Microstructural evolution and mechanical performance of in-situ TiB2/AlSi10Mg composite manufactured by selective laser melting

In-situ TiB2/AlSi10Mg composites were prepared by casting, gas atomization, and selective laser melting (SLM), respectively. Microstructural evolution of the composites in as-cast, atomized, and SLMed were investigated. Compared with the as-cast composite, the SLMed sample has no texture and is composed of extremely fine grains and crystal cells. The in-situ TiB2 particles uniformly distribute over the grain boundaries, the acicular Si phase is replaced by a network of fine Si particles and there are nano-sized Si precipitations in the crystal cell. The formation of this microstructure is due to the continuous solidification of non-equilibrium eutectic Al-Si during the rapid cooling process of SLM. The SLMed TiB2/AlSi10Mg composite obtains excellent strength (tensile strength similar to 451 MPa, bending strength similar to 674 MPa), hardness (similar to 151 HV0.1) and good friction coefficient (similar to 0.4), which are higher than that of the as-cast TiB2/AlSi10Mg composite and the SLMed AlSi10Mg alloy. The formation mechanism of this particular structure and its strengthening effect were discussed. (c) 2020 Elsevier B.V. All rights reserved.

Automated summary

In-situ TiB2/AlSi10Mg composites were prepared via casting, gas atomization, and selective laser melting (SLM), with SLMed samples showing a microstructure of fine grains and no texture. The composites exhibited excellent strength, hardness, and friction coefficient, outperforming the as-cast composite and SLMed AlSi10Mg alloy. The formation mechanism and strengthening effect of this unique structure were discussed.