Development of metal matrix composites through solid-state additive friction deposition

Metal matrix composites (MMCs), particularly AA2014-based systems, are attractive for aerospace and automotive applications owing to their high strength-to-weight ratio. Incorporating SiC as a reinforcement significantly enhances their wear resistance; however, conventional fusion-based additive manufacturing (AM) processes often encounter challenges such as dilution, reinforcement segregation, porosity, deleterious interfacial reactions, and solidification-induced cracking. Therefore, in this work, a novel solid-state AM approach based on additive friction deposition (AFD) is demonstrated for the fabrication of MMCs, thereby overcoming these limitations. AFD experiments were conducted using AA2014-T6 consumable rods (20 mm diameter), containing multiple pre-drilled holes (2 mm diameter) filled with silicon carbide powder (SiC P , D 50 ∼25 ± 5 μm). Single and multi-layer AA2014/SiC P composite deposits were successfully fabricated on AA2014-T6 substrate. Microstructural analysis revealed fine, dynamically recrystallized equiaxed grains (∼ 2-3 μm) with a uniform dispersion of SiC particles (12 ± 2 vol.%), and no evidence of any deleterious interfacial reaction products. The AA2014/SiC P deposits showed ∼85% higher microhardness (240 ± 5 HV) and ∼36 % lower wear loss compared to monolithic AA2014-T6 (130 ± 5 HV). Notably, the hardness of the AFD composites exceeded that of similar materials produced by conventional processing methods. Shear testing confirmed strong metallurgical bonding between the deposit and the substrate, with the composite achieving a shear strength of 140 ± 5 MPa, close to that of the AA2014-T6 substrate (160 ± 5 MPa). Overall, these results demonstrate that AFD is a promising solid-state approach for fabricating AA2014/SiC P composites with enhanced mechanical and tribological properties suitable for fabrication of AM-MMC components, surface engineering and repair applications.