Cold spray additive manufacturing of metal matrix composites (MMCs) using a novel nano-TiB2-reinforced 7075Al powder

A gas-atomized 7075Al (Al–Zn–Mg–Cu) composite powder reinforced with in-situ nanosized TiB 2 particles was used as the novel feedstock to fabricate metal matrix composite (MMC) components by cold spraying (CS). The effect of CS processing conditions (i.e. particle impact velocity , particle impact temperature, and gas type) on microstructure evolution of the as-sprayed samples was investigated by X-ray diffraction (XRD), scanning (SEM) and transmission electron microscopy (TEM) and electron backscatter diffraction (SEM/EBSD). Mechanical performance was evaluated by microhardness and tensile test . The results indicated that the as-fabricated composite samples generally exhibit a fully dense and crack-free feature with the nanosized TiB 2 particles uniformly dispersed in the Al matrix . The phase composition of the feedstock is well preserved and nanosized precipitates are formed inside the severely deformed Al grains. It was also found that a higher particle impact velocity leads to more pronounced particle deformation and enhanced grain refinement. Fracture morphologies of the composite samples display a brittle feature in the low processing condition, while slight improvement of tensile strength and elongation is obtained at a higher particle impact velocity and temperature. The advantage by integrating the nanosized TiB 2 particles is that it results in an extensively refined structure to improve microhardness as well as tensile strength . This study demonstrates the potential of the gas-atomized composite powder for additive manufacturing of MMCs by CS.