Atomic-scale insights into microscopic mechanisms of grain boundary segregation in Al−Cu alloys  

铝铜合金晶界偏析微观机理的原子尺度研究

作　　者：Xiong SHUAI Hong MAO Sai TANG Yi KONG Yong DU 帅熊;毛鸿;唐赛;孔毅;杜勇(中南大学粉末冶金国家重点实验室,长沙410083;湖南理工学院机械工程学院,岳阳414006;中南大学轻质高强结构材料国家级重点实验室,长沙410083)

机构地区：[1]State Key Laboratory of Powder Metallurgy,Central South University,Changsha 410083,China [2]College of Mechanical Engineering,Hunan Institute of Science and Technology,Yueyang 414006,China [3]National Key Laboratory of Science and Technology on High-strength Structural Materials,Central South University,Changsha 410083,China

出　　处：《Transactions of Nonferrous Metals Society of China》2025年第1期1-12,共12页中国有色金属学报(英文版)

基　　金：supported by grants from the National Natural Science Foundation of China(Nos.52031017,51801237);the National Key Laboratory of Science and Technology on High-strength Structural Materials in Central South University,China(No.6142912200106).

摘　　要：This study aims to clarify the mechanisms for the grain boundary(GB)segregation through investigating the absorption of excess solute atoms at GBs in Al−Cu alloys by using the hybrid molecular dynamics/Monte Carlo simulations.Two segregation mechanisms,substitutional and interstitial mechanisms,are observed.The intergranular defects,including dislocations,steps and vacancies,and the intervals in structural units are conductive to the prevalence of interstitial mechanism.And substitutional mechanism is favored by the highly ordered twin GBs.Furthermore,the two mechanisms affect the GB structure differently.It is quantified that interstitial mechanism is less destructive to GB structure than substitutional one,and often leads to a segregation level being up to about 6 times higher than the latter.These findings contribute to atomic scale insights into the microscopic mechanisms about how solute atoms are absorbed by GB structures,and clarify the correlation among intergranular structures,segregation mechanisms and kinetics.通过采用分子动力学/蒙特卡洛联合模拟方法模拟铝铜合金中的过剩溶质原子在晶界的偏析过程,从而揭示晶界偏析的原子尺度微观机理。研究发现,晶界偏析过程中存在置换偏析和间隙偏析两种原子迁移机制。间隙偏析主要发生在晶界缺陷如位错、台阶面、空位和结构单元的空隙中;而置换偏析主要发生在具有较高有序度的孪晶界中。两种偏析机制对晶界结构的影响完全不同,间隙机制对晶界结构的破环性小于置换机制,并能够形成比后者更高(可达6倍)的溶质偏析程度。研究结果揭示了过量的溶质原子被吸附到晶界的原子尺度微观机理,并阐明了晶间结构、晶界偏析机理和偏析动力学之间的内在联系。

关 键 词：grain boundaries segregation Al−Cu alloy intergranular structure molecular dynamics simulation Monte Carlo simulation 

分 类 号：TG146.21[一般工业技术—材料科学与工程]