Martensite phase structure of Mg-Sc lightweight shape memory alloy and the effect of rare earth elements doping

With the continual increase of application requirement of lightweight shape memory alloys (SMAs), MgSc alloys have drawn great attention as a new SMA. However, the ambiguous martensitic structure, unclear transformation path, and low martensitic transformation temperature (T-m) of Mg-Sc alloys are still issues. Herein, the martensitic structure and transformation path of Mg-Sc alloys were investigated systematically. The martensite phase was identified finally to be an orthorhombic structure by formation energy. Moreover, to improve the T-m, the effect of rare earth elements doping on T-m was studied, and T-m was increased by 28.2 K with 1.25 at.% Gd doping. The total density of states indicated that the phase stability determined the increase of T-m. Furthermore, the partial density of states indicated that the d orbital electrons coupling between Sc and Gd atom led to the changing of T-m. Our results provide a firm base for designing the new Mg-Sc-based lightweight SMAs. (c) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.