冲击加载下孔洞诱导相变形核分析

用分子动力学方法模拟了冲击加载(沿［001］向)下单晶Fe中孔洞诱导相变形核及生长过程,并分析了初始温度对这一生长过程的影响.数值模拟显示：1) 相变形核首先出现在孔洞周围的(110)和(110)面上,并分别沿［110］,［110］向和［110］,［110］向生长成片状,之后核的生长方向则变为沿〈111〉向,形成“V”形板条状新相颗粒;2) 在相同冲击压力下,初始温度为300 K时在新相晶核边缘出现许多核胚,生成的新相颗粒比60 K时明显减小.这些现象表明,孔洞诱导相变形核及生长过程沿着特定晶向进行,而初 关键词： 相变 孔洞 分子动力学

Study of nucleation of void-induced phase transformation under shock compression

Molecular dynamics simulations have been used to study the nucleation and growth of void-induced phase transformation of single crystal Fe under shock-wave loading along the ［001］ direction and effects of initial temperature on the process. It was found that: 1) phase transformation nucleates firstly on the (110) and (110) planes around the void and grows along the ［110］,［110］ and ［110］,［110］ directions, respectively, and then grow along 〈111〉 directions of the (110) and (110) planes, and ultimately “V" shaped grains form; 2) under the same shock compression, grains at initial temperature 300 K are smaller than those at 60 K, and at the same time, many embryos appear around the grains. These phenomena indicate that void-induced phase transformation nucleates and grows along certain directions, and increasing the initial temperature can diversify the action. Finally, we calculate the statictics of pressure-volume tensor and energy distributions, and give a preliminary analysis of the nucleation and growth of phase transformation.