@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 {2391, title = {Orientation-Adaptive Virtual Imaging of Defects using EBSD}, year = {2025}, abstract = {

EBSD is a foundational technique for characterizing crystallographic orientation, phase distribution, and lattice strain. Embedded within EBSD patterns lies latent information on dislocation structures, subtly encoded due to their deviation from perfect crystallinity - a feature often underutilized. Here, a novel framework termed orientation-adaptive virtual apertures (OAVA) is introduced. OAVAs enable the generation of virtual images tied to specific diffraction conditions, allowing the direct visualization of individual dislocations from a single EBSD map. By dynamically aligning virtual apertures in reciprocal space with the local crystallographic orientation, the method enhances contrast from defect-related strain fields, mirroring the principles of diffraction-contrast imaging in TEM, but without sample tilting. The approach capitalizes on the extensive diffraction space captured in a single high-quality EBSD scan, with its effectiveness enhanced by modern direct electron detectors that offer high-sensitivity at low accelerating voltages, reducing interaction volume and improving spatial resolution. We demonstrate that using OAVAs, identical imaging conditions can be applied across a polycrystalline field-of-view, enabling uniform contrast in differently oriented grains. Furthermore, in single-crystal GaN, threading dislocations are consistently resolved. Algorithms for the automated detection of dislocation contrast are presented, advancing defect characterization. By using OAVAs across a wide range of diffraction conditions in GaN, the visibility/invisibility of defects, owing to the anisotropy of the elastic strain field, is assessed and linked to candidate Burgers vectors. Altogether, OAVA offers a new and high-throughput pathway for orientation-specific defect characterization with the potential for automated, large-area defect analysis in single and polycrystalline materials.

}, author = {Della Ventura, Nicol{\`o} M and Lamb, James D and Lenthe, William C and Echlin, McLean P and P{\"u}rstl, Julia T and Trageser, Emily S and Quevedo, Alejandro M and Begley, Matthew R and Pollock, Tresa M and Gianola, Daniel S and De Graef, Marc} } @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} } @article {2311, title = {Resolving crystallographic geometrically necessary dislocations in three dimensions in a hexagonal close packed titanium alloy}, journal = {Model. Simul. Mat. Sci. Eng.}, volume = {32}, year = {2024}, pages = {065035}, abstract = {

Abstract Geometrically necessary dislocation (GND) content is measured from mm3-scaled Ti7Al three-dimensional (3D) microstructural data using a theory extended for hexagonal close packed crystals, which accounts for basal, prismatic and pyramidal \⟨ c + a \⟩ type dislocation content. The Ti7Al samples have been mechanically pre-strained to two different strain levels, and will then be strained along the same axis in uniaxial tension during simulation. Both inter- and intragranular GNDs across the microstructures have been characterized, with a large contribution of pyramidal \⟨ c + a \⟩ GNDs, consistent with the relative slip activity involved in pre-straining. The spatially resolved crystallographic GND distributions within the 3D microstructures are used to instantiate a microstructure model for forward modeling deformation simulations by a dislocation density hardening elasto-viscoplastic fast Fourier transform framework. Coarsening the voxel resolution during the initial microstructure construction procedure is shown to strongly impact both the magnitude and spatial distribution of the GNDs and in turn the forward deformation response of the pre-strained material. This study indicates that the voxel resolution desired when transferring from measured to model microstructures need not only be proportionally scaled with the microstructure but also sufficiently fine to capture the subgranular orientation gradients that may already be present in the material.

}, author = {Witzen, Wyatt A and Lamb, James D and Arul Kumar, Mariyappan and Echlin, McLean P and Pollock, Tresa M and Beyerlein, Irene J} } @article {2341, title = {Resolving crystallographic geometrically necessary dislocations in three dimensions in a hexagonal close packed titanium alloy}, journal = {Model. Simul. Mat. Sci. Eng.}, volume = {32}, year = {2024}, pages = {065035}, abstract = {

Abstract Geometrically necessary dislocation (GND) content is measured from mm3-scaled Ti7Al three-dimensional (3D) microstructural data using a theory extended for hexagonal close packed crystals, which accounts for basal, prismatic and pyramidal \⟨ c + a \⟩ type dislocation content. The Ti7Al samples have been mechanically pre-strained to two different strain levels, and will then be strained along the same axis in uniaxial tension during simulation. Both inter- and intragranular GNDs across the microstructures have been characterized, with a large contribution of pyramidal \⟨ c + a \⟩ GNDs, consistent with the relative slip activity involved in pre-straining. The spatially resolved crystallographic GND distributions within the 3D microstructures are used to instantiate a microstructure model for forward modeling deformation simulations by a dislocation density hardening elasto-viscoplastic fast Fourier transform framework. Coarsening the voxel resolution during the initial microstructure construction procedure is shown to strongly impact both the magnitude and spatial distribution of the GNDs and in turn the forward deformation response of the pre-strained material. This study indicates that the voxel resolution desired when transferring from measured to model microstructures need not only be proportionally scaled with the microstructure but also sufficiently fine to capture the subgranular orientation gradients that may already be present in the material.

}, author = {Witzen, Wyatt A and Lamb, James D and Arul Kumar, Mariyappan and Echlin, McLean P and Pollock, Tresa M and Beyerlein, Irene J} } @article {2316, title = {On the role of geometrically necessary dislocations in void formation and growth in response to shock loading conditions in wrought and additively manufactured Ta}, journal = {J. Mater. Res. Technol.}, volume = {31}, year = {2024}, pages = {3035{\textendash}3049}, author = {Lamb, James D and Mullin, Kaitlyn M and Christodoulou, Paul G and Witzen, Wyatt A and Echlin, McLean P and Beyerlein, Irene J and Pollock, Tresa M} } @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} }