Defects control of aluminum alloys and their composites fabricated via laser powder bed fusion: A review

Laser powder bed fusion (L-PBF) technique, as the mainstream technology in metal additive manufacturing, enables the fabrication of aluminum alloys and their composite components with high precision and design freedom, thereby advancing structural lightweighting in various application domains, such as aerospace and transportation. Nevertheless, aluminum powders present challenges including high laser reflectivity, high thermal conductivity, low melting point, and susceptibility to oxidation. Consequently, defects such as pores, solidification cracks, orientation anisotropy, and surface roughness commonly exist in L-PBFed aluminum alloy and composite parts. These defects severely compromise the mechanical performance and dimensional accuracy of L-PBFed parts. Thus, extensive research efforts have been focused on defect control in the L-PBFed aluminum alloys and their composites. However, a systematic summary and in-depth analysis of the formation mechanism and controlling strategy of various defects is still absent, which is the key to develop high performance aluminum alloys and their composites via L-PBF. In this review, a thorough analysis and summary of the causes of defects are provided, followed by an in-depth analysis and conclusion of defect control strategies and mechanism in LPBF. Furthermore, we also present an outlook on the challenges and research opportunities in L-PBFed aluminum alloys and their composites in the last section, which we hope could inspire more new development of highperformance aluminum alloys and their composites via L-PBF.