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

摘要

Following a previous paper, (Materials Transactions, Vol. 53 (2012), p. 1858), which reports on the dynamic misorientation change absorbed by the grain boundaries themselves during one-pass equal-channel angular pressing (ECAP), the effect of grain boundary structure on the misorientation change during ECAP was examined as the next step. Two bicrystals with a S3 {111} grain boundary and a random one were subjected to ECAP for one pass, and compared. Both the bicrystals were designed to have a similar.slip pattern where slip activity was concentrated on one slip plane. Direct evidence of misorientation changes absorbed by grain boundary themselves was obtained again, and its marked dependency on grain boundary structure became evident. Namely, in S3 grain boundary, misorientation was partially carried by the grain interior in its vicinity, which stems from the dislocation accumulation. On the other hand, in the random grain boundary, most of the misorientation was carried by the boundary itself. These differences are discussed in terms of the capability as a sink of lattice dislocations during severe plastic deformation.