Local Structure and Dynamics Procedure of Impurities Fe,Al and Mn in Melt Beryllium  

熔体铍中杂质Fe、Al和Mn的局域结构和动力学过程

作　　者：Zhang Jiqiang Jin Lei Luo Jiangshan Luo Bingchi Wu Weidong 张吉强;金雷;罗江山;罗炳池;吴卫东(中国工程物理研究院激光聚变研究中心,四川绵阳621900)

机构地区：[1]Research Center of Laser Fusion,China Academy of Engineering Physics,Mianyang 621900,China

出　　处：《稀有金属材料与工程》2024年第11期3046-3052,共7页Rare Metal Materials and Engineering

基　　金：National Natural Science Foundation of China(12104425);Supported by State Key Laboratory of Special Rare Metal Materials,Northwest Rare Metal Materials Research Institute Ningxia Co.,Ltd(SKL2020K001)。

摘　　要：The local structure and dynamics of impurities Fe,Al and Mn in beryllium were investigated on an atomic scale using ab initio molecular dynamics and statistical physics methods.The analysis of the radial distribution function centered on impurity atoms shows that the density of beryllium atoms around Fe and Mn is 8.4%and 8.6%higher than that around Al,respectively.The statistics of the measure square displacement of impurity atoms show that the diffusion coefficients of Al atoms are 114%and 133%larger than that of Fe and Mn atoms in the melt beryllium,respectively.Statistical analysis of velocity autocorrelation function of impurity atom shows that Fe and Mn atoms collide strongly with beryllium atoms in the first coordination layer,indicating that they are tightly surrounded and bound by the surrounding beryllium atoms in the central position,while the beryllium atoms around Al are loosely arranged and have weak binding forces with Al.The analysis of the activity coefficients of the impurities shows that when Fe or Mn enters the melt beryllium,it reduces the free energy of the system,whereas when Al enters,it increases the system energy.In summary,the interatomic force of BeAl is weak,so they do not form intermetallic compounds,and Al diffuses quickly in beryllium.While BeFe and BeMn have strong interatomic forces,and tend to form more BeFe and BeMn bonds to reduce the free energy of the system,so Fe and Mn diffuse slowly in beryllium.Ab initio molecular dynamics can be used to forecast the best experimental temperature for the vacuum distillation of beryllium.采用从头算分子动力学和统计物理方法,从原子尺度上研究了铍中杂质Fe、Al和Mn的局域结构和动力学过程。以杂质原子为中心的径向分布函数分析表明,Fe和Mn周围的铍原子密度分别比Al周围的铍原子密度高8.4%和8.6%。杂质原子平方位移的测度统计表明,熔融铍中Al原子的扩散系数分别比Fe和Mn原子大114%和133%。杂质原子速度自相关函数的统计分析表明,Fe和Mn原子在第一配位层与铍原子发生强烈碰撞,表明它们在中心位置被周围的铍原子紧密包围和束缚,而Al周围的铍原子排列松散,与Al的结合力较弱。杂质活度系数分析表明,当Fe或Mn进入熔体铍时,它降低了体系的自由能,而当Al进入时,它增加了体系能量。综上所述,BeAl原子间作用力较弱,因此它们不会形成金属间化合物,并且Al在铍中扩散迅速。而Be-Fe和Be-Mn具有很强的原子间作用力,并且倾向于形成更多的BeFe和BeMn键以降低体系的自由能,因此Fe、Mn在铍中扩散缓慢。从头算分子动力学可用于预测铍真空蒸馏的最佳实验温度。

关 键 词：BERYLLIUM PURIFICATION ab initio molecular dynamics local structure activity coefficients 

分 类 号：TG146.24[一般工业技术—材料科学与工程]