@article {2256,
	title = {Misfit and the mechanism of high temperature and low stress creep of Ni-base single crystal superalloys},
	journal = {Acta Materialia},
	volume = {264},
	year = {2024},
	pages = {119576},
	abstract = {<p>
	The present work proposes a new elementary deformation mechanism which governs high temperature and low stress creep of single crystal superalloys (SXs), where the misfit between the \&gamma;- and the \&gamma;\&prime;-phase plays a central role. In the coherent two phase SX microstructure, there is a tendency to minimize the overall elastic strain energy. This is accomplished by the formation of dislocation networks in the \&gamma;-phase close to the \&gamma;/\&gamma;\&rsquo;-interfaces. The stress fields of the network dislocations and misfit stresses accommodate each other to keep the overall strain energy of the system at a minimum. Previous work has shown that dynamic recovery is associated with knitting-out reactions, where dislocations from the network shear the \&gamma;\&rsquo;-phase and annihilate with dislocations of opposite sign on the other side of the \&gamma;\&rsquo;-phase region. Due to the presence of the misfit this results in an increase of elastic strain energy which is counteracted by coupled knitting-in reactions where newly arriving \&gamma;-channel dislocations re-establish the minimum energy configuration. Here we provide microstructural evidence for knitting-out and knitting-in reactions and show that while these reactions clearly occur, dislocation network spacings stay constant. The misfit between the \&gamma;- and the \&gamma;\&prime;-phase accounts for a constant network spacing. Dislocation networks are not static but represent dynamic steady state equilibrium structures in an evolving microstructure. Knitting regular networks requires climb processes which are suggested to be rate controlling. This new view of high temperature and low stress creep mechanism of SXs allows to rationalize previous results published in the literature.
</p>
},
	keywords = {Creep, Dislocations, Misfit, Superalloy single crystals, Transmission electron microscopy},
	issn = {1359-6454},
	doi = {https://doi.org/10.1016/j.actamat.2023.119576},
	url = {https://www.sciencedirect.com/science/article/pii/S1359645423009059},
	author = {A.B. Parsa and D. B{\"u}rger and T.M. Pollock and G. Eggeler}
}
@article {1626,
	title = {Measurement of elastic and rotation fields during irreversible deformation using Heaviside-digital image correlation},
	journal = {Materials Characterization},
	volume = {169},
	year = {2020},
	month = {11/2020},
	pages = {110600},
	abstract = {<p>
	The recent development of the high resolution and discontinuity-tolerant digital image correlation technique enables the extraction of discontinuities within a displacement field. The technique provides quantitative analysis of discontinuities arising from slip, shear bands, cracks, and grain boundary sliding in a variety of material systems, including polycrystalline metallic materials. The discontinuity-tolerant digital image correlation method can be implemented to retrieve not only quantitative discontinuity analysis but also the local strain and rotation fields that operate near these discontinuities. The present implementation includes high-resolution digital image correlation (HR-DIC) measurements collected in a scanning electron microscope for analysis of both the plastic and elastic fields that develop during deformation of polycrystalline metallic materials. The combination of the discontinuity-tolerant DIC technique with the computation of internal gradients enables extraction of non-localized strain and rotation fields during plastic deformation of a nickel-based superalloy. Therefore the lattice rotation/expansion and plastic localization that occur during deformation can be determined in a single experiment. This method is validated using synthetic images with preset deformation, and experimental measurements using the electron back scatter diffraction (EBSD) technique.
</p>
},
	doi = {https://doi.org/10.1016/j.matchar.2020.110600},
	url = {https://www.sciencedirect.com/science/article/abs/pii/S1044580320320714},
	author = {J.C. Stinville and M.A. Charpagne and F. Bourdin and P.G. Callahan and Z. Chen and M.P. Echlin and D. Texier and J. Cormier and P. Villechaise and T.M. Pollock and V. Valle}
}
