Micrograin Superplasticity: Characteristics and Utilization

Micrograin Superplasticity refers to the ability of fine-grained materials (1 µm < d < 10 μm, where d is the grain size) to exhibit extensive neck-free elongations during deformation at elevated temperatures. Over the past three decades, good progress has been made in rationalizing this phenomenon. The present paper provides a brief review on this progress in several areas that have been related to: (a) the mechanical characteristics of micrograin superplasticity and their origin; (b) the effect of impurity content and type on deformation behavior, boundary sliding, and cavitation during superplastic deformation; (c) the formation of cavity stringers; (d) dislocation activities and role during superplastic flow; and (e) the utilization of superplasticity.