Microstructure and mechanical properties of a novel (TiB2+TiC)/AlSi10Mg composite prepared by selective laser melting

The (TiB2+TiC)/AlSi10Mg composite powders with 1.5 wt% nano-TiB2 particles and 1.5 wt% nano-TiC particles were prepared by ball milling. Aluminum matrix composites (AMCs) reinforced by TiB2 and TiC were fabricated via SLM with optimal processing parameters. The (TiB2+TiC)/AlSi10Mg composites showed a very high ultimate tensile strength -552.4 MP and excellent ductility -12%, which is 40.3% and 166.7% higher than that of unreinforced AlSi10Mg, respectively. The effects of TiB2 and TiC nanoparticles on the SLM processability, microstructures, grain size, and crystallographic texture of (TiB2+TiC)/AlSi10Mg composite were systematically investigated to uncover its underlying strengthening mechanisms. The results showed that the addition of 1.5 wt % nano-TiB2 and nano-TiC particles can obtain fine-equiaxed grains, facilitate microstructural homogeneity, and consequently improved mechanical properties of AlSi10Mg alloy. With the addition of TiB2 and TiC nano particles, the coarse columnar grains are completely transformed into equiaxed grains and the average grain size decreases from 12.1 mu m to 1.5 mu m.