Microstructure and mechanical properties of in-situ nano-TiB2 particle reinforced AlSi10Mg composite components produced by cold spraying

A novel in-situ nano-TiB2 reinforced AlSi10Mg composite powder was fabricated by gas-atomization and was used to successfully produce fully dense TiB2/AlSi10Mg composite components by cold spraying (CS). Following this, the influence of post heat treatment on microstructure and mechanical properties were studied. The results, in terms of XRD and SEM characterization, showed that the microstructure of the feedstock powder was largely conserved in the as-sprayed components including the uniform distribution of the TiB2 particles and the cellular-like network of ultrafine eutectic Si particles embedded in the Al matrix. CS introduced the additional nanosized Si particles inside the network, which precipitated out from the initial supersaturated Al-Si matrix due to particle heating. With increasing the annealing temperature in the range 300-500 ¡ãC, the size of the Si particles increased up to several micrometers, whereas their number significantly decreased. Further, the cold sprayed TiB2/AlSi10Mg component showed higher microhardness and better wear performance compared to those of the pure AlSi10Mg counterpart. However, the microhardness reduced with increasing the annealing temperature due mainly to coarsening of the Si particles. This study demonstrates the potential of the gas-atomized composite powder for additive manufacturing of metal matrix composites by cold spraying.