@article {1356,
	title = {Dislocation dynamics in a nickel-based superalloy via in-situ transmission scanning electron microscopy},
	journal = {Acta Materialia},
	volume = {168},
	year = {2019},
	pages = {152{\textendash}166},
	abstract = {<p>
	Micro-tensile specimens of nickel-based superalloy oligocrystals were tested in-situ in an scanning electron microscope in transmission mode (TSEM) enabling observation of dislocations. The dynamics of dislocation motion during tensile loading were captured and correlated with the measured intermittencies during plastic flow recorded by high load- and temporal-resolution sensors. This investigation in particular focused on the dislocation behavior near twin boundaries with different slip configurations. A multiplicity of deformation mechanisms at the dislocation scale were observed within individual slip bands, including precipitate shearing, dislocation decorrelation and antiphase boundary-coupled shearing. These processes affect strain localization near twin boundaries and provide new defect-level insights on plastic localization and fatigue crack initiation in these alloys.
</p>
},
	keywords = {Dislocations dynamic, In-situ transmission scanning electron microscopy (TSEM), Nickel-based superalloy ren{\'e} 88DT, Plastic localization, STEM detector, Twin boundary},
	issn = {13596454},
	doi = {10.1016/j.actamat.2018.12.061},
	url = {https://doi.org/10.1016/j.actamat.2018.12.061},
	author = {Stinville, J. C. and Yao, Eric R. and Callahan, Patrick G. and Shin, Jungho and Wang, Fulin and Echlin, Mclean P. and Pollock, Tresa M. and Gianola, Daniel S.}
}
@article {1326,
	title = {Defects and 3D structural inhomogeneity in electron beam additively manufactured Inconel 718},
	journal = {Materials Characterization},
	volume = {143},
	year = {2018},
	pages = {171{\textendash}181},
	abstract = {<p>
	Material structure and defects created during additive manufacturing contribute to the variability in mechanical properties of these parts, limiting their use for critical applications. Three-dimensional crystallographic, structural, and chemical information in electron beam melted Inconel 718 was collected from the sub-micron to the millimeter scale using the TriBeam tomography system. The relationship of defects to the surrounding microstructure has been studied in detail. Lack of fusion defects created sharp discontinuities in the grain morphology that extended several build layers beyond the layer where the defect originated. Nitrides and carbides in the size range of 1.25 \&mu;m to 10 \&mu;m were observed throughout the volume, with pronounced nitride clustering. The similarities between solidification in additive manufacturing and traditional manufacturing processes are demonstrated by the comparable size and distribution of carbides measured for industrial-scale samples of 718. Defects created during additive manufacturing cannot be easily remedied via standard post-processing techniques, and will likely diminish the mechanical performance of additively manufactured parts.
</p>
},
	keywords = {Additive manufacturing, Electron beam melting, Lack of fusion, Microstructure, Tomography},
	issn = {10445803},
	doi = {10.1016/j.matchar.2018.02.020},
	author = {Polonsky, Andrew T. and Echlin, Mclean P. and Lenthe, William C. and Dehoff, Ryan R. and Kirka, Michael M. and Pollock, Tresa M.}
}
