Effect of Y and Ce Micro-alloying on Microstructure and Hot Tearing of As-Cast Al-Cu-Mg Alloy

In this work, the Al-Cu-Mg alloy with different Y (0-0.2 wt%) and Ce (0.5-1.5 wt%) are designed. The effect of mixed addition of Y and Ce on the grain structure and hot tearing for Al-4.4Cu-1.5Mg-0.15Zr alloy was investigated using "cross" hot tearing mould. The results indicate that as rare earth Y and Ce increases, the grain size becomes finer, the grain morphology changes from dendrite to equiaxed grain, and effectively reduce the hot tearing sensitivity coefficient (HTS1) and crack susceptibility coefficient (CSC) of the alloy. With the increase of Ce element (0.5-1.5 wt%), the hot tearing susceptibility of the alloy decreases first and then increases. With the increase of Y element (0-0.2 wt%), the hot tearing sensitivity of the alloy decreases. When the content of rare earth is 0.2 wt% Y + 1.0 wt% Ce, the minimum HTS1 value and CSC value of the alloy are 68 and 0.53, respectively. Rare earth Ce refines the alloy microstructure, shortens the feeding channel, and reduces the hot tearing initiation. Meanwhile, the rare earth Y can form Al6Cu6Y phase at the grain boundary, improve the feeding capacity of the alloy. Therefore, appropriate addition of rare earth Y and Ce can effectively reduce the hot tearing tendency of the alloy.