Cavitation and cavity sintering during compressive deformation of a superplastic microduplex Cu–Zn–Ni alloy

Abstract

A superplastic microduplex α–β nickel silver alloy has been deformed in tension and compression. Cavitation occurred during superplastic tensile flow, but not during homogeneous compressive deformation. In those regions of the compression specimens which were subjected to barrelling and transient tensile stress, however, a measurable level of cavitation was detected. Application of compressive stress caused cavities introduced during prior tensile deformation to sinter and the degree of sintering increased with increasing compressive strain, but was relatively independent of strain rate. The closure rate of cavities was found to be consistent with a viscous mechanism of sintering and was much greater than the closure rate predicted by stress-directed vacancy diffusion.