Structure and Properties of Al-Ce-based eutectic alloys created by Laser Powder-Bed fusion

Commercial precipitation-strengthened aluminum alloys are widely used in the automotive and aerospace industries for their low cost and high strength-to-weight ratio, but typically cannot be used in load-bearing applications for extended periods (months) above ~250 °C, because the nanoscale precipitates coarsen or dissolve into the Al matrix [1]. On the other hand, the most common aluminum casting alloys, which are based on the eutectic Al-Si system [2], contain large Si particles that are relatively thermally stable but provide little strengthening to the fast-creeping Al matrix [3–6]. Recent aluminum alloy development efforts have revealed that additions of rare-earth elements (REE) improve casting behavior through increased melt fluidity, and improve mechanical properties due to microstructural refinement and the formation of stable, high-melting intermetallic compounds [7,8]. A particularly inexpensive REE is cerium, which is often discarded during the refinement of more valuable REEs such as Nd and Dy, resulting in an excess Ce supply that makes it an economically feasible alloying element for aluminum even in high-volume production [9,10].