In-situ formation of TiN/Al composites by wire-based friction stir additive manufacturing

Aluminum-matrix composites were fabricated via wire-based friction stir additive manufacturing using pure Al wire pre-coated with TiN by multi-arc ion plating. The TiN coating underwent fragmentation and redistribution within the Al matrix during deposition, driven by the synergistic effects of extrusion, thermo-plasticization, and pin-assisted stirring. This process refined grains from 4.12 μm to 1.95 μm and increased the high-angle grain boundary fraction from 88.64% to 92.55%. Consequently, the microhardness and ultimate tensile strength increased from 28 ± 1 HV to 40 ± 3 HV and from 96 ± 3 MPa to 125 ± 6 MPa, respectively, while retaining considerable ductility with an elongation of 27.5 ± 2.5%.