Kinetics of transient liquid phase diffusion bonding process for joining aluminium metal matrix composite

Abstract

The mechanism and kinetics of the transient liquid phase diffusion bonding process in a 6061–15 wt-SiCp composite at 570°C, 0·2 MPa, with 200 μm thick copper foil interlayer, has been investigated by microstructural characterisation of the bond region using optical microscopy, scanning electron microscopy and electron probe microanalysis. The kinetics of isothermal solidification, representing the displacement of the solid/liquid interface y (in micrometres) as a function of time t (in seconds), followed a power law relationship y = 157t^0·07. According to this kinetic equation, the effective diffusivity of copper in the composite system was found to be ∼10⁶ times higher than the lattice diffusivity, indicating the dominance of short circuit diffusion through the defect rich particle/matrix interface.