2012 Volume 53 Issue 1 Pages 87-95
A Zn–22% Al eutectoid alloy was processed by equal-channel angular pressing for 8 passes at 473 K and then tested in tension at 473 K over a range of strain rates. A highest elongation of 2230% was recorded at a strain rate of 1.0 × 10−2 s−1 representing high strain rate superplasticity. Quantitative cavity measurements and a cavity volume analysis were undertaken to investigate the growth of internal cavities during superplastic flow. The results demonstrate a clear transition from the superplastic diffusion growth of cavities at the lower elongations to plasticity-controlled cavity growth at the higher elongations. A cavity growth diagram provides an excellent description of the cavity growth processes including the transition from superplastic diffusion growth to plasticity-controlled growth at cavity radii larger than ∼2.1 µm.
