Effect of heat treatment patterns on microstructure and mechanical properties of selective laser melting fabricated SiC/AlSi10Mg composite

Selective laser melting (SLM) of SiC/Al-Si-Mg composites hold tremendous potential for engineering applications. However, there has been a lack of systematic research on their heat treatment patterns. This paper utilizes the Box-Behnken response surface method to establish a relationship model between SLM process parameters and the relative density of the 10 wt%SiC/AlSi10Mg composite. Simultaneously, 300 degrees C, 400 degrees C, and 500 degrees C treatments (T300, T400, T500) were used to investigate the porosity, microstructure, and mechanical properties of the 10 wt%SiC/AlSi10Mg composite. The results indicate that optimal process parameters were laser power of 331 W, scanning speed of 1243 mm/s, and hatching spacing of 120 mu m. Under these process parameters, the fabricated samples exhibited a relative density of over 99 % and presented a refined microstructure. The porosity of the as-built (AB) samples remained at a low level of similar to 0.38 %, while the porosity of T300, T400, T500 samples increased to similar to 0.7 %, similar to 0.78 %, similar to 0.92 %, respectively. Pores at the molten pool boundary (MPB) of the AB samples expanded into the melt pool inner (MPI) of the T300-T500 samples. The addition of SiC reinforcement significantly improved the strength and hardness of the composite materials, reaching 471 MPa and 151 HV, respectively. After heat treatment, the original fine network microstructure was disrupted due to the fracture, spheroidization growth, and coarsening of the eutectic networks. The elongation of the composite after heat treatment increased substantially from 3 % to 5.95 %, with a decrease in hardness and strength, a transition from brittle to ductile fracture behavior.