Improved High-Temperature Aluminum Alloys Containing Cerium
A common rare earth (cerium) when added to aluminum in compositions up to the eutectic compositions of around 10 wt.% improves the high-temperature performance of aluminum alloys. In the early 1980s, some promising research and development efforts focused on powder metallurgy revealed that aluminum alloys containing 4 wt.% cerium exhibit high-temperature mechanical properties exceeding those of the best commercial aluminum casting alloys then in production. Those compositions, which also included high levels of iron, were difficult to process. Recently, magnesium replaces iron to reduce density and improve processing. Cerium oxide is an abundant rare earth oxide that is often discarded during the refining of more valuable rare earths such as Nd and Dy. Therefore, the economics are compelling for cerium as an alloy additive. In this review, we report results obtained during an investigation of the processing and properties of aluminum-cerium alloys produced via casting, extrusion and additive manufacturing. The results show mechanical properties are retained at higher temperatures than other aluminum alloys and show complete recovery of mechanical properties at room temperature when exposed to elevated temperatures as high as 500 °C for 1000 h. Alloys containing cerium also have superior corrosion properties when compared to most aluminum alloys.