2008 Volume 48 Issue 5 Pages 616-623
Microstructural evaluation during transient liquid phase diffusion (TLPD) bonding of extruded aluminium based metal matrix composite (6061-15 wt% SiCP) using 50 μm thick copper interlayer was investigated by optical microscopy, scanning electron microscopy (SEM) together with SEM-based energy dispersive X-ray spectroscopy (EDS) and pulse echo ultrasonic test. Microstructural changes in the joint region were examined at five different holding time (20 min, 1 h, 2 h, 3 h and 6 h) for a bonding temperature of 560°C under two different applied pressures (0.1 MPa and 0.2 MPa). Kinetics of the bonding process was significantly accelerated in presence of reinforcement (SiC). This acceleration is attributed to the increased solute diffusivity through defect-rich SiC particle/matrix interface and porosity. The segregated particle at bond interface caused significant attenuation of ultrasonic wave, especially at lower bonding time. The attenuation effect decreased with increasing bonding time as width of particle segregation decreased.
