双相纳米结构CuZr合金力学行为的模拟研究

Simulations on the mechanical behavior of dual-phase nanostructured CuZr alloy

摘要:

采用分子动力学方法研究了在拉伸载荷作用下，晶粒尺寸对纳米多晶Cu和双相纳米结构CuZr复合材料塑性变形机制的影响. 研究结果表明，小晶粒尺寸的纳米多晶Cu的变形机制以晶粒旋转以及晶界迁移为主，并伴随着少量位错的成核与滑移. 晶粒尺寸较大的纳米多晶Cu的塑性变形机制则以裂纹的成核与生长为主. 对于双相纳米结构Cu/CuZr复合材料，非晶相的塑性变形在复合材料的塑性变形过程中起主导作用，且这种现象与晶粒尺寸无关. 此外，当晶粒尺寸增加到一定尺寸时，复合材料的晶界处也出现了晶界裂纹，但非晶相明显延缓和阻碍了裂纹的成核与扩展. 研究表明非晶相的引入能有效提升纳米多晶Cu的塑性.

Abstract:

The effects of grain size on the deformation mechanisms of nano-polycrystal Cu and dual-phase nanostructured Cu/CuZr composites under tensile loading are studied by molecular dynamics method. The results show that for nano-polycrystal Cu with small grain size, the deformation mechanism is mainly dominated by grain rotation and grain boundary migration, accompanied by the nucleation and emission of a few dislocations. For nano-polycrystal Cu with large grain size, the plastic deformation mechanism is mainly dominated by the nucleation and growth of cracks. However, for the dual-phase nanostructured Cu/CuZr composites, the plastic deformation of amorphous phase plays a dominant role during plastic deformation, regardless of grain sizes. In addition, when the grain size becomes large, the grain boundary cracks also appear at the grain boundary of the composites, but the amorphous phase obviously hinders the nucleation and propagation of the cracks. The research shows that the introduction of amorphous phase can effectively enhance the plasticity of nano-polycrystal Cu.