In this paper, the two-phase zone continuous casting (TZCC) technique was used to prepare 2D12 aluminum alloy tubes and a 3D model of TZCC was established to investigate the electromagnetic-thermal coupling as well as fluid flow behaviors under different mold temperatures. The calculated temperature in the induction heated mold agrees well with the measurement. It was found that the heat flux from the mold to the melt leads to a convex isoliquid fraction line of dendrite coherency point and circular thermal convection in front of the mushy zone. The velocity of the transverse flow increases remarkably with increasing mold temperature while the upward flow velocities at the outer wall are nearly constant. Experimental results indicate that the surface exudations with segregated solute appear at the surface of tubes when the mold temperature is higher than 883 K, and their size and quantity increase with increasing mold temperature. The serious solute redistribution and the thermal convection lead to solute segregation at the surface of tubes. Further, the residual liquid with segregated solutes flows to the surface of the tube and forms the surface exudation due to its lower freezing point than the Al matrix.

本文采用两相区连续铸造（TZCC）技术制备2D12铝合金管，并建立TZCC的3D模型研究电磁热耦合以及不同模具温度下的流体流动行为。感应加热模具中计算出的温度与测量结果非常吻合。发现从模具到熔体的热通量导致枝状相干点的凸等温等分线和糊状区前面的圆形热对流。横向流动的速度随着模具温度的升高而显着增加，而外壁处的向上流动速度几乎是恒定的。实验结果表明，当模具温度高于883 K时，在管子表面出现溶质偏析的表面渗出物，且其大小和数量随模具温度的升高而增加。严重的溶质再分布和热对流导致溶质在管子表面偏析。此外，具有分离的溶质的残留液体流到管的表面并由于其凝固点比Al基体的凝固点低而形成表面渗出物。