不同过冷度条件下HCP-Mg凝固过程中的空位捕获  

Vacancy trapping during HCP-Mg solidification under different degrees of undercooling

作　　者：付佳豪 张伯阳 张开 周涛 汪昊 吴永全 FU Jiahao;ZHANG Boyang;ZHANG Kai;ZHOU Tao;WANG Hao;WU Yongquan(State Key Laboratory of Advanced Special Steel,School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China)

机构地区：[1]上海大学材料科学与工程学院,省部共建高品质特殊钢冶金与制备国家重点实验室,上海200444

出　　处：《上海大学学报（自然科学版）》2023年第2期323-335,共13页Journal of Shanghai University:Natural Science Edition

基　　金：国家自然科学基金资助项目(52074178)。

摘　　要：采用不同的分子动力学(molecular dynamics, MD)技术模拟了密排六方(hexagonal close-packed, HCP)金属Mg在深、中、浅过冷度条件下的凝固及退火过程,并利用新建的时间平均原子体积谱(time-averaged atomic volume spectrum, TAVS)方法对空位进行了标定分析.结果表明:凝固过程中的空位捕获效应非常明显,即过冷度越大,捕获空位的浓度就越高,且远高于对应的平衡空位浓度.同时发现, HCP-Mg在凝固过程中存在一定量的自间隙原子.这与对称性更高的面心立方(face-centered cubic, FCC)金属Al完全不同.此外,HCP-Mg的空位原子(vacancy atoms, VA)笼存在外扩位移,而不是目前普遍公认的金属空位原子的内缩位移.Different molecular dynamics(MD)techniques were used to simulate the solid-ification and annealing processes of hexagonal close-packed(HCP)metal Mg under deep,medium,and shallow undercooling conditions.A newly constructed time-averaged atomic volume spectrum(TAVS)method was then utilized to locate and analyse the trapped va-cancies.The results showed that the vacancy trapping effect worked dramatically during solidification,meaning that the greater the degree of undercooling,the higher was the con-centration of trapped vacancies.In addition,the trapping concentration was much higher than the corresponding equilibrium concentration.Moreover,it was found that HCP-Mg had a certain number of self-interstitial atoms during the solidification process,which con-trasted fully with the more symmetrical face-centred cubic(FCC)metal Al.Finally,the atomic cage of vacancy in HCP-Mg featured a remarkable outward displacement instead of the generally accepted inward displacement of vacancy atoms(VA)in metals.

关 键 词：空位捕获 时间平均原子体积谱 分子动力学模拟 金属凝固 过冷度 

分 类 号：TG111.2[金属学及工艺—物理冶金]