Misorientation Change of the Grain Boundary in Pure Copper Bicrystals Subjected to One-Pass Equal-Channel Angular Pressing

Abstract

Grain boundaries can change their misorientation by absorbing lattice dislocations at relatively high temperature under moderate straining. The same phenomenon is believed to occur during severe plastic deformation down to room temperature leaving grain boundaries in the nonequilibrium state. Direct evidence of misorientation change of the grain boundary during severe plastic deformation was obtained in copper bicrystals subjected to equal-channel angular pressing (ECAP) for one pass. Marked dependence of misorientaion change on the initial orientation was revealed, and is associated with the unique slip patterns of ECAP, where the shear deformation is restricted to the narrow zone parallel to the intersecting plane of the two channels. The degree of change can be related to slip geometry in terms of grain boundary plane orientation.

Effect of Grain Boundary Structure on Misorientation Change of Pure Copper Bicrystals Pressed by One-Pass Equal-Channel Angular Pressing

“…Bicrystals with a well-defined grain boundary offer a very effective approach in this respect. In a previous study, 8) we pressed pure copper bicrystals for one pass by ECAP, and obtained direct evidence of dynamic misorientation change of the GB by as high as 15°during ECAP. This change shows a marked dependency on slip geometry in terms of the slip plane of ECAP.…”