Grain boundary induced deformation mechanisms in nanocrystalline Al by molecular dynamics simulation: From interatomic potential perspective
Grain boundary induced deformation mechanisms in nanocrystalline Al by molecular dynamics simulation: From interatomic potential perspective
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DOI：
10.1016/j.commatsci.2018.10.021
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发表时间：
2019-01
影响因子：
3.3
通讯作者：
Liang Zhang;Y. Shibuta;Xiaoxu Huang;Cheng Lu;Mao Liu
中科院分区：
文献类型：
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作者：
Liang Zhang;Y. Shibuta;Xiaoxu Huang;Cheng Lu;Mao Liu
纳米晶金属具有许多优异的力学性能，其变形机制已得到广泛的研究。设计良好的原子模拟可以在实验之前预测材料的力学行为，并提供足够的原子尺度信息。选择合适的原子间相互作用势是任何原子模拟的主要问题之一，需要认真考虑，以获得可靠的结果。在这项研究中，我们研究了纳米晶铝在单轴加载下的力学响应和变形机制的分子动力学（MD）模拟与不同的嵌入原子方法（EAM）原子间势。电位的选取对模拟结果有重要影响，并根据文献中已有的实验数据对这些电位的可靠性进行了评估。在弹性阶段，模拟样品的应力应变响应和杨氏模量随电位的不同而变化。利用单晶铝的三个独立弹性常数预测了多晶铝样品的各向同性弹性模量。在塑性阶段，观察到多种晶界（GB）诱导变形机制，包括GB迁移，沿晶断裂，从GB的位错形核，和变形孪生。采用分子动力学方法计算了不同势下Al的广义层错能，讨论了它们对位错形核和形变孪晶机制的影响。这项工作标志着在纳米晶金属在塑性变形过程中发挥的重要作用，并强调了使用适当的原子间势的一个特定的模拟问题的意义。
Nanocrystalline metals exhibit many excellent mechanical properties and their underlying deformation mechanisms have been studying widespread. The well-designed atomistic simulations can predict the mechanical behavior of materials ahead of experiments and provide sufficient information on the atomic scale. The choice of appropriate interatomic potential is one of the main concerns of any atomistic simulation that needs to be seriously considered in order to obtain reliable results. In this study, we investigated the mechanical response and the deformation mechanisms of nanocrystalline Al under uniaxial loading by molecular dynamics (MD) simulations with different embedded atom method (EAM) interatomic potentials. The selection of potential has a significant influence on the simulation result, and the reliability of these potentials was evaluated based on the available experimental data in the literature. In the elastic stage, the stress-strain response and Young’s modulus of the simulated samples varied with different potentials. Three independent elastic constants of single crystal Al were used to predict the isotropic elastic modulus of the polycrystal Al sample. In the plastic stage, multiple grain boundary (GB) induced deformation mechanisms were observed, including GB migration, intergranular fracture, dislocation nucleation from GB, and deformation twinning. The generalized stacking fault energies of Al were calculated by MD simulation using different potentials, and their effects on the dislocation nucleation and deformation twinning mechanisms were discussed. This work signifies the important role of GBs play in nanocrystalline metals during plastic deformation and highlights the significance of using the appropriate interatomic potential for a specific simulation problem.