An in-depth investigation of the microstructural evolution and dynamic properties of Zr77Rh23 metallic liquids and glasses: A molecular dynamics simulation study

Abstract

The microstructural evolutions and dynamic properties of the Zr77Rh23 alloy during the rapid cooling process have been studied by molecular dynamics (MD) simulations using tight-binding (TB) potential. The total pair distribution functions [or structure factors, S( q)], g( r), calculated at different temperatures are in good agreement with the ab initio MD (AIMD) simulation (or experimental) results. The splitting in the second peak of all g( r) is notable for the formation and development of a medium-range order (MRO) in the Zr77Rh23 system. Moreover, the total number of atoms determined from TB-MD simulations at 300 K is also consistent with the number of atoms of the three shells for the Bergman-type MRO cluster and AIMD simulation results. By analyzing the structure of the system with methods such as the Honeycutt–Andersen index, Voronoi tessellation, and bond-angle distribution, it has been shown that the icosahedron short-range order (SRO) increases upon cooling. The dominant short-range structure in Zr77Rh23 metallic glass is found to consist mostly of perfect and distorted icosahedral clusters. The findings show that, for all temperatures, Zr atoms have greater mobility than Rh atoms. The critical temperature Tc estimated from fitting the mode-coupling theory equation is ∼993 K. A dynamic crossover is observed at temperatures around Tc. The present findings contribute to understanding the nature of the atomic local structures of the Zr77Rh23 alloy during the cooling process and the formation of SRO/MROs in metallic glasses.