| Experiments were conducted on a magnesium AZ31 alloy to evaluate the role of cavitation in high temperature superplasticity. Samples were processed by equal-channel angular pressing (ECAP) and then pulled to failure in tension at a temperature of 623K. Similar tests were also conducted on the as-received alloy. The results show the development of significant internal cavitation in this alloy when testing both the as-received samples and the samples processed by ECAP at strain rates up to 10-3 s-1. An analysis of the cavity morphologies shows the cavities grow initially by a diffusion process in which vacancies are absorbed from the surrounding grain boundaries but there is a transition to plasticity-controlled growth for the larger cavities. |
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