Effect of rare earth Th on thermophysical properties of ternary Co–Fe–Th liquid alloy
Effect of rare earth Th on thermophysical properties of ternary Co–Fe–Th liquid alloy
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DOI：
10.1016/j.jallcom.2012.07.106
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发表时间：
2012-12
影响因子：
6.2
通讯作者：
W. Yao;J. Li;Jinjin Wang;N. Wang
中科院分区：
文献类型：
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作者：
W. Yao;J. Li;Jinjin Wang;N. Wang
利用EAM势的蒙特卡罗方法，计算了液态Co–50at%Fe和Co–48.5at%Fe–3at%Th合金在不同温度下的热物理性质，包括表面张力（σ）、粘度（η）和扩散系数（D）。研究了 Th 对热物理参数的影响。在1500~2000K温度范围内，表面张力从σb=1.795−5.140×10−4(T−Tm)N/m减小到σb=1.630−6.433×10−4(T–T0)N/m，粘度从ηb=1.173e15,169RTmPas增大到添加Th后，ηt=1.159e16,660RTmPas。同时，随着Th的添加，Fe和Co的扩散系数降低了9.2%，扩散活化能增加了3.8%，从29,997增加到31,165Jmol−1。正是由于Th元素的加入，其原子半径较大，原子质量较大，核外电子排列复杂，导致表面张力降低，粘度增大，扩散活化能增强。 Th 对扩散系数贡献的根本机制应归因于液体中不同短程和中程有序结构的形成。
By Monte Carlo method with EAM potentials, the thermophysical properties, including the surface tension (σ), the viscosity (η), and the diffusion coefficient (D) of liquid Co–50at%Fe and Co–48.5at%Fe–3at%Th alloys at different temperatures are calculated. The effect of Th on the thermophysical parameters is examined. Over the temperature range from 1500 to 2000K, the surface tension decreases from σb=1.795−5.140×10−4(T−Tm)N/m to σb=1.630−6.433×10−4(T–T0)N/m, and the viscosity increases from ηb=1.173e15,169RTmPas to ηt=1.159e16,660RTmPas after Th was added. Meanwhile, with the addition of Th, the diffusion coefficients of Fe and Co decrease 9.2% and the diffusion activation energy increases 3.8% from 29,997 to 31,165Jmol−1. It is the addition of Th element which has bigger atomic radius, larger atomic mass, and complex arrangement of extranuclear electron, leads to the reduced surface tension, increased viscosity, and enhanced diffusion activation energy. The underlying mechanism of the contribution of the Th to the diffusion coefficient should be ascribed to the formation of different short and medium range order structures in liquids.