Cu64Zr36合金非晶剪切带形成的分子动力学模拟

Molecular Dynamics Simulation of Deformation of Shear Bands in Alloy Glass Metal Cu64Zr36

摘要:

用分子动力学 (MD) 模拟方法研究在轴向压缩下，冷却速率、应变率、环境温度、裂缝对Cu64Zr36二元非晶合金力学性能的影响。在模拟中，采用EAM势函数表述原子间的相互作用。计算结果表明：非晶的弹性模量和抗压强度都比晶体试样大一倍多，而当应变≥15%时两种试样的流动应力几乎相等；冷却速率缓慢得到的非晶试样由于原子发生重组变疏松，产生剪切带，而冷却速率较快得到的试样则没有发生重组；试样的弹性模量、抗压强度和流动应力对应变率变化很不敏感；随着环境温度的升高，流动应力、抗压强度和弹性模量降低；有初始裂纹的试样剪切带集中，从裂纹尖端开始，与加载方向呈45o方向扩展

Abstract:

The dynamic mechanical properties of a model binary Cu64Zr36 metallic glass under axial compression were obtained by molecular dynamics (MD) simulation. Cooling rate, strain rate, surrounding temperature and initial crack were investigated. In the simulation, EAM potential function was adopted to describe the relationship between atoms. Results show that the elastic modulus and the compressive strength of the metallic glass are twice more than those of the crystal metal. A main shear is generated in the specimen prepared at a slow cooling rate because of the rearrangement of atoms, while in the specimen prepared at fast cooling rate no atom rearrangement takes place. The elastic modulus, falling stress and flow stress are non-sensitive to strain rate. However, they decrease with increasing of surrounding temperature. The specimens with initial cracks show highly localized shear bands which are generated from the crack tip and propagate at the angle of 45o away from the loading direction