Computer Simulation of Effect of Sub-nano Particle for Dynamic and Thermal Behavior and Mechanical Properties in Amorphous and Crystalline Materials

1.采用分子动力学方法模拟了涂层与基体复合材料的纳米压痕损伤。分析了影响力学性能变化的因素。模拟模型由一个正方形底座的正棱锥压头、涂层和基体组成。原子间相互作用势用Lennard-Jones势近似。在恒定载荷和温度条件下，压头被迫进入涂层。材料的原子结构差异，即，改变了二元非晶和fcc晶体结构以及涂覆层的宽度。原子间相互作用势参数控制涂层的弹性常数、晶格常数和涂层与基体的结合能。涂层较大的杨氏模量减小了涂层的损伤。涂层中的压缩相干应变对材料的损伤较小。2.对纳米晶弥散非晶固体在恒定应力条件下的拉伸变形进行了分子动力学模拟。该系统由Ar-Al纳米晶体和Ar-Al非晶基体组成。分析了纳米晶的摩尔比、界面结合能和纳米晶的弹性常数对非晶复合材料的应变速率和屈服应力的影响。由杨氏模量和体积模量计算的刚性模量满足线性混合定律。

1.Molecular dynamics simulation was performed for damage of composites consisting of a coated layer and a substrate by nano indentation. Factors for the change of mechanical properties are analyzed. Simulation model is consisted of an indenter in the form of a right pyramid with a square base, coated layer and substrate. Interatomic potential are approximated by Lennard-Jones potential. The indenter is forced into the coated layer under constant load and temperature condition. Atomistic structure difference of the material, i.e., binary amorphous and fcc crystalline structure and width of the coated layer are changed. Elastic constant, lattice constant and binding energy between coated layer and substrate are controlled by the interatomic potential parameters. Large Young's modulus of the coated layer reduces the damage of layer. Compressive coherency strain in coating layer causes less damage of the material.2.Molecular dynamics simulation is performed for tensile deformation of Nano-crystal dispersed amorphous solid under constant stress condition. The system consists of Xe nano crystals and an Ar-Xe amorphous matrix. Effects of molar ratio of nano crystal, binding energy at inerface and elastic constants of nano crystal to strain rate and yield stress of the amorphous composit are analyzed. Rigidity modulus calculated from Young's modulus and bulk modulus satisfies the linear mixing law.