Interfacial characterization using transmission electron microscopy examination of the diffusion bonding of SiC whisker-reinforced aluminum alloys

This paper describes the microstructural characterization, using transmission electron microscopy (TEM), of the solid-state, diffusion-bonded interfaces generated in a SiC whisker-reinforced, aluminum composite. Diffusion bonding was carried out using an aluminum-lithium alloy as the bonding interlayer. Two kinds of bonded interface were studied: those generated between the composite matrix and the metallic interlayer (metallic-metallic) and other ceramic-metallic interfaces formed between the interlayer and the SiC whiskers. The first showed the formation of zones of recrystallization across the original bond interface, and the second generally presented a high degree of continuity without the formation of interface reaction layers between the SiC whiskers and the interlayer. However, the formation of a degradation oxide layer was detected in some of the whisker/interlayer diffusion bonds. Its presence is due to the reaction between the alloying elements of the Al–Li interlayer and the SiO2 layer which surround some of the whiskers of the parent composite.