温度对超薄铜膜疲劳性能影响的分子动力学模拟

用嵌入原子势的分子动力学方法模拟了温度对超薄铜膜疲劳性能的影响. 通过模拟, 首先给出了超薄铜膜的总能及应力随循环周次的变化曲线; 根据叠加经验式得出的叠加量随循环周次变化曲线, 判断出各种恒定温度下超薄铜膜的疲劳寿命. 由 200–400 K温度范围内超薄铜膜的疲劳寿命-温度变化曲线, 可以发现存在两个温度区域: 在约370 K以下, 超薄铜膜的疲劳寿命随温度升高缓慢增加, 而在约370 K以上增加较快. 建立了模型并用位错演化机制解释了超薄铜膜疲劳寿命的温度依赖关系. 关键词： 分子动力学 疲劳 温度效应 位错

Temperature dependence of fatigue properties of ultrathin copper films: molecular dynamics simulations

The molecular dynamics simulations are performed with single-crystal copper thin films under cyclic loading to investigate temperature effects on the mechanical responses. First, the method to determine the number of cycles to failure is reported: the total energy-the number of cycles curve and the stress-the number of cycles curve for nanoscale copper film are obtained; using the two curves and an additional quantitative expression, we obtain the additional quantity-the number of cycles curve, from which fatigue life of copper film is obtained. Next, under cyclic loading, with temperature rising, the number of cycles to failure of copper films increases in different manners at different temperatures: when the temperature is above about 370 K, the number of cycles to failure goes up quickly with temperature; when below about 370 K, the number of cycles rises slowly. Finally, the mechanisms of the strange temperature dependence of cyclic deformation can be explained by our developed model based on the evolutionary features of dislocation.
Keywords： molecular dynamics fatigue temperature effect dislocation