Mg2Ca相对镁合金形变和失效机理的影响

Effects of Mg2Ca phase on deformation and failure mechanisms of Mg alloys

摘要:

采用分子动力学(MD)模拟方法，在分析Mg-Ca合金中Mg基质和Mg2Ca稳定相机械性能基础上，对比揭示了Mg2Ca对多晶镁合金形变和失效机理的影响. 特定方向的单轴载荷下，单晶Mg伴随着活跃的锥面和柱面位错，有显著塑性形变. 单晶Mg2Ca无明显塑性形变，高刚度且脆性强烈. 对比多晶Mg/Mg2Ca复合材料的微观结构，在塑性形变过程中，Mg2Ca晶粒因其高刚度能减少合金位错并阻断相邻Mg基质中活跃的基面和锥面位错的传播，从而锚定周围原子. 而较弱的Mg/Mg2Ca界面容易产生裂缝，引起晶间断裂，最终使多晶镁合金失效.

Abstract:

Based on the analyzation of mechanical properties of Mg matrix and stable Mg2Ca phase, the effects of Mg2Ca on deformation and failure mechanisms of Mg-Ca alloys is revealed using molecular dynamic (MD) simulations. Under specific uniaxial loads, single crystal Mg has plastic deformation with active basal prismatic and pyramidal dislocations. Mg2Ca shows strong brittleness with high rigidity. Dynamic micro- mechanism of Mg/Mg2Ca nanocomposite reveals that Mg2Ca can reduce dislocations and block propagation of active basal and pyramidal dislocations in adjacent Mg matrix because of high rigidity, then anchor surrounding atoms in plastic deformation. Meantime, crack transferred from weaker Mg/Mg2Ca interface cause material intergranular fracture, leading to the final material failure.