller, V. M. and Jones, J. W. and Pollock, T. M. and LeBeau, S. E.} } @article {1351, title = {BisQue for 3D Materials Science in the Cloud: Microstructure{\textendash}Property Linkages}, journal = {Integrating Materials and Manufacturing Innovation}, volume = {8}, year = {2019}, pages = {52{\textendash}65}, abstract = {

Accelerating the design and development of new advanced materials is one of the priorities in modern materials science. These efforts are critically dependent on the development of comprehensive materials cyberinfrastructures which enable efficient data storage, management, sharing, and collaboration as well as integration of computational tools that help establish processing\–structure\–property relationships. In this contribution, we present implementation of such computational tools into a cloud-based platform called BisQue (Kvilekval et al., Bioinformatics 26(4):554, 2010). We first describe the current state of BisQue as an open-source platform for multidisciplinary research in the cloud and its potential for 3D materials science. We then demonstrate how new computational tools, primarily aimed at processing\–structure\–property relationships, can be implemented into the system. Specifically, in this work, we develop a module for BisQue that enables microstructure-sensitive predictions of effective yield strength of two-phase materials. Towards this end, we present an implementation of a computationally efficient data-driven model into the BisQue platform. The new module is made available online (web address: https://bisque.ece.ucsb.edu/module_service/Composite_Strength/) and can be used from a web browser without any special software and with minimal computational requirements on the user end. The capabilities of the module for rapid property screening are demonstrated in case studies with two different methodologies based on datasets containing 3D microstructure information from (i) synthetic generation and (ii) sampling large 3D volumes obtained in experiments.

}, keywords = {Cloud-based computing, Homogenization, Materials cyberinfrastructure, Reduced order models}, isbn = {4019201900}, issn = {21939772}, doi = {10.1007/s40192-019-00128-5}, author = {Latypov, Marat I. and Khan, Amil and Lang, Christian A. and Kvilekval, Kris and Polonsky, Andrew T. and Echlin, McLean L.P. and Beyerlein, Irene J. and Manjunath, B. S. and Pollock, Tresa M.} } @article {1386, title = {Computational homogenization for multiscale forward modeling of resonant ultrasound spectroscopy of heterogeneous materials}, journal = {Materials Characterization}, volume = {158}, year = {2019}, pages = {109945}, abstract = {

We present a computational framework for multiscale forward modeling of ultrasound resonance in heterogeneous materials that accounts for microstructure. The approach includes two steps. The first step is the accurate determination of the elastic properties of heterogeneous materials with finite element simulations on a representative volume element of the microstructure at the mesoscopic length scale. The second step is modeling resonance frequencies of a macroscopic component made of an effective homogeneous medium having the same elastic properties as the actual material with microstructure. The approach is validated in a case study on a Cu\–W two-phase composite, for which resonance frequencies predicted with the proposed framework are compared against the experimental measurements. The present multiscale modeling approach, involving computational homogenization and leveraging 3D microstructure data, showed better accuracy compared to classical Voigt/Reuss bounds often used for forward modeling of resonant ultrasound spectroscopy.

}, keywords = {Computational homogenization, Finite elements, Forward modeling, Non-destructive evaluation, Resonant ultrasound spectroscopy}, issn = {10445803}, doi = {10.1016/j.matchar.2019.109945}, url = {https://doi.org/10.1016/j.matchar.2019.109945}, author = {Latypov, Marat I. and Charpagne, Marie Agathe and Souther, Mason and Goodlet, Brent R. and Echlin, Mclean P. and Beyerlein, Irene J. and Pollock, Tresa M.} } @article {1501, title = {In-plane and out-of-plane deformation at the sub-grain scale in polycrystalline materials assessed by confocal microscopy}, journal = {Acta Materialia}, volume = {169}, year = {2019}, pages = {260{\textendash}274}, abstract = {

High-resolution digital image correlation (HR-DIC) techniques have become essential in material mechanics to assess strain measurements at the scale of the elementary mechanisms responsible of the deformation in polycrystalline materials. The purpose of this study is to demonstrate the use of laser scanning confocal microscopy (LSCM) coupled with DIC techniques to deepen knowledge on the deformation process of a polycrystalline nickel-based superalloy at room temperature. The LSCM technique is capable of detecting both in-plane and out-of-plane strain localization within slip bands at the sub-grain level. The LSCM observations are consistent with previous in-situ scanning electron microscopy (SEM) studies: The onset of crystal plasticity occurs primarily near \Σ3 twin boundaries with macroscopic loading in the elastic domain (macroscopic stress as low as 80\% of the 0.2\% offset yield strength (Y.S. 0.2\% )). This intense irreversible strain localization occurs with either a high Schmid factor (\μ \> 0.43) or a significant elastic modulus difference between the pair of twins (\Δ\Ε \> 100 GPa). In the plastic deformation domain, transgranular slip activity following slip systems with the highest Schmid factor is mostly responsible for the deformation at the grain level, thus leading to strain percolation. The simultaneous in-plane and out-of-plane deformation assessment via the HR-LSCM-DIC technique was found to be essential for the identification of active slip systems. Finally, the HR-LSCM-DIC technique enabled the quantification of the glide amplitude involved in the three-dimensional shearing process at the grain level that solely in-plane measurements cannot provide.

}, keywords = {High Resolution-Digital Image Correlation (HR-DIC), In-situ tensile testing, Laser scanning confocal microscopy (LSCM), Nickel-based polycrystalline superalloy, Strain localization}, issn = {13596454}, doi = {10.1016/j.actamat.2019.03.001}, url = {https://doi.org/10.1016/j.actamat.2019.03.001}, author = {Liu, J. H. and Vanderesse, N. and Stinville, J. C. and Pollock, T. M. and Bocher, P. and Texier, D.} } @article {1391, title = {Oxidation Behavior Across Composition Space Relevant to Co-based γ/γ' Alloys}, journal = {Metallurgical and Materials Transactions A}, volume = {50}, year = {2019}, pages = {5445{\textendash}5458}, issn = {1073-5623}, doi = {10.1007/s11661-019-05413-8}, url = {https://doi.org/10.1007/s11661-019-05413-8}, author = {Stewart, Colin A. and Suzuki, Akane and Rhein, Robert K. and Pollock, Tresa M. and Levi, Carlos G.} } @article {1376, title = {Protocols for High Temperature Assisted-Microwave Preparation of Inorganic Compounds}, journal = {Chemistry of Materials}, volume = {31}, year = {2019}, pages = {7151{\textendash}7159}, abstract = {

Assisted-microwave heating involves the use of a susceptor to initially heat up reactants in a microwave reaction. Once hot, the reactants themselves become directly susceptible to microwave heating and interdiffuse to form products. Assisted-microwave methods are appealing for a wide variety of high temperature solid-state reactions, reaching reaction temperatures of 1500 \°C and more. Among the many advantages are that the direct volumetric heating associated with microwaves allows for rapid reaction times while employing significantly less energy than conventional furnace-based preparation. Shorter reaction times and selective heating permit volatile reactants to be incorporated stoichiometrically in the product. Undesirable reactions with containers or enclosures are also minimized. The morphology of powders obtained through microwave reactions are also more uniform and comprise smaller particles than obtained conventionally. This Methods/Protocols article is presented as a user manual for carrying out assisted-microwave preparation of bulk complex oxides in air or reducing atmospheres and sol-gel based processing of complex oxides, air sensitive intermetallics, and transition metal chalcogenides.

}, issn = {15205002}, doi = {10.1021/acs.chemmater.9b02594}, author = {Levin, Emily E. and Grebenkemper, Jason H. and Pollock, Tresa M. and Seshadri, Ram} } @article {1361, title = {Three-dimensional Analysis and Reconstruction of Additively Manufactured Materials in the Cloud-Based BisQue Infrastructure}, journal = {Integrating Materials and Manufacturing Innovation}, volume = {8}, year = {2019}, pages = {37{\textendash}51}, abstract = {

A microstructure analytics and 3D reconstruction software package, DREAM.3D, was integrated as a module into a cloud-based platform, BisQue. Parallelization of DREAM.3D module executions and the ability to parameterize pipeline variables over a range of values have led to insights about the grain segmentation misorientation tolerance in TriBeam-collected 3D EBSD datasets of additively manufactured materials with complex anisotropic microstructures. Furthermore, a comparison in grain size measurements was made between standard 2D metallographic slices and 3D measures using BisQue\&$\#$39;s parallelized DREAM.3D module executions. The direction of cloud-based data infrastructure and the prospects for impact in material science are also discussed.

}, keywords = {3D materials science, 3D metal printing, Additive manufacturing, Cloud infrastructure, Microstructure analytics, Tomography}, isbn = {4019201900}, issn = {21939772}, doi = {10.1007/s40192-019-00126-7}, author = {Polonsky, Andrew T. and Lang, Christian A. and Kvilekval, Kristian G. and Latypov, Marat I. and Echlin, McLean L.P. and Manjunath, B. S. and Pollock, Tresa M.} } @article {1431, title = {Advanced detector signal acquisition and electron beam scanning for high resolution SEM imaging}, journal = {Ultramicroscopy}, volume = {195}, year = {2018}, pages = {93{\textendash}100}, abstract = {

The advancement of materials science at the mesoscale requires improvements in both sampling volumes/areas and spatial resolution in order to make statistically significant measurements of microstructures that influence higher-order material properties, such as fatigue and fracture. Therefore, SEM-based techniques have become desirable due to improvements in imaging resolution, large sample handling capability, and flexibility for in-situ instrumentation. By using fast sampling of SEM electron detector signals, intrinsic beam scanning defects have been identified that are related to the response time of the SEM electron beam deflectors and electron detectors. Mitigation of these beam scanning defects using detector sampling approaches and an adaptive model for settling time is shown to produce higher resolution SEM images, at faster image acquisition times, with a means to quantify the different response functions for various beam deflectors and detectors including those for electrons and ions.

}, keywords = {High resolution digital image correlation, Image processing, Imaging defects, Scan generator, Scanning electron microscopy, SEM}, issn = {18792723}, doi = {10.1016/j.ultramic.2018.08.025}, url = {https://doi.org/10.1016/j.ultramic.2018.08.025}, author = {Lenthe, William C. and Stinville, Jean Charles and Echlin, Mclean P. and Chen, Zhe and Daly, Samantha and Pollock, Tresa M.} } @article {1471, title = {Application of chord length distributions and principal component analysis for quantification and representation of diverse polycrystalline microstructures}, journal = {Materials Characterization}, volume = {145}, year = {2018}, pages = {671{\textendash}685}, abstract = {

Quantification of mesoscale microstructures of polycrystalline materials is important for a range of practical tasks of materials design and development. The current protocols of quantifying grain size and morphology often rely on microstructure metrics (e.g., mean grain diameter) that overlook important details of the mesostructure. In this work, we present a quantification framework based on directionally resolved chord length distribution and principal component analysis as a means of extracting additional information from 2-D microstructural maps. Towards this end, we first present in detail a method for calculating chord length distribution based on boundary segments available in modern digital datasets (e.g., from microscopy post-processing) and their low-rank representations by principal component analysis. The utility of the proposed framework for capturing grain size, morphology, and their anisotropy for efficient visualization, representation, and specification of polycrystalline microstructures is then demonstrated in case studies on datasets from synthetic generation, experiments (on Ni-base superalloys), and simulations (on steel during recrystallization).

}, keywords = {Chord length distribution, EBSD, Grain size, Microstructure, Principal component analysis}, issn = {10445803}, doi = {10.1016/j.matchar.2018.09.020}, url = {https://doi.org/10.1016/j.matchar.2018.09.020}, author = {Latypov, Marat I. and K{\"u}hbach, Markus and Beyerlein, Irene J. and Stinville, Jean Charles and Toth, Laszlo S. and Pollock, Tresa M. and Kalidindi, Surya R.} } @article {1426, title = {Bayesian inference of elastic properties with resonant ultrasound spectroscopy}, journal = {The Journal of the Acoustical Society of America}, volume = {143}, year = {2018}, pages = {71{\textendash}83}, abstract = {

\© 2018 Acoustical Society of America. Bayesian modeling and Hamiltonian Monte Carlo (HMC) are utilized to formulate a robust algorithm capable of simultaneously estimating anisotropic elastic properties and crystallographic orientation of a specimen from a list of measured resonance frequencies collected via Resonance Ultrasound Spectroscopy (RUS). Unlike typical optimization procedures which yield point estimates of the unknown parameters, computing a Bayesian posterior yields probability distributions for the unknown parameters, and HMC is an efficient way to compute this posterior. The algorithms described are demonstrated on RUS data collected from two parallelepiped specimens of structural metal alloys. First, the elastic constants for a specimen of fine-grain polycrystalline Ti-6Al-4 V with random crystallographic texture and isotropic elastic symmetry are estimated. Second, the elastic constants and crystallographic orientation for a single crystal Ni-based superalloy CMSX-4 specimen are accurately determined, using only measurements of the specimen geometry, mass, and resonance frequencies. The unique contributions of this paper are as follows: the application of HMC for sampling the Bayesian posterior of a probabilistic RUS model, and the procedure for simultaneous estimation of elastic constants and lattice-specimen misorientation. Compared to previous approaches these algorithms demonstrate superior convergence behavior, particularly when the initial parameterization is unknown, and enable substantially simplified experimental procedures.

}, issn = {0001-4966}, doi = {10.1121/1.5017840}, author = {Bales, Ben and Petzold, Linda and Goodlet, Brent R. and Lenthe, William C. and Pollock, Tresa M.} } @article {1441, title = {Competing Modes for Crack Initiation from Non-metallic Inclusions and Intrinsic Microstructural Features During Fatigue in a Polycrystalline Nickel-Based Superalloy}, journal = {Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science}, volume = {49}, year = {2018}, pages = {3865{\textendash}3873}, abstract = {

Cyclic fatigue experiments in the high and very high cycle fatigue regimes have been performed on a Ren\é 88DT polycrystalline nickel-based superalloy. The microstructural configurations that favor early strain localization and fatigue crack initiation at high temperature from 400\ \°C to 650\ \°C have been investigated. Competing failure modes are observed in the high to the very high cycle fatigue regime. Fatigue cracks initiate from non-metallic inclusions and from intrinsic internal microstructural features. Interestingly, as stresses are reduced into the very high cycle regime, there is a transition to initiation only at crystallographic facets. At higher stress in the high cycle fatigue regime, a significant fraction of specimens initiate cracks at non-metallic inclusions. This transition is analyzed with regard to microstructural features that favor strain localization and accumulate damage early during cycling.

}, isbn = {1166101847803}, issn = {10735623}, doi = {10.1007/s11661-018-4780-3}, url = {https://doi.org/10.1007/s11661-018-4780-3}, author = {Stinville, Jean Charles and Martin, Etienne and Karadge, Mallikarjun and Ismonov, Shak and Soare, Monica and Hanlon, Tim and Sundaram, Sairam and Echlin, McLean L.P. and Callahan, Patrick G. and Lenthe, William C. and Miao, Jiashi and Wessman, Andrew E. and Finlay, Rebecca and Loghin, Adrian and Marte, Judson and Pollock, Tresa M.} } @article {1326, title = {Defects and 3D structural inhomogeneity in electron beam additively manufactured Inconel 718}, journal = {Materials Characterization}, volume = {143}, year = {2018}, pages = {171{\textendash}181}, abstract = {

Material structure and defects created during additive manufacturing contribute to the variability in mechanical properties of these parts, limiting their use for critical applications. Three-dimensional crystallographic, structural, and chemical information in electron beam melted Inconel 718 was collected from the sub-micron to the millimeter scale using the TriBeam tomography system. The relationship of defects to the surrounding microstructure has been studied in detail. Lack of fusion defects created sharp discontinuities in the grain morphology that extended several build layers beyond the layer where the defect originated. Nitrides and carbides in the size range of 1.25 \μm to 10 \μm were observed throughout the volume, with pronounced nitride clustering. The similarities between solidification in additive manufacturing and traditional manufacturing processes are demonstrated by the comparable size and distribution of carbides measured for industrial-scale samples of 718. Defects created during additive manufacturing cannot be easily remedied via standard post-processing techniques, and will likely diminish the mechanical performance of additively manufactured parts.

}, keywords = {Additive manufacturing, Electron beam melting, Lack of fusion, Microstructure, Tomography}, issn = {10445803}, doi = {10.1016/j.matchar.2018.02.020}, author = {Polonsky, Andrew T. and Echlin, Mclean P. and Lenthe, William C. and Dehoff, Ryan R. and Kirka, Michael M. and Pollock, Tresa M.} } @article {1311, title = {Elastic Properties of Novel Co- and CoNi-Based Superalloys Determined through Bayesian Inference and Resonant Ultrasound Spectroscopy}, journal = {Metallurgical and Materials Transactions A}, volume = {49A}, year = {2018}, month = {06/2018}, pages = {2324{\textendash}2339}, issn = {1543-1940}, doi = {10.1007/s11661-018-4575-6}, url = {https://doi.org/10.1007/s11661-018-4575-6}, author = {Goodlet, Brent R and Mills, Leah and Bales, Ben and Charpagne, Marie-agathe and Murray, Sean P and Lenthe, William C and Petzold, Linda and Pollock, Tresa M} } @article {1421, title = {Enhancing thermoelectric properties through control of Nickel Interstitials and phase separation in Heusler/Half-Heusler TiNi1.1Sn composites}, journal = {Materials}, volume = {11}, year = {2018}, pages = {1{\textendash}12}, abstract = {

Thermoelectric devices, which allow direct conversion of heat into electrical energy, require materials with improved figures of merit (zT) in order to ensure widespread adoption. Several techniques have been proposed to increase the zT of known thermoelectric materials through the reduction of thermal conductivity, including heavy atom substitution, grain size reduction and inclusion of a semicoherent second phase. The goal in these approaches is to reduce thermal conductivity through phonon scattering without modifying the electronic properties. In this work, we demonstrate that Ni interstitials in the half-Heusler thermoelectric TiNiSn can be created and controlled in order to improve physical properties. Ni interstitials in TiNi1.1Sn are not thermodynamically stable and, instead, are kinetically trapped using appropriate heat treatments. The Ni interstitials, which act as point defect phonon scattering centers and modify the electronic states near the Fermi level, result in reduced thermal conductivity and enhance the Seebeck coefficient. The best materials tested here, created from controlled heat treatments of TiNi1.1Sn samples, display zT = 0.26 at 300 K, the largest value reported for compounds in the Ti-Ni-Sn family.

}, keywords = {Heusler, Phonon scattering, Point defect, Thermoelectric, TiNi2Sn, TiNiSn}, issn = {19961944}, doi = {10.3390/ma11060903}, author = {Levin, Emily E. and Long, Francesca and Douglas, Jason E. and Buffon, Malinda L.C. and Lamontagne, Leo K. and Pollock, Tresa M. and Seshadri, Ram} } @article {1346, title = {Fatigue deformation in a polycrystalline nickel base superalloy at intermediate and high temperature: Competing failure modes}, journal = {Acta Materialia}, volume = {152}, year = {2018}, pages = {16{\textendash}33}, abstract = {

The microstructural configurations that favor early strain localization and fatigue crack initiation at intermediate and high temperature (400 \°C\–650 \°C) have been investigated using novel experimental techniques, including high resolution digital image correlation and transmission scanning electron microscopy. Cyclic fatigue experiments in the high and low cycle fatigue regimes have been performed on a Ren\é 88DT polycrystalline nickel-base superalloy at temperatures up to 650 \°C and compared to previous fatigue results obtained from tests in the very high cycle fatigue regime. Competing failure modes are observed along with an inversion in the temperature fatigue life dependence of fatigue strength from the low to high cycle fatigue regime. Oxidation-assisted processes are dominant at high applied stresses while cyclic plastic localization and accumulation govern fracture at low applied stresses. In addition, a second competing mode exists in the high and very high cycle fatigue regime from non-metallic inclusions as compared to internal intrinsic initiation sites. The grain-scale features that exhibit strain localization and crack initiation were investigated in detail. Transmission electron microscopy (TEM), transmission scanning electron microscopy (TSEM) and electron channeling contrast imaging have been conducted on samples removed from targeted regions with microstructural configurations that favor crack initiation to characterize the associated dislocation sub-structure and its evolution with temperature. Plasticity is observed to be less localized during cyclic loading at high temperature compared to room temperature. The microstructural features that drive initiation across the temperature range investigated are: twin-parent grains pairs that are at the upper end of the size distribution, are oriented for near maximum elastic modulus mismatch, and have high stresses along planes parallel to the twin boundaries.

}, keywords = {Coherent twin boundary, Elastic anisotropy, Fatigue crack initiation at intermediate and high temperature, High resolution digital image correlation, Microstructural effect, Polycrystalline microstructure, Ren{\'e} 88DT polycrystalline superalloy, Strain localization}, issn = {13596454}, doi = {10.1016/j.actamat.2018.03.035}, url = {https://doi.org/10.1016/j.actamat.2018.03.035}, author = {Stinville, Jean Charles and Martin, Etienne and Karadge, Mallikarjun and Ismonov, Shak and Soare, Monica and Hanlon, Tim and Sundaram, Sairam and Echlin, Mclean P. and Callahan, Patrick G. and Lenthe, William C. and Miller, V. M. and Miao, Jiashi and Wessman, Andrew E. and Finlay, Rebecca and Loghin, Adrian and Marte, Judson and Pollock, Tresa M.} } @article {1451, title = {Grain size effects on NiTi shape memory alloy fatigue crack growth}, journal = {Journal of Materials Research}, volume = {33}, year = {2018}, pages = {91{\textendash}107}, abstract = {

Fatigue cracking in polycrystalline NiTi was investigated using a multiscale experimental framework for average grain sizes (GS) from 10 to 1500 nm for the first time. Macroscopic fatigue crack growth rates, measured by optical digital image correlation, were connected to microscopic crack opening and closing displacements, measured by scanning electron microscope DIC (SEM-DIC) using a high-precision external SEM scan controller. Among all grain sizes, the 1500 nm GS sample exhibited the slowest crack growth rate at the macroscale, and the largest crack opening level (stress intensity at first crack opening) and minimum crack opening displacements at the microscale. Smaller GS samples (10, 18, 42, and 80 nm) exhibited nonmonotonic trends in their fatigue performance, yet the correlation was strong between macroscale and microscale behaviors for each GS. The samples that exhibited the fastest crack growth rates (42 and 80 nm GS) showed a small crack opening level and the largest crack opening displacements. The irregular trends in fatigue performance across the nanocrystalline GS samples were consistent with nonmonotonic values in the elastic modulus reported previously, both of which may be related to the presence of residual martensite only evident in the small GS samples (10 and 18 nm).

}, keywords = {fatigue, nanostructure, scanning electron microscopy (SEM)}, issn = {20445326}, doi = {10.1557/jmr.2017.395}, author = {Lepage, William S. and Ahadi, Aslan and Lenthe, William C. and Sun, Qing Ping and Pollock, Tresa M. and Shaw, John A. and Daly, Samantha H.} } @article {1461, title = {High-Resolution Deformation Mapping Across Large Fields of View Using Scanning Electron Microscopy and Digital Image Correlation}, journal = {Experimental Mechanics}, volume = {58}, year = {2018}, pages = {1407{\textendash}1421}, abstract = {

This paper details the creation of experimental and computational frameworks to capture high-resolution, microscale deformation mechanisms and their relation to microstructure over large (mm-scale) fields of view. Scanning electron microscopy with custom automation and external beam control was used to capture 209 low-distortion micrographs of 360\ \μm \× 360\ \μm each, that were individually correlated using digital image correlation to obtain displacement/strain fields with a spatial resolution of 0.44\ \μm. Displacement and strain fields, as well as secondary electron images, were subsequently stitched to create a 5.7\ mm\ \×\ 3.4\ mm field of view containing 100 million (7678 \× 13,004) data points. This approach was demonstrated on Mg WE43 under uniaxial compression, where effective strain was shown to be relatively constant with respect to distance from the grain boundary, and a noticeable increase in the effective strain was found with an increase in the basal Schmid factor. The ability to obtain high-resolution deformations over statistically relevant fields of view enables large data analytics to examine interactions between microstructure, microscale strain localizations, and macroscopic properties.

}, keywords = {Alignment, Digital image correlation (DIC), Distortion, External scan, Stitching}, issn = {17412765}, doi = {10.1007/s11340-018-0419-y}, author = {Chen, Z. and Lenthe, W. and Stinville, J. C. and Echlin, M. and Pollock, T. M. and Daly, S.} } @article {1436, title = {Measurements of plastic localization by heaviside-digital image correlation}, journal = {Acta Materialia}, volume = {157}, year = {2018}, pages = {307{\textendash}325}, abstract = {

In polycrystalline metallic materials, quantitative and statistical assessment of the plasticity in relation to the microstructure is necessary to understand the deformation processes during mechanical loading. Plastic deformation often localizes into physical slip bands at the sub-grain scale. Detrimental microstructural configurations that result in the formation and evolution of slip bands during loading require advanced strain mapping techniques for the identification of these atomically sharp discontinuities. A new discontinuity-tolerant DIC method, Heaviside-DIC, has been developed to account for discontinuities in the displacement field. Displacement fields have been measured at the scale of the physical slip bands over large areas in nickel-based superalloys by high resolution scanning electron microscopy digital image correlation (SEM DIC). However, conventional DIC methods cannot quantitatively measure plastic localization in the presence of discontinuous kinematic fields such as those produced by slip bands. The Heaviside-DIC technique can autonomously detect discontinuities, providing information about their location, inclination, and identify slip systems (in combination with orientation mapping). Using Heaviside-DIC, discontinuities are physically evaluated as sharp shear-localization events, allowing for the quantitative measure of strain amplitude nearby the discontinuities. Measurements using the new Heaviside-DIC technique are compared to conventional DIC methods for identical materials and imaging conditions.

}, keywords = {Discontinuities measurements, High resolution digital image correlation, Ren{\'e} 88DT polycrystalline superalloy, Scanning electron microscopy, Slip band offset, Slip band shearing, Slip system identification, Strain localization}, issn = {13596454}, doi = {10.1016/j.actamat.2018.07.013}, url = {https://doi.org/10.1016/j.actamat.2018.07.013}, author = {Bourdin, F. and Stinville, J. C. and Echlin, M. P. and Callahan, P. G. and Lenthe, W. C. and Torbet, C. J. and Texier, D. and Bridier, F. and Cormier, J. and Villechaise, P. and Pollock, T. M. and Valle, V.} } @article {1456, title = {Microstructure and property based statistically equivalent RVEs for intragranular γ-γ{\textquoteright} microstructures of Ni-based superalloys}, journal = {Acta Materialia}, volume = {157}, year = {2018}, pages = {245{\textendash}258}, abstract = {

This paper develops statistically equivalent RVEs or SERVEs for intragranular microstructures of Ni-based superalloys, characterized by \γ-\γ\&$\#$39; phase distribution. The SERVE represents an optimal computational domain to be used for micromechanical simulations for effective properties or response variables in the microstructure. The SERVE is further classified as a microstructure-based SERVE or M-SERVE or property-based SERVE or P-SERVE, depending on whether the statistics of morphological characteristics or convergence of chosen material properties are its determinants. Starting from FIB-SEM data for the superalloy Ren\é 88DT, the paper systematically develops a host of algorithms for generating validated statistically equivalent virtual microstructures, from which the M-SERVE is estimated from convergence of selected morphological and spatial distributions. Subsequently the P-SERVEs are established for global properties like yield strength and hardening rate, and local variables including dislocation density and the maximum resolved shear stress. Spatially-averaged quantities are found to converge quicker than the local distributions for both M-SERVE and P-SERVE.

}, keywords = {M-SERVE, Ni-based superalloys, P-SERVE, SEVM, Two-point correlation function, γ-γ{\textquoteright} distribution}, issn = {13596454}, doi = {10.1016/j.actamat.2018.07.034}, url = {https://doi.org/10.1016/j.actamat.2018.07.034}, author = {Pinz, M. and Weber, G. and Lenthe, W. C. and Uchic, M. D. and Pollock, T. M. and Ghosh, S.} } @article {1491, title = {Microstructure and Property-Based Statistically Equivalent Representative Volume Elements for Polycrystalline Ni-Based Superalloys Containing Annealing Twins}, journal = {Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science}, volume = {49}, year = {2018}, pages = {5727{\textendash}5744}, abstract = {

This paper has three major objectives related to the development of computational micromechanics models of Ni-based superalloys, containing a large number of annealing twins. The first is the development of a robust methodology for generating 3D statistically equivalent virtual polycrystalline microstructures (3D-SEVPM) of Ni-based superalloys. Starting from electron backscattered diffraction (EBSD) images of sections, the method develops distributions and correlation functions of various morphological and crystallographic parameters. To incorporate twins in the parent grain microstructure, the joint probability of the number of twins and parent grain size, and the conditional probability distributions of twin thickness and twin distance are determined. Subsequently, a method is devised for inserting twins following the distribution functions. The overall methodology is validated by successfully comparing various statistics of the virtual microstructures with 3D EBSD data. The second objective is to establish the microstructure-based statistically equivalent representative volume element or M-SERVE that corresponds to the minimum SERVE size at which the statistics of any morphological or crystallographic feature converge to that of the experimental data. The Kolmogorov\–Smirnov (KS) test is conducted to assess the convergence of the M-SERVE size. The final objective is to estimate the property-based statistically equivalent RVE or P-SERVE, defined as the smallest SERVE, which should be analyzed to predict effective material properties. The crystal plasticity finite-element model is used to simulate SERVEs, from which the overall material response is computed. Convergence plots of material properties including the yield strength and hardening rate are used to assess the P-SERVE. A smaller P-SERVE compared to the M-SERVE indicates that the characteristic features of twins implemented in determining the M-SERVE are more stringent than those for determining material properties.

}, issn = {10735623}, doi = {10.1007/s11661-018-4858-y}, url = {https://doi.org/10.1007/s11661-018-4858-y}, author = {Bagri, Akbar and Weber, George and Stinville, Jean Charles and Lenthe, William and Pollock, Tresa and Woodward, Christopher and Ghosh, Somnath} } @article {1171, title = {Oxidation-Assisted Crack Growth in Single-Crystal Superalloys during Fatigue with Compressive Holds}, journal = {Metallurgical and Materials Transactions A}, volume = {49}, year = {2018}, pages = {105{\textendash}116}, doi = {10.1007/s11661-017-4392-3}, author = {Lafata, M. A. and Rettberg, L. H. and He, M. Y. and Pollock, T. M.} } @article {1321, title = {Rapid Assessment of Oxidation Behavior in Co-Based γ/γ' Alloys}, journal = {Oxidation of Metals}, volume = {90}, year = {2018}, pages = {485{\textendash}498}, keywords = {Cobalt-base superalloys, Combinatorial synthesis, Oxidation, Photostimulated luminescence spectroscopy}, isbn = {0030-770X}, issn = {0030770X}, doi = {10.1007/s11085-018-9849-2}, url = {https://doi.org/10.1007/s11085-018-9849-2}, author = {Stewart, Colin A. and Suzuki, Akane and Pollock, Tresa M. and Levi, Carlos G.} } @article {1476, title = {Shearing of γ{\textquoteright} particles in Co-base and Co-Ni-base superalloys}, journal = {Acta Materialia}, volume = {161}, year = {2018}, pages = {99{\textendash}109}, abstract = {

Shearing mechanisms of the primary strengthening phase in cobalt-base and cobalt-nickel-base superalloys, \γ\′ (L12), are investigated at the elementary defect level by using a combination of generalized-stacking-fault energy (GSF) calculations and phase field simulations. The GSF energy surfaces of the \γ and \γ\′ phases, as determined from available experimental data and ab initio calculations, are used in the phase field simulations. Sophisticated deformation pathways leading to various planar defects including antiphase boundaries (APB), remnant superlattice intrinsic stacking faults (SISF), APB-SISF-APB ribbons and SISF islands are predicted as a function of alloy composition and particle shapes. The predicted stacking fault configurations for both alloys are consistent with recent transmission electron microscopy observations. Effects of dislocation line tension difference in \γ and \γ\′ phases and planar defect energy variation due to segregation at the planar defects are discussed. The detailed dislocation core structures, effects of dislocation line tension differences on deformation mechanisms, and unique deformation mechanisms uncovered, which include stacking fault ribbon shearing, antiphase boundary shearing, and mixed modes, could be used to improve constitutive microstructure-property relationships in advanced crystal plasticity modeling and to assist in alloy design.

}, keywords = {Ab initio calculation, Dislocation creep, Phase field simulation, Precipitation hardening, Stacking fault ribbon}, issn = {13596454}, doi = {10.1016/j.actamat.2018.09.013}, author = {Feng, L. and Lv, D. and Rhein, R. K. and Goiri, J. G. and Titus, M. S. and Van der Ven, A. and Pollock, T. M. and Wang, Y.} } @article {1446, title = {Electrically pumped continuous wave quantum dot lasers epitaxially grown on patterned, on-Axis (001) Si}, journal = {Optics Express}, volume = {25}, year = {2017}, pages = {3927{\textendash}3934}, keywords = {III-V on Silicon, Monolithic Integration, Quantum dot lasers, Silicon Photonics}, isbn = {9784885523069}, issn = {08999406}, doi = {10.1364/ol.42.000338}, author = {Norman, Justin and Kennedy, M.J. and Selvidge, Jennifer and Li, Quang and Wan, Yating and Liu, Alan Y. and Callahan, Patrick G. and Echlin, Mclean P. and Pollock, Tresa M. and Lau, Kei May and Gossard, Arthur C. and Bowers, John E.} } @article {1236, title = {Microstructural Statistics for Fatigue Crack Initiation in Polycrystalline Nickel-base Superalloys}, journal = {International Journal of Fracture}, volume = {208}, year = {2017}, pages = {240}, chapter = {221}, doi = {https://doi.org/10.1007/s10704-017-0241-z}, url = {https://link.springer.com/article/10.1007/s10704-017-0241-z}, author = {Stinville, JC and Lenthe, William C and Echlin, MP and Callahan, PG and Texier, Damien and Pollock, TM} } @article {1181, title = {Thermoelectric performance and the role of anti-site disorder in the 24-electron Heusler TiFe2Sn}, journal = {Journal of Physics: Condensed Matter}, volume = {29}, year = {2017}, month = {Apr}, pages = {405702}, doi = {10.1088/1361-648x/aa81e7}, author = {Buffon, Malinda L C and Laurita, Geneva and Lamontagne, Leo and Levin, Emily E and Mooraj, Shahryar and Lloyd, Demetrious L and White, Natalie and Pollock, Tresa M and Seshadri, Ram} } @article {1186, title = {Tuning the magnetocaloric response in half-Heusler/Heusler MnNi1 xSb solid solutions}, journal = {Physical Review Materials}, volume = {1}, year = {2017}, doi = {10.1103/physrevmaterials.1.075003}, author = {Levin, Emily E. and Bocarsly, Joshua D. and Wyckoff, Kira E. and Pollock, Tresa M. and Seshadri, Ram} } @article {jorgensen2016bond, title = {Bond coatings with high rumpling resistance: Design and characterization}, journal = {Surface and Coatings Technology}, volume = {300}, year = {2016}, pages = {25{\textendash}34}, publisher = {Elsevier}, author = {Jorgensen, David J and Suzuki, Akane and Lipkin, Don M and Pollock, Tresa M} } @article {stinville2016combined, title = {A combined grain scale elastic{\textendash}plastic criterion for identification of fatigue crack initiation sites in a twin containing polycrystalline nickel-base superalloy}, journal = {Acta Materialia}, volume = {103}, year = {2016}, pages = {461{\textendash}473}, publisher = {Pergamon}, author = {Stinville, JC and Lenthe, WC and Miao, J and Pollock, TM} } @article {buffon2016enhancement, title = {Enhancement of thermoelectric properties in the Nb{\textendash}Co{\textendash}Sn half-Heusler/Heusler system through spontaneous inclusion of a coherent second phase}, journal = {Journal of Applied Physics}, volume = {120}, number = {7}, year = {2016}, pages = {075104}, publisher = {AIP Publishing}, author = {Buffon, Malinda LC and Laurita, Geneva and Verma, Nisha and Lamontagne, Leo and Ghadbeigi, Leila and Lloyd, Demetrious L and Sparks, Taylor D and Pollock, Tresa M and Seshadri, Ram} } @article {echlin2016femtosecond, title = {Femtosecond Laser Damage in Metals and Semiconductors During TriBeam Tomography}, journal = {Microsc. Microanal}, volume = {22}, year = {2016}, pages = {3}, author = {Echlin, MP and Titus, M and Lenthe, WC and Straw, M and Gumbsch, P and Pollock, TM and Fraunhofer, IWM} } @article {rettberg2016growth, title = {Growth Stresses in Thermally Grown Oxides on Nickel-Based Single-Crystal Alloys}, journal = {Metallurgical and Materials Transactions A}, volume = {47}, number = {3}, year = {2016}, pages = {1132{\textendash}1142}, publisher = {Springer US}, author = {Rettberg, Luke H and Laux, Britta and He, Ming Y and Hovis, David and Heuer, Arthur H and Pollock, Tresa M} } @article {echlin2016incipient, title = {Incipient slip and long range plastic strain localization in microtextured Ti-6Al-4V titanium}, journal = {Acta Materialia}, volume = {114}, year = {2016}, pages = {164{\textendash}175}, publisher = {Pergamon}, author = {Echlin, McLean P and Stinville, Jean Charles and Miller, Victoria M and Lenthe, William C and Pollock, Tresa M} } @article {douglas2016magnetic, title = {Magnetic hardening and antiferromagnetic/ferromagnetic phase coexistence in Mn 1- x Fe x Ru 2 Sn Heusler solid solutions}, journal = {Physical Review B}, volume = {94}, number = {9}, year = {2016}, pages = {094412}, publisher = {American Physical Society}, author = {Douglas, Jason E and Levin, Emily E and Pollock, Tresa M and Castillo, Juan C and Adler, Peter and Felser, Claudia and Kr{\"a}mer, Stephan and Page, Katharine L and Seshadri, Ram} } @article {verma2016microstructure, title = {Microstructure Evolution of Biphasic TiNi1+ x Sn Thermoelectric Materials}, journal = {Metallurgical and Materials Transactions A}, year = {2016}, pages = {1{\textendash}12}, publisher = {Springer US}, author = {Verma, Nisha and Douglas, Jason E and Kr{\"a}mer, Stephan and Pollock, Tresa M and Seshadri, Ram and Levi, Carlos G} } @article {lenthe2016prediction, title = {Prediction of Fatigue-Initiating Twin Boundaries in Polycrystalline Nickel Superalloys Informed by TriBeam Tomography}, journal = {Microscopy and Microanalysis}, volume = {22}, number = {S3}, year = {2016}, pages = {1732{\textendash}1733}, publisher = {Cambridge University Press}, author = {Lenthe, William C and Stinville, Jean-Charles and Echlin, McLean P and Pollock, Tresa M} } @article {echlin2015situ, title = {In situ Femtosecond Laser and Argon Ion Beams for 3D Microanalysis using the TriBeam}, journal = {Microscopy and Microanalysis}, volume = {21}, number = {S3}, year = {2015}, pages = {1847{\textendash}1848}, publisher = {Cambridge University Press}, author = {Echlin, MP and Lenthe, WC and Douglas, J and Titus, M and Guerts, R and Straw, M and Pollock, TM} } @article {lenthe2015quantitative, title = {Quantitative Analysis of Correlated 3D Strontium Titanate Datasets Collected by TriBeam and Diffraction Contrast Tomography}, journal = {Microscopy and Microanalysis}, volume = {21}, number = {S3}, year = {2015}, pages = {2043{\textendash}2044}, publisher = {Cambridge University Press}, author = {Lenthe, WC and Echlin, MP and Syha, M and Trenkle, A and Gumbsch, P and Pollock, TM} } @article {lenthe2015quantitative, title = {Quantitative voxel-to-voxel comparison of TriBeam and DCT strontium titanate three-dimensional data sets}, journal = {Journal of Applied Crystallography}, volume = {48}, number = {4}, year = {2015}, pages = {1034{\textendash}1046}, publisher = {International Union of Crystallography}, author = {Lenthe, William C and Echlin, MP and Trenkle, Andreas and Syha, Melanie and Gumbsch, Peter and Pollock, Tresa M} } @article {douglas2015three, title = {Three-dimensional multimodal imaging and analysis of biphasic microstructure in a Ti{\textendash}Ni{\textendash}Sn thermoelectric material}, journal = {APL Materials}, volume = {3}, number = {9}, year = {2015}, pages = {096107}, publisher = {AIP Publishing}, author = {Douglas, Jason E and Echlin, McLean P and Lenthe, William C and Seshadri, Ram and Pollock, Tresa M} } @article {adharapurapu2014combinatorial, title = {A combinatorial investigation of palladium and platinum additions to $\beta$-NiAl overlay coatings}, journal = {Acta Materialia}, volume = {77}, year = {2014}, pages = {379{\textendash}393}, publisher = {Pergamon}, author = {Adharapurapu, Raghavendra R and Zhu, Jun and Dheeradhada, Voramon S and Lipkin, Don M and Pollock, Tresa M} } @article {pollock2014design, title = {Design constraints and higher temperature intermetallic bond coatings}, year = {2014}, author = {Pollock, TM and Jorgensen, D and Jackson, RW and He, M and Suzuki, A and Lipkin, D} } @article {adharapurapu2014effective, title = {Effective Hf-Pd Co-doped $\beta$-NiAl (Cr) coatings for single-crystal superalloys}, journal = {Acta Materialia}, volume = {76}, year = {2014}, pages = {449{\textendash}462}, publisher = {Pergamon}, author = {Adharapurapu, Raghavendra R and Zhu, Jun and Dheeradhada, Voramon S and Lipkin, Don M and Pollock, Tresa M} } @conference {suzuki2014oxide, title = {Oxide-assisted crack growth in hold-time low-cycle-fatigue of single-crystal superalloys}, booktitle = {MATEC Web of Conferences}, volume = {14}, year = {2014}, pages = {04004}, publisher = {EDP Sciences}, organization = {EDP Sciences}, author = {Suzuki, Akane and Gao, Yan and Lipkin, Don and Singhal, Anjali and Krug, Matthew and Konitzer, Douglas and Almer, Jonathan and Pollock, Tresa and Bewlay, Bernard} } @article {miller2014simulation, title = {Simulation of diffusion-limited lateral growth of dendrites during solidification via liquid metal cooling}, journal = {Acta Materialia}, volume = {69}, year = {2014}, pages = {47{\textendash}59}, publisher = {Pergamon}, author = {Miller, JD and Yuan, L and Lee, PD and Pollock, TM} } @article {jackson2014thermal, title = {Thermal barrier coating adherence to Hf-modified B2 NiAl bond coatings}, journal = {Acta Materialia}, volume = {80}, year = {2014}, pages = {39{\textendash}47}, publisher = {Pergamon}, author = {Jackson, RW and Lipkin, DM and Pollock, TM} } @article {echlin2014three, title = {Three-dimensional sampling of material structure for property modeling and design}, journal = {Integrating Materials and Manufacturing Innovation}, volume = {3}, number = {1}, year = {2014}, pages = {1}, publisher = {Springer Berlin Heidelberg}, author = {Echlin, McLean P and Lenthe, William C and Pollock, Tresa M} } @article {pollock2013feedback, title = {The feedback loop between theory, simulation and experiment for plasticity and property modeling}, journal = {Current Opinion in Solid State and Materials Science}, volume = {17}, number = {1}, year = {2013}, pages = {10{\textendash}18}, publisher = {Elsevier}, author = {Pollock, Tresa M and LeSar, Richard} } @article {birkel2013improving, title = {Improving the thermoelectric properties of half-Heusler TiNiSn through inclusion of a second full-Heusler phase: microwave preparation and spark plasma sintering of TiNi 1+ x Sn}, journal = {Physical Chemistry Chemical Physics}, volume = {15}, number = {18}, year = {2013}, pages = {6990{\textendash}6997}, publisher = {Royal Society of Chemistry}, author = {Birkel, Christina S and Douglas, Jason E and Lettiere, Bethany R and Seward, Gareth and Verma, Nisha and Zhang, Yichi and Pollock, Tresa M and Seshadri, Ram and Stucky, Galen D} } @article {birkel2013influence, title = {Influence of Ni nanoparticle addition and spark plasma sintering on the TiNiSn{\textendash}Ni system: structure, microstructure, and thermoelectric properties}, journal = {Solid State Sciences}, volume = {26}, year = {2013}, pages = {16{\textendash}22}, publisher = {Elsevier Masson}, author = {Birkel, Christina S and Douglas, Jason E and Lettiere, Bethany R and Seward, Gareth and Zhang, Yichi and Pollock, Tresa M and Seshadri, Ram and Stucky, Galen D} } @article {lenaburg2013outcomes, title = {Outcomes from research collaborations: What are they and how long do they take?}, journal = {MRS bulletin}, volume = {38}, number = {07}, year = {2013}, pages = {526{\textendash}528}, publisher = {Cambridge Univ Press}, author = {Lenaburg, Lubella A and Sciaky, Elizabeth S and Pollock, Tresa M} } @article {jackson2013oxidation, title = {The oxidation and rumpling behavior of overlay B2 bond coats containing Pt, Pd, Cr and Hf}, journal = {Surface and Coatings Technology}, volume = {221}, year = {2013}, pages = {13{\textendash}21}, publisher = {Elsevier}, author = {Jackson, RW and Lipkin, DM and Pollock, TM} } @article {pollock2012multifunctional, title = {Multifunctional coating interlayers for thermal-barrier systems}, journal = {MRS bulletin}, volume = {37}, number = {10}, year = {2012}, pages = {923{\textendash}931}, publisher = {Cambridge Univ Press}, author = {Pollock, TM and Lipkin, DM and Hemker, KJ} } @article {birkel2012rapid, title = {rapid microwave preparation of thermoelectric TiNiSn and TiCoSb half-heusler compounds}, journal = {Chemistry of Materials}, volume = {24}, number = {13}, year = {2012}, pages = {2558{\textendash}2565}, publisher = {American Chemical Society}, author = {Birkel, Christina S and Zeier, Wolfgang G and Douglas, Jason E and Lettiere, Bethany R and Mills, Carolyn E and Seward, Gareth and Birkel, Alexander and Snedaker, Matthew L and Zhang, Yichi and Snyder, G Jeffrey and others} } @article {rhein2011bimetallic, title = {Bimetallic low thermal-expansion panels of Co-base and silicide-coated Nb-base alloys for high-temperature structural applications}, journal = {Materials Science and Engineering: A}, volume = {528}, number = {12}, year = {2011}, pages = {3973{\textendash}3980}, publisher = {Elsevier}, author = {Rhein, RK and Novak, MD and Levi, CG and Pollock, TM} } @article {miller2011heat, title = {Heat Extraction and Structure Evolution in LMC Single-Crystal Growth}, journal = {Minerals, Metals and Materials Society/AIME, 420 Commonwealth Dr., P. O. Box 430 Warrendale PA 15086 United States.[np]. Feb}, year = {2011}, publisher = {Minerals, Metals and Materials Society/AIME, 420 Commonwealth Dr., P. O. Box 430 Warrendale PA 15086 United States}, author = {Miller, Jonathan and Yuan, Lang and Eisman, Michael and Lee, Peter and Pollock, Tresa} } @article {liu2011situ, title = {In situ synchrotron X-ray imaging of high-cycle fatigue crack propagation in single-crystal nickel-base alloys}, journal = {Acta Materialia}, volume = {59}, number = {13}, year = {2011}, pages = {5103{\textendash}5115}, publisher = {Elsevier}, author = {Liu, L and Husseini, NS and Torbet, CJ and Lee, W-K and Clarke, R and Jones, JW and Pollock, TM} } @article {pollock2011oxide, title = {Oxide-Assisted Degradation of Ni-Base Single Crystals During Cyclic Loading: the Role of Coatings}, journal = {Journal of the American Ceramic Society}, volume = {94}, number = {s1}, year = {2011}, publisher = {Blackwell Publishing Inc}, author = {Pollock, Tresa M and Laux, Britta and Brundidge, Clinique L and Suzuki, Akane and He, Ming Y} } @article {van2010elemental, title = {Elemental partitioning of platinum group metal containing Ni-base superalloys using electron microprobe analysis and atom probe tomography}, journal = {Acta Materialia}, volume = {58}, number = {6}, year = {2010}, pages = {1952{\textendash}1962}, publisher = {Pergamon}, author = {Van Sluytman, JS and La Fontaine, A and Cairney, JM and Pollock, TM} } @booklet {adharapurapu2010high, title = {High-Temperature Cyclic Oxidation of Pd/Pt-Modified Nial Bond Coats}, howpublished = {Minerals, Metals and Materials Society/AIME, 420 Commonwealth Dr., P. O. Box 430 Warrendale PA 15086 USA.[np]. 14-18 Feb}, year = {2010}, publisher = {Minerals, Metals and Materials Society/AIME, 420 Commonwealth Dr., P. O. Box 430 Warrendale PA 15086 USA}, author = {Adharapurapu, Raghavendra and Widrevitz, Dan and Zhu, Jun and Lipkin, Don and Dheeradhada, Voroman and Pollock, Tresa} } @booklet {huang2010mechanical, title = {On Mechanical Properties and Microstructures of TTMP Wrought Mg Alloys}, howpublished = {Minerals, Metals and Materials Society/AIME, 420 Commonwealth Dr., P. O. Box 430 Warrendale PA 15086 USA.[np]. 14-18 Feb}, year = {2010}, publisher = {Minerals, Metals and Materials Society/AIME, 420 Commonwealth Dr., P. O. Box 430 Warrendale PA 15086 USA}, author = {Huang, Jack and Arbel, Tamir and Ligeski, Laura and McCaffrey, Jesse and Kulkarni, Sanjay and Jones, J and Pollock, Tresa and Decker, Raymond and LeBeau, Steve} } @article {chen2010pulsed, title = {Pulsed-terahertz reflectometry for health monitoring of ceramic thermal barrier coatings}, journal = {Optics express}, volume = {18}, number = {4}, year = {2010}, pages = {3477{\textendash}3486}, publisher = {Optical Society of America}, author = {Chen, Chia-Chu and Lee, Dong-Joon and Pollock, Tresa and Whitaker, John F} } @article {das2008detection, title = {Detection of a marker layer in a 7YSZ thermal barrier coating by femtosecond laser-induced breakdown spectroscopy}, journal = {Surface and Coatings Technology}, volume = {202}, number = {16}, year = {2008}, pages = {3940{\textendash}3946}, publisher = {Elsevier}, author = {Das, Dipak K and McDonald, Joel P and Levi, Carlos G and Yalisove, Steve M and Pollock, Tresa M} } @article {liu2008situ, title = {In situ imaging of high cycle fatigue crack growth in single crystal nickel-base superalloys by synchrotron X-radiation}, journal = {Journal of Engineering Materials and Technology}, volume = {130}, number = {2}, year = {2008}, pages = {021008}, publisher = {American Society of Mechanical Engineers}, author = {Liu, Liu and Husseini, Naji S and Torbet, Christopher J and Kumah, Divine P and Clarke, Roy and Pollock, Tresa M and Jones, J Wayne} } @conference {chen2008terahertz, title = {Terahertz characterization of interfacial oxide layers and voids for health monitoring of ceramic coatings}, booktitle = {2009 34th International Conference on Infrared, Millimeter, and Terahertz Waves}, year = {2008}, author = {Chen, Chia-Chu and Lee, Dong-Joon and Pollock, Tresa and Whitaker, John F} } @article {suzuki2007effect, title = {Effect of Sr additions on the microstructure and strength of a Mg-Al-Ca ternary alloy}, journal = {Metallurgical and Materials Transactions A}, volume = {38}, number = {2}, year = {2007}, pages = {420{\textendash}427}, publisher = {Springer US}, author = {Suzuki, Akane and Saddock, ND and Riester, L and Lara-Curzio, E and Jones, JW and Pollock, TM} } @article {tryon2007hybrid, title = {Hybrid intermetallic Ru/Pt-modified bond coatings for thermal barrier systems}, journal = {Surface and Coatings Technology}, volume = {202}, number = {2}, year = {2007}, pages = {349{\textendash}361}, publisher = {Elsevier}, author = {Tryon, B and Murphy, KS and Yang, JY and Levi, CG and Pollock, TM} } @article {tryon2006multilayered, title = {Multilayered ruthenium-modified bond coats for thermal barrier coatings}, journal = {Metallurgical and Materials Transactions A}, volume = {37}, number = {11}, year = {2006}, pages = {3347{\textendash}3358}, publisher = {Springer}, author = {Tryon, B and Feng, Q and Pollock, TM and Wellman, RG and Nicholls, JR and Murphy, KS and Yang, J and Levi, CG} } @article {tryon2006ruthenium, title = {Ruthenium-containing bond coats for thermal barrier coating systems}, journal = {JoM}, volume = {58}, number = {1}, year = {2006}, pages = {53{\textendash}59}, publisher = {Springer}, author = {Tryon, B and Cao, F and Murphy, KS and Levi, CG and Pollock, TM} } @article {feng2005femtosecond, title = {Femtosecond laser micromachining of a single-crystal superalloy}, journal = {Scripta materialia}, volume = {53}, number = {5}, year = {2005}, pages = {511{\textendash}516}, publisher = {Elsevier}, author = {Feng, Q and Picard, YN and Liu, H and Yalisove, SM and Mourou, G and Pollock, TM} } @conference {shyam2004development, title = {Development of ultrasonic fatigue for rapid, high temperature fatigue studies in turbine engine materials}, booktitle = {10th International Symposium on Superalloys, Champion, PA, September}, year = {2004}, pages = {19{\textendash}23}, author = {Shyam, A and Torbet, CJ and Jha, SK and Larsen, JM and Caton, MJ and Szczepanski, CJ and Pollock, TM and Jones, JW} } @article {lu2004transmission, title = {Transmission electron microscopy study of complex planar faults in Ru{\textendash}Al{\textendash}0.5 at.\% B}, journal = {Philosophical Magazine}, volume = {84}, number = {22}, year = {2004}, pages = {2317{\textendash}2329}, publisher = {Taylor \& Francis}, author = {Lu, D-C and De Graef, M and Pollock{\textdagger}, TM} } @article {pollock2001comparative, title = {A comparative analysis of low temperature deformation in B2 aluminides}, journal = {Materials Science and Engineering: A}, volume = {317}, number = {1}, year = {2001}, pages = {241{\textendash}248}, publisher = {Elsevier}, author = {Pollock, TM and Lu, DC and Shi, X and Eow, K} } @article {li2001effect, title = {On the effect of low and high pressure hydrogen charging on the oxidation of a Ti{\textendash}48Al{\textendash}2Cr{\textendash}2Nb alloy}, journal = {Materials Science and Engineering: A}, volume = {318}, number = {1}, year = {2001}, pages = {224{\textendash}234}, publisher = {Elsevier}, author = {Li, K and Pollock, TM and De Graef, M and Habel, U and Thompson, AW} } @article {lu1999low, title = {Low temperature deformation and dislocation substructure of ruthenium aluminide polycrystals}, journal = {Acta materialia}, volume = {47}, number = {3}, year = {1999}, pages = {1035{\textendash}1042}, publisher = {Elsevier}, author = {Lu, DC and Pollock, TM} } @conference {lu1998low, title = {Low temperature deformation kinetics of ruthenium aluminide alloys}, booktitle = {MRS Proceedings}, volume = {552}, year = {1998}, pages = {KK7{\textendash}11}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, author = {Lu, DC and Pollock, TM} } @article {eow1998rate, title = {Rate sensitivities for low temperature deformation in ruthenium aluminide alloys}, journal = {Scripta materialia}, volume = {38}, number = {7}, year = {1998}, pages = {1065{\textendash}1069}, publisher = {Pergamon}, author = {Eow, K and Lu, D and Pollock, TM} } @article {li1995new, title = {A new phase in hydrogen-charged Ti 48Al 2Cr 2Nb}, journal = {Scripta metallurgica et materialia}, volume = {32}, number = {7}, year = {1995}, pages = {1009{\textendash}1014}, publisher = {Pergamon}, author = {Li, K and Pollock, TM and Thompson, AW and De Graef, M} }