高压条件下简单金属熔体的输运性质及其熵标度关系

Transport Properties and Entropy-Scaling Laws in Simple Liquid Metals under High Pressures

摘要: 本文利用经典分子动力学方法研究了在高温高压条件下Fe，Mo，Ta，W，Ni和Cu六种金属熔体的自扩散系数、粘度系数以及对关联熵随温度和压强的变化，验证了Rosenfeld提出的输运系数熵标度关系在高压条件下对金属熔体的适用性。研究结果表明金属熔体的自扩散系数(粘度系数)在给定的压强下满足Arrhenius关系，并且扩散激活能和粘度激活能随压强的增大而增大；Rosenfeld提出的输运系数熵标度关系在高温高压条件下对金属熔体依然使用。为此，在高温高压条件下实验中很难测量得到的金属熔体的输运性质(自扩散系数和粘度)可以通过较容易测量得到的结构性质(对分布函数或结构因子)利用输运系数熵标度关系计算得到。

Abstract: Molecular dynamic simulations are applied to study the temperature and pressure dependences of self-diffusion coefficient, viscosity and pair correlation entropy of the liquid Fe, Mo, Ta, W, Ni and Cu under high temperature and high pressure conditions. Our results suggest that the tem-perature dependences of self-diffusion coefficients and viscosity are well described by the Arrhenius law at given pressure and that the activation energy increases with increasing pressure. In particular, we find that the entropy-scaling laws proposed by Rosenfeld for self-diffusion coefficients and viscosity still hold well for the liquid metals under high temperature and pressure conditions. Using the entropy-scaling laws, we can obtain transport properties that are difficult to measure from the structural properties (the pair distribution functions or structural factor) which are easier to measure.