@article {2431, title = {Detection and classification of cracking via acoustic emission during laser-melting screening for additive manufacturing}, journal = {JOM (1989)}, volume = {77}, year = {2025}, pages = {7274{\textendash}7286}, author = {Raeker, Evan B and Tulshibagwale, Nikhil and Mullin, Kaitlyn M and Lamb, James D and Pollock, Tresa M} } @article {2376, title = {Non-destructive evaluation of bulk metallic glass components using resonance ultrasound spectroscopy}, journal = {Appl. Mater. Today}, volume = {42}, year = {2025}, pages = {102529}, author = {Kube, Sebastian A and Bordeenithikasem, Punnathat and Ziemke, Patrick and Lamb, James and Rossin, Jeff and Torbet, Chris and Begley, Matthew R and Dillon, R Peter and Pollock, Tresa M} } @inbook {2336, title = {3D characterization of defects and microstructure in high density LPBF prints of a CoNi alloy}, booktitle = {The Minerals, Metals \& Materials Series}, series = {The minerals, metals \& materials series}, year = {2024}, pages = {811{\textendash}821}, publisher = {Springer Nature Switzerland}, organization = {Springer Nature Switzerland}, address = {Cham}, author = {Lamb, James D and Raeker, Evan B and Pusch, Kira M and Echlin, McLean P and Forsik, Stephane A J and Zhou, Ning and Dicus, Austin D and Pollock, Tresa M} } @article {2286, title = {Deformation mechanisms and defect structures in Heusler intermetallic MnCu2Al}, journal = {Acta Mater.}, volume = {268}, year = {2024}, pages = {119711}, author = {Rhodes, Bailey E and Mayer, Justin A and Xu, Shuozhi and Lamb, James D and Wendorf, Joe and Echlin, McLean P and Pollock, Tresa M and Eggeler, Yolita M and Beyerlein, Irene J and Gianola, Daniel S} } @inbook {2331, title = {Solidification and crack defect formation on the single melt track scale for high $$\textbackslashupgamma ^\textbackslashprime $$ CoNi-base superalloy variants}, booktitle = {The Minerals, Metals \& Materials Series}, series = {The minerals, metals \& materials series}, year = {2024}, pages = {948{\textendash}957}, publisher = {Springer Nature Switzerland}, organization = {Springer Nature Switzerland}, address = {Cham}, author = {Raeker, Evan B and Pusch, Kira M and Mullin, Kaitlyn M and Lamb, James D and Zhou, Ning and Forsik, Stephane A J and Dicus, Austin D and Kirka, Michael M and Pollock, Tresa M} } @article {2276, title = {Solute-solute interactions in dilute Nb-X-O alloys from first principles}, journal = {Acta Mater.}, volume = {266}, year = {2024}, pages = {119621}, author = {Reynolds, Colleen and Pollock, Tresa M and Van der Ven, Anton} } @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 {2271, title = {Transpiration cooling of a porous Nb-based alloy in high heat flux conditions}, journal = {Int. J. Therm. Sci.}, volume = {196}, year = {2024}, pages = {108758}, author = {Mullin, Kaitlyn M and Martin, John H and Roper, Christopher S and Levi, Carlos G and Pollock, Tresa M} } @article {2321, title = {Understanding the influence of boron in additively manufactured GammaPrint\textregistered-700 CoNi-based superalloy}, journal = {Addit. Manuf.}, volume = {92}, year = {2024}, pages = {104370}, author = {Ren, Qing-Qiang and Raeker, Evan B and Pusch, Kira M and Pollock, Tresa M and Forsik, Stephane A J and Zhou, Ning and Dicus, Austin D and Kirka, Michael M and Poplawsky, Jonathan D} } @article {1871, title = {Decoupling build orientation-induced geometric and texture effects on the mechanical response of additively manufactured IN625 thin-walled elements}, journal = {Materials Science and Engineering: A}, volume = {870}, year = {2023}, month = {02}, pages = {144826}, doi = {10.1016/j.msea.2023.144826}, author = {Banerjee, Arunima and Rossin, Jeff and He, Mo-Rigen and Musinski, William and Shade, Paul and Cox, Marie and Schwalbach, Edwin and Pollock, Tresa and Hemker, K.} } @article {1846, title = {Inducing skyrmion flop transitions in Co 8 Zn 8 Mn 4 at room temperature}, journal = {Physical Review Materials}, volume = {7}, year = {2023}, month = {04}, doi = {10.1103/PhysRevMaterials.7.044401}, author = {Meynell, Simon and Eggeler, Yolita and Bocarsly, Joshua and Kitchaev, Daniil and Rhodes, Bailey and Pollock, Tresa and Wilson, Stephen and Ven, Anton and Seshadri, Ram and Graef, Marc and Jayich, Ania and Gianola, Daniel} } @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 {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 {1851, title = {Perspective: Machine learning in experimental solid mechanics}, journal = {Journal of the Mechanics and Physics of Solids}, volume = {173}, year = {2023}, month = {04}, pages = {105231}, doi = {10.1016/j.jmps.2023.105231}, author = {Brodnik, N.R. and Muir, C. and Tulshibagwale, N. and Rossin, J. and Echlin, M.P. and Hamel, C.M. and Kramer, S.L.B. and Pollock, T.m. and Kiser, J.D. and Smith, C. and Daly, S.H.} } @article {1986, title = {Boundary characterization using 3D mapping of geometrically necessary dislocations in AM Ta microstructure}, journal = {Journal of Materials Science}, volume = {57}, year = {2022}, month = {06}, doi = {10.1007/s10853-022-07074-2}, author = {Witzen, Wyatt and Polonsky, Andrew and Rottmann, Paul and Pusch, Kira and Echlin, Mclean and Pollock, Tresa and Beyerlein, Irene} } @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 {1931, title = {Materials for extreme environments}, journal = {Nature Reviews Materials}, volume = {8}, year = {2022}, month = {11}, doi = {10.1038/s41578-022-00496-z}, author = {Eswarappa Prameela, Suhas and Pollock, Tresa and Raabe, Dierk and Meyers, Marc and Aitkaliyeva, Assel and Chintersingh, Kerri-Lee and Cordero, Zachary and Graham-Brady, Lori} } @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 {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 {1991, title = {Scan strategies in EBM-printed IN718 and the physics of bulk 3D microstructure development}, journal = {Materials Characterization}, volume = {190}, year = {2022}, month = {06}, pages = {112043}, doi = {10.1016/j.matchar.2022.112043}, author = {Polonsky, Andrew and Raghavan, Narendran and Echlin, Mclean and Kirka, M. and Dehoff, Ryan 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} } @conference {2061, title = {3D Characterization of the Columnar-to-Equiaxed Transition in Additively Manufactured Inconel 718.}, year = {2021}, month = {09}, doi = {10.2172/1886524}, author = {Polonsky, Andrew and Raghavan, Narendran and Echlin, Mclean and Kirka, Michael and Dehoff, Ryan 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 {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 {2151, title = {Rejuvenation of Directionally Solidified and Single-Crystal Nickel-Base Superalloys}, journal = {Metallurgical and Materials Transactions A}, volume = {52}, year = {2021}, month = {03}, doi = {10.1007/s11661-021-06150-7}, author = {Rettberg, Luke and Callahan, P. and Goodlet, Brent and Pollock, T.} } @article {1671, title = {Temperature dependence of single crystal elastic constants in a CoNi-Base alloy: A new methodology}, journal = {Materials Science and Engineering A}, volume = {803}, year = {2021}, pages = {140507}, abstract = {

A novel experimental setup combining induction heating, contactless (infrared thermometer) temperature measurements, and custom 15 cm length SiC-tipped piezoelectric transducers has been developed to rapidly collect resonant ultrasound spectroscopy (RUS) data from metallic rectangular parallelepiped (RP) specimens heated in air. This setup is used to collect over 70 of the lowest-frequency resonance modes from a single crystal of the novel CoNi-based superalloy SB-CoNi-10+\—an alloy identified for further study due to a promising set of high temperature properties. RUS spectra from room temperature (RT) to 927 \°C (1200 K) along with dilatometry measurements of the thermal expansion behavior are supplied to a robust, open-sourced, Bayesian inference code for simultaneous estimation of: three single crystal elastic constants, three crystal axis misorientation parameters, and a noise parameter. This study is the first application of the Bayesian RUS methodology at elevated temperatures, and the first to characterize SB-CoNi-10+. A monotonic decrease in elastic constants (C11,C12,C44) from (236.4, 150.8, 134.1) GPa to (190.7, 138.1, 95.2) GPa and a 15\% increase in elastic anisotropy from A = 3.131 \→ 3.618 is observed upon heating from RT to 927 \°C, with an increased rate of softening above 600 \°C (873 K).

}, keywords = {Bayesian inference, Elastic constants, High-temperature, Resonant ultrasound spectroscopy, Single crystal, Superalloy}, issn = {09215093}, doi = {10.1016/j.msea.2020.140507}, url = {https://doi.org/10.1016/j.msea.2020.140507}, author = {Goodlet, Brent R. and Murray, Sean P. and Bales, Ben and Rossin, Jeff and Torbet, Chris J. and Pollock, Tresa M.} } @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} } @article {1806, title = {Assessment of grain structure evolution with resonant ultrasound spectroscopy in additively manufactured nickel alloys}, journal = {Materials Characterization}, volume = {167}, year = {2020}, pages = {110501}, abstract = {

Despite the advantages of metal additive manufacturing (AM), ensuring integrity and reproducibility for built components is a barrier to the implementation of AM components in critical applications. Component qualification necessitates Non-Destructive Evaluation (NDE), but existing NDE frameworks are insufficient for the rapid and cost effective screening of variable AM components. In this study, alterations in laser powder bed fusion (LPBF) AM process parameters were characterized using resonant ultrasound spectroscopy (RUS). Samples that were subjected to a Hot Isostatic Press (HIP) and Heat Treatment (HT) post-processing step exhibited changes in resonance frequencies that varied in magnitude and direction with the type of resonance mode. The initial build direction prior to HIP and HT had a negligible effect on resonant frequency changes after recrystallization. The change in resonant frequencies at each process condition was predicted using Finite Element Modeling (FEM) informed with Electron Backscatter Diffraction (EBSD) data. FEM identified that the experimentally measured change in resonant response between the initially textured state and the recrystallized state was dominated by grain orientation dependent changes in elasticity. The EBSD-estimated elastic constants and FEM results were validated using experimental laser vibrometry and RUS inversion of elastic constants. RUS Inversion by Bayesian inference and Hamiltonian Monte Carlo has not been used to characterize an AM nickel-base alloy prior to this work. These results demonstrate that RUS is capable of detecting part to part microstructure variability between built AM components.

}, keywords = {Additive manufacturing, Bayesian inference, Elastic constant inversion, Finite element modeling, Recrystallization, Resonance ultrasound spectroscopy}, issn = {1044-5803}, doi = {https://doi.org/10.1016/j.matchar.2020.110501}, url = {https://www.sciencedirect.com/science/article/pii/S1044580320319720}, author = {Jeff Rossin and Brent Goodlet and Chris Torbet and William Musinski and Marie Cox and Jonathan Miller and Michael Groeber and Alexander Mayes and Eric Biedermann and Stephen Smith and Samantha Daly and Tresa Pollock} } @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 {1341, title = {Low Cycle Fatigue of Single Crystal γ'-containing Co-based Superalloys at 750 {\textdegree}C}, journal = {Metallurgical and Materials Transactions A}, volume = {51}, year = {2020}, pages = {200{\textendash}213}, abstract = {

A new class of \γ\′-containing Co-based superalloys that are promising for high temperature applications has been investigated under cyclic loading conditions. A series of single crystal variants of these Co-based superalloys have been cyclically loaded above their elastic limit at 750 \°C in air to study their behavior in the low cycle regime. Interrupted testing was performed to observe the early stages of fatigue failure. Optical microscopy, scanning electron microscopy, and transmission electron microscopy were used to characterize post-mortem specimens. Fatigue failure occurred due to surface cracks that developed during the early stages of cycling in the aluminide-coated sample gauge sections. Growth of these surface cracks into the substrate was associated with extensive oxidation and intermetallic phase precipitation, which accelerated crack propagation as compared to Ni-based superalloys. These observations suggest that improvements in the oxidation resistance and high temperature strength of \γ\′-containing Co-based superalloys will enhance their fatigue behavior.

}, issn = {1543-1940}, doi = {10.1007/s11661-019-05508-2}, url = {https://doi.org/10.1007/s11661-019-05508-2}, author = {Murray, Sean P and Stinville, Jean-Charles and Callahan, Patrick G and Rhein, Robert K and Pollock, Tresa M} } @article {1691, title = {Multiplicity of dislocation pathways in a refractory multiprincipal element alloy}, journal = {Science}, volume = {370}, year = {2020}, pages = {95{\textendash}101}, abstract = {

Refractory multiprincipal element alloys (MPEAs) are promising materials to meet the demands of aggressive structural applications, yet require fundamentally different avenues for accommodating plastic deformation in the body-centered cubic (bcc) variants of these alloys. We show a desirable combination of homogeneous plastic deformability and strength in the bcc MPEA MoNbTi, enabled by the rugged atomic environment through which dislocations must navigate. Our observations of dislocation motion and atomistic calculations unveil the unexpected dominance of nonscrew character dislocations and numerous slip planes for dislocation glide. This behavior lends credence to theories that explain the exceptional high temperature strength of similar alloys. Our results advance a defect-aware perspective to alloy design strategies for materials capable of performance across the temperature spectrum.

}, issn = {10959203}, doi = {10.1126/science.aba3722}, author = {Wang, Fulin and Balbus, Glenn H. and Xu, Shuozhi and Su, Yanqing and Shin, Jungho and Rottmann, Paul F. and Knipling, Keith E. and Stinville, Jean Charles and Mills, Leah H. and Senkov, Oleg N. and Beyerlein, Irene J. and Pollock, Tresa M. and Gianola, Daniel S.} } @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 {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 {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 {1316, title = {Creep Behavior of Quinary γ'-Strengthened Co-Based Superalloys}, journal = {Metallurgical and Materials Transactions A}, volume = {49}, year = {2018}, pages = {4090{\textendash}4098}, issn = {1073-5623}, doi = {10.1007/s11661-018-4768-z}, url = {http://link.springer.com/10.1007/s11661-018-4768-z}, author = {Rhein, Robert K. and Callahan, Patrick G. and Murray, Sean P. and Stinville, Jean-Charles and Titus, Michael S. and Van der Ven, Anton and Pollock, Tresa M.} } @article {1486, title = {Femtosecond laser rejuvenation of nanocrystalline metals}, journal = {Acta Materialia}, volume = {156}, year = {2018}, pages = {183{\textendash}195}, abstract = {

Nanocrystalline metals are distinct from traditional engineering materials due to their high concentration of grain boundaries and corresponding structural disorder at grain boundaries. The effect of local disorder in nanocrystalline materials manifests in ways reminiscent of fully amorphous materials, such as mesoscale shear localization and pressure-dependent yielding, owing to the high concentration of grain boundaries and their predominance in governing plasticity. Relaxation processes in nanocrystalline materials that facilitate reconfigurations of grain boundaries and lower their energy, such as low temperature annealing, have been shown to enhance mechanical strength. However, processes that raise the energy of a nanocrystalline metal have not been observed, limiting the tunability of properties and the prospect for suppressing shear localization. Here, we use femtosecond laser processing as a unique non-equilibrium process that can generate complex stress states due to ultrafast electronic excitation and subsequent relaxation events. Experiments on nanocrystalline Al-O and Cu-Zr alloys indicate that sub-ablation femtosecond laser pulses cause up to an 87\% reduction in hardness with no change in grain size, which can be ascribed to grain boundary-mediated processes. Parallels between our results and rejuvenation processes in glassy systems will be discussed in the context of controlling metastable structural configurations through novel processing routes.

}, keywords = {Femtosecond lasers, Grain boundaries, Nanocrystalline, Rejuvenation}, issn = {13596454}, doi = {10.1016/j.actamat.2018.06.027}, url = {https://doi.org/10.1016/j.actamat.2018.06.027}, author = {Balbus, Glenn H. and Echlin, Mclean P. and Grigorian, Charlette M. and Rupert, Timothy J. and Pollock, Tresa M. and Gianola, Daniel S.} } @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 {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 {rettberg2016detecting, title = {Detecting Recrystallization in a Single Crystal Ni-Base Alloy using Resonant Ultrasound Spectroscopy}, journal = {NDT \& E International}, year = {2016}, publisher = {Elsevier}, author = {Rettberg, LH and Goodlet, BR and Pollock, TM} } @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 {rhein2015role, title = {Role of vibrational and configurational excitations in stabilizing the L 1 2 structure in Co-rich Co-Al-W alloys}, journal = {Physical Review B}, volume = {92}, number = {17}, year = {2015}, pages = {174117}, publisher = {American Physical Society}, author = {Rhein, Robert K and Dodge, Philip C and Chen, Min-Hua and Titus, Michael S and Pollock, Tresa M and Van der Ven, Anton} } @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 {rettberg2014localized, title = {Localized recrystallization during creep in nickel-based superalloys GTD444 and Ren{\'e} N5}, journal = {Acta Materialia}, volume = {73}, year = {2014}, pages = {287{\textendash}297}, publisher = {Pergamon}, author = {Rettberg, LH and Pollock, TM} } @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} } @article {madison2012fluid, title = {Fluid flow and defect formation in the three-dimensional dendritic structure of nickel-based single crystals}, journal = {Metallurgical and Materials Transactions A}, volume = {43}, number = {1}, year = {2012}, pages = {369{\textendash}380}, publisher = {Springer}, author = {Madison, J and Spowart, JE and Rowenhorst, DJ and Aagesen, LK and Thornton, K and Pollock, TM} } @article {rettberg2012rejuvenation, title = {Rejuvenation of Nickel-Based Superalloys GTD444 (DS) and Ren{\'e} N5 (SX)}, journal = {Superalloys 2012}, year = {2012}, pages = {341{\textendash}349}, publisher = {John Wiley \& Sons, Inc.}, author = {Rettberg, LH and Tsunekane, M and Pollock, TM} } @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} } @booklet {pollock20103d, title = {3D simulations for property determination via reconstructed microstructure in nickel-base superalloys.}, year = {2010}, publisher = {Sandia National Laboratories}, author = {Pollock, Tresa M and Thornton, Katsuyo and Rowenhorst, David J and Spowart, Jonathan E and Madison, Jonathan D} } @article {madison2010modeling, title = {Modeling fluid flow in three-dimensional single crystal dendritic structures}, journal = {Acta Materialia}, volume = {58}, number = {8}, year = {2010}, pages = {2864{\textendash}2875}, publisher = {Elsevier}, author = {Madison, J and Spowart, J and Rowenhorst, D and Aagesen, LK and Thornton, K and Pollock, TM} } @booklet {madison2010permeability, title = {Permeability Determination via 3 D Reconstruction of the Mushy Zone of Nickel-Base Single Cyrstals}, 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 = {Madison, Jonathan and Spowart, Jonathan and Rowenhorst, Dave and Thornton, Katsuyo and Pollock, Tresa} } @article {madison2008three, title = {The three-dimensional reconstruction of the dendritic structure at the solid-liquid interface of a Ni-based single crystal}, journal = {JOM}, volume = {60}, number = {7}, year = {2008}, pages = {26{\textendash}30}, publisher = {Springer}, author = {Madison, J and Spowart, JE and Rowenhorst, DJ and Pollock, TM} } @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} } @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} } @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 {biery2002use, title = {Use of Weibull statistics to quantify property variability in TiAl alloys}, journal = {Metallurgical and Materials Transactions A}, volume = {33}, number = {10}, year = {2002}, pages = {3127{\textendash}3136}, publisher = {Springer}, author = {Biery, Nicholas and De Graef, Marc and Beuth, Jack and Raban, Rafel and Elliott, Andrew and Pollock, Tresa M and AUSTIN, CURT} } @article {rishel1998cast, title = {Cast structure and property variability in gamma titanium aluminides}, journal = {Intermetallics}, volume = {6}, number = {7}, year = {1998}, pages = {629{\textendash}636}, publisher = {Elsevier}, author = {Rishel, LL and Biery, NE and Raban, R and Gandelsman, VZ and Pollock, TM and Cramb, AW} } @booklet {harding1997impact, title = {Impact damage and fatigue behavior of gamma TiAl}, year = {1997}, publisher = {The Minerals, Metals and Materials Society, Warrendale, PA (United States)}, author = {Harding, TS and Jones, JW and Pollock, TM and Steif, PS and Rubal, MP} } @article {steif1997surface, title = {Surface damage due to impact and fatigue strength reduction in gamma titanium aluminides}, journal = {Minerals, Metals and Materials Society/AIME(USA),}, year = {1997}, pages = {435{\textendash}442}, author = {Steif, PS and Jones, JW and Harding, T and Rubal, MP and Gandelsman, VZ and Biery, N and Pollock, TM} } @article {walston1996renfi, title = {RENfi N6: THIRD GENERATION SINGLE CRYSTAL SUPERALLOY}, year = {1996}, author = {Walston, WS and O{\textquoteright}hara, KS and Ross, EW and Pollock, TM and Murphy, WH} } @booklet {walston1995nickel, title = {Nickel-base superalloy and article with high temperature strength and improved stability}, year = {1995}, note = {US Patent 5,455,120}, author = {Walston, William S and Ross, Earl W and Pollock, Tresa M and O{\textquoteright}hara, Kevin S and Murphy, Wendy H} }