Migration dynamics for liquid/solid interface during levitation melting of metallic materials

The migration dynamics of liquid/solid interface for bulk metallic materials under the electromagnetic levitation (EML) condition were investigated by the combination of numerical simulation and related EML experiments. Based on the apparent heat capacity method and the Carman–Kozeny relationship, a thermo-electromagnetic-hydrodynamic model was established to explore the phase transition including the migration of liquid/solid interface, the evolution of melt flow and the temperature distribution. The details of migration process were quantitatively analyzed under different levitation conditions. The space and time evolutions of liquid/solid interface migration features were strongly correlated with the electromagnetic field in levitation space. In addition, the correlation between the heat transfer characteristics and the levitation conditions was explored by the levitated sample with a preset deformation shape. In heating process, the sample reached the lowest equilibrium temperature and the minimum melting rate when it was levitated in the middle of the levitation zone. A defined number related to sample properties D²ρσ⁻¹k⁻¹ was proposed to quantitatively describe the temperature difference of levitated solid sample. The migration details were validated by EML experiment that an oval molten pool formed near the lower sample surface firstly. Then, the liquid/solid interface gradually moved up to sample top. The migration behaviors under extreme conditions were predicted by simulation that molten pools formed simultaneously on the upper and lower surfaces when the sample was balanced near the levitation ceiling.