Liquid-phase impact diffusion welding of SiCp/6061Al and its mechanism

Liquid-phase impact diffusion welding (LPIDW) technique was used to join the aluminum matrix composite SiC_p/6061Al. The composite joints welded successfully, gave tensile strength up to 260 MPa and radial deformation below 3%. Analysis of the microstructure and tensile strength of the welded joints showed: (i) the achievement of prominent joint interface between SiC particles and the matrix; (ii) the change of pernicious contact-state from reinforcement (SiC)/reinforcement (SiC) to reinforcement (SiC)/matrix/reinforcement (SiC) of the reinforcement particles; (iii) the disappearance of the harmful microstructure/brittle phase of Al₄C₃ from the welded joint; (iv) the density of dislocation in the matrix next to the interface being higher; (v) the sign of intensively mutual entwisting of dislocation; and (vi) the deformation mainly taking place in the matrix grain. Furthermore, the rapid thermal pressing offered a denser nucleus area for matrix crystal and their deforming matrices around SiC particles engendered intensive aberration, which was favorable for forming nano-grains and for improving the properties of the welded composite joints.