A Molecular Dynamics Study on the Local Structure of Al90Sm10 Marginal Metallic Glass and Liquid

The liquid and the amorphous Al 90 Sm 10 marginal metallic glassy alloy are investigated using Molecular Dynamics. The Al 90 Sm 10 system consisting of 32,000 atoms is simulated under the constant number of atoms, pressure, and temperature (NPT) ensemble where the temperature and pressure are controlled via Nose–Hoover thermostat and barostat, respectively. The corresponding liquid model is initially held at 2300 K; then, the liquid is continuously cooled down to 300 K with a constant cooling rate of 10 10 Ks −1 , during which representative structures were obtained at each 200 K intervals. At every critical interval, radial distribution functions and structure factors are calculated. Local structural arrangements are analyzed using the Voronoi tessellation technique. These analyses indicate a chemically inhomogeneous liquid structure with large pure Al regions divided by a network of Sm-rich clusters, due to the high correlation of Al atoms at high temperatures. As the temperature of the liquid decreases, the amount of Al correlated with Sm in the first shell neighborhood increases . This makes the pure Al regions become smaller in size and widely separated. These pure Al regions in the amorphous solid are thought to be the possible nucleation sites for fcc-Al nanocrystals observed upon the devitrification of marginal metallic glasses.