Study of Microstructure and Mechanical Properties of Transient Liquid Phase bonded of Al / Al2O3

Todays, aluminum matrix composites are widely used in many industrial applications due to their superior properties such as high strength to weight ratio. However, joining problems of these composite materials is a challenge which limits their applications. Consternation of alumina particles, micro-cracks and porosity were found in the joint areas that were filled from α-Al solid phase and fine CuAl2 precipitated particles. The filled areas increased as the joint temperature increase. It is due to a higher amount of the molten material produced during joining. Moreover, the amount of CuAl2 precipitated particles reduced as the joining temperature increased, resulting in reduction of the hardness of the α-Al solid phase in the joint area. The shear strength of the bonded joints was also evaluated using a tension test system. The maximum shear strength (82% of the base metal shear strength) was achieved at the bonding temperature of 590°C and process duration of 30 minutes. Analysis of the fractured surfaces showed plastic deformation, shear dimples and partially ductile failure. Some alumina particles were observed on the fractured surface. At low joining temperatures, the joint strength improved by increasing bonding time, whiles at high joining temperatures, the joint strength decreased due to reduction of CuAl2 particles in the α-Al solid phase.