Melting of Cu under hydrostatic and shock wave loading to high pressures

Abstract

Molecular dynamics simulations are performed to investigate hydrostatic melting and shock-induced melting of single crystal Cu described by an embedded-atom method potential. The thermodynamic (equilibrium) melting curve obtained from our simulations agrees with static experiments and independent simulations. The planar solid–liquid interfacial energy is found to increase with pressure. The amount of maximum superheating or supercooling is independent of pressure, and is 1.24 ± 0.01 and 0.68 ± 0.01 at a heating or cooling rate of 1 K ps−1, respectively. We explore shock loading along three main crystallographic directions: , and . Melting along the principal Hugoniot differs considerably from and , possibly due to different extents of solid state disordering. Along , the solid is superheated by about 20%, before it melts with a pronounced temperature drop. In contrast, melting along and is quasi-continuous, and premelting (∼7%) is observed.