科研之友
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摘要
The processing of a magnesium AZ31 alloy by equal-channel angular pressing refines the grain size to similar to 2.2 mu m, but annealing for 30 min at 673 K coarsens the grains to similar to 6.0 mu m. Despite this microstructural instability, the alloy is superplastic when pulled in tension at temperatures in the range of 623-723 K with elongations up to > 1000% at strain rates at and below 10(-4) s(-1). Experiments within the superplastic regime show the strain rate sensitivity is similar to 0.5 and the activation energy is close to the value for grain boundary diffusion. It is demonstrated by calculation that the experimental results are in good agreement with a model for superplasticity based on grain boundary sliding.
- 出版日期2008-12
