Experimental research on directional solidification of Al-4.5wt% Cu alloy by ACRT method

Accelerated crucible rotation technique (ACRT) has been used for the directional solidification of Al-4.5wt% Cu binary alloy. By rotating the crucible at varying rate and direction, forced liquid flows are aroused. These flows include Ekman flow, Couette flow and Spiral Shear flow. Especially, Ekman flow acts directly at the L/S interface, changes diffusion and heat exchange conditions and has strong influences on the morphology of L/S interface. Experimental results show that, compared with normal Bridgman specimens, the solidification region is much narrower and the cell spacing is much smaller in ACRT specimens. These influences become much stronger when the accelerating rate is increased.