In-situ synthesis of Mg-based bulk metallic glass matrix composites with primary α-Mg phases

Abstract

Abstract Herein, we systematically investigate the in-situ synthesis and mechanical properties of Mg-based bulk metallic glass matrix composites (BMGMCs). From a well-known Mg65Cu25Gd10 bulk glass former, a series of Mg65+xCu20–2x/3Zn5Gd10−x/3 (x\xa0=\xa00–18\xa0at%) alloys are systematically designed and Mg-rich (>77\xa0at% Mg) glassy/crystalline matrix composites containing primary α-Mg phases are successfully developed. Mg77Cu12Zn5Gd6 BMGMC (x\xa0=\xa012\xa0at%) exhibits over two times higher compressive fracture strength (773\xa0±\xa020.6\xa0MPa) and specific strength (2.6\xa0×\xa0105 N\xa0m\xa0kg−1) than commercial Mg alloys such as AZ31 or AZ91. In particular, compared with monolithic Mg-based BMGs, the BMGMC displays obvious yielding, serrated plastic flow and plastic strain of 0.22\xa0±\xa00.02%. This result is attributed to the dispersed primary α-Mg phases which prevent the rapid propagation of shear bands and promote the formation of multiple shear bands. The Mg-rich crystalline matrix composites (x\xa0=\xa014-18\xa0at%) containing primary α-Mg phases exhibit an enhancement in the plastic strain (from 0% to 1.51%) and pronounced work hardening at the expense of yield strength (