Evolution of liquid phase during homogenous non-equilibrium melting of Ta at superheating temperature.

Homogenous melting at superheating temperature is commonly described by classical nucleation theory (CNT), but the atomic mechanism of the formation and development of critical liquid nuclei is still unclear. Molecular dynamics simulations were conducted to analyze the melting process of Ta. It is found that the process of subcritical liquid clusters evolving into critical liquid nucleus occupies most of the melting time, and merging between neighboring liquid clusters is the main path for subcritical liquid clusters to grow in size. Total melting time is strongly affected by the distribution of formation sites of subcritical liquid clusters, which has been considered random in homogenous melting. This work depicts a clear picture of the formation and development of liquid phase during the homogeneous melting process at superheating temperature and suggests an internal factor of melting mechanism.