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采用多尺度准连续介质法(简称QC方法)对单晶Ag薄膜纳米压痕过程进行模拟,研究压头宽度对纳米压痕过程中接触应力分布、位错形核临界载荷以及纳米硬度的影响,并用Rice-Thomson位错模型(简称R-T位错模型)进行分析。结果表明,纳米压痕获得的载荷-位移曲线呈现出的不连续性与位错之间的协同作用密切相关;压头尺寸对纳米压痕过程中接触应力分布、位错形核临界载荷以及纳米硬度具有明显的影响:随着压头宽度的增加,法向和切向接触应力以及纳米硬度值递减,呈现出明显的压头尺寸效应;而压头下方薄膜内位错形核临界载荷却递增,且与压头半宽度的平方根成正比。模拟结果与相应实验结果以及R-T位错模型计算结果吻合。
The multi-scale quasi-continuous media method (QC method) was used to simulate the nanoindentation process of single-crystal Ag thin films. The influence of indenter width on the contact stress distribution, the critical load of dislocation nucleation and the nano-hardness during nanoindentation was studied. The Rice-Thomson dislocation model (referred to as RT dislocation model) was used for analysis. The results show that the discontinuity of the load-displacement curve obtained by nanoindentation is closely related to the synergy between the dislocations. The influence of indenter size on the contact stress distribution, the critical load of dislocation nucleation, Hardness has a significant effect: With the increase of indenter width, the normal and tangential contact stress and nanohardness value decrease, showing a significant effect of head size; while under the indenter, the critical load of dislocation nucleation increases , And is proportional to the square root of the half width of the indenter. The simulation results are in good agreement with the corresponding experimental results and the R-T dislocation model.