@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 {2216, title = {High Temperature B2 Precipitation in Ru-Containing Refractory Multi-principal Element Alloys}, journal = {Metallurgical and Materials Transactions A}, year = {2024}, abstract = {

Ru-based B2 phases present an opportunity to design two-phase BCC + B2 refractory multi-principal element alloys (RMPEAs) with higher temperature stability compared to B2 phases observed in RMPEAs. In this investigation, seven equiatomic Ru-containing RMPEAs were characterized in the as-cast and annealed conditions. Of the two Hf-free alloys, Mo$$_25$$Nb$$_25$$Ta$$_25$$Ru$$_25$$was determined to be a single-phase B2 alloy and Mo$$_20$$Nb$$_20$$Ta$$_20$$W$$_20$$Ru$$_20$$was single-phase BCC. Within all five Hf-containing alloys, phases formed during solidification included HfRu\–B2, disordered BCC, and HfO$$_{2}$$phases. The Hf-containing alloys also precipitated B2 nanoparticles within the BCC phases after further cooling in the solid. All phases were still present after annealing at 1500 $$^\circ$$C to 1600 $$^\circ$$C. The HfRu\–B2 nanoparticles in as-cast Hf$$_20$$Mo$$_20$$Nb$$_20$$Ta$$_20$$Ru$$_20$$were characterized by transmission electron microscopy (TEM), and a lattice misfit of \< 1 pct between the BCC phase and B2 nanoparticles was calculated. Room-temperature micropillar compression tests were performed on BCC + B2 nanoparticle regions in annealed Hf$$_20$$Mo$$_20$$Nb$$_20$$Ta$$_20$$Ru$$_20$$. Post-mortem TEM analysis revealed precipitate shearing by dislocations, resulting in paired dislocations, along with bowing of dislocations around precipitates. Utilizing the insights from this investigation, compositions for RMPEAs with solutionable B2 precipitates stable above 1200 $$^\circ$$C are suggested.

}, issn = {1543-1940}, doi = {10.1007/s11661-024-07368-x}, url = {https://doi.org/10.1007/s11661-024-07368-x}, author = {Frey, Carolina and You, Haojun and Kube, Sebastian and Balbus, Glenn H and Mullin, Kaitlyn and Oppenheimer, Scott and Holgate, Collin S and Pollock, Tresa M} } @article {2196, title = {Navigating the BCC-B2 refractory alloy space: Stability and thermal processing with Ru-B2 precipitates}, journal = {Acta Materialia}, volume = {265}, year = {2024}, pages = {119628}, abstract = {

Refractory multi-principal element alloys (RMPEAs) could provide next-generation high temperature alloys, but their ductility and high temperature strength need significant improvement. Emulating superalloy \γ-\γ\’ microstructures, RMPEAs combining a ductile BCC matrix with embedded B2 precipitates for strengthening could meet this goal. Two-phase BCC-B2 RMPEAs have recently been demonstrated, but the B2 phase typically exhibits insufficient thermodynamic stability for operating temperatures \≥1300 \°C. Using high-throughput CALPHAD predictions, we screen across 3,500 potential BCC-B2 systems. Promising compositions are predicted for alloys combining Ru-based B2s with refractory BCC elements. A total of 20 such compositions were arc-melted to characterize their as-cast and heat-treated microstructures. In these alloys, the RuHf B2 exhibits exceptional stability beyond 1900 \°C but cannot be solutionized. By contrast, RuTi does solutionize and reprecipitate between 1300 and 1900 \°C, providing a robust thermal processing pathway. RuAl can be solutionized but also tends to form competing intermetallic phases. Altogether, Ru-B2 RMPEAs offer great design flexibility and surpass the stability and thermal processability of previously studied BCC-B2 refractory alloys.

}, keywords = {B2 phase, Calphad, Combinatorial, High temperature materials, Precipitation strengthening, Refractory multi principal element alloys, Thermal processing}, issn = {1359-6454}, doi = {https://doi.org/10.1016/j.actamat.2023.119628}, url = {https://www.sciencedirect.com/science/article/pii/S1359645423009564}, author = {Sebastian A. Kube and Carolina Frey and Chiyo McMullin and Ben Neuman and Kaitlyn M. Mullin 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 {2201, title = {Strength vs temperature for refractory complex concentrated alloys (RCCAs): A critical comparison with refractory BCC elements and dilute alloys}, journal = {Acta Materialia}, volume = {266}, year = {2024}, pages = {119692}, abstract = {

To support the development of refractory complex, concentrated alloys (RCCAs), a clear understanding of the effect of temperature on strength is needed. Body-centered cubic (BCC) refractory metals and dilute refractory alloys show a strong temperature dependence of yield stress (\σy) at low and high temperatures, with a relatively temperature-independent regime in between. RCCAs may introduce important changes in deformation and strengthening mechanisms, so it is not clear if RCCAs will show the same thermal dependencies. The objective of this work is to answer the question, \“Is the temperature dependence of strength similar or different for RCCAs compared to BCC refractory elements and dilute refractory alloys ?\” We evaluate \σy vs. temperature for 61 RCCAs by analyzing data curated from the literature. We find that \σy increases progressively from refractory BCC elements, to dilute alloys, to single- and multi-phase RCCAs. Single-phase RCCAs show the same three thermal regimes, but the stresses are higher and the intermediate plateau is shorter and is sometimes steeper. The thermal dependence of \σy in multi-phase RCCAs shows more substantial differences. Six factors that contribute to the higher \σy of RCCAs are discussed: (i) higher solute concentration; (ii) dispersion in atomic sizes; (iii) the shear modulus magnitude; (iv) the type of principal elements; (v) the solvus temperature of predicted secondary phases; and (vi) microstructure. Based on the present observations and analyses, suggestions for future research are made, especially regarding improved models for the effect of temperature on strength.

}, keywords = {High-entropy alloys, Refractory complex concentrated alloys (RCCAs), Temperature effects, Yield strength}, issn = {1359-6454}, doi = {https://doi.org/10.1016/j.actamat.2024.119692}, url = {https://www.sciencedirect.com/science/article/pii/S1359645424000454}, author = {D.B. Miracle and O.N. Senkov and C. Frey and S. Rao and T.M. Pollock} } @article {1886, title = {Minor Elements and Solidification Cracking During Laser Powder-Bed Fusion of a High γ' CoNi-Base Superalloy}, journal = {Metallurgical and Materials Transactions}, volume = {54}, year = {2023}, month = {02}, pages = {1-14}, doi = {10.1007/s11661-023-06957-6}, author = {Raeker, Evan and Pusch, Kira and Forsik, St{\'e}phane and Zhou, Ning and Dicus, Austin and Ren, Qing-Qiang and Poplawsky, Jonathan and Kirka, M. and Pollock, Tresa} } @article {1881, title = {Morphological Stability of Solid-Liquid Interfaces Under Additive Manufacturing Conditions}, journal = {Acta Materialia}, volume = {250}, year = {2023}, month = {03}, pages = {118858}, doi = {10.1016/j.actamat.2023.118858}, author = {Tourret, Damien and Klemm-Toole, Jonah and Eres-Castellanos, Adriana and Rodgers, Brian and Becker, Gus and Saville, Alec and Ellyson, Ben and Johnson, Chloe and Milligan, Brian and Copley, John and Ochoa, Ruben and Polonsky, Andrew and Pusch, Kira and Haines, Michael and Fezzaa, Kamel and Sun, Tao and Clarke, Kester and Babu, Suresh and Pollock, Tresa and Clarke, Amy} } @article {1891, title = {Quantitative Benchmarking of Acoustic Emission Machine Learning Frameworks for Damage Mechanism Identification}, journal = {Integrating Materials and Manufacturing Innovation}, year = {2023}, month = {02}, pages = {1-12}, doi = {10.1007/s40192-023-00293-8}, author = {Muir, C. and Tulshibagwale, N. and Furst, A. and Swaminathan, B. and Almansour, Amjad and Sevener, Kathleen and Presby, Michael and Kiser, J. and Pollock, T. and Daly, S. and Smith, C.} } @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 {2011, title = {A high stability B2-containing refractory multi-principal element alloy}, journal = {Acta Materialia}, volume = {229}, year = {2022}, month = {03}, pages = {117767}, doi = {10.1016/j.actamat.2022.117767}, author = {Frey, Carolina and Silverstein, Ravit and Pollock, Tresa} } @article {1981, title = {In Situ X-ray Radiography and Computational Modeling to Predict Grain Morphology in β-Titanium during Simulated Additive Manufacturing}, journal = {Metals}, volume = {12}, year = {2022}, month = {07}, pages = {1217}, doi = {10.3390/met12071217}, author = {Jasien, Chris and Saville, Alec and Becker, Chandler and Klemm-Toole, Jonah and Fezzaa, Kamel and Sun, Tao and Pollock, Tresa and Clarke, Amy} } @article {1996, title = {Microstructure Evolution and Tensile Properties of a Selectively Laser Melted CoNi-Base Superalloy}, journal = {Metallurgical and Materials Transactions A}, volume = {53}, year = {2022}, month = {05}, doi = {10.1007/s11661-022-06716-z}, author = {Murray, Sean and Raeker, Evan and Pusch, Kira and Frey, Carolina and Torbet, Chris and Zhou, Ning and Forsik, St{\'e}phane and Dicus, Austin and Colombo, Gian and Kirka, M. 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 {1926, title = {Temperature-dependent tensile behavior of the HfNbTaTiZr multi-principal element alloy}, journal = {Acta Materialia}, volume = {245}, year = {2022}, month = {12}, pages = {118618}, doi = {10.1016/j.actamat.2022.118618}, author = {Mills, Leah and Emigh, Megan and Frey, Carolina and Philips, Noah and Murray, Sean and Shin, Jungho and Gianola, Daniel and Pollock, Tresa} } @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 {2181, title = {A High Stability B2-Containing Refractory Multi-Principal Element Alloy}, journal = {SSRN Electronic Journal}, year = {2021}, month = {01}, doi = {10.2139/ssrn.3965527}, author = {Frey, Carolina and Silverstein, Ravit and Pollock, Tresa} } @article {2036, title = {A machine learning framework for damage mechanism identification from acoustic emissions in unidirectional SiC/SiC composites}, journal = {npj Computational Materials}, volume = {7}, year = {2021}, month = {12}, doi = {10.1038/s41524-021-00620-7}, author = {Muir, C. and Swaminathan, B. and Fields, K. and Almansour, Amjad and Sevener, Kathleen and Smith, C. and Presby, Michael and Kiser, J. and Pollock, T. and Daly, S.} } @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 {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} } @conference {1596, title = {3D Characterization of the Columnar-to-Equiaxed Transition in Additively Manufactured Inconel 718}, booktitle = {Superalloys 2020}, year = {2020}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, abstract = {

Additive manufacturing (AM) provides enormous process- ing flexibility, enabling novel part geometries and opti- mized designs. Access to a local heat source further per- mits the potential for local microstructure control on the scale of individual melt pools, which can enable local con- trol of part properties. In order to design tailored process- ing strategies for target microstructures, models predict- ing the columnar-to-equiaxed transition must be extended to the high solidification velocities and complex thermal histories present in AM. Here, we combine 3D charac- terization with advanced modeling techniques to develop a more complete understanding of the solidification pro- cess and evolution of microstructure during electron beam melting (EBM) of Inconel 718. Full calibration of existing microstructure prediction models demonstrates the differ- ences between AM processes and more conventional weld- ing techniques, underlying the need for accurate deter- mination of key parameters that can only be measured directly in 3D. The ability to combine multisensor data in a consistent 3D framework via data fusion algorithms is essential to fully leverage these advanced characteriza- tion approaches. Thermal modeling provides insight on microstructure development within isolated solidification events and demonstrates the role of Marangoni effects on controlling solidification behavior.

}, keywords = {Additive manufacturing, Microstructure, Solidification, Tomography}, isbn = {9783030518349}, doi = {10.1007/978-3-030-51834-9}, url = {http://dx.doi.org/10.1007/978-3-030-51834-9_65}, author = {Polonsky, Andrew T. and Raghavan, Narendran and Echlin, Mclean P. and Kirka, Michael M. and Dehoff, Ryan R. and Pollock, Tresa M.}, editor = {Tin, Sammy and Hardy, Mark and Clews, Justin and Cormier, Jonathan and Feng, Qiang and Marcin, John and O{\textquoteright}Brien, Chris and Suzuki, Akane} } @conference {1611, title = {Creep, Fatigue, and Oxidation Interactions During High and Very High Cycle Fatigue at Elevated Temperature of Nickel-Based Single Crystal Superalloys}, booktitle = {Superalloys 2020}, year = {2020}, abstract = {

High-temperature fatigue of Ni-based single crystal superalloys is studied at 1000 \°C in a wide range of loading conditions (\−1 ? R ? 0.8) and number of cycles (103 \− 109). Under fully reversed conditions, a competition between crack initiations from the surface\— assisted by oxidation\—and from internal metallurgical defects\—mostly large casting pores\—is observed. Increasing the testing frequency shifts the competition to a higher number of cycles. Conversely, decreasing the casting pore size or coating the specimen promotes surface initiations. When a positive mean stress is added (R ? 0), a creep deformation/damage mechanism mainly controls fatigue life, despite fracture surfaces presenting a variety of initiation types. Fatigue life can be predicted by a simple creep law if the contribution of the alternating stress is considered. A linear damage summation method that considers pure fatigue and pure creep damage is used to predict the fatigue lives, and Haigh diagrams for different alloys are presented.

}, keywords = {Creep, fatigue, High temperature, Superalloy}, isbn = {9783030518349}, doi = {10.1007/978-3-030-51834-9}, url = {http://dx.doi.org/10.1007/978-3-030-51834-9_65}, author = {Cervellon, A. and Yi, J. Z. and Corpace, F. and Hervier, Z. and Rigney, J. and Wright, P. K. and Torbet, C. J. and Cormier, J. and Jones, J. W. and Pollock, T. M.}, editor = {Tin, Sammy and Hardy, Mark and Clews, Justin and Cormier, Jonathan and Feng, Qiang and Marcin, John and O{\textquoteright}Brien, Chris and Suzuki, Akane} } @article {1571, title = {Design of Nickel-Cobalt-Ruthenium Multi-Principal Element Alloys}, journal = {Acta Materialia}, year = {2020}, pages = {16013}, keywords = {Alloy design, Density functional theory, High Entropy Alloys, planar fault energies, TRIP, TWIP}, issn = {1359-6454}, doi = {10.1016/j.actamat.2020.05.003}, url = {https://doi.org/10.1016/j.actamat.2020.05.003}, author = {Charpagne, M A and Vamsi, K V and Eggeler, Y M and Murray, S P and Frey, C and Kolli, S K and Pollock, T M} } @article {1651, title = {Expanded dataset of mechanical properties and observed phases of multi-principal element alloys}, journal = {Scientific Data}, volume = {7}, year = {2020}, pages = {1{\textendash}6}, abstract = {

This data article presents a compilation of mechanical properties of 630 multi-principal element alloys\ (MPEAs). Built upon recently published MPEA databases, this article includes updated records from previous reviews (with minor error corrections) along with new data from articles that were published since 2019. The extracted properties include reported composition, processing method, microstructure, density, hardness, yield strength, ultimate tensile strength (or maximum compression strength), elongation (or maximum compression strain), and Young\&$\#$39;s modulus. Additionally, descriptors (e.g. grain size) not included in previous reviews were also extracted for articles that reported them. The database is hosted and continually updated on an open data platform, Citrination. To promote interpretation, some data are graphically presented.

}, issn = {20524463}, doi = {10.1038/s41597-020-00768-9}, author = {Borg, Christopher K.H. and Frey, Carolina and Moh, Jasper and Pollock, Tresa M. and Gorsse, St{\'e}phane and Miracle, Daniel B. and Senkov, Oleg N. and Meredig, Bryce and Saal, James E.} } @conference {1591, title = {Microstructure and Tensile Properties of a CoNi-Based Superalloy Fabricated by Selective Electron Beam Melting}, booktitle = {Superalloys 2020}, year = {2020}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, abstract = {

Successful application of selective electron beam melting to a novel CoNi-based superalloy named SB-CoNi-10 is demonstrated. Crack-free as-printed microstructures exhibit excellent ductilities above 30\% and ultimate tensile strengths above 1.1 GPa at room temperature in tension. Conventional post-processing consisting of a super-solvus hot isostatic pressing (HIP), a solution heat treatment (SHT), and a low-temperature aging has been applied to remove microstructural inhomogeneities present in the as-printed microstructure. The microstructures of the as-printed and HIP+SHT+Aged alloys have been investigated to determine the effect of post-processing heat treatments on the nanoscale \γ/\γ\&$\#$39; microstructure and the mesoscale grain structure. Tensile tests have been conducted at room temperature and elevated temperatures above 850 {\textopenbullet}C to investigate mechanical properties in both the as-printed and HIP+SHT+Aged conditions. The high- temperature ductility and strength are strongly affected by the microstructure, with a mostly columnar-grained microstructure in the as-printed condition exhibiting superior ductility to the fully recrystallized microstructure in the HIP+SHT+Aged condition.

}, keywords = {Additive manufacturing, CoNi-based superalloys, Mechanical properties}, isbn = {9783030518349}, doi = {10.1007/978-3-030-51834-9}, url = {http://dx.doi.org/10.1007/978-3-030-51834-9_65}, author = {Murray, Sean P. and Pusch, Kira M. and Polonsky, Andrew T. and Torbet, Chris J. and Seward, Gareth G. E. and Nandwana, Peeyush and Kirka, Michael M. and Dehoff, Ryan R. and Zhou, Ning and Forsik, St{\'e}phane A. J. and Slye, William and Pollock, Tresa M.}, editor = {Tin, Sammy and Hardy, Mark and Clews, Justin and Cormier, Jonathan and Feng, Qiang and Marcin, John and O{\textquoteright}Brien, Chris and Suzuki, Akane} } @conference {1606, title = {Role of Non-metallic Inclusions and Twins on the Variability in Fatigue Life in Alloy 718 Nickel Base Superalloy}, booktitle = {Superalloys 2020}, year = {2020}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, abstract = {

Non-metallic inclusions (NMIs) and slip bands parallel to and slightly offset from twin boundaries are observed to be preferential sites for fatigue crack nucleation in wrought superalloys. Potential interactions between NMI cracking and slip activity within neighboring grains or at twin boundaries were investigated under monotonic tensile loading (up to 1.3\% total strain) at room temper- ature. High resolution- and Heaviside-digital image correlation measurements were performed during inter- rupted tensile loading to identify strain localization, associated slip systems, and damage initiation. Different mechanisms and scenarios were identified: (1) Microplas- ticity generally starts at twin boundaries even at stresses as low as 70\% of the macroscopic yield strength, (2) transgranular slip activity intensively develops above the macroscopic yield stress, (3) intense slip activity develops near and parallel to 21\% of the twin boundaries intercepting NMIs, (4) 7\% of the twin boundaries inter- cepting NMIs lead to slip-assisted NMI cracking, (5) no transgranular slip activity participates in NMI cracking, (6) the fraction of cracked NMIs progressively increases with the load, and (7) within the NMIs that initiated cracks, 67\% cracked below 90\% of the macroscopic yield strength without the presence of slip activity in the neighboring grains. While slip-assisted NMI cracking was evidenced in the present study, most NMI cracking is due to strain incompatibility between NMIs and neighboring grains at the high end of the elastic regime without slip interaction.

}, keywords = {fatigue, High Resolution-Digital Image Correlation (HR-DIC), In-situ tensile testing, Non-metallic inclusions (NMIs), Twin boundary}, isbn = {9783030518349}, doi = {10.1007/978-3-030-51834-9}, url = {http://dx.doi.org/10.1007/978-3-030-51834-9_65}, author = {Texier, Damien and Stinville, Jean-Charles and Charpagne, Marie-agathe and Chen, Zhe and Valle, Valery and Villechaise, Patrick and Pollock, Tresa M. and Cormier, Jonathan}, editor = {Tin, Sammy and Hardy, Mark and Clews, Justin and Cormier, Jonathan and Feng, Qiang and Marcin, John and O{\textquoteright}Brien, Chris and Suzuki, Akane} } @conference {1616, title = {Tuning Strain Localization in Polycrystalline Nickel-Based Superalloys by Thermomechanical Processing}, booktitle = {Superalloys 2020}, year = {2020}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, abstract = {

Thermomechanical processing routes are used to produce microstructures that minimize plastic strain localization at the sub-grain scale in a polycrystalline \γ \− \γ\&$\#$39; nickel- based superalloy. This novel approach is made possible by the use of innovative experimental tools and statistical data analysis that capture slip events over large represen- tative fields of view. Results are correlated to conventional observations of fatigue crack initiation and early stage of propagation. The effect of coherent twin boundaries and primary \γ\&$\#$39; precipitates on fatigue properties and plastic localization is detailed.

}, keywords = {3D microstructure, Annealing twin boundaries, Nickel-based superalloy, Primary γ{\textquoteright} precipitates, Slip bands}, isbn = {9783030518349}, doi = {10.1007/978-3-030-51834-9}, url = {http://dx.doi.org/10.1007/978-3-030-51834-9_65}, author = {Charpagne, M. A. and Stinville, J. C. and Polonsky, A. T. and Echlin, M. P. and Murray, S. P. and Chen, Z. and Bozzolo, N. and Cormier, J. and Valle, V. and Pollock, T. M.}, editor = {Tin, Sammy and Hardy, Mark and Clews, Justin and Cormier, Jonathan and Feng, Qiang and Marcin, John and O{\textquoteright}Brien, Chris and Suzuki, Akane} } @conference {1601, title = {The Yield Strength Anomaly in Co-Ni Design Space}, booktitle = {Superalloys 2020}, year = {2020}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, abstract = {

A new computational approach to model precipitate compositions and properties in the CoNi-design space for yield strength anomaly prediction is presented. The antiphase boundary (APB) energies on {111} and {010} and the degree of elastic anisotropy are known to influence the yield strength anomaly. APB energies were estimated by a diffuse multi-layer fault (DMLF) model using the structural energies of proximate structures: L12, ca\′, and D023. The elastic moduli were calculated via the energy-strain approach using density functional theory calculations. (Ni1\−xCox)3(Al1\−yWy) was chosen as the model system, and Yoo\&$\#$39;s criterion is evaluated over the entire range ofcompositions to identify regions that exhibit the yield strength anomaly. (Ni0.65Co0.35)3(Al0.5W0.5) has the maximum APB (111) and any two-phase alloy (c + c') in Ni\–Co\–Al\–W system with this precipitate composition might exhibit higher strength upon shearing by a matrix dislocation. ThermoCalc was employed to identify stable L12 regions in (Ni1\−xCox)3(Al1\−yWy). The effect of Co on the yield strength anomaly was investigated experimen- tally in three (Ni1\−xCox)3Al alloys with L12 structure. All three alloys exhibited the yield strength anomaly, validat- ing the computational approach. The addition of Co provides solid solution strengthening to Ni3Al at room temperature; however, this contribution to the overall strength diminished as a function of temperature. CoNi-alloys displayed strengths similar to Ni3Al at elevated temperatures with Co addition resulting in a marginal increase in strength at the peak temperature. The present study elucidates that APB energies from a DMLF model combined with elastic moduli can be employed to predict yield strength anomaly using Yoo\&$\#$39;s criteria.

}, keywords = {Antiphase boundaries, CoNi-based superalloys, Yield strength anomaly}, isbn = {9783030518349}, doi = {10.1007/978-3-030-51834-9}, url = {http://dx.doi.org/10.1007/978-3-030-51834-9_65}, author = {Vamsi, K. V. and Murray, Sean P. and Pollock, Tresa M.}, editor = {Tin, Sammy and Hardy, Mark and Clews, Justin and Cormier, Jonathan and Feng, Qiang and Marcin, John and O{\textquoteright}Brien, Chris and Suzuki, Akane} } @article {1521, title = {New frontiers for the materials genome initiative}, journal = {npj Computational Materials}, volume = {5}, year = {2019}, pages = {1{\textendash}23}, abstract = {

The Materials Genome Initiative (MGI) advanced a new paradigm for materials discovery and design, namely that the pace of new materials deployment could be accelerated through complementary efforts in theory, computation, and experiment. Along with numerous successes, new challenges are inviting researchers to refocus the efforts and approaches that were originally inspired by the MGI. In May 2017, the National Science Foundation sponsored the workshop \“Advancing and Accelerating Materials Innovation Through the Synergistic Interaction among Computation, Experiment, and Theory: Opening New Frontiers\” to review accomplishments that emerged from investments in science and infrastructure under the MGI, identify scientific opportunities in this new environment, examine how to effectively utilize new materials innovation infrastructure, and discuss challenges in achieving accelerated materials research through the seamless integration of experiment, computation, and theory. This article summarizes key findings from the workshop and provides perspectives that aim to guide the direction of future materials research and its translation into societal impacts.

}, issn = {20573960}, doi = {10.1038/s41524-019-0173-4}, url = {http://dx.doi.org/10.1038/s41524-019-0173-4}, author = {de Pablo, Juan J. and Jackson, Nicholas E. and Webb, Michael A. and Chen, Long Qing and Moore, Joel E. and Morgan, Dane and Jacobs, Ryan and Pollock, Tresa and Schlom, Darrell G. and Toberer, Eric S. and Analytis, James and Dabo, Ismaila and DeLongchamp, Dean M. and Fiete, Gregory A. and Grason, Gregory M. and Hautier, Geoffroy and Mo, Yifei and Rajan, Krishna and Reed, Evan J. and Rodriguez, Efrain and Stevanovic, Vladan and Suntivich, Jin and Thornton, Katsuyo and Zhao, Ji Cheng} } @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 {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 {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 {1256, title = {Modelling the elastic properties of bi-continuous composite microstructures captured with TriBeam serial-sectioning}, journal = {Computational Materials Science}, volume = {131}, year = {2017}, pages = {187{\textendash}195}, doi = {10.1016/j.commatsci.2017.01.026}, author = {Mignone, Paul J. and Echlin, Mclean P. and Pollock, Tresa M. and Finlayson, Trevor R. and Riley, Daniel P. and Sesso, Mitchell L. and Franks, George V.} } @article {pebley2016exchange, title = {Exchange bias and spin glass behavior in biphasic NiFe 2 O 4/NiO thin films}, journal = {Journal of Magnetism and Magnetic Materials}, year = {2016}, publisher = {North-Holland}, author = {Pebley, Andrew C and Fuks, Preston E and Pollock, Tresa M and Gordon, Michael J} } @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 {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 {texier2016microstructural, title = {Microstructural features controlling the variability in low-cycle fatigue properties of alloy Inconel 718DA at intermediate temperature}, journal = {Metallurgical and Materials Transactions A}, volume = {47}, number = {3}, year = {2016}, pages = {1096{\textendash}1109}, publisher = {Springer US}, author = {Texier, Damien and G{\'o}mez, Ana Casanova and Pierret, St{\'e}phane and Franchet, Jean-Michel and Pollock, Tresa M and Villechaise, Patrick and Cormier, Jonathan} } @article {echlin2015tribeam, title = {The TriBeam system: Femtosecond laser ablation in situ SEM}, journal = {Materials Characterization}, volume = {100}, year = {2015}, pages = {1{\textendash}12}, publisher = {Elsevier}, author = {Echlin, McLean P and Straw, Marcus and Randolph, Steven and Filevich, Jorge and Pollock, Tresa M} } @article {echlin2014three, title = {Three-dimensional characterization of the permeability of W{\textendash}Cu composites using a new {\textquotedblleft}TriBeam{\textquotedblright} technique}, journal = {Acta Materialia}, volume = {64}, year = {2014}, pages = {307{\textendash}315}, publisher = {Pergamon}, author = {Echlin, McLean P and Mottura, Alessandro and Wang, Michael and Mignone, Paul J and Riley, Daniel P and Franks, George V and Pollock, Tresa M} } @conference {white2009time, title = {TIME DOMAIN TERAHERTZ NON-DESTRUCTIVE EVALUATION OF AEROTURBINE BLADE THERMAL BARRIER COATINGS}, booktitle = {REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION: Proceedings of the 35th Annual Review of Progress in Quantitative Nondestructive Evaluation}, volume = {1096}, number = {1}, year = {2009}, pages = {434{\textendash}439}, publisher = {AIP Publishing}, organization = {AIP Publishing}, author = {White, Jeffrey and Fichter, G and Chernovsky, A and Whitaker, John F and Das, D and Pollock, Tresa M and Zimdars, David} } @article {carroll2008interfacial, title = {Interfacial Dislocation Networks and creep in directional coarsened Ru-containing nickel-base single-crystal superalloys}, journal = {Metallurgical and Materials Transactions A}, volume = {39}, number = {6}, year = {2008}, pages = {1290{\textendash}1307}, publisher = {Springer US}, author = {Carroll, LJ and Feng, Q and Pollock, TM} } @conference {white2008time, title = {Time-domain terahertz mapping of thickness and degradation of aircraft turbine blade thermal barrier coatings}, booktitle = {Conference on Lasers and Electro-Optics}, year = {2008}, pages = {CThN7}, publisher = {Optical Society of America}, organization = {Optical Society of America}, author = {White, Jeffrey and Fichter, G and Chernovsky, A and Zimdars, David A and Whitaker, John F and Das, D and Pollock, Tresa M} } @article {feng2007cyclic, title = {Cyclic oxidation of Ru-containing single crystal superalloys at 1100 C}, journal = {Materials Science and Engineering: A}, volume = {458}, number = {1}, year = {2007}, pages = {184{\textendash}194}, publisher = {Elsevier}, author = {Feng, Q and Tryon, B and Carroll, LJ and Pollock, TM} } @article {carroll2007elemental, title = {Elemental partitioning in Ru-containing nickel-base single crystal superalloys}, journal = {Materials Science and Engineering: A}, volume = {457}, number = {1}, year = {2007}, pages = {292{\textendash}299}, publisher = {Elsevier}, author = {Carroll, LJ and Feng, Q and Mansfield, JF and Pollock, TM} } @conference {wang2007influence, title = {Influence of Ru and Cr on the heat-treated microstructure of Ni-based superalloys}, booktitle = {Materials science forum}, volume = {546}, year = {2007}, pages = {1207{\textendash}1210}, publisher = {Trans Tech Publications}, organization = {Trans Tech Publications}, author = {Wang, WB and Feng, Qiang and Carroll, LJ and Wang, YL and Chen, Guo Liang and Pollock, TM} } @article {yi2007ultrasonic, title = {Ultrasonic fatigue of a single crystal Ni-base superalloy at 1000 C}, journal = {Materials Science and Engineering: A}, volume = {443}, number = {1}, year = {2007}, pages = {142{\textendash}149}, publisher = {Elsevier}, author = {Yi, JZ and Torbet, CJ and Feng, Q and Pollock, TM and Jones, JW} } @article {feng2006femtosecond, title = {Femtosecond laser machining of single-crystal superalloys through thermal barrier coatings}, journal = {Materials Science and Engineering: A}, volume = {430}, number = {1}, year = {2006}, pages = {203{\textendash}207}, publisher = {Elsevier}, author = {Feng, Q and Picard, YN and McDonald, JP and Van Rompay, PA and Yalisove, SM and Pollock, TM} } @article {carroll2006high, title = {High refractory, low misfit Ru-containing single-crystal superalloys}, journal = {Metallurgical and Materials Transactions A}, volume = {37}, number = {10}, year = {2006}, pages = {2927{\textendash}2938}, publisher = {Springer}, author = {Carroll, LJ and Feng, Q and Mansfield, JF 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 {feng2006soldification, title = {Soldification segregation in ruthenium-containing nickel-base superalloys}, journal = {Metallurgical and Materials Transactions A}, volume = {37}, number = {6}, year = {2006}, pages = {1949{\textendash}1962}, publisher = {Springer-Verlag}, author = {Feng, Q and Carroll, LJ 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 {feng2005new, title = {New phases in a multicomponent high ruthenium single crystal superalloy}, booktitle = {Materials Science Forum}, volume = {475}, year = {2005}, pages = {655{\textendash}660}, publisher = {Trans Tech Publications}, organization = {Trans Tech Publications}, author = {Feng, Q and Rowland, LJ and Pollock, TM} } @article {feng2004deformation, title = {Deformation of Ru{\textendash}Al{\textendash}Ta ternary alloys}, journal = {Intermetallics}, volume = {12}, number = {7}, year = {2004}, pages = {755{\textendash}762}, publisher = {Elsevier}, author = {Feng, Q and Nandy, TK and Tryon, B and Pollock, TM} } @article {tryon2004intermetallic, title = {Intermetallic phases formed by ruthenium{\textendash}nickel alloy interdiffusion}, journal = {Intermetallics}, volume = {12}, number = {7}, year = {2004}, pages = {957{\textendash}962}, publisher = {Elsevier}, author = {Tryon, B and Feng, Q and Pollock, T} } @conference {feng2004new, title = {New Phases in Ruthenium-Containing Single-Crystal Superalloys}, booktitle = {Superalloys 2004: The Tenth International Symposium on Superalloys}, year = {2004}, pages = {769{\textendash}778}, author = {Feng, Q and Nandy, TK and Rowland, LJ and Tryon, B and Banerjee, D and Pollock, TM} } @article {feng2004observation, title = {Observation of a Ru-rich Heusler phase in a multicomponent Ni-base superalloy}, journal = {Scripta materialia}, volume = {50}, number = {6}, year = {2004}, pages = {849{\textendash}854}, publisher = {Elsevier}, author = {Feng, Q and Nandy, TK and Pollock, TM} } @article {feng2004re, title = {The Re (Ru)-rich $δ$-phase in Ru-containing superalloys}, journal = {Materials Science and Engineering: A}, volume = {373}, number = {1}, year = {2004}, pages = {239{\textendash}249}, publisher = {Elsevier}, author = {Feng, Q and Nandy, TK and Pollock, TM} } @article {nandy2003deformation, title = {Deformation of a platinum-containing RuAl intermetallic by< 111> dislocations}, journal = {Scripta materialia}, volume = {48}, number = {8}, year = {2003}, pages = {1087{\textendash}1092}, publisher = {Elsevier}, author = {Nandy, TK and Feng, Q and Pollock, TM} } @article {nandy2003elevated, title = {Elevated temperature deformation and dynamic strain aging in polycrystalline RuAl alloys}, journal = {Intermetallics}, volume = {11}, number = {10}, year = {2003}, pages = {1029{\textendash}1038}, publisher = {Elsevier}, author = {Nandy, TK and Feng, Q and Pollock, TM} } @conference {nandy2003mechanical, title = {Mechanical Behavior of Ternary and Quaternary RuAl Alloys}, booktitle = {MATERIALS RESEARCH SOCIETY SYMPOSIUM PROCEEDINGS}, volume = {753}, year = {2003}, pages = {89{\textendash}96}, publisher = {Cambridge Univ Press}, organization = {Cambridge Univ Press}, author = {Nandy, TK and Feng, Q and Banerjee, D and Gigliotti, MFX and Pollock, TM} } @article {feng2003solidification, title = {Solidification of high-refractory ruthenium-containing superalloys}, journal = {Acta Materialia}, volume = {51}, number = {1}, year = {2003}, pages = {269{\textendash}284}, publisher = {Elsevier}, author = {Feng, Q and Nandy, TK and Tin, S and Pollock, TM} } @article {pollock2002dislocations, title = {Dislocations and high-temperature plastic deformation of superalloy single crystals}, journal = {Dislocations in solids}, volume = {11}, year = {2002}, pages = {547{\textendash}618}, publisher = {Elsevier}, author = {Pollock, TM and Field, RD} } @conference {nandy2002mechanical, title = {Mechanical Behavior of Ternary and Quaternary Rual Alloys}, booktitle = {MRS Proceedings}, volume = {753}, year = {2002}, pages = {BB2{\textendash}11}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, author = {Nandy, TK and Feng, Q and Banerjee, D and Gigliotti, MFX and Pollock, TM} } @article {fahrmann1999determination, title = {Determination of matrix and precipitate elastic constants in ($\gamma${\textendash}$\gamma$') Ni-base model alloys, and their relevance to rafting}, journal = {Materials Science and Engineering: A}, volume = {260}, number = {1}, year = {1999}, pages = {212{\textendash}221}, publisher = {Elsevier}, author = {F{\"a}hrmann, M and Hermann, W and F{\"a}hrmann, E and Boegli, A and Pollock, TM and Sockel, HG} } @article {paris1997early, title = {Early stages of precipitate rafting in a single crystal Ni Al Mo model alloy investigated by small-angle X-ray scattering and TEM}, journal = {Acta materialia}, volume = {45}, number = {3}, year = {1997}, pages = {1085{\textendash}1097}, publisher = {Pergamon}, author = {Paris, O and Fa, M and Fa, E and Pollock, TM and Fratzl, P and others} } @article {fahrmann1997element, title = {Element partitioning during coarsening of ($\gamma$- $\gamma$') Ni-Al-Mo alloys}, journal = {Metallurgical and Materials Transactions A}, volume = {28}, number = {9}, year = {1997}, pages = {1943{\textendash}1945}, publisher = {Springer}, author = {F{\"a}hrmann, M and F{\"a}hrmann, E and Pollock, TM and Johnson, WC} } @article {faehrmann1997element, title = {Element partitioning during coarsening of ($\{$gamma$\}$$\{$minus$\}$$\{$gamma$\}$$\{$prime$\}$) Ni-Al-Mo alloys}, journal = {Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science}, volume = {28}, number = {9}, year = {1997}, author = {Faehrmann, M and Faehrmann, E and Pollock, TM and Johnson, WC} } @article {fahrmann1996experimental, title = {An experimental study of the role of plasticity in the rafting kinetics of a single crystal Ni-base superalloy}, year = {1996}, author = {F{\"a}hrmann, M and F{\"a}hrmann, E and Paris, O and Fratzl, P and Pollock, TM} } @article {fahrmann1996influence, title = {The influence of microstructure on the measurement of $\gamma$-$\gamma$' lattice mismatch in single-crystal Ni-base superalloys}, journal = {Materials Science and Engineering: A}, volume = {210}, number = {1}, year = {1996}, pages = {8{\textendash}15}, publisher = {Elsevier}, author = {F{\"a}hrmann, M and Wolf, JG and Pollock, TM} } @article {fahrmann1996influence, title = {The influence of microstructure on the measurement of yy{\textquoteright}lattice mismatch in single-crystal Ni-base superalloys}, journal = {Materials Science \& Engineering A}, volume = {1}, number = {210}, year = {1996}, pages = {8{\textendash}15}, author = {F{\"a}hrmann, M and Wolf, JG and Pollock, TM} } @article {field1992development, title = {The Development of gamma/ gamma Interfacial Dislocation Networks During Creep in Nickel-Base Superalloys}, journal = {Superalloys 1992}, year = {1992}, pages = {557{\textendash}566}, author = {Field, RD and Pollock, TM and Murphy, WH} }