论文部分内容阅读
通过分子动力学方法,研究了3种含相同半径、不同深度空洞的镍基单晶合金模型与理想模型纳米压痕过程的区别.采用中心对称参数分析4种模型在不同压入深度时基体内部位错形核、长大的过程以及空洞和错配位错对纳米压痕过程的影响.材料的压入荷载-压入深度曲线显示,空洞最浅的模型与理想模型相差最大.空洞对材料纳米压痕过程有2种作用,当压入深度较浅时(h<0.375 nm),空洞的存在会弱化材料,而当压入深度处于0.375~0.567 nm之间时,空洞表面的原子对位错的长大起到阻碍作用,使得压入荷载增加;空洞的坍塌会吸收一部分应变能,减少g相中层错的形成;当空洞完全坍塌后,位错会在空洞原始位置纠缠,并产生大量层错,使得压入荷载减小.g/g’相相界面存在空洞时,当达到最大压入深度,部分错配位错分解,且被g相表面吸收,形成表面台阶.处在最深位置的空洞并未对材料纳米压痕过程产生影响.
The molecular dynamics method was used to study the difference between three nano-single crystal alloy models with the same radius and different depths and the ideal model nanoindentation process.The center symmetry parameters were used to analyze the effect of four models on the microstructure, And the effect of void and mismatch dislocations on the nanoindentation process.The indentation load-depth curve of the material shows that the hollowed-out model has the largest difference from the ideal model.Void-to-material The nanoindentation process has two kinds of functions. When the depth of pressing is low (h <0.375 nm), the presence of voids weakens the material. When the depth of pressing is between 0.375 and 0.567 nm, the atomic alignment The wrong growth and obstruction will make the press-in load increase. The collapse of the void will absorb some of the strain energy and reduce the formation of layer faults in the g-phase. When the void completely collapses, the dislocation will entangle in the original position of the cavity and produce a large amount of Layer fault, so that the press-in load is reduced.When there is a cavity in the g / g ’phase interface, when the maximum depth of indentation is reached, part of the misfit dislocations are decomposed and absorbed by the g phase surface, forming a surface step. The hole is not material Material nano-indentation process has an impact.