▎ 摘　　要

Magnesium alloy is regarded as a lightest engineering structural metal material due to its low density, butits wide application is limited due to poor plastic deformation behavior. Therefore, the comprehensivemechanical properties of enhanced magnesium alloy have become a research focus in the material science. Here,the effect of graphene on the deformation behavior and that on the mechanical properties of magnesium undertensile loading are studied by molecular dynamics simulation. The results show that the introduction ofgraphene can significantly improve the mechanical properties of pure magnesium. Comparing with puremagnesium, the Young's modulus and the first peak stress of the graphene magnesium matrix (GR/Mg)composites are increased by about 27.5% and 36.5% respectively, which is mainly due to the excellentmechanical properties of graphene. The results also indicate that the embedded position of graphene has littleeffect on the Young's modulus or peak stress of the GR/Mg composites, but it will significantly affect the plasticdeformation behavior of the GR/Mg composites after the second peak stress. With the increase of the embeddedheight of graphene, the average flow stress of the GR/Mg composites first increases in the later stage of plasticdeformation. When the embedded height reaches 0.4L, the average flow stress of the GR/Mg composites reachesa maximum value, and then decreases. This phenomenon of the Gr/Mg composites can be explained by theplastic deformation behavior of the magnesium matrix above and below graphene. The embedded position ofgraphene has a great influence on the plastic deformation behavior of the upper and lower magnesium matrix ofthe GR/Mg composites. When the embedded height of graphene is small, the plastic deformation capability ofmagnesium matrix under graphene is strong and dislocation slip is easy to occur. And when the embeddedheight of graphene is large, the plastic deformation capabilities of the two parts of magnesium matrix above andbelow graphene are equal, and their plastic deformation behavior tends to be synchronous. The results showthat the plastic deformation behavior of the GR/Mg composite is the same as that of pure magnesium, and thephase transition from HCP to BCC and then to HCP occurs in the process of the plastic deformation. Thephase transition mechanism of magnesium matrix is also analyzed in detail. The results of this study havecertain theoretical guiding significance in designing the high performance graphene metal matrix composites