Effect of Y Element on Microstructure and Hot Tearing Sensitivity of As-Cast Al–4.4Cu–1.5Mg–0.15Zr Alloy

In this paper, the effect of Y content on hot tearing properties of cast Al–Cu–Mg alloy was studied. The effect and mechanism of Y on hot tearing of cast Al–4.4Cu–1.5Mg–0.15Zr alloy were studied by analyzing the microstructure evolution, phase structure, solidification process and hot tearing sensitivity coefficient of the alloy with different Y additions, and determined the appropriate amount of Y element. The results showed that Y improves hot tearing resistance of Al–4.4Cu–1.5Mg–0.15Zr alloy by refining microstructure and reducing the solidification temperature range. The suitable amount of Y is 0.15 wt%. At this time, a certain amount of Al6Cu6Y low melting point phase is formed in the alloy, and the grain structure is the smallest, which significantly improves the hot tearing resistance of Al–4.4Cu–1.5Mg–0.15Zr alloy. The microstructure coarsening and hot tearing tendency increase with increasing Y content. The experimental results are basically consistent with the hot tearing sensitivity predicted by the Clyne–Davies model.