Arrhenius relationship and two-step scheme in AF hyperdynamics simulation of diffusion of Mg/Zn interface  

Mg/Zn界面的AF超动力学中的阿累尼乌斯方程及两步法模拟机制(英文)

作　　者：吴永全[1] 陆秀明[1] 沈通[1] 

机构地区：[1]上海大学材料科学与工程学院,现代冶金与材料制备重点实验室,上海200072

出　　处：《Transactions of Nonferrous Metals Society of China》2013年第2期508-516,共9页中国有色金属学报（英文版）

基　　金：Project (2012CB722805) supported by the National Basic Research Program of China;Projects (50974083, 51174131) supported by the National Natural Science Foundation of China;Project (50774112) supported by the Joint Fund of NSFC and Baosteel, China;Project(07QA4021) supported by the Shanghai "Phosphor" Science Foundation, China

摘　　要：The accelerating factor （AF） method is a simple and appropriate way to investigate the atomic long-time deep diffusion at solid-solid interface. In the framework of AF hyperdynamics （HD） simulation, the relationship between the diffusion coefficient along the direction of z-axis which is normal to the Mg/Zn interface and temperature was investigated, and the AF＇s impact on the diffusion constant （D0） and activation energy （Q^＊） was studied. Then, two steps were taken to simulate the atomic diffusion process and the formation of new phases： one for acceleration and the other for equilibration. The results show that： the Arrhenius equation works well for the description of Dz with different accelerating factors; the AF has no effect on the diffusion constant Do in the case of no phase transition; and the relationship between Q＊ and Q conforms to Q^＊=Q/A. Then, the new Arrhenius equation for AFHD is successfully constructed as Dz=Doexp[-Q/（ART）]. Meanwhile, the authentic equilibrium conformations at any dynamic moment can only be reproduced by the equilibration simulation of the HD-simulated configurations. Key words： accelerating factor method; Arrhenius equation; two-steps scheme; Mg/Zn interface; hyperdynamic simulation加速因子(AF)法是解决固体界面原子深层扩散简单且适用的方法。在AF超动力学模拟的框架内,以Mg/Zn界面为例,首先研究原子沿界面z轴方向上的一维扩散系数Dz与温度的关系,进而探讨加速因子A对扩散常数、扩散激活能的影响;然后,在AF法的基础上,通过两步法对Mg/Zn界面的原子扩散及相形成过程进行模拟。结果表明,不同加速因子下的扩散系数Dz均较好地遵循Arrhenius方程;在没有发生相变的情况下,当扩散机制一定时,扩散常数D0的值与A无关;采用AF超动力学模拟时原子的扩散激活能Q*与原激活能Q的关系符合Q*=Q/A。据此,构建了AF超动力学模拟下的一维阿累尼乌斯方程:Dz=D0exp[Q/(ART)]。同时,AF法可以对界面相形成过程及其变化趋势作预测,且只有两步法才能确切得到不同传质阶段的体系平衡结构及平衡能量。

关 键 词：accelerating factor method Arrhenius equation two-steps scheme Mg/Zn interface hyperdynamic simulation 

分 类 号：TG111.6[金属学及工艺—物理冶金]