Influence of Laser Energy Density on Microstructure of Selective Laser Melting Formed Al₄SiC₄/AlSi10Mg Composites

The Al₄SiC₄/AlSi10Mg composite was fabricated by selective laser melting process with ball-milling mixed powders of SiC and AlSi10Mg. The effect of laser energy density (76.2, 80.0, 91.5 J·mm^-3) on the microstructure of the composite was explored. The results show that a sub-micro scale Al₄SiC₄ reinforcing phase was produced by the interaction between the laser beam and the composite powder. The phase exhibited needle-like morphology and distributed in clusters or parallel arrangement around the original SiC particles. With the increase of the laser energy density, the Marangoni convection intensified in the melt pool, promoting the generation of Al₄SiC₄; so the original SiC reinforcements were transformed into Al₄SiC₄ grandually. In addition, the morphology of the Al₄SiC₄ phase changed from needle-like to cluster-like or parallel-arranged sheet-like morphology.