DISLOCATION INTERACTIONS WITH GRAIN BOUNDARIES

摘要

In-situ TEM deformation studies of dislocation interactions with grain boundaries have shown that the slip system selected by the grain boundary for continuing strain accommodation by dislocation motion is determined by the magnitude of the Burgers vector of the residual grain boundary dislocation. This condition is applicable in metals with an FCC crystal structure and perhaps in ones with an HCP structure. It also is predictive in irradiated FCC stainless steel with the caveat that the locally resolved shear stress must be of sufficient magnitude to push the dislocations through the irradiation-induced obstacle field. It is proposed that the conditions for causing intergranular failure due to external factors are driven by dislocation interactions with grain boundaries. A new tool, electron tomography, for analyzing and visualizing dislocation interactions with grain boundaries is introduced and applied.