Cu-50%Ni合金快速凝固过程中原子团簇演变的分子动力学模拟  

MOLECULAR DYNAMIC SIMULATION OF ATOMIC CLUSTERS EVOLUTION IN Cu-50%Ni ALLOY DURING RAPID SOLIDIFICATION

作　　者：刘俊[1] 赵九洲[1] 胡壮麒[1] 

机构地区：[1]中科院金属研究所,沈阳110016

出　　处：《金属学报》2005年第2期219-224,共6页Acta Metallurgica Sinica

基　　金：国家自然科学基金资助项目50395104

摘　　要：采用NPT分子动力学模拟方法,应用周期边界条件,模拟了Cu-50％Ni(原子分数)合金熔体在不同冷却过程中原子团簇的演变情况,给出了以1×1014K/s冷速冷却至室温时Cu-50％Ni非晶体系中存在的各种结构单元,并研究了Cu,Ni原子在这些结构单元中的排列情况.结果表明,较高冷速下形成的非晶具有较高的能量和较高的非晶转变温度(Tg).在冷却过程中,原子间的短程作用逐渐加强,PCF图第一峰值逐渐增大. 1551键对在非晶体系中占主导地位,且受冷速影响较大.体系中除了正二十面体外,还存在着各种缺陷多面体,其中含1551键对较多的缺陷多面体其数目也较多. FK多面体与Bernal多面体数目始终很少.大原子(Cu)易于占据多面体顶点,而小原子(Ni)则倾向于占据各多面体中心较大的空隙.随着冷速的降低,各多面体数目均有不同程度的下降.The molecular dynamic simulations have been performed to study the atomic clusters evolution during various cooling processes of Cu-50%Ni alloy (atomic fraction). The basic structure unit of Cu-50%Ni glass formed at the cooling rate Of 1x 10(14) K/s and the arrangement of Cu and Ni atoms in these structures are investigated. The results indicate that the glass formed at higher cooling rate has higher energy and higher glass transition temperature (T-g). The short-range interaction between atoms becomes stronger and stronger in the cooling process. 1551 bonded pair plays an important role in the glass system and is sensitive to cooling rates. Not only icosahedra but also various defective polyhedra are found in the glass. In these defective polyhedra, those composed with more 1551 bonded pairs have a larger number. There are few Frank-Kasper and Bernal polyhedra in the alloy. Generally Cu atoms tend to locate at the vertexes while Ni atoms prefer to occupy the interspaces at the center of the polyhedra. The total number of the polyhedra decreases with the decrease of the cooling rate.

关 键 词：Cu—Ni合金 快速凝固 原子团簇 分子动力学 

分 类 号：O561.1[理学—原子与分子物理]