液态纯Mg黏度与自扩散系数的分子动力学模拟研究  

Research on Viscosity and Self-diffusion Coefficient of Liquid Mg by Molecular Dynamics Simulation

作　　者：肖钧江 赵旭 吴永全[1] XIAO Junjiang;ZHAO Xu;WU Yongquan(State Key Laboratory of Advanced Special Steel,Shanghai Key Laboratory of Advanced Ferrometallurgy,School of Materials Science and Engineering,Shanghai University,Shanghai 200072,China)

机构地区：[1]省部共建高品质特殊钢冶金与制备国家重点实验室,上海市钢铁冶金新技术开发应用重点实验室,上海大学材料科学与工程学院,上海200072

出　　处：《安徽工业大学学报（自然科学版）》2023年第3期261-268,共8页Journal of Anhui University of Technology（Natural Science）

基　　金：国家自然科学基金项目(52074178;51374141)。

摘　　要：Mg作为工业应用中最常见的金属之一,因高温活性的特点难以对其高温液态的黏度及扩散系数等性质参数进行实验检测。为此,通过均方位移(mean square displacement,MSD)和速度自相关函数(velocity auto-correlation function,VACF)2种方法,基于分子动力学(molecular dynamics,MD)模拟实验,计算液态Mg在不同温度下的自扩散系数;同时,通过压力自相关函数(stress auto-correlation function,SACF)计算其不同温度下的黏度。充分利用MD模拟的特征,将温度范围从熔点以上一直延伸至最大过冷度,即延伸至整个亚稳液态的温度区间。结果发现:MSD和VACF计算的对象分别是位置和速度,均为单粒子性能,计算时既能对时间做平均又能对空间做平均,2种方法的收敛性较SACF好;自扩散系数和温度之间符合阿伦尼乌斯公式,相应的活化能分别为30.05,29.87 kJ/mol;黏度(η)和温度(T)之间符合经验公式log η=-1.1+1 090/T。As one of the most common metals in industrial applications,it is difficult to experimentally measure the viscosity and diffusion coefficient of liquid Mg due to its high-temperature activity.Therefore,based on molecular dynamics(MD)simulation experiments,mean square displacement(MSD)and velocity auto-correlation function(VACF)were used to calculate the self-diffusion coefficient,and stress auto-correlation function(SACF)was used to calculate the viscosity of the liquid Mg.The merit of MD simulation was fully utilized to extend the temperature range from above the melting point to the maximum undercooling,that is,extending to the entire temperature range of the metastable liquid.The objects calculated by MSD and VACF are position and velocity,respectively,and both are single particle characters and are averaged on time and space,and thus the convergence of MSD and VACF methods is better than that of SACF.Besides,the temperature dependence of the self-diffusion coefficient agrees Arrhenius formula well and accordingly the cativity energies are achieved as 30.05,29.87 kJ/mol,respectively.Finally,an emprical formula,i.e.logη=-1.1+1090/T,is also achieved to describe the temperature dependence of viscosity.

关 键 词：液态Mg 分子动力学 黏度 自扩散系数 

分 类 号：TG146.2[一般工业技术—材料科学与工程]