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Grain Boundary Dislocations and Stacking Defects in the 9R Phase at an Incoherent Twin Boundary in Copper

Published online by Cambridge University Press:  02 July 2020

D.L. Medlin
Affiliation:
Materials and Engineering Sciences Center, Sandia National Laboratories, Livermore, California, 94550
G.H. Campbell
Affiliation:
Chemistry and Materials Science Directorate, University of California, Lawrence Livermore National Laboratory, Livermore, California, 94550
C. Barry Carter
Affiliation:
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, 55455
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Extract

Experiment and modeling show that there is a general mode of grain boundary dissociation, common in low stacking fault energy FCC metals, that can be well understood in terms of the emission of arrays of stacking faults from the grain boundary plane. Most extensively studied of such dissociated interfaces are the Σ=3 incoherent twin boundaries. Numerous observations now exist of grain boundary dissociation at such interfaces showing a layer that is well described as a narrow, several nanometer wide slab of 9R stacked material. The 9R stacking sequence is equivalent to a close-packed stacking of FCC ﹛111﹜ planes with an intrinsic stacking fault inserted every three planes (i.e., a stacking sequence of ABC/BCA/CBA …). The width of the 9R layer is sensitive to the local stress state. Figure 1 shows results of an atomistic calculation simulating the effect of an applied shear strain parallel to the boundary.

Type
Spatially-Resolved Characterization of Interfaces in Materials
Copyright
Copyright © Microscopy Society of America

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