Chemical bonding effects on the brittle-to-ductile transition in metallic glasses
Chemical bonding effects on the brittle-to-ductile transition in metallic glasses
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DOI：
10.1016/j.actamat.2020.02.002
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发表时间：
2020-04
期刊：
影响因子：
9.4
通讯作者：
F. Moitzi;D. Şopu;D. Holec;D. Perera;N. Mousseau;J. Eckert
中科院分区：
文献类型：
--
作者：
F. Moitzi;D. Şopu;D. Holec;D. Perera;N. Mousseau;J. Eckert
采用大尺度分子动力学模拟方法研究了成分和温度对非晶态PdSi金属-类金属合金拉伸变形行为的影响。通过基于密度泛函理论电子结构计算的晶体轨道汉密尔顿布居分析，揭示了高方向性Si-Si键与形变机制之间的相关性.从垂直于加载方向的开裂到剪切带的转变可以通过提高温度或减少硅的量来实现。采样的鞍点上的势能表面上显示，高分数的刚性共价Si-Si键增加了原子重排的能量障碍。这些热激活的原子弛豫事件改变了弹性区域中的应力和应变状态，并且是局部塑性的前兆。高激活能阻碍应力和应变的重新分布，并导致解理样裂纹由于塑性的开始延迟。
The influence of composition and temperature on the tensile deformation behavior of amorphous PdSi metal-metalloid alloys is investigated using large-scale molecular dynamics simulations. A correlation between highly directional Si-Si bonds and the deformation mechanisms is revealed by a Crystal Orbital Hamilton Population analysis based on electronic structure calculations from density functional theory. A transition from cracking perpendicular to the loading direction to shear banding can be achieved by increasing the temperature or decreasing the amount of silicon. Sampling of the saddle points on the potential energy surface reveals that a high fraction of rigid covalent Si-Si bonds increases the energy barriers for atomic rearrangements. These thermally-activated atomic relaxation events change the stress and strain state in the elastic regime and are precursor of local plasticity. High activation energies impede both the stress and the strain redistribution and cause cleavage-like cracking due to a delay of the onset of plasticity.