Structure of liquid metals by ab initio molecular-dynamics simulations

Probing the self-diffusion process in Aluminium

An in-depth understanding of the diffusion process in liquid metals is a key to design and engineering new high-performance materials. In this study, using molecular dynamics simulations supplemented with the embedded atom potential, we investigate/compare the self-diffusion process in liquid Aluminium. To understand the self-diffusion process, we analyse the radial distribution functions, velocity distributions, mean square displacements, and self-diffusion coefficients at various temperatures well above the melting temperature of Aluminium in the temperature range of 1000 K to 1800 K. As a key result, in both the [Formula: see text] and [Formula: see text] phases, the self-diffusion coefficients show a non-linear variation with rise in temperatures in the range of 1000 K to 1200 K. From 1300 K to 1800 K, the self-diffusion coefficients increase more or less monotonically with rise in temperature. We found that a higher temperature in the range of 1300 K to 1800 K leads to a greater self-diffusion coefficient, suggesting the more violent movement of the atoms around their equilibrium positions. The results presented in this work can help to understand the differences in the self-diffusion process in the technologically relevant Al phases.

Pressure dependence of the structure of liquid NiTi: a molecular dynamics study

We evaluate the structure of liquid NiTi under various pressures from 0 GPa to 40 GPa in the atomic level using molecular dynamics simulations. The structure factor and radial distribution function are used to investigate the general structural change of the system. Further identification of the local structures is examined by the bond-angle method and bond-angle distribution analysis. From our results, we found that the count of the local structure of fcc, hcp, bcc, and icosahedral short-range order monotonically increase when the pressures increase. We also observed in our results that the size of the local cluster grows as the pressure increases, and the long-range connectivity of the quasi-crystal is achieved at high pressure.