Internal stress superplasticity in polycrystalline AZ31 magnesium alloy

Internal stress superplastic deformation in polycrystalline AZ31 magnesium alloy was examined through isothermal and thermal cycling compression creep tests. The alloy showed typical class-I creep behavior under the isothermal condition with the activation energy of Qc = 124kJ/mol. On the other hand, the alloy showed linear creep behavior under the thermal cycling condition and the average strain rates were much higher than the corresponding isothermal creep rates. The magnitude of the average strain rates was quantitatively explained using the proposed model for internal stress superplasticity.