马志超, 汤笑之, 郭雅芳. 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[J]. 工程科学学报, 2021, 43(4): 545-551. DOI: 10.13374/j.issn2095-9389.2020.02.18.004
引用本文: 马志超, 汤笑之, 郭雅芳. 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[J]. 工程科学学报, 2021, 43(4): 545-551. DOI: 10.13374/j.issn2095-9389.2020.02.18.004
MA Zhi-chao, TANG Xiao-zhi, GUO Ya-fang. Atomistic simulation of detwinning process and its interaction with self-interstitial atoms in magnesium[J]. Chinese Journal of Engineering, 2021, 43(4): 545-551. DOI: 10.13374/j.issn2095-9389.2020.02.18.004
Citation: MA Zhi-chao, TANG Xiao-zhi, GUO Ya-fang. Atomistic simulation of detwinning process and its interaction with self-interstitial atoms in magnesium[J]. Chinese Journal of Engineering, 2021, 43(4): 545-551. DOI: 10.13374/j.issn2095-9389.2020.02.18.004

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

Atomistic simulation of detwinning process and its interaction with self-interstitial atoms in magnesium

  • 摘要: 采用分子动力学方法研究了镁中\left\ 10\bar 12 \right\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。

     

    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 10\bar 12 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 10\bar 12 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 interactions with CTB in detwinning process. Given that the crystal defects such as dislocation loops can be induced by the dense distribution of SIAs at a long timescale, this study clarifies the fatigue mechanical properties of magnesium and magnesium alloys subjected to periodic loading.

     

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