Superplasticity in thin magnesium alloy sheets and deformation mechanism maps for magnesium alloys at elevated temperatures

Rolling processes for fabricating thin AZ61 and AZ31 alloy sheets adequate for superplastic forming have been developed. Superplastic behavior of the sheets was evaluated in the temperature range 573-693 K and compared that of the initial materials having relatively coarse grains. Existing deformation mechanism maps for face-centered cubic and body-centered cubic metals were reviewed and found to be deficient in predicting the deformation behavior of magnesium alloys with hexagonal close-packed crystal structure. Using the experimental data for a number of Mg alloys, which are associated with various deformation mechanisms competing at elevated temperatures, deformation mechanism maps for Mg alloys could be constructed. Excellent prediction capability of the maps was verified at temperatures of 573-673 K. (C) 2001 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.