Low temperature superplasticity of ECAE processed Mg-10 % Li-1% Zn alloy

Abstract

In order to achieve low temperature superplasticity at relatively high strain rate in magnesium alloys, Mg-10 mass%Li-1 mass%Zn (LZ101) α + β two phase alloy was subjected to ECAE (Equal Channel Angular Extrusion) processing and tensile tests of the obtained specimens of the alloy were carried out to investigate the superplastic properties. In a specimen of the LZ101 alloy, which has improved microstructure through repetitive ECAE processing at 323 K, superplasticity occurs at 423 K, which is below Tm/2 (Tm: melting point of the alloy), under a relatively high strain rate of 1 × 10-3 s-1 with fracture elongation of 391%. Such a specimen after tensile test contains fine grains due to dynamic recrystallization and the precipitation of β phase along the grain boundaries and at triple points in recrystallized α phase. This microstructural change enhances grain boundary sliding, resulting in the occurrence of low temperature superplasticity at relatively high strain rate.