Cooling rate dependence of simulated $\mathrm{C}{\mathrm{u}}_{64.5}\mathrm{Z}{\mathrm{r}}_{35.5}$ metallic glass structure

Abstract

Using molecular dynamics simulations with embedded atom model potential, we study structural evolution of $\mathrm{C}{\mathrm{u}}_{64.5}\mathrm{Z}{\mathrm{r}}_{35.5}$ alloy during the cooling in a wide range of cooling rates $\gamma \in (1.5\cdot 10^9,10^{13})$ K/s. Investigating short- and medium-range order, we show that structure of $\mathrm{C}{\mathrm{u}}_{64.5}\mathrm{Z}{\mathrm{r}}_{35.5}$ metallic glass essentially depends on cooling rate. In particular, a decrease of the cooling rate leads to a increase of abundances of both the icosahedral-like clusters and Frank-Kasper Z16 polyhedra. The amounts of these clusters in the glassy state drastically increase at the ${\gamma }_{\min }=1.5\cdot 10^9$ K/s. Analysing the structure of the glass at ${\gamma }_{\min }$, we observe the formation of nano-sized crystalline grain of $\mathrm{C}{\mathrm{u}}_2\mathrm{Zr}$ intermetallic compound with the structure of $\mathrm{C}{\mathrm{u}}_2\mathrm{Mg}$ Laves phase. The structure of this compound is isomorphous with that for $\mathrm{C}{\mathrm{u}}_5\mathrm{Zr}$ intermetallic compound. Both crystal lattices consist of two type of clusters: Cu-centered 13-atom icosahedral-like cluster and Zr-centered 17-atom Frank-Kasper polyhedron Z16. That suggests the same structural motifs for the metallic glass and intermetallic compounds and explains the drastic increase of the abundances of these clusters observed at ${\gamma }_{\min }$.

12 pages, 11 figures

References in corpus (3)

• The role of local structure in dynamical arrest
• Identification of long-lived clusters and their link to slow dynamics in a model glass former
• Gauge theory description of glass transition

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• Excellent glass former Ni${}_{62}$Nb${}_{38}$ crystallizing under combined shear and ultra-high pressure
• Green-Kubo stress correlation function at the atomic scale and a long-range bond-orientational ordering in a model liquid
• Polytetrahedral short-range order and crystallization stability in supercooled $\mathrm{C}{\mathrm{u}}_{64.5}\mathrm{Z}{\mathrm{r}}_{35.5}$ metallic liquid
• Anomalous behavior and structure of a liquid of particles interacting through the harmonic-repulsive pair potential near the crystallization transition