The laser powder bed fusion of particle-reinforced aluminum alloy matrix composites

Laser powder bed fusion (LPBF) enables the fabrication of aluminum matrix particulate composites (AMPCs) with opportunities for microstructural refinement and precipitation strengthening. However, reported mechanical responses remain highly non-monotonic with respect to particle content. Strength improvements are often accompanied by limited or inconsistent gains in ductility, fatigue performance, and damage tolerance. This review adopts a constraint-first perspective and organizes the literature along a processing-linked constraint pathway. The performance of LPBF-processed AMPCs is interpreted in terms of a hierarchy of coupled physical constraints that become active at different stages. These include processing stability associated with melting behavior, interfacial mechanical and chemical compatibility under rapid thermal cycling, particle redistribution during melt-pool transport and solidification, and the transition of crack initiation control among competing defect populations. Evidence is synthesized across the full processing chain, from energy coupling at the powder bed to melt-pool dynamics, particle redistribution, and defect evolution. This framework helps explain why particle additions lead to improved mechanical performance in some cases, but not in others where processing-induced constraints become dominant. Based on this synthesis, a transferable design framework is proposed. It emphasizes stable processing conditions, interface states that sustain load transfer, control of particle clustering, and performance evaluation based on defect severity rather than average properties. Overall, this review frames LPBF-processed AMPCs as a constraint-governed system, and provides a basis for interpreting scattered results and improving cross-study comparability.