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.