Transient liquid phase diffusion bonding of 6061-15 wt% SiCp in argon environment

Extruded 6061-15 wt% SiCp composite was joined by transient liquid phase diffusion (TLPD) bonding process in argon environment using 50-μm thick copper foil interlayer. The bonding was carried out at 560 °C with two different applied pressures (0.1 and 0.2 MPa) and five different holding times (20 min, 1, 2, 3 and 6 h). Kinetics of the bonding process was significantly accelerated in the presence of reinforcement (SiC). This acceleration is attributed to the increased solute diffusivity through defect-rich SiC particle/matrix interface and porosity. Adequate bond strength (90% of the original composite strength) was achieved for bonding at 0.2 MPa pressure with 6 h of holding. This is very close to the reported highest bond strength achieved (92% of the original composite strength) for joining aluminium-based metal matrix composite by TLPD process in vacuum followed by isostatic pressing. The rejection of oxide at periphery on completion of isothermal solidification, and elimination of void at bond interface through solid state diffusion at higher pressure (0.2 MPa) were the main reasons of achieving high bond strength.