On Coble creep in Mg–9Al–1Zn alloy with ultrafine-grained microstructure

High-temperature deformation behavior of AZ91 alloy with ultrafine grains was studied at 473–573 K. Analyses based on the deformation mechanism maps for Mg and comparison of the experimental data with the values predicted by equations for several deformation mechanisms indicated that Coble creep was the rate-controlling deformation mechanism in low strain rate range. The critical grain size where Coble creep can be detected in Mg at a given strain rate and temperature was calculated.