Differences between grain boundary sliding with crystal slip and that without it are investigated by the use of orientation controlled cadmium bicrystals.
Without crystal slip, the rate of grain boundary sliding varied in proportion to applied stress and was controlled by grain boundary diffusion. With crystal slip, the rate of grain boundary sliding was found to vary in proportion to the square of applied stress and the activation energy for grain boundary sliding was almost equal to that of volume diffusion.
McLean’s model for grain boundary sliding with crystal slip is developed by assuming that the number of dislocations in the grain boundary is proportional to shear stress on the slip system. It is found that the model can explain the variation of grain boundary sliding rate with changes in shear stress on the slip systems.