Superplasticity is phenomenologically defined as an ability of a polycrystalline material to exhibit extraordinarily large elongations in tension at elevated temperatures. The fine structure superplasticity is a property commonly found in many metals, alloys, intermetallics, and ceramics at temperatures >2/3Tm (where Tm is the absolute melting point), when the grain size is very small (less than several micrometers for metals and less than 1 mm for ceramics) and
stable during deformation