合金元素比例对铜铅合金纳米拉伸力学特性的影响

铜铅合金由于铜的高塑性、高强度以及铅的自润滑功能,是经过实践检验证明的优良减磨材料,广泛应用于精密机械和航空航天领域中.为研究元素比例在铜铅合金材料纳米拉伸过程中对其力学特性的影响,采用Poisson-Voronoi和Monte Carlo方法建立大规模多晶铜分子动力学模型,在此基础上,采用混合蒙特卡洛/分子动力学方法(hybrid Monte Carlo/molecular dynamics, MC/MD)建立铜铅合金模型.根据真实铜铅合金比例成分建立具有不同铅原子比例的铜铅合金模型并与多晶铜纳米拉伸模型对比,模拟计算多晶体及铜铅合金的纳米拉伸过程,计算各模型的缺陷结构的配位数、内应力、原子势能等参数.结果表明:具有不同元素比例的铜铅合金纳米拉伸过程存在显著的规律性,铜铅合金和多晶铜的静水压力及势能分布相似,铅原子能够抑制铜铅合金晶界处位错的形核与扩展从而使合金材料结构更稳定,合金材料塑性变形过程中晶粒和晶界的势能变化特点相反,铅原子的加入主要影响晶界状态,晶界结构组成在合金塑性变形过程中具有主要作用.因而,通过改变铜铅合金中的元素比例,可改变合金材料各方面性能,本文的研究结果为制备高性能铜铅合金材料提供一定的理论指导.

Influence of fraction of alloy element on mechanical properties of copper-lead alloy materials during nano-tensile process

Due to the high plasticity and strength of copper and the self-lubricating function of lead, they are excellent wear antifriction material that have been tested and proved by practice and are widely used in the fields of precision machinery and aerospace. To study the effect of fraction of alloy element on the mechanical properties of copper-lead alloy during the nano-tensile process, a large-scale molecular dynamics simulation model of polycrystalline copper is structured by Poisson-Voronoi method and Monte Carlo method, and hybrid Monte Carlo/molecular dynamics (hybrid MC/MD) method is adopted to build the copper-lead alloy model. According to the real copper-lead materials, the model of copper-lead alloy with different element fraction and polycrystalline copper simulation are established. The nano-tensile process with different element fraction are simulated by molecular dynamics method, and the coordination number, internal stress and atomic potential energy of the atoms are calculated. The results show that there are significant regularities in the nano-tensile process of copper-lead alloy with different element fraction. The hydrostatic pressure and atomic potential energy distribution are similar between copper-lead alloy and polycrystalline copper, and lead atoms can suppress the dislocation of copper-lead alloy grain boundary, making the structure of grain boundary interface of the alloy material more stable. The variations of the potential energy of the grain cell and grain boundary interface during the plastic deformation of the alloy material is opposite. The fraction of lead atoms mainly affects the grain boundary interface state, and the grain boundary interface plays a major role in the plastic deformation process. Therefore, the properties of the alloy materials can be changed by changing the fraction of elements in copper-lead alloy. The research results in this paper provide some theoretical guidance for the preparation of high-performance copper-lead alloy materials.