工程科学学报.第43卷，第4期：545-551.2021年4月 Chinese Journal of Engineering,Vol.43,No.4:545-551,April 2021 https://doi.org/10.13374/j.issn2095-9389.2020.02.18.004;http://cje.ustb.edu.cn 金属镁中去李晶过程与自间隙原子交互作用的分子动 力学模拟 马志超，汤笑之，郭雅芳区 北京交通大学土木建筑工程学院力学系，北京100044 ☒通信作者，E-mail:yfguo(@bjtu.edu.cn 摘要采用分子动力学方法研究了镁中102拉伸李晶在剪切载荷下的去孪晶过程，并探讨了去孪晶过程中孪晶界面与自 间隙原子的交互作用.研究结果表明：去李品过程中共格孪晶界对自间隙原子具有吸附作用，自间隙原子被共格李晶界吸附 并随之迁移，且随着共格孪晶界的消失而被释放.通过吸收和释放这两种交互作用，去孪晶过程将导致自间隙原子分布更为 密集.研究进一步给出了共格孪晶界对自间隙原子的吸附机理，即共格李晶界存在一个自间隙原子的自发吸收区，0K下宽 度约为0.752m,273K下约为3.59nm.去孪晶过程与自间隙原子的交互作用也将导致自间隙原子构型的变化.由于自间隙 原子的密集分布可在更长时间尺度上诱发位错环等晶体缺陷，这一研究有助于深入理解镁及镁合金的疲劳力学性能. 关键词镁：分子动力学：102拉伸孪晶：去孪晶：自间隙原子 分类号TG146.22 Atomistic simulation of detwinning process and its interaction with self-interstitial atoms in magnesium MA Zhi-chao,TANG Xiao-zhi.GUO Ya-fang Institute of Engineering Mechanics,School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China Corresponding author,E-mail:yfguo@bitu.edu.cn ABSTRACT Magnesium and its alloys have attracted extensive attention due to their favorable mechanical properties,such as low density and high specific strength.The detwinning process of (1012)tensile twins subjected to periodic loading is one of the microscopic mechanisms of fatigue damage in magnesium and its alloys.Moreover,self-interstitial atoms (SIAs)widely exist as a typical kind of point defects in metals.The migration,aggregation,and interaction with other defects,of SIAs affect the metal mechanical properties.In this work,molecular dynamics simulation was employed to study the detwinning process of(1012)twins under shear loads in magnesium,focusing on the interaction between the twin boundary and SIAs in the detwinning process.A simulation system containing two coherent twin boundaries(CTBs)with periodic boundary conditions applied along the two in-plane directions was adopted.The classic embedded atom method(EAM)interatomic potential developed by Liu et.al was used for simulation accuracy and comparison with other studies.The simulation results show that the SIAs are absorbed by the CTBs and migrate along with them.The absorbed SIAs can be released with the disappearance of the CTBs during the detwinning process.By the SIA adsorption and release,detwinning process will result in a more concentrated SIA distribution.The simulation results reveal that SIAs will be adsorbed by CTB if the distance between the CTB and SIA is less than 0.752 nm at 0K and 3.59 nm at 273 K.The energy barrier of the adsorption process is also obtained using the nudged elastic band (NEB)method.The SIA spatial distribution changes after the SIA 收稿日期：2020-02-18 基金项目：国家自然科学基金“面上"资助项目(11972071,11772043)金属镁中去孪晶过程与自间隙原子交互作用的分子动 力学模拟 马志超，汤笑之，郭雅芳苣 北京交通大学土木建筑工程学院力学系，北京 100044 苣通信作者，E-mail: yfguo@bjtu.edu.cn { 1012¯ } 摘    要    采用分子动力学方法研究了镁中 拉伸孪晶在剪切载荷下的去孪晶过程，并探讨了去孪晶过程中孪晶界面与自 间隙原子的交互作用. 研究结果表明：去孪晶过程中共格孪晶界对自间隙原子具有吸附作用，自间隙原子被共格孪晶界吸附 并随之迁移，且随着共格孪晶界的消失而被释放. 通过吸收和释放这两种交互作用，去孪晶过程将导致自间隙原子分布更为 密集. 研究进一步给出了共格孪晶界对自间隙原子的吸附机理，即共格孪晶界存在一个自间隙原子的自发吸收区，0 K 下宽 度约为 0.752 nm，273 K 下约为 3.59 nm. 去孪晶过程与自间隙原子的交互作用也将导致自间隙原子构型的变化. 由于自间隙 原子的密集分布可在更长时间尺度上诱发位错环等晶体缺陷，这一研究有助于深入理解镁及镁合金的疲劳力学性能. { 1012¯ } 关键词    镁；分子动力学； 拉伸孪晶；去孪晶；自间隙原子 分类号    TG146.22 Atomistic simulation of detwinning process and its interaction with self-interstitial atoms in magnesium MA Zhi-chao，TANG Xiao-zhi，GUO Ya-fang苣 Institute of Engineering Mechanics, School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China 苣 Corresponding author, E-mail: yfguo@bjtu.edu.cn 1012¯ 1012¯ ABSTRACT    Magnesium and its alloys have attracted extensive attention due to their favorable mechanical properties, such as low density and high specific strength. The detwinning process of { } tensile twins subjected to periodic loading is one of the microscopic mechanisms of fatigue damage in magnesium and its alloys. Moreover, self-interstitial atoms (SIAs) widely exist as a typical kind of point defects in metals. The migration, aggregation, and interaction with other defects, of SIAs affect the metal mechanical properties. In this work, molecular dynamics simulation was employed to study the detwinning process of { } twins under shear loads in magnesium, focusing on the interaction between the twin boundary and SIAs in the detwinning process. A simulation system containing two coherent twin boundaries (CTBs) with periodic boundary conditions applied along the two in-plane directions was adopted. The classic embedded atom method (EAM) interatomic potential developed by Liu et. al was used for simulation accuracy and comparison with other studies. The simulation results show that the SIAs are absorbed by the CTBs and migrate along with them. The absorbed SIAs can be released with the disappearance of the CTBs during the detwinning process. By the SIA adsorption and release, detwinning process will result in a more concentrated SIA distribution. The simulation results reveal that SIAs will be adsorbed by CTB if the distance between the CTB and SIA is less than 0.752 nm at 0 K and 3.59 nm at 273 K. The energy barrier of the adsorption process is also obtained using the nudged elastic band (NEB) method. The SIA spatial distribution changes after the SIA 收稿日期: 2020−02−18 基金项目: 国家自然科学基金“面上”资助项目（11972071，11772043） 工程科学学报，第 43 卷，第 4 期：545−551，2021 年 4 月 Chinese Journal of Engineering, Vol. 43, No. 4: 545−551, April 2021 https://doi.org/10.13374/j.issn2095-9389.2020.02.18.004; http://cje.ustb.edu.cn