Composite melt processing device and method for preparing fine grain homogenous casting

The invention relates to a composite melt processing device and method for preparing a fine grain homogenous casting, and belongs to the field of metal material processing. The device is composed of atundish for storing a large-volume alloy melt, a heating unit, an external magnetic force generator, a cooler, an infusion tube, an internal magnetic force generator and a traction mechanism; the infusion tube goes deep into the tundish, the inlet end of the infusion tube is located at the lower portion of the tundish, the external magnetic force generator and the cooler are arranged around the infusion tube around the tundish, the internal magnetic force generator is arranged at the periphery of the infusion tube inside the tundish, the heating unit is arranged at the inner side of the top of the tundish, and the traction mechanism is fixed to the lower portion of the tundish. The invention further discloses a composite melt processing method for preparing the fine grain homogenous casting based on the device. T