Microstructure diversity dominated by the interplay between primary intermetallics and eutectics for Al-Ce heat-resistant alloys

Abstract

Al-Ce alloys emerge as promising heat-resist aluminum alloys with service temperatures above 250 °C. Here we report the solidification behavior and the microstructure diversity of Al-Ce alloys, aiming to bridge the gap between solidification condition and microstructures. Both conventional casting and arc surface rapid melting (ASRM) are employed to generate varied solidification conditions. Owing to the large entropy of fusion, intermetallic Al11Ce3 phases are grown in a faceted mode with a strong growth anisotropy, and Chinese-script Al11Ce3/α-Al eutectics are produced upon conventional casting. The addition of Mg restrains the coupled growth of eutectics and promotes the generation of divorced eutectics in cast Al-Ce alloys. Upon rapid solidification during ASRM, regular lamellar and rod-like eutectics prevail in Al-Ce binary alloys, and fishbone eutectics dominate the Al-Ce-Mg ternary alloys. Also, the transition from a hypereutectic microstructure to a fully eutectic microstructure is triggered by ASRM. The interplay of intermetallic Al11Ce3 and Al11Ce3/α-Al eutectics is discussed and the formation of refined regular eutectics is highlighted.