Microstructure and Fracture Behavior of SiCp/6063 Composite Laser Welded Joints with Al75Cu20Ti5 Nanocrystal Alloy

The 55% SiCp/6063 composites were laser welded using the Al75Cu20Ti5 alloy. The microstructure and fracture surface were investigated and analyzed by SEM, XRD, and tensile test. The results show that the Al75Cu20Ti5 interlayer metal grains prepared by single-roll fast coagulation were refined to 100 similar to 200 nm. The maximum tensile strength of 212 MPa was achieved when the joint was welded at the laser power of 350 W, welding speed of 1.5 cm/s, and plate surface of - 1 mm. The microstructure of the joint was altered by the inclusion of the Al75Cu20Ti5 alloy, and the main compound in the weld was TiCu4. The mechanical properties of the joint improved when SiC particles entered the weld and the SiC edge was passivated. A large number of fractured SiC particles and a small number of pits left after the debonding of SiC particles were distributed on the fracture surface, the fracture was brittle. The fracture position was the fusion transition zone. The particle-bearing process was the main strengthening mechanism of the joint.