@article {2421, title = {Coupled infrared imaging and multiphysics modeling to predict three-dimensional thermal characteristics during selective laser melting}, year = {2025}, abstract = {

Laser heating during additive manufacturing (AM) induces extreme and transient thermal conditions which critically influence the microstructure evolution and mechanical properties of the resulting component. However, accurately resolving these conditions with sufficient spatiotemporal accuracy remains a central challenge. We demonstrate a unique approach that couples high-speed infrared imaging, during selective laser melting of MAR-M247, with a transient three-dimensional (3D) multiphysics simulation to reconstruct the dynamic sub-surface temperature distribution of the melt pool. This integrated framework enables the estimation of experimentally-validated, 3D solidification conditions-including solidification velocities and cooling rates-at the solid-liquid interface while also significantly lowering computational cost. By quantifying solidification conditions, we predict variations in microstructure size and orientation driven by laser processing parameters and validate them with ex situ scanning electron microscopy and electron backscatter diffraction maps. Our findings substantiate that an integrated experimental-computational approach is crucial to realize in situ prediction and optimization of microstructures in commercial AM.

}, author = {Kumar, Vijay and Mullin, Kaitlyn M and Park, Hyunggon and Gerigk, Matthew and Bresk, Andrew and Pollock, Tresa M and Zhu, Yangying} } @article {2346, title = {Cracking and precipitation behavior of refractory BCC{\textendash}B2 alloys under laser melting conditions}, journal = {Metall. Mater. Trans. A}, volume = {55}, year = {2024}, pages = {3809{\textendash}3823}, author = {Mullin, Kaitlyn M and Kube, Sebastian A and Wu, Sophia K and Pollock, Tresa M} } @article {2101, title = {Corrigendum to {\textquotedblleft}Defects and 3D structural inhomogeneity in electron beam additively manufactured Inconel 718{\textquotedblright} [Materials Characterization 143 (2018) 171{\textendash}181]}, journal = {Materials Characterization}, volume = {176}, year = {2021}, month = {06}, pages = {111069}, doi = {10.1016/j.matchar.2021.111069}, author = {Polonsky, Andrew and Echlin, Mclean and Lenthe, William and Dehoff, Ryan and Kirka, M. and Pollock, Tresa} } @article {2081, title = {Crack initiation anisotropy of Ni-based SX superalloys in the very high cycle fatigue regime}, journal = {Materials Science and Engineering: A}, volume = {825}, year = {2021}, month = {08}, pages = {141920}, doi = {10.1016/j.msea.2021.141920}, author = {Cervellon, Alice and Torbet, Chris and Pollock, Tresa} } @article {2121, title = {Crystallography and elastic anisotropy in fatigue crack nucleation at nickel alloy twin boundaries}, journal = {Journal of the Mechanics and Physics of Solids}, volume = {155}, year = {2021}, month = {06}, pages = {104538}, doi = {10.1016/j.jmps.2021.104538}, author = {Zhang, Xiaoxian and Stinville, Jean-Charles and Pollock, Tresa and Dunne, Fionn} } @article {1556, title = {Closing the science gap in 3D metal printing}, journal = {Science}, volume = {368}, year = {2020}, pages = {583{\textendash}584}, abstract = {

Additive manufacturing [three-dimensional (3D) printing] methodologies for high\–melting point metallic materials are being used in the advanced aerospace and biomedical sectors to fabricate high-value and geometrically complex parts in moderate production volumes. One barrier to more widespread applications is the gaps in the understanding of the processes that occur during the layer-by-layer buildup by beam heating and melting of powder or wire layers. For example, the absorption of energy in powder layers that are only a few particles thick is poorly understood. On page 660 of this issue, Khairallah et al. (1) used in situ x-ray synchrotron observations of powder dynamics coupled to thermal and hydrodynamic flow modeling to study energy absorption at the scale of powder particles. The presence of the powder, relative to a flat plate without powder, improves absorptivity at low laser power, but as power approaches 200 W, the details of the powder become far less important.

}, doi = {10.1126/science.abb4938}, author = {Polonsky, Andrew T. and Pollock, Tresa M.} } @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 {1386, title = {Computational homogenization for multiscale forward modeling of resonant ultrasound spectroscopy of heterogeneous materials}, journal = {Materials Characterization}, volume = {158}, year = {2019}, pages = {109945}, abstract = {

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

}, keywords = {Computational homogenization, Finite elements, Forward modeling, Non-destructive evaluation, Resonant ultrasound spectroscopy}, issn = {10445803}, doi = {10.1016/j.matchar.2019.109945}, url = {https://doi.org/10.1016/j.matchar.2019.109945}, author = {Latypov, Marat I. and Charpagne, Marie Agathe and Souther, Mason and Goodlet, Brent R. and Echlin, Mclean P. and Beyerlein, Irene J. and Pollock, Tresa M.} } @article {1516, title = {Correction of Electron Back-scattered Diffraction datasets using an evolutionary algorithm}, journal = {arXiv}, year = {2019}, pages = {1{\textendash}10}, abstract = {

In materials science and particularly electron microscopy, Electron Back-scatter Diffraction (EBSD) is a common and powerful mapping technique for collecting local crystallographic data at the sub-micron scale. The quality of the reconstruction of the maps is critical to study the spatial distribution of phases and crystallographic orientation relationships between phases, a key interest in materials science. However, EBSD data is known to suffer from distortions that arise from several instrument and detector artifacts. In this paper, we present an unsupervised method that corrects those distortions, and enables or enhances phase differentiation in EBSD data. The method uses a segmented electron image of the phases of interest (laths, precipitates, voids, inclusions) gathered using detectors that generate less distorted data, of the same area than the EBSD map, and then searches for the best transformation to correct the distortions of the initial EBSD data. To do so, the Covariance Matrix Adaptation Evolution Strategy (CMA-ES) is implemented to distort the EBSD until it matches the reference electron image. Fast and versatile, this method does not require any human annotation and can be applied to large datasets and wide areas, where the distortions are important. Besides, this method requires very little assumption concerning the shape of the distortion function. Some application examples in multiphase materials with feature sizes down to 1 \$\backslashmu\$m are presented, including a Titanium alloy and a Nickel-base superalloy.

}, url = {http://arxiv.org/abs/1903.02982}, author = {Strub, Florian and Charpagne, Marie-agathe and Pollock, Tresa M.} } @article {1396, title = {Creep resistance of bulk copper{\textendash}niobium composites: An inverse effect of multilayer length scale}, journal = {Acta Materialia}, volume = {176}, year = {2019}, pages = {189{\textendash}198}, abstract = {

Metallic multilayer systems show promising performance in extreme environments, with high stability of bi-metal interfaces down to nanometer length scales. The creep behavior of bulk, accumulative roll bonded (ARB) Copper\–Niobium (Cu\–Nb) composites has been studied at 400 \°C as a function of layer thickness, ranging from 2 \μm to 65 nm. Similar to single phase metallic systems, three regimes are observed during creep: transient, steady-state and tertiary. The mechanism controlling minimum creep rate for all conditions tested has a strong dependence on stress, consistent with dislocation-dominated creep. Unlike the conventional effect of grain size on creep resistance, this study reveals that decreasing length scale increases creep resistance.

}, keywords = {Creep, Cu-Nb, Length scale, Multilayer}, issn = {13596454}, doi = {10.1016/j.actamat.2019.06.029}, url = {https://doi.org/10.1016/j.actamat.2019.06.029}, author = {Avallone, Jaclyn T. and Nizolek, Thomas J. and Bales, Benjamin B. and Pollock, Tresa M.} } @article {1441, title = {Competing Modes for Crack Initiation from Non-metallic Inclusions and Intrinsic Microstructural Features During Fatigue in a Polycrystalline Nickel-Based Superalloy}, journal = {Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science}, volume = {49}, year = {2018}, pages = {3865{\textendash}3873}, abstract = {

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

}, isbn = {1166101847803}, issn = {10735623}, doi = {10.1007/s11661-018-4780-3}, url = {https://doi.org/10.1007/s11661-018-4780-3}, author = {Stinville, Jean Charles and Martin, Etienne and Karadge, Mallikarjun and Ismonov, Shak and Soare, Monica and Hanlon, Tim and Sundaram, Sairam and Echlin, McLean L.P. and Callahan, Patrick G. and Lenthe, William C. and Miao, Jiashi and Wessman, Andrew E. and Finlay, Rebecca and Loghin, Adrian and Marte, Judson and Pollock, Tresa M.} } @article {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 {stinville2016combined, title = {A combined grain scale elastic{\textendash}plastic criterion for identification of fatigue crack initiation sites in a twin containing polycrystalline nickel-base superalloy}, journal = {Acta Materialia}, volume = {103}, year = {2016}, pages = {461{\textendash}473}, publisher = {Pergamon}, author = {Stinville, JC and Lenthe, WC and Miao, J and Pollock, TM} } @article {titus2015creep, title = {Creep-induced planar defects in L1 2-containing Co-and CoNi-base single-crystal superalloys}, journal = {Acta Materialia}, volume = {82}, year = {2015}, pages = {530{\textendash}539}, publisher = {Pergamon}, author = {Titus, Michael S and Eggeler, Yolita M and Suzuki, Akane and Pollock, Tresa M} } @article {adharapurapu2014combinatorial, title = {A combinatorial investigation of palladium and platinum additions to $\beta$-NiAl overlay coatings}, journal = {Acta Materialia}, volume = {77}, year = {2014}, pages = {379{\textendash}393}, publisher = {Pergamon}, author = {Adharapurapu, Raghavendra R and Zhu, Jun and Dheeradhada, Voramon S and Lipkin, Don M and Pollock, Tresa M} } @article {steuer2014creep, title = {Creep behavior under isothermal and non-isothermal conditions of AM3 single crystal superalloy for different solutioning cooling rates}, journal = {Materials Science and Engineering: A}, volume = {601}, year = {2014}, pages = {145{\textendash}152}, publisher = {Elsevier}, author = {Steuer, S and Hervier, Z and Thabart, S and Castaing, C and Pollock, TM and Cormier, J} } @article {eggeler2014creep, title = {Creep deformation-induced antiphase boundaries in L1 2-containing single-crystal cobalt-base superalloys}, journal = {Acta Materialia}, volume = {77}, year = {2014}, pages = {352{\textendash}359}, publisher = {Pergamon}, author = {Eggeler, Yolita M and Titus, Michael S and Suzuki, Akane and Pollock, Tresa M} } @article {vermaak2013cyclic, title = {Cyclic oxidation of high temperature coatings on new $\gamma$'-strengthened cobalt-based alloys}, journal = {Corrosion Science}, volume = {75}, year = {2013}, pages = {300{\textendash}308}, publisher = {Pergamon}, author = {Vermaak, N and Mottura, A and Pollock, TM} } @article {titus2012creep, title = {Creep and directional coarsening in single crystals of new $\gamma${\textendash}$\gamma$' cobalt-base alloys}, journal = {Scripta Materialia}, volume = {66}, number = {8}, year = {2012}, pages = {574{\textendash}577}, publisher = {Elsevier}, author = {Titus, Michael S and Suzuki, Akane and Pollock, Tresa M} } @article {adharapurapu2011carburization, title = {Carburization of W-and Re-rich Ni-based alloys in impure helium at 1000{\textdegree} C}, journal = {Corrosion Science}, volume = {53}, number = {1}, year = {2011}, pages = {388{\textendash}398}, publisher = {Elsevier}, author = {Adharapurapu, Raghavendra R and Kumar, Deepak and Zhu, Jun and Pollock, Tresa M} } @article {adharapurapu2011chromia, title = {Chromia-Assisted Decarburization of W-Rich Ni-Based Alloys in Impure Helium at 1273 K (1000{\textdegree} C)}, journal = {Metallurgical and Materials Transactions A}, volume = {42}, number = {5}, year = {2011}, pages = {1229{\textendash}1244}, publisher = {Springer}, author = {Adharapurapu, Raghavendra R and Kumar, Deepak and Zhu, Jun and Torbet, Christopher J and Was, Gary S and Pollock, Tresa M} } @article {mercer2011comparative, title = {A comparative investigation of oxide formation on EQ (Equilibrium) and NiCoCrAlY bond coats under stepped thermal cycling}, journal = {Surface and Coatings Technology}, volume = {205}, number = {8}, year = {2011}, pages = {3066{\textendash}3072}, publisher = {Elsevier}, author = {Mercer, C and Kawagishi, K and Tomimatsu, T and Hovis, D and Pollock, TM} } @article {terbush2011creep, title = {Creep and Elemental Partitioning Behavior of Mg-Al-Ca-Sn Alloys with the Addition of Sr}, journal = {Magnesium Technology 2011}, year = {2011}, pages = {215{\textendash}222}, publisher = {John Wiley \& Sons, Inc.}, author = {TerBush, Jessica R and Chen, Olivia H and Jones, J Wayne and Pollock, Tresa M} } @article {torralva2011critical, title = {The Critical Role of Shock Melting in Ultrafast Laser Machining}, journal = {Minerals, Metals and Materials Society/AIME, 420 Commonwealth Dr., P. O. Box 430 Warrendale PA 15086 United States.[np]. Feb}, year = {2011}, publisher = {Minerals, Metals and Materials Society/AIME, 420 Commonwealth Dr., P. O. Box 430 Warrendale PA 15086 United States}, author = {Torralva, Ben and Ma, S and Kumar, A and Yalisove, SM and Pollock, TM and Thornton, K} } @article {suzuki2010crack, title = {Crack progression during sustained-peak low-cycle fatigue in single-crystal Ni-base superalloy Ren{\'e} N5}, journal = {Metallurgical and Materials Transactions A}, volume = {41}, number = {4}, year = {2010}, pages = {947{\textendash}956}, publisher = {Springer US}, author = {Suzuki, A and Gigliotti, MFX and Hazel, BT and Konitzer, DG and Pollock, TM} } @article {miao2009crystallographic, title = {Crystallographic fatigue crack initiation in nickel-based superalloy Ren{\'e} 88DT at elevated temperature}, journal = {Acta Materialia}, volume = {57}, number = {20}, year = {2009}, pages = {5964{\textendash}5974}, publisher = {Pergamon}, author = {Miao, Jiashi and Pollock, Tresa M and Jones, J Wayne} } @conference {terbush2008comparative, title = {A comparative examination of aging and creep behavior of die-cast MRI230D and AXJ530}, booktitle = {Symposium on Magnesium Technology 2008 (TMS 9 March 2008 to 13 March 2008)}, year = {2008}, pages = {117{\textendash}122}, publisher = {The Minerals, Metals \& Materials Society (TMS)}, organization = {The Minerals, Metals \& Materials Society (TMS)}, author = {TerBush, Jessica and Jones, J and Pollock, Tresa} } @article {cao2008creep, title = {Creep deformation mechanisms in Ru-Ni-Al ternary B2 alloys}, journal = {Metallurgical and Materials Transactions A}, volume = {39}, number = {1}, year = {2008}, pages = {39{\textendash}49}, publisher = {Springer}, author = {Cao, F and Pollock, TM} } @conference {cao2007compression, title = {COMPRESSION CREEP BEHAVIOR OF B 2 AL-NI-RU TERNARY ALLOYS}, booktitle = {Advanced Intermetallic-Based Alloys(MRS Symposium Proceedings Series Volume 980)}, volume = {980}, year = {2007}, pages = {45{\textendash}50}, author = {Cao, Fang 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} } @conference {cao2006compression, title = {Compression Creep Behavior of B2 AL-Ni-Ru Ternary Alloys}, booktitle = {MRS Proceedings}, volume = {980}, year = {2006}, pages = {0980{\textendash}II01}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, author = {Cao, Fang and Pollock, Tresa M} } @article {gilchrist2001cast, title = {Cast gamma titanium aluminides for low pressure turbine blades: a design case study for intermetallics}, journal = {Minerals, Metals and Materials Society/AIME, Structural Intermetallics 2001(USA),}, year = {2001}, pages = {3{\textendash}12}, author = {Gilchrist, Alan and Pollock, Tresa M} } @article {pollock2001comparative, title = {A comparative analysis of low temperature deformation in B2 aluminides}, journal = {Materials Science and Engineering: A}, volume = {317}, number = {1}, year = {2001}, pages = {241{\textendash}248}, publisher = {Elsevier}, author = {Pollock, TM and Lu, DC and Shi, X and Eow, K} } @conference {tin2000carbides, title = {Carbides and grain defect formation in directionally solidified nickel-base superalloys}, booktitle = {Advanced Technologies for Superalloy Affordability as held at the 2000 TMS Annual Meeting}, year = {2000}, pages = {2000}, author = {Tin, S and Pollock, T and Murphy, W} } @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} } @article {pollock1998creep, title = {Creep deformation and the evolution of precipitate morphology in nickel-based single crystals}, journal = {Modelling of Microstructural Evolution in Creep Resistant Materials}, year = {1998}, pages = {1998}, author = {Pollock, TM} } @article {pollock1993creep, title = {CREEP RESISTANCE OF CMSX-3 NICKEL-BASE SUPERALLOY SINGLE-CRYSTALS (VOL 40, PG 1, 1992)}, journal = {ACTA METALLURGICA ET MATERIALIA}, volume = {41}, number = {7}, year = {1993}, pages = {2253{\textendash}2253}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, author = {Pollock, TM and Argon, AS} } @article {pollock1992creep, title = {Creep resistance of CMSX-3 nickel base superalloy single crystals}, journal = {Acta Metallurgica et Materialia}, volume = {40}, number = {1}, year = {1992}, pages = {1{\textendash}30}, publisher = {Pergamon}, author = {Pollock, TM and Argon, AS} } @article {thompson1991creep, title = {Creep of $\alpha$ 2+ $\beta$ Titanium Aluminide Alloys}, journal = {ISIJ International}, volume = {31}, number = {10}, year = {1991}, pages = {1139{\textendash}1146}, publisher = {社団法人 日本鉄鋼協会}, author = {THOMPSON, Anthony W and Pollock, Tresa M} } @booklet {pollock1990creep, title = {Creep Resistance of CMSX-3 Nickel Base Superalloy Single Crystals: Source of Resistance}, year = {1990}, publisher = {MIT}, author = {Pollock, TM and Argon, AS} } @booklet {pollock1990creep, title = {Creep Resistance of CMSX-3 Nickel Base Superalloy Single Crystals: Experimental Observations}, year = {1990}, publisher = {MIT}, author = {Pollock, TM and Argon, AS} } @article {pollock1990creep, title = {Creep resistance of nickel-base superalloy single crystals}, journal = {Creep and fracture of engineering materials and structures}, year = {1990}, pages = {287{\textendash}301}, author = {POLLOCK, TRESAM and ARGON, ALIS} }