Effect of cooling rate on solidified microstructure and mechanical properties of aluminium-A356 alloy

A fast-cooling technology using a copper mould cooled by a phase-transition medium was used to prepare cast aluminium-A356 alloy by solidification of the melt. The cooling rate achieved with this technique is in the order of 102 K/s. As-cast samples with a diameter of 10 mm were produced. The microstructure and mechanical properties of this alloy have been investigated. The results show that both the primary and secondary dendrite arm spacing (DAS) are better refined by using this technology than with a conventional casting method. The cooling rate can be controlled to some extent by changing the amount of cooling medium. The DAS decreases with increasing cooling rate, and the microhardness and strength increase correspondingly.