Theoretical investigation into melt and shock behaviors of tantalum under extremes

Tantalum is a crucial refractory metal, but its behaviors during melting and shock compression are very elusive. Here, we introduce how to improve this situation via simple theories in quantum physics. First, we develop a new interatomic potential based on the extended Rydberg model and the first-principles equation of state. This potential can work effectively over a wide range of pressures and temperatures. Subsequently, the statistical moment method is applied to derive the free energy from the Rydberg parameters. This method allows us to go beyond the quasiharmonic limit without strenuous efforts. Finally, we calculate tantalum melt and shock profiles by the modified work-heat equivalence principle and the Rankine–Hugoniot equation. Our calculations agree quantitatively well with modern experiments and simulations. This agreement is unlikely to be achieved via other cost-saving approaches. Thus, our results would facilitate future studies on tantalum to realize its potential applications under extreme conditions.