Microstructure Evolution and Mechanical Properties of 20%SiC/Al Joint Prepared via Laser Welding.

SiC particles-reinforced Al matrix composites (SiC/AMCs) have been widely used in the aerospace structural components. In this work, 20 vol% SiC/2A14 joint was fabricated by laser welding technology. The effects of different laser power/welding velocity on the 20 vol% SiC/2A14 joint forming, microstructure evolution and mechanical properties were studied in detail. The results showed that, under the same heat input, the high power/high welding velocity was beneficial to reduce the porosity of SiC/2A14 joint and inhibited the formation of brittle phase of AlC. At 8 kW-133 mm/s welding parameters, the maximum tensile strength of the SiC/2A14 joint reached 199 MPa, which is ~64% higher than that of the SiC/2A14 joint prepared at 4 kW-66 mm/s welding parameters. By analyzing the fracture morphology and SEM image of SiCp/2A14 joint section, it is was found that the porosity of weld and AlC brittle phase were the important factors limiting the strength of SiCp/2A14 joint. This work provides a reference for the process window design of laser welding SiC/2A14 composites.