Effect of Rare Earth Metals (Ce and La) Addition on the Performance of Al-Si-Cu-Mg Cast Alloys

The present research work aimed at evaluating the effect of Ce and La rare earth (RE) additions on the formation of intermetallics in an Al-8.0Si-2.4Cu-0.4Mg-0.4Fe-0.6Mn-0.15Ti alloy (coded D0). These alloys were solidified at a rate of ~0.7°C/s. Microstructural analyses revealed the presence of two types of RE-containing intermetallic phases: (i) a gray phase with a fixed composition of Al 21 Ti 2 RE(Ce/La) and (ii) a white RE-containing intermetallic phase stemming from the reaction of the RE (Ce/La) with Si, Fe, and Cu. The present study aimed as well at studying the influence of the additions of Ce and La elements (0–1.0%) on the high-temperature (250 °C) tensile properties of the Al-8.0Si-2.4Cu-alloys. The results showed that T6-treated alloys, Sr-modified alloys, or those containing Ce/La exhibited UTS values comparable to the solution heat-treated, T5, and T7 alloys.