薄W(111)和W(110)晶面熔化的原子模拟  

Atomistic Simulation of the Melting of Thin W(111) and W(110) Planes

作　　者：阳喜元[1] 

机构地区：[1]湖南文理学院,湖南常德415000

出　　处：《稀有金属材料与工程》2012年第2期289-293,共5页Rare Metal Materials and Engineering

基　　金：湖南省自然科学基金(08JJ3091);湖南省'十一五'重点建设学科(光学)资助

摘　　要：根据改进分析型嵌入原子法(MAEAM),利用分子动力学(MD)模拟研究含表面薄W(111)和W(110)晶面熔化机制。首先研究温度对晶面表层原子均方位移(MSD)的影响,表明表面和非谐效应对晶面结构和性质影响明显,且原子振动呈现各向异性的特点。在此基础上进一步分析其原子密度函数(ADF)和结构因子(SF)随温度变化,发现薄W(111)和W(110)晶面熔化机制不同,对于W(111)晶面,表面在其熔化转变过程中起主要作用,在3700K完全熔化,拟合无序原子分数随温度变化表明W(111)晶面预熔-熔化转变温度为3550K;而W(110)晶面则出现过热,直到4000K完全熔化,非谐效应在其熔化转变中起主要作用。By means of molecular dynamics （MD） simulations, the melting mechanism of thin W（111） and W（110） planes with free surfaces has been studied with the modified analytic embedded-atom method （MAEAM）. Firstly, the results obtained by calculating the temperature dependence of mean square displacement （MSD） indicate that the influence of surface and anharmonic effect on the microstructure and properties of planes are significant and the vibration of atoms locating in the surface region is anisotropic. Then, according to providing further investigation into the temperature dependence of the atomic density function （ADF） and structural factor （SF） of the given atomic planes, it is found that the melting mechanisms and processes of both membranes are different. For the W（111） plane, the free surface plays an important role in the melting transition. The W（111） plane entirely becomes disordering at 3700 K which is in agreement with the calculated melting temperature. The fitted relation between the fraction of the disordered atom and the temperature demonstrates that the premelting-melting transition temperature is about 3550 K. Instead, the W（110） plane is melted when the temperature reaches 4000 K, which is so-called superheating. And the melting transition of this plane relies strongly on the anharmonic effect.

关 键 词：熔化 微观结构 薄晶面 原子模拟 

分 类 号：TG111[金属学及工艺—物理冶金]