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 0.8 urn was developed by equal-channel angular extrusion. Superplastic behavior of this alloy was examined in the temperature range 150-250℃ at strain rates ranging from 1.4 x 10~(-5) to 5.6 x 10~(-2)s~(-1). A maximum elongation-to-failure of 440% was recorded at 175℃ (0.5T_m, where T_m is the melting point) and a strain rate of 2.8 x 10~(-5)s~(-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.