Fabrication and Characterization of SiC/Al Composites Prepared by Laser Powder Bed Fusion (LPBF) Combined with Vacuum Pressure Infiltration

A novel method has been developed to fabricate SiC/Al composites by the combination of laser powder bed fusion (LPBF) and vacuum-pressure infiltration. The effects of the SiC particle size distribution and pre-oxidation on the microstructure and properties of SiC/Al composites were investigated. A new phenomenon of severe lamellar cracking was observed in SiC/Al composites without pre-oxidation treatment, which can be explained in terms of the mechanism of interlayer bonding. The results showed that the residual porosity of the sample without pre-oxidation treatment s was higher than 3 %, with a maximum of (8.16 +/- 0.57) %, which was much higher than that of the pre-oxidised samples(1 % - 2%). The bulk density of the powders was significantly improved by designing the material system with mono-, bi-, and tri-modal particle size distributions and the density of final SiC/Al samples gradually increases from 2.804 +/- 0.009 to 2.871 +/- 0.008 g/cm3, and the volume fraction of SiC increases from 36.7 vol% to 50.1 vol%. As a result, the coefficients of thermal expansion (CTE) of SiC/Al composites varies consistently with the volume fraction of SiC, decreasing from 13.72 to 10.84x10-6 degrees C- 1. Our study shows that this method has the potential for great applications.