铌对单晶γ-TiAl合金裂纹扩展影响的分子动力学模拟

摘要

With molecular dynamics method the study of the crack propagation in single crystal γ-TiAl if mixed with Niobium in the atomic scale level was carried on.The atomic trajectory figure and energy evolution figure have been obtained by the simulation based on the crack propagation process under the establishment of a crystal structure model of γ-TiAl alloys.The energy and stress-strain relation of the γ-TiAl were analyzed in terms of the effect of niobium on crack propagation.The results indicate that the fracture time is prolonged at the same strain rate,and two crests and significant fluctuations in the energy varying curve can be found after adding niobium element;With the increase of strain,the stress increases firstly then decreases gradually;The growth of crack propagation is slow and the cross section is not smooth with the configuration of crack propagation changing.%为了研究微观尺度下铌元素对单晶γ-TiAl裂纹扩展过程的影响,运用分子动力学方法,建立γ-TiAl合金的晶体结构模型,模拟边缘裂纹扩展的过程,得到了裂纹扩展的轨迹图和能量演变图,分析了铌元素对γ-TiAl能量和应力-应变关系的影响,进而揭示了铌元素对裂纹扩展的影响.研究结果表明:加入铌元素后,在相同的应变率条件下,试件的断裂时间延长,能量变化曲线有两个波峰并且出现明显的上下波动的现象;随着应变增加,应力先增大后逐渐减小;裂纹扩展缓慢,形成的断面不平滑,而且裂纹扩展的形态也发生变化.