Microstructural evolution and martensitic transformation mechanisms during solidification processes of liquid metal Pb
Microstructural evolution and martensitic transformation mechanisms during solidification processes of liquid metal Pb
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DOI：
10.1080/14786435.2011.630689
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发表时间：
2012-01
影响因子：
1.6
通讯作者：
L. Zhou;R. Liu;Z. Tian;H.R. Liu;Z. Hou;P. Peng;Q.H. Liu
中科院分区：
文献类型：
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作者：
L. Zhou;R. Liu;Z. Tian;H.R. Liu;Z. Hou;P. Peng;Q.H. Liu
采用分子动力学模拟方法研究了液态金属Pb凝固过程中的组织演变和马氏体相变（bcc-hcp和bcc-fcc）机理。结果表明，随着温度的降低，体系经历了两个相变：首先从液态过渡到亚稳的bcc相，然后从bcc相过渡到hcp和fcc相共存的晶体结构。利用聚类指数法（CTIM）和示踪法可以清晰地观察到复杂的马氏体相变过程。这两种转换机制在原子水平上非常相似；两者的本质区别在于，在bcc-hcp变换中，相邻两层的移动方向相反，而在bcc-fcc变换中，顶层和底层相对于中间层的移动方向相反。确认了bcc-hcp和bcc-fcc转化的具体机制分别对应于修正后的Burgers机制和Bain机制。
The microstructural evolution and the martensitic transformation (bcc–hcp and bcc–fcc) mechanisms during the solidification process of liquid metal Pb were studied by molecular dynamics simulation. Results indicate that, with the decrease of temperature, the system undergoes two phase transitions: from the liquid state into a metastable bcc phase first and then from the bcc phase into a coexisting crystal structure of hcp and fcc phases. Moreover, the complicated martensitic transformation processes are clearly observed by cluster type index method (CTIM) and the tracing method. The two transformation mechanisms are very analogous at the atomic level; the essential difference between them is that, in the bcc–hcp transformation, two adjacent layers shift in opposite directions, whereas in the bcc–fcc transformation, the top layer and bottom layer shift in opposite directions relative to the middle layer. The specific mechanisms for the bcc–hcp and bcc–fcc transformations are confirmed to correspond to the revised Burgers mechanism and Bain mechanism, respectively.