Structural evolution and atomic dynamics in Ni–Nb metallic glasses: A molecular dynamics study
In this work, the composition and temperature dependence of static and dynamic structures in NixNb1–x (x = 50–70 at. %) were systematically studied using molecular dynamics with a new-released semi-empirical embedded atom method potential by Mendelev. The calculated pair correlation functions and the structure factor match well with the experimental data, demonstrating the reliability of the potential within relatively wide composition and temperature ranges. The local atomic structures were then characterized by bond angle distributions and Voronoi tessellation methods, demonstrating that the icosahedral $$\langle$$0,0,12,0$$\rangle$$ is only a small fraction in the liquid state but increases significantly during cooling and becomes dominant at 300 K. The most abundant clusters are identified as $$\langle$$0,0,12,0$$\rangle$$ and distorted icosahedron$$\langle$$0,2,8,2$$\rangle$$. The large fraction of these two clusters hints that the relatively good glass forming ability is near the eutectic point. Unlike Cu–Zr alloys, both the self-diffusion coefficient and shear viscosity are insensitive to compositions upon cooling in Ni–Nb alloys. The breakdown of the Stokes-Einstein relation happens at around 1.6Tg (Tg: glass transition temperature). In the amorphous state, the solid and liquid-like atoms can be distinguished based on the Debye-Waller factor $$\langle$$u2$$\rangle$$. The insensitivity of the dynamic properties of Ni–Nb alloys to compositions may result from the relatively simple solidification process in the phase diagram, in which only one eutectic point exists in the studied composition range.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- National Natural Science Foundation of China (NSFC); National Key Research and Development Program of China; Natural Science Foundation of Zhejiang Province; Fundamental Research Funds for the Central Universities
- Grant/Contract Number:
- Z1110196; Y4110192
- OSTI ID:
- 1608887
- Journal Information:
- Journal of Chemical Physics, Vol. 147, Issue 14; ISSN 0021-9606
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- ENGLISH
Web of Science
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