Composites and Alloys Based on the Al-Ce System

Abstract

Aluminum alloys containing small amounts of cerium have been investigated to improve the grain refining, casting characteristics, and mechanical properties of aluminum alloys. These additions were usually made at levels of 1% or less but did not produce appreciable improvements. Recent work has shown that additions between 4% and the approximate eutectic composition of 10% improve the high-temperature performance of aluminum alloys. Corrosion performance of aluminum alloys can also be improved through the addition of Ce. Traditional aluminum alloying elements such as magnesium and silicon can be used to control casting characteristics and thermal and physical properties. Cerium oxide is the predominate oxide in rare earth mining. Much of it is discarded after separation from the heavy rare earth oxides containing Nd and Dy. The beneficial use of Ce should reduce the cost of the more desirable rare earths. Results of using Ce as an addition to aluminum in mul-tiple manufacturing methods such as additive manufacturing, extrusion, and casting are explored. The results show significant strengthening and improved mechanical property retention at higher temperatures than in other aluminum alloys and, in some compositions, show complete recovery of mechanical properties at room temperature when exposed to elevated temperatures as high as 500°C for 1000 hours.