Controlling mechanism during superplastic deformation of ZK40 alloy processed by ECAP was identified. Effects of twinning and dynamic strain aging on superplasticity were analyzed. Amplitude in stress oscillation was correlated with solute atom concentration theoretically. Twinning could be an enhancing factor in grain boundary sliding and dynamic strain aging had apparent influence on stress fluctuation; they were accommodation mechanisms for superplastic deformation through grain reorientation and interaction between solute atoms and dislocations, respectively. The interaction between mobile and forest dislocations played a dominant role for the occurrence of dynamic strain aging, when dislocation density was relatively low in large grains. The effect of dynamic strain aging became more active with increasing temperature, although grain boundary sliding was the controlling mechanism throughout the whole process of superplastic deformation under elevated temperatures.

Grain Boundary Sliding and Accommodation Mechanisms during Superplastic Deformation of ZK40 Alloy Processed by ECAP. L.Lin, W.Wu, L.Yang, L.Chen, Z.Liu: Journal of Materials Science, 2006, 41[2], 409-15