Premelting of iron at high pressures under conditions of contact with amorphous argon

Experiments involving shock-wave loading systematically produce higher melting temperatures than those obtained in experiments involving the use of diamond anvils (DAC). The melting temperature in DAC experiments is determined by structural changes on the surface of a solid in contact with another substance (for example, with argon). We use the method of molecular dynamics to investigate the process of iron melting from the surface in single-component and two-component (in the presence of argon as medium) cases at pressures of $\sim100$ GPa. In the argon-iron two-component model aimed at reproducing the conditions of static DAC measurements, premelting is observed at a temperature below $T_m$. The layer of iron adjacent to argon may make a transition to disordered state under certain conditions. The temperature interval at constant pressure, in which this effect is observed, is comparable in magnitude with the difference between the melting temperatures obtained as a result of dynamic and static measurements. Therefore, this effect may be one of the reasons for discrepancy between the experimental results for the melting curve of iron and other metals.