Cooling rate dependence of simulated Cu64.5Zr35.5 metallic glass structure
RE Ryltsev and BA Klumov and NM Chtchelkatchev and KY Shunyaev, JOURNAL OF CHEMICAL PHYSICS, 145, 034506 (2016).
Using molecular dynamics simulations with embedded atom model potential, we study structural evolution of Cu64.5Zr35.5 alloy during the cooling in a wide range of cooling rates gamma is an element of (1.5 center dot 10(9),10(13)) K/s. Investigating short-and medium-range orders, we show that the structure of Cu64.5Zr35.5 metallic glass essentially depends on cooling rate. In particular, a decrease of the cooling rate leads to an 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 center dot 10(9) K/s. Analysing the structure of the glass at gamma(min), we observe the formation of nano-sized crystalline grain of Cu2Zr intermetallic compound with the structure of Cu2Mg Laves phase. The structure of this compound is isomorphous with that for Cu5Zr intermetallic compound. Both crystal lattices consist of two types 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 of Cu-Zr system and explains the drastic increase of the abundances of these clusters observed at gamma(min). Published by AIP Publishing.
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