Pulse current auxiliary TLP diffusion bonding of SiCp/2024Al composite sheet using mixed Al-Cu-Ti powder interlayer

Pulse current auxiliary transient liquid-phase (TLP) diffusion bonding of SiCp/2024Al composite sheet was investigated at 580 C using mixed Al-Cu-Ti powder interlayer. The optimal process parameters were applied as follows: pulse current density of 1.15 × 10² A/mm², pressure of 0.5 MPa, vacuum of 1.3 × 10^-3 Pa, and bonding time from 15 to 60 min. The bonding quality is evaluated by microstructure characterization and mechanical properties of the joints. The mechanism of pulse current auxiliary TLP diffusion bonding process is analyzed. The results indicated that the dense joints without cavity consisted of the Al-based solid solution, pure Ti, Al ₂Cu, and TiAl₃ intermetallic phase. Microhardness of joints was obviously higher than Cu diffusion zone and substrate materials zone. The shear strength of the joints monotonically increased with bonding time. The maximum value exceeded 154.1 MPa in bonding time of 60 min. Pulse current generated Joule heat, high-temperature spark plasma, and electromigration, which guarantee the feasibility of bonding process and high-quality joint.