The effect of Y on the hot-tearing resistance of Al–5 wt.% Cu based alloy

It is well known that the continuing quest for Al–Cu alloy with improved casting defects is driven by the need in aerospace industries. Especially, the wide crystallization range of Al–5 wt.% Cu based alloys results in generation of hot-tearing. In Al–5 wt.% Cu alloy, the hot-tearing susceptibility is influenced by the larger crystallization range, the quantity and distribution of the eutectic microstructure in the grain boundary and the size of primary α (Al) particles. The effect of Y content on the hot-tearing resistance in Al–5 wt.% Cu based alloys was studied by ZQS-2000 twin Bar Tester of Thermo-Cracking-Linear Contraction Tester. The hot-tearing behavior was studied by thermal analysis, optical microscopy (OM) and scanning electron microscopy (SEM). It was found that Y promoted the end-solidification temperature and decreased the quantity of eutectic in grain boundary. Y-rich phase precipitation caused a depression of the begin-solidifying temperature of α (Al), narrowed the crystallization range, increased the hot-tearing resistance and decreased the hot-tearing susceptibility significantly.