Selective laser remelting of in-situ Al2O3 particles reinforced AlSi10Mg matrix composite: Densification, microstructure and microhardness

Abstract

Selective laser melting (SLM) was employed to fabricate an AlSi10Mg matrix composite reinforced by in-situ Al2O3 particles in this study. Immediate laser remelting was then employed to remelt the already solidified layer during SLM. The results show that the laser remelting reduces the large irregular pores and enhances the relative density. However, the laser remelting increases the number density of gas pores and results in a high porosity level. The laser remelting also has a significant effect on the microstructure by generating the small melt pools with a homogeneous morphology and refining the cell-like microstructure. Besides, the laser remelting promotes the epitaxial growth of the grains with a preferred <001> orientation and the in-situ formation of Al2O3 particles. Although the promoted formation of Al2O3 particles and fine cell-like microstructure can provide the remarkable hardening effect, the laser remelting can not improve the microhardness due to the porosity-induced softening behavior.