Effects of Ti on the forming, microstructure and mechanical properties of laser welded joints of SiCp/2A14 composites

Despite the tremendous application potential of SiCp/Al composites, their use has been restricted by poor weldability. To investigate the effect of Ti addition on the laser weld quality of SiCp/Al composite materials, pure titanium foil with a thickness of 0-300 mu m was used as the interlayer to join the SiCp/Al composite material by laser welding. The forming morphology, phase identification, microstructure evolution and mechanical properties of weld joints with different Ti addition were analyzed systematically. The results showed that the addition of Ti effectively inhibited the growth of Al4C3 and generated a new TiC reinforcing phase. When the thickness of Ti foil exceeded 200 mu m, the flaky Al4C3 phase in the weld was replaced by TiC particles with the size of less than 5 mu m, enhancing the fluidity of the melt in the molten pool and thus improving weld formation. The tensile strength of the joint increased from 156.2 MPa to 311.1 MPa due to the improved weld forming quality and the dispersion hardening effect caused by the TiC particles. Addition of 300-mu m-thick Ti produced large Al3Ti sheets that reduced the tensile strength of the joint. These results elucidate the mechanism of the forming morphology, microstructure evolution, and joint strengthening of the SiCp/Al composite weld joint with Ti content change, and provide theoretical guidance for selecting the appropriate Ti addition for laser welding of SiCp/Al composites.