Wen T Q, Tang L, Sun Y, Ho K M, Wang C Z, Wang N
MOE Key Laboratory of Materials Physics and Chemistry under Extraordinary Conditions, School of Natural and Applied Sciences, Northwestern Polytechnical University, Xi'an 710072, China.
Phys Chem Chem Phys. 2017 Nov 22;19(45):30429-30438. doi: 10.1039/c7cp05976k.
The marginal glass-forming ability (GFA) of a binary Ni-Zr system is an issue to be explained considering numerous bulk metallic glasses (BMGs) found in a Cu-Zr system. Using molecular dynamics, the structures and dynamics of NiZr metallic liquid and glass are investigated at the atomistic level. To achieve a well-relaxed glassy sample, a sub-T annealing method is applied and the final sample is closer to the experiments than the models prepared by continuous cooling. With the state-of-the-art structural analysis tools such as cluster alignment and pair-wise alignment methods, two glass-forming motifs with some mixed traits of a metastable B2 crystalline phase and a crystalline Ni-centered B33 motif are found to be dominant in the undercooled liquid and glass samples. A new chemical order characterization on each short-range order (SRO) structure is accomplished based on the cluster alignment method. The significant amount of the crystalline motif and the few icosahedra in the glassy sample deteriorate the GFA.
考虑到在铜锆体系中发现的大量块体金属玻璃（BMG），二元镍锆体系的边际玻璃形成能力（GFA）是一个有待解释的问题。利用分子动力学，在原子水平上研究了镍锆金属液体和玻璃的结构与动力学。为了获得充分弛豫的玻璃态样品，采用了亚T退火方法，最终样品比通过连续冷却制备的模型更接近实验结果。借助团簇排列和成对排列方法等先进的结构分析工具，发现在过冷液体和玻璃样品中，具有亚稳B2晶相和以镍为中心的B33晶相混合特征的两种玻璃形成基序占主导地位。基于团簇排列方法，对每个短程有序（SRO）结构完成了新的化学有序表征。玻璃态样品中大量的晶体基序和少量的二十面体降低了玻璃形成能力。
