Evolution of local atomic structure during solidification of Al2Au liquid: An ab initio study

Abstract

The local atomic structure evolution in Al2Au alloy during solidification from 2000K to 400K was studied by ab initio molecular dynamics simulations and analyzed using the structure factor, pair correlation functions, bond angle distributions, the Honeycutt–Anderson (HA) index and Voronoi tessellation methods. It was found that the icosahedral-like clusters are negligible in the Al2Au stable liquid and supercooled liquid states, and the most abundant clusters are those having HA indices of 131 and 120 or Voronoi indices of 〈0,4,4,0〉, 〈0,3,6,0〉 and 〈0,4,4,2〉 with coordination numbers of 8, 9 and 10, respectively. These clusters are similar to the local atomic structures in the CaF2-type Al2Au crystal, revealing the existence of structure heredity between liquid and crystalline phase in Al2Au alloy.