Synchronous improvement in thermal conductivity and mechanical properties of Al-7Si-0.6Fe-0.5Zn cast alloy by B/La/Sr composite modification

In this paper, the effects of four modification processes (B, Sr, B/Sr and B/La/Sr modification process) on the thermal conductivity and mechanical properties of base alloy (Al-7Si-0.6Fe-0.5Zn) were systematically studied. Compared with the base alloy, different modification processes could synchronously improve the thermal conductivity and integrated mechanical properties by different degree. The synchronous improvement of B/0.15La/Sr composite modified alloy was the highest among all modified alloys, and the increasing rate of thermal conductivity, elongation and UTS were 25.6%, 150.2% and 26.8%, respectively. The microstructure variation was the main reason for the synchronous improvement in thermal conductivity and integrated mechanical properties. Especially, the morphology variation of the eutectic Si phases from flak to fiber could significantly improve the thermal conductivity and integrated mechanical properties.