Figueiredo, Roberto B. and Langdon, Terence G.
Developing superplasticity in a magnesium AZ31 alloy by ECAP
Journal of Materials Science, 43, (23-24), . (doi:10.1007/s10853-008-2846-0).
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The processing of a magnesium AZ31 alloy by equal-channel angular pressing refines the grain size to ~2.2 ?m, but annealing for 30 min at 673 K coarsens the grains to ~6.0 ?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 ~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.
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