Deformation analysis of amorphous metals based on atomic elastic stiffness coefficients
Deformation analysis of amorphous metals based on atomic elastic stiffness coefficients
复制标题
DOI：
10.1088/0965-0393/14/4/004
复制
发表时间：
2006-04
影响因子：
1.8
通讯作者：
K. Yashiro;M. Nishimura;Y. Tomita
中科院分区：
文献类型：
--
作者：
K. Yashiro;M. Nishimura;Y. Tomita
晶体的弹性极限可以用弹性刚度系数的正性来评价。我们已经证明了位错和解理裂纹等晶格缺陷的成核可以用每个原子点的原子Bijkl来预测。由于非晶金属和大块金属玻璃被认为是晶格缺陷的极限，因此无论这些标准是否适用，它们都引起了人们的强烈兴趣。本研究采用常规的熔断模拟法制备了非晶态Ni-Al二元合金，并采用分子动力学模拟方法对其进行了拉伸。在模拟过程中，讨论了所有原子的Bijkl正性。与Ni-Al晶体相反，许多原子在加载前甚至在非晶的初始平衡状态下也显示负值。这些不稳定原子原来是非簇原子或局部簇的外层，如12（0,0,12,0）二十面体。另一方面，局部团簇的中心原子表现出较高的稳定性，导致整个系统的正Bijkl。结果还表明，原子Bijkl的变化可以揭示变形过程中局部团簇的坍缩和重构。
The elastic limit of a crystal can be evaluated by the positiveness of elastic stiffness coefficients, Bijkl. We had demonstrated that the nucleation of lattice defects such as dislocation and cleavage cracking can be predicted by the atomic Bijkl at each atom point. Amorphous metals and bulk metallic glasses draw intense interest whether the criteria are applicable or not since they are regarded as the ultimate of lattice defects. In the present study, an amorphous Ni–Al binary alloy is made by a usual melt–quench simulation and subjected to tension by means of molecular dynamics simulation. During simulations, the positiveness of atomic Bijkl is discussed for all atoms. Contrary to an Ni–Al crystal, many atoms show negative value even in the initial equilibrium of the amorphous before loading. These unstable atoms turn out to be the non-clustered atom or the outer-shell of the local cluster such as 12(0, 0, 12, 0) icosahedron. On the other hand, the centre atoms of the local clusters show high stability resulting in the positive Bijkl of the whole system. It is also demonstrated that the change in the atomic Bijkl can reveal the collapse and re-configuration of local clusters during the deformation.