Molecular-dynamics study of the local symmetry changes in metallic liquids

Abstract

It has been conjectured that the local structure of simple monoatomic liquids is mainly of five-fold symmetry. Experimental evidence for such icosahedral building blocks has recently been found in liquid droplets of lead adjacent to a silicon wall and in deeply undercooled melts of pure metallic elements like bcc iron, fcc nickel and bcc zirconium. We have used molecular dynamics in order to investigate supercooling effects in the melt of another pure element (aluminum) on the basis of a common neighbor analysis. In the simulation we have employed an embedded atom method potential optimized with the help of ab initio calculations for aluminum. The simulations confirm the recent experimental results that, independent of the system, the icosahedral short-range order strongly increases with the degree of undercooling.