Research status of laser powder bed fusion Al–Li alloys and its improvement measures

Abstract

Laser powder bed fusion (LPBF) Al–Li alloy technology demonstrates adaptability to the development requirements of structural complexity and functional integration, making it a promising area of research in additive manufacturing for the aerospace, defense industry, and other fields. However, challenges such as microstructure anisotropy and metallurgical defects inevitably arise during the LPBF process of lightweight alloys, significantly impeding further enhancements in their formability properties. Some improvement measures offer a viable solution to enhance the microstructure, mitigate metallurgical defects, and optimize residual stress distribution in additive structures, thereby enabling high–performance Al–Li alloy production by LPBF. This paper first introduces the fundamental principle of LPBF and discusses the process of parameter optimization for LPBF Al–Li alloys. It then describes the typical microstructures and common metallurgical defects of LPBF Al–Li alloys, along with examining the evolution process of microstructures and formation mechanism of metallurgical defects. Specifically, it focuses on discussing the influence of Li element on solidification structure. On this basis, it presents the mechanical properties and anisotropy of mechanical properties for LPBF Al–Li alloys. Afterward, a comprehensive review is provided of the current research status regarding LPBF improvement measures, including powder alloying, heat treatment, and other technologies. Emphasis is placed on improvements in microstructure anisotropy and reductions in metallurgical defects through these improvement measures. Finally, this article summarizes the research progress made in LPBF Al–Li alloys and its improvement measures while also prospecting future research work.