Atomic mechanism of homogeneous melting of bcc Fe at the limit of superheating

Atomic mechanism of homogeneous melting of bcc Fe is studied via monitoring spatiotemporal arrangements of the liquid-like atoms, which are detected by the Lindemann criterion of melting, during the heating process. Calculations are performed by molecular dynamics (MD) simulations. Calculations show that liquid-like atoms occur randomly in the crystalline matrix at temperature far below the melting point due to local instability of the crystalline lattice. Number of liquid-like atoms increases with increasing temperature and they have a tendency to form clusters. Subsequently, a single percolated liquid-like cluster is formed in the crystalline model and at the melting point 99% atoms in the model become liquid-like to form a liquid phase. Melting is also accompanied by the sudden changes in various static and thermodynamic quantities. However, total melting is reached just at the point above the melting one. Three characteristic temperatures of the homogeneous melting of bcc Fe are determined.