Microalloying Al alloys with Sc: a review

As a kind of important light alloys, the Al alloys exhibit mechanical properties that are closely related to the microstructures. Changing the main alloying elements and adjusting heat treatments are usually approaches to tune the microstructure and hence artificially control the mechanical properties. However, the windows for the two approaches have become quite narrow, after extensive studies in the last half of century. Microalloying has become the most promising strategy to further modify the microstructure and improve the mechanical properties of Al alloys, among which the element of scandium (Sc) is especially powerful. In this paper, the recent progresses in Al alloys microalloyed with Sc are briefly reviewed, focusing on the microstructural characterization, strengthening response, and underlying mechanisms. The possible key research points are also proposed for the further development of Al alloys microalloyed with Sc and other rare earth elements.