A Kind of New Stress-Induced Bcc-Hcp Martensitic Transformation at Room Temperature in �-Type Mg-35wt.%Sc Alloy

Abstract

The β-type Mg-Sc alloys have attracted intensive attention due to their martensitic transformation behavior. However, the relatively low martensitic transformation temperature limits their practical application. In this paper, the β-type Mg-35wt.%Sc alloy sheet with a thickness of 2 mm was prepared by quenching. The stress-induced martensitic transformation was found in the β-type alloy during tensile testing at room temperature, while the phase transformation does not occur in the fractured α-type alloy. The stress-induced martensite was confirmed to be an hcp-based structure. Both of lath and lenticular martensites can be observed in the fractured β-type alloy. The substructure of lath martensite is the high-density dislocations, while the substructure of lenticular martensite is twins and dislocations. In addition, the reason for the occurence of bcc-hcp martensitic transformation in β-type Mg-35wt.%Sc was discussed. The finding of new bcc-hcp martensitic transformation at room temperature is of great significance to overcome the strength-ductility trade-off of Mg alloys.

Keywords: Magnesium alloy, Scandium, Stress-induced martensitic transformation, Hexagonal close-packed structure, Substructure.