Importance of diffusional creep in fine grained Mg-3Al-1Zn alloys

Deformation mechanisms of fine-grained Mg-3Al-Zn (AZ31) alloys that were prepared by using severe plastic deformation were identified at elevated temperatures between 473 K and 573 K by examining their stress-strain rate relations at different grain sizes and temperatures. Unlike the previous reports where grain boundary sliding has been suggested to be the rate-controlling deformation mechanism in the fine-grained AZ31 alloy, the current analysis indicated that Coble creep competes with grain boundary sliding and the contribution of Coble creep to overall strain rate increases as grain size decreases and temperature increases. Making the efforts to minimize grain growth during sample heating and tensile deformation is, however, important for observing Coble creep. Texture variation took place during the tensile deformation and differed depending on the type of dominant deformation mechanism operating under the given testing condition.