Zhao S, Li J H, An S M, Li S N, Liu B X
Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
Phys Chem Chem Phys. 2017 May 17;19(19):12056-12063. doi: 10.1039/c7cp00466d.
A realistic interatomic potential was first constructed for the Ca-Mg-Ni system and then applied to Monte Carlo simulations to predict the favored composition for metallic glass formation in the ternary system. The simulations not only predict a hexagonal composition region, within which the Ca-Mg-Ni metallic glass formation is energetically favored, but also pinpoint an optimized sub-region within which the amorphization driving force, i.e. the energy difference between the solid solution and disordered phase, is larger than that outside. The simulations further reveal that the physical origin of glass formation is the solid solution collapsing when the solute atom exceeds the critical solid solubility. Further structural analysis indicates that the pentagonal bi-pyramids dominate in the optimized sub-region. The large atomic size difference between Ca, Mg and Ni extends the short-range landscape and facilitates the development of a hybridized packing model in the medium-range, and eventually enhancing the glass formation in the system. The predictions are well supported by the experimental observations reported so far, and could be of help for designing the ternary glass formation.
首先为Ca-Mg-Ni体系构建了一个现实的原子间势，然后将其应用于蒙特卡罗模拟，以预测三元体系中形成金属玻璃的有利成分。模拟不仅预测了一个六边形成分区域，在该区域内Ca-Mg-Ni金属玻璃的形成在能量上是有利的，而且还确定了一个优化的子区域，在该子区域内非晶化驱动力，即固溶体和无序相之间的能量差，比外部更大。模拟进一步揭示，玻璃形成的物理起源是当溶质原子超过临界固溶度时固溶体的崩塌。进一步的结构分析表明，五角双锥体在优化子区域中占主导地位。Ca、Mg和Ni之间较大的原子尺寸差异扩展了短程结构，并促进了中程杂化堆积模型的发展，最终增强了体系中的玻璃形成。到目前为止，这些预测得到了实验观察结果的有力支持，并且可能有助于设计三元玻璃形成。
