Grain Boundary Responses to Local and Applied Stress: An In Situ TEM Deformation Study

Abstract

Deformation experiments at temperatures between 300 and 750 K have been performed in situ in the transmission electron microscope to investigate dislocation interactions and reactions with grain boundaries and other obstacles. Dislocations, both partial and perfect, as well as deformation twins have been observed being emitted from grain boundaries and, in some cases, even the same grain boundary. The ejection of dislocations from the grain boundary can result in its partial or total annihilation. In the latter case, the disintegration of the grain boundary was accompanied by grain growth and a change in misorientation.

Energy barriers associated with slip–twin interactions

“…It is shown that the barriers for glide through a CTB are significantly higher compared to a regular dislocation glide case (Figure 6a) supporting a significant level of strengthening associated with non-deformation twins. The reemission behavior of an incident dislocation from a CTB is reported experimentally [50]; in this study, we provide the associated energy barrier.…”

Strength prediction in NiCo alloys – The role of composition and nanotwins

“…Further investigation of modifying either of these two variables, and the associated change in the mechanism would be one interesting future research. Earlier literature have addressed the details of individual reactions both theoretically and experimentally: (a) incorporation (Asaro and Kulkarni, 2008;Jin et al, 2006;Müllner and Solenthaler, 1997), (b) transmission (Kacher et al, 2014;Zhu et al, 2007), (c) multiplication (Miller et al, 2006), (d) transmission and incorporation (Evans, 1974;Jin et al, 2008;Mahajan and Chin, 1973), and (e) blockage by a Lomer lock formation (Karnthaler, 1978;Wang and Huang, 2006). The relative preference for these reactions bears important implications regarding the macroscopic strength and ductility.…”