Formation and evolution of metastable bcc phase during solidification of liquid Ag: a molecular dynamics simulation study.
Formation and evolution of metastable bcc phase during solidification of liquid Ag: a molecular dynamics simulation study.
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DOI：
10.1021/jp804836b
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发表时间：
2008-12
期刊：
影响因子：
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通讯作者：
Z. Tian;Rang-su Liu;C. Zheng;Hai-rong Liu;Z. Hou;P. Peng
中科院分区：
文献类型：
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作者：
Z. Tian;Rang-su Liu;C. Zheng;Hai-rong Liu;Z. Hou;P. Peng
基于量子Sutton-Chen势，采用分子动力学方法研究了液态银在四种冷却速率下的快速凝固过程。采用多种分析方法，对冷却过程中微观组织之间的竞争和转变进行了深入的分析。发现在所有的模拟过程中都存在两个相变。第一种是从液态到亚稳（过渡）体心立方（bcc）相。初始晶化温度T（ic）随冷却速率的降低而升高。第二阶段是从体心立方相到最终固相的转变。该研究验证了Ostwald的台阶规则，并为亚稳bcc相首先由液相形成的预测提供了证据。进一步的分析表明，在273 K时，最终的固体可以是密排六方（hcp）和面心立方（fcc）结构的混合物，且两者的比例不同，冷却速度越慢，fcc结构所占的比例越高。
On the basis of the quantum Sutton-Chen potential, the rapid solidification processes of liquid silver have been studied by molecular dynamics simulation for four cooling rates. By means of several analysis methods, the competitions and transitions between microstructures during the cooling processes have been analyzed intensively. It is found that there are two phase transitions in all simulation processes. The first one is from liquid state to metastable (transitional) body-centered cubic (bcc) phase. The initial crystallization temperature T(ic) increases with the decrease of the cooling rate. The second one is from the transitional bcc phase to the final solid phase. This study validates the Ostwald's step rule and provides evidence for the prediction that the metastable bcc phase forms first from liquid. Further analyses reveal that the final solid at 273 K can be a mixture of hexagonal close-packed (hcp) and face-centered cubic (fcc) microstructures with various proportions of the two, and the slower the cooling rate is, the higher proportion the fcc structure occupies.