Phase field simulation of solidification under supergravity

In order to understand the influence of supergravity on the microstructure of materials, crystal nucleation, dendritic growth, and polycrystal solidification under supergravity are investigated by using the modified nucleation theory and phase field models. Firstly, supergravity is considered in the nucleation theory by using pressure-dependent Gibbs free energy. It is found that the critical radius decreases and the nucleation rate increases when supergravity rises. Secondly, anisotropic heat transport is proposed in the phase field model to investigate the influence of supergravity on dendritic growth. Phase field simulations show that supergravity promotes the secondary dendritic growth in the direction parallel to supergravity. Finally, a multiply phase field model with pressure-dependent interfacial energy is employed to simulate the polycrystalline solidification under supergravity. Due to the depth-dependent pressure by supergravity, crystal grains are significantly refined by high pressure. In addition, gradient distribution of grain size is obtained in the solidification morphology of polycrystalline, which is consistent with previous experimental observations. Results of this work suggest that supergravity can be used to tune the microstructures and properties of materials.