Structural features and the microscopic dynamics of the three-componentă Zr47Cu46Al7 system: Equilibrium melt, supercooled melt, and amorphousă alloy

International audienceThe structural and dynamic properties of the three-component Zr47Cu46Al7ă system are subjected to a molecular dynamics simulation in theă temperature range T = 250-3000 K at a pressure p = 1.0 bar. Theă temperature dependences of the Wendt-Abraham parameter and theă translation order parameter are used to determine the glass transitionă temperature in the Zr47Cu46Al7 system, which is found to be T (c) ae 750ă K. It is found that the bulk amorphous Zr47Cu46Al7 alloy containsă localized regions with an ordered atomic structures. Cluster analysis ofă configuration simulation data reveals the existence of quasi-icosahedrală clusters in amorphous metallic Zr-Cu-Al alloys. The spectral densitiesă of time radial distribution functions of the longitudinal (CI integrală (L)(k, omega)) and transverse (CI integral (T) (k, omega)) fluxes areă calculated in a wide wavenumber range in order to study the mechanismsă of formation of atomic collective excitations in the Zr47Cu46Al7 system.ă It was found that a linear combination of three Gaussian functions isă sufficient to reproduce the (CI integral (L) (k, omega)) spectra,ă whereas at least four Gaussian contributions are necessary to exactlyă describe the (CI integral (T) (k, omega)) spectra of the supercooledă melt and the amorphous metallic alloy. It is shown that the collectiveă atomic excitations in the equilibrium melt at T = 3000 K and in theă amorphous metallic alloy at T = 250 K are characterized by twoă dispersion acoustic-like branches related with longitudinal andă transverse polarizations