| Abstract: | Aluminium metal matrix composites (AlMMCs) offer several advantages relative to monolithic aluminium alloys such as high stiffness, strength, wear resistance, low thermal expansion coefficient, etc. However, despite considerable improvements in developing AlMMCs, the lack of reliable joining methods restrict their greater application. Fusion welding of AlMMCs has not proved successful because high temperature nature of the process normally causes unfavorable reactions between the reinforcement and the matrix, leading to the formation of a variety of defects. On the other hand, solid-state welding and diffusion bonding may not be suitable due to the presence of chemically stable surface layer of aluminium oxide, which, being insoluble in aluminium, inhibits metal-to-metal contact during diffusion bonding. Furthermore, diffusion bonding requires a very smooth and clean contact surface, which is difficult to obtain in industrial applications. As an alternative, transient liquid phase (TLP) diffusion bonding, which operates at a lower temperature, can be used to circumvent the problems associated with the oxide layer. The formation of liquid phase (eutectic) can assist the disruption of the oxide layer and promote metallic contact. The composite material used in the present study consisted of 6061 alloy containing 15 volume % of SiC particulates of 23 μm diameter. TLP bonding was carried out at 560 ˚C in argon atmosphere using copper as an interlayer with different pressures and holding times. TLP-bonded AlMMCs were characterized by optical and scanning electron microscopy, microhardness survey, and shear tests. The results indicated that adequate bond strength could be achieved with suitable bonding parameters such as holding time and initial pressure. |
