The Portevin-Le Chatelier effect and strain-rate-induced plasticity enhancement in Mg-4Li and Mg-4Li-1Al alloys

Abstract The effects of strain rate on deformation behavior of the Mg-4Li and Mg-4Li-1Al alloys were investigated through tension testing and microstructure analysis. The Portevin-Le Chatelier effect was detected in tension testing of Mg-4Li alloy in the strain rate range of 5 × 10 –4 s −1 ∼ 1 × 10 –2 s −1 , and the effect was enhanced by the addition of 1% Al. The mechanism of Portevin-Le Chatelier effect was ascribed to the interaction between primary dislocations and pre-existing secondary forest dislocations. The strain rate sensitivity indexes of both Mg-4Li and Mg-4Li-1Al alloys were found as negative. With increasing strain rate, the yield strength and tensile strength of both alloys decreased, while the elongation increased.