Achievement of Low Temperature Superplasticity in a Commercial Aluminium Alloy Processed by Equal-Channel Angular Extrusion

摘要

A commercial Al-4.1%Mg-2.0%Li-0.16%Sc-0.07%Zr alloy was used as a starting material. The submicrocrystalline structure with an average grain size of about 0.8μm was developed by equal-channel angular extrusion. Superplastic behavior of this alloy was examined in the temperature range 150-250°C at strain rates ranging from 1.4×10{sup}(-5) to 5.6×10{sup}(-2)s{sup}(-1). A maximum elongation-to-failure of 440% was recorded at 175°C (0.5T{sub}m, where T{sub}m is the melting point) and a strain rate of 2.8×{sup}(-5)s{sup}(-1). The strain rate sensitivity was measured as -0.32 at these conditions. This temperature is exceptionally low for superplasticity in Al-based alloys, as it has been reported to date. Features of superplastic deformation at such the low temperature are considered.