Heat treatment and microstructural evolution of the Al-10Si-0.4Mg/SiC composites fabricated by Selective Laser Melting

This work examined the effect of artificial aging (AA), solution heat treatment (SHT) and T6 (SHT followed by AA) heat treatment on the microstructural evolution and mechanical properties of Al-10Si-0.4Mg (mass%)/SiC composites fabricated by Selective Laser Melting (SLM) method. The microstructure of the As-build specimen consisted of an α-Al (fcc) phase, a (α-Al-Si) eutectic phase, SiC particles and needle-like Al4SiC4 compound. SHT results in coarsening of Si particles from eutectic phase. While, fine Mg2Si was supposed to be precipitated by AA. The spheroidizing of Al4SiC4 was partially enhanced by SHT. As-build specimen exhibited high compressive strength (＝564 MPa), and the strength was decreased by SHT process due to coarse Si particles. Interestingly, we found that AA improved Young's modulus of the Al-10Si-0.4Mg/SiC composites.