Diffusion-induced liquid migration during thermal stabilization in presence of temperature gradients with different directions

摘要

The initial growth conditions of directional solidification are obtained after the thermal stabilization stage during which a mushy zone is formed. The difference in melt concentrations within the liquid droplets in the mushy zone by the axial temperature gradient can induce simultaneous remelting/resolidification by temperature gradient zone melting (TGZM). This is known as the liquid migration which is closely related to the initial growth condition of directional solidification. However, a radial temperature gradient is always present in addition to the axial one, while the influence of it on liquid migration has not been discussed yet. Thus, the liquid migration in the presences of both axial and radial temperature gradients was investigated in Sn-Ni peritectic alloy. A diffusion-controlled model was established to predict liquid migration when both the axial and radial temperature gradients are taken into consideration. Both analytical result and experimental measurement confirmed that the radial temperature gradient played an important role in liquid migration. Further analysis has shown that the influence of the radial gradient was different at different parts of the mushy zones.