Guo K F, Zhang J C, Sha Z D, Pei Q X
International Center for Applied Mechanics, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi'an Jiaotong University, Xi'an 710049, China.
Institute of High Performance Computing, A*STAR, Singapore 138632, Singapore.
Phys Chem Chem Phys. 2021 Jan 21;23(2):1335-1342. doi: 10.1039/d0cp05715k.
Although minor alloying in metallic glasses (MGs) has been extensively investigated, the effect of O doping is still a debatable topic. In the present study, the atomic-level structures and mechanical properties of Zr-based MGs doped with different O contents have been analyzed using ab initio molecular dynamics simulations. It is revealed that O atoms prefer to bond to Zr atoms due to their low mixing enthalpy, and that O atoms degrade the properties of Zr-lean MGs but hardly affect the properties of Zr-rich MGs, with results suggesting a compositional dependence of O doping. For Zr-lean MGs, the fraction of full icosahedra, size of the medium-range-order clusters, Young's modulus and shear modulus decrease sharply with O content, while accompanied by a sharp increase of the non-Frank-Kasper polyhedra, and the ratio of bulk modulus to shear modulus and Poisson's ratio, indicating decreased strength and improved plasticity. For Zr-rich MGs, however, the above-mentioned structural and mechanical features experience little change or only change slightly after O doping, showing low oxygen sensitivity. It is shown that the high Zr content weakens the effect of Zr-O bonding to some extent. The present study not only sheds light on the atomic-level structures of O-doped MGs, which may provide guidelines for designing MGs with low-grade materials, but also helps to explain the previous conflicting results based on the composition-dependence effect.
尽管对金属玻璃（MGs）中的微量合金化已进行了广泛研究，但氧掺杂的影响仍是一个有争议的话题。在本研究中，使用从头算分子动力学模拟分析了不同氧含量掺杂的Zr基金属玻璃的原子级结构和力学性能。结果表明，由于氧原子的混合焓较低，它们倾向于与Zr原子键合，并且氧原子会降低贫Zr金属玻璃的性能，但对富Zr金属玻璃的性能影响很小，结果表明氧掺杂存在成分依赖性。对于贫Zr金属玻璃，随着氧含量的增加，全二十面体的比例、中程有序团簇的尺寸、杨氏模量和剪切模量急剧下降，同时非Frank-Kasper多面体、体积模量与剪切模量之比以及泊松比急剧增加，表明强度降低而塑性提高。然而，对于富Zr金属玻璃，上述结构和力学特征在氧掺杂后几乎没有变化或仅略有变化，显示出低氧敏感性。结果表明，高Zr含量在一定程度上削弱了Zr-O键的作用。本研究不仅揭示了氧掺杂金属玻璃的原子级结构，可为用低等级材料设计金属玻璃提供指导，还有助于基于成分依赖性效应解释先前相互矛盾的结果。
