Abstract
Superplastic deformation mechanisms have been investigated, based on experimental results of Al-33%Cu and Al-33%Cu-0.3%Cr alloys.
Though Cr bearing had little effect both on the flow stress in the regions II and III and on the deformation induced grain growth in the regions I and II, it increased the flow stress in the region I. These results were explained by the following superplastic deformation model: while the main mechanism is grain boundary sliding in the regions I and II, its rate controlling process is diffusional accommodation in the region II and threshold process in the region I, respectively, and in the region III the ordinary dislocation creep also contributes.
The diffusional accommodation of grain boundary sliding divided experimentally was considered to be the grain boundary diffusion for grain switching because of its grain size dependence and its absolute flow stress.
