On the contribution of extrinsic grain boundary dislocations to grain boundary sliding in bicrystals

The possibility of separating the contributions of extrinsic grain boundary dislocations of different origins to the overall grain boundary shear is shown using the model of grain boundary sliding operating under the conditions of plastic incompatibility. The approach suggested is applied to the case of deformation of incompatible zinc bicrystals with a 29 degrees[<10(1)over bar 0>] symmetric tilt boundary which is close to the Sigma = 15{<1(2)over bar 11>} coincidence boundary. Quantitative estimates of contributions of extrinsic grain boundary dislocations to grain boundary sliding and intragranular strain in the vicinity of the boundary are obtained. (C) 1997 Acta Metallurgica Inc.