Molecular dynamics simulation study on non-equilibrium melting of sodium crystals at high heating rates

The non-equilibrium melting of Na crystals at high heating rates and the evolutions of the atomic clusters are studied by the MD method and PTM analysis. Results show that as the heating rate rises from 1 × 1011 K/s to 2 × 1013 K/s, the non-equilibrium melting temperature of Na increases non-linearly from 417 K to 480 K, the melting temperature difference experienced increases from 7 K to 27 K, while the melting time decreases from 70 ps to 1 ps. Through the PTM analysis, it is found that some BCC clusters transform into the disordered Other clusters through intermediate HCP and FCC clusters with increasing temperature, and the BCC cluster's reduction rate and the Other cluster's growth rate are getting slower with increasing heating rate. There is a good correspondence between the evolutions of the atomic clusters, the changes of macroscopic physical parameters, and the peaks and valleys of RDF with temperature.