The influence of chromium on the structure and superplasticity of Al-Mg-Mn alloys

The structure and superplasticity of Al-Mg-Mn-Cr alloys that have different Mg contents are studied. An increase in magnesium content provides finer grains and improves the superplasticity of the chromium alloys. Transmission electron microscopy analyses indicate that there are differences in alloy particle fragmentation processes during mechanical and heat treatment when chromium is present. Fine particles (<60 nm) and fine grains (5 mu m) are formed prior to the superplastic deformation when chromium is present. The Al-6.3Mg-0.7Mn alloy with Cr (0.3 wt.%) demonstrates good superplasticity. Specifically, the strain rate sensitivity index, m, is 0.6, and the elongation is over 400% at a constant strain rate of 5 x 10(-3) s(-1). (c) 2013 Elsevier B.V. All rights reserved.