Structural and chemical orders in N i64.5 Z r35.5 metallic glass by molecular dynamics simulation

Abstract

The atomic structure of Ni64.5Zr35.5 metallic glass has been investigated by molecular dynamics (MD) simulations. The calculated structure factors from the MD glassy sample at room temperature agree well with the x-ray diffraction (XRD) and neutron diffraction (ND) experimental data. Using the pairwise cluster alignment and clique analysis methods, we show that there are three types of dominant short-range order (SRO) motifs around Ni atoms in the glass sample of Ni64.5Zr35.5, i.e., mixed-icosahedron(ICO)-cube, intertwined-cube, and icosahedronlike clusters. Furthermore, chemical order and medium-range order (MRO) analysis show that the mixed-ICO-cube and intertwined-cube clusters exhibit the characteristics of the crystalline B2 phase. Our simulation results suggest that the weak glass-forming ability (GFA) of Ni64.5Zr35.5 can be attributed to the competition between the glass forming ICO SRO and the crystalline mixed-ICO-cube and intertwined-cube motifs.