Cheng Yun, Peng Chuanxiao, Zhang Zhenting, Wang Pengfei, Yuan Shengzhong, Wang Li
School of Mechanical, Electrical & Information Engineering, Shandong University (Weihai), 180 Wenhua Xi Road, Weihai 264209, China.
Materials (Basel). 2017 Nov 27;10(12):1361. doi: 10.3390/ma10121361.
Although pressured metallic glass (MG) has been reported in the literature; there are few studies focusing on pressure effects on the structure; dynamics and its plastic deformation. In this paper; we report on and characterize; via molecular dynamics simulation, the structure and dynamics heterogeneity of pressured MGs, and explore a causal link between local structures and plastic deformation mechanism of pressured glass. The results exhibit that the dynamical heterogeneity of metallic liquid is more pronounced at high pressure, while the MGs were less fragile after the release of external pressure, reflected by the non-Gaussian parameter (NGP). High pressure glass shows better plastic deformation; and the local strain zone distributed more uniformly than of in normal glass. Further research indicates that although the number of icosahedrons in pressured glass was much larger than that in normal glass, while the interpenetrating connections of icosahedra (ICOI) exhibited spatial correlations were rather poor; In addition, the number of 'fast' atoms indexed by the atoms' moving distance is larger than that in normal glass; leading to the sharp decreasing in number of icosahedrons during deformation. An uniform distribution of 'fast' atoms also contributed to better plastic deformation ability in the pressured glass. These findings may suggest a link between the deformation and destruction of icosahedra with short-range order.
尽管文献中已报道了受压金属玻璃（MG），但很少有研究关注压力对其结构、动力学及其塑性变形的影响。在本文中，我们通过分子动力学模拟报告并表征了受压金属玻璃的结构和动力学非均匀性，并探索了受压玻璃的局部结构与塑性变形机制之间的因果关系。结果表明，金属液体的动力学非均匀性在高压下更为明显，而外部压力释放后，金属玻璃的脆性降低，这由非高斯参数（NGP）反映出来。高压玻璃表现出更好的塑性变形能力，且局部应变区比普通玻璃分布更均匀。进一步研究表明，尽管受压玻璃中二十面体的数量比普通玻璃多得多，但二十面体的相互贯穿连接（ICOI）的空间相关性相当差；此外，以原子移动距离为指标的“快速”原子数量比普通玻璃多，导致变形过程中二十面体数量急剧减少。“快速”原子的均匀分布也有助于受压玻璃具有更好的塑性变形能力。这些发现可能表明二十面体的变形与破坏与短程有序之间存在联系。
