Microstructure and mechanical properties of TiB2 reinforced Al2319 matrix composites produced using laser-arc hybrid additive manufacturing

Particulate reinforced composites are expected to solve the problem of grain growth and strength reduction caused by multiple thermal cycles during additive manufacturing. In this work, TiB₂/2319Al composite was fabricated by oscillating laser-arc hybrid additive manufacturing (O-LAHAM). The microstructure, mechanical properties and fracture of tensile samples were studied. The results show that TiB₂/2319Al composites were composed of fine equiaxed grains due to the stirring effect of laser beam and the particle strengthening effect of TiB₂. Although ultimate tensile strength (UTS) of the TiB₂/2319Al composite did not increase significantly, it had a higher yield strength (YS), especially stimulated by T6 heat treatment. Compared with 2319 aluminum alloy, YS of the as-deposited and heat-treated composites was 137 MPa and 355 MPa, respectively, which increased by 19% and 10%. However, the elongation decreased significantly, which is caused by the presence of micro pores that promoted crack propagation.