〈100〉间隙型位错环在纯钨及含氦杂质钨(010)表面下运动行为的分子动力学模拟  

Molecular dynamics simulation of dynamic migration of〈100〉interstitial dislocation loops under(010)surfaces of pure W and W containing helium impurity

作　　者：秦梦飞 王英敏[2] 张红玉 孙继忠 Qin Meng-Fei;Wang Ying-Min;Zhang Hong-Yu;Sun Ji-Zhong(School of Physics,Dalian University of Technology,Dalian 116023,China;School of Materials Science and Engineering,Dalian University of Technology,Dalian 116023,China)

机构地区：[1]大连理工大学物理学院,大连116023 [2]大连理工大学材料科学与工程学院,大连116023

出　　处：《物理学报》2023年第24期212-219,共8页Acta Physica Sinica

基　　金：国家磁约束核聚变能发展研究专项(批准号:2019YFE03030004);国家自然科学基金(批准号:12275040)资助的课题。

摘　　要：在聚变辐照环境下,面向等离子体材料钨的近表层中会产生位错环缺陷,影响材料的力学性能和氢/氦滞留.本文通过分子动力学方法,从原子层次研究了半径1 nm的〈100〉间隙位错环在W-(010)近表面的迁移行为,分析取向、温度、深度因素和间隙原子对的存在对位错环运动的影响.结果表明:b//n(b代表柏氏矢量,n代表表面法线方向)位错环易向表面移动,b⊥n位错环倾向滞留在材料内,移动过程中伴随着惯习面翻转和内应力释放;b//n位错环在温度高于800 K且深度小于5 nm时逸出表面的概率超过90%,其他模拟情况下基本全滞留;b⊥n位错环可在温度800 K且深度小于2 nm时逸出表面,而在更深处位错环不易移动,但会在温度升高时发生〈100〉环分解为1/2〈111〉位错的现象;氦原子对的存在阻碍位错环迁移,延长其在材料内的滞留时间,同时内应力场的变化导致氦在近表层分布不均匀.In the fusion irradiation environment,dislocation loop defects occurring under plasma-facing tungsten surface affect its mechanical properties and hydrogen/helium retention.This paper studies the dynamic〈100〉(010)behaviors of a loop with a radius of 1 nm under the W surface by using molecular dynamics simulation at the atomic level.It is found that the dislocation loop direction,bulk temperature,depth,and b//nhelium atoms can greatly affect the motion of dislocation loops,showing that the dislocation loop,where b n is the Burgers vector and denotes the surface normal direction,tends to move towards the surface and the b⊥n dislocation loop tends to stay in the material.In the course of its migration,the habit plane of dislocation b//nloop may change and the internal stress decreases gradually.The probability of a b⊥n dislocation loops escaping from the surface is over 90%when the temperature is higher than 800 K and their initial depth is less b//nthan 5 nm.The dislocation loop can escape from the surface when the temperature is 800 K and the〈100〉1/2〈111〉initial depth is less than 2 nm.It is found that dislocation loops decompose into dislocations at elevated temperatures.Helium atoms impede the migration of dislocation loops and increase their retention time.The existence of dislocation loops results in the uneven distribution of helium atoms under the W surface,and will potentially affect the surface morphology of tungsten.

关 键 词：分子动力学模拟 位错环 映像力 氦 

分 类 号：O561[理学—原子与分子物理]