Effect of Impurity Content on Cavitation in the Superplastic Zn-22 Pct Al Alloy

Micrograin superplasticity refers to the ability of some materials to exhibit neck-free strains of several hundred percent upon deformation. The two basic prerequisites for the observation of micrograin superplasticity are (a) a temperature greater than about one half of the melting point,T _m, and (b) a fine, stable, and equiaxed grain size that does not undergo significant growth during elevatedtemperature deformation. In addition to these two prerequisites, grain boundaries need to be mobile, high-angled, and able to resist tensile separation.