Effect of Ti and B4C Inoculation on the Microstructure and Mechanical Properties of Powder Bed Fusion Laser Beam Processed Al–Cu–Mg Alloy: Role of Process Parameters and Heat Treatment

Aluminum alloys with high strength-to-weight ratios are attractive for demanding aerospace and automotive applications. However, processing high-strength alloys, particularly 2xxx, 6xxx, and 7xxx series, by laser powder bed fusion (PBF-LB/M) remains challenging due to their high cracking susceptibility. To overcome these limitations, aluminum metal matrix composites (AMMCs) have emerged as a promising alternative. This study investigates the processability of Al2024-RAM2, containing Ti and B4C particles as inoculants that promote in situ reactions during processing. The effect of reaction extent, influenced by different processing parameter combinations and heat treatment, was analyzed in relation to the resulting microstructure and mechanical properties. EBSD mapping revealed a fully fine equiaxed microstructure, attributed to a columnar-to-equiaxed transition (CET) during solidification promoted by the reinforcing particles, which increase the density of nucleation sites. Under optimized processing conditions and heat treatment, relative densities of up to ~99.9% were achieved. The resulting material exhibited a hardness of 160 HV, tensile strength exceeding 480 MPa, and elongation close to 10%. These results demonstrate the effectiveness of the reinforcement strategy in improving the PBF-LB/M processability of a high-strength Al2024-based alloy while achieving a favorable combination of strength and ductility.