INTERFACIAL REACTION AND STRENGTH OF SIC FIBERS COATED WITH ALUMINUM-ALLOYS

Silicon carbide fibres (Nicalon) were coated with pure aluminium and aluminium alloys containing silicon. The coated fibres were annealed to produce an interfacial reaction zone between the coated layer and the fibre. The effect of this reaction zone on the tensile strength of the fibre was investigated. During the early stages of growth the reaction zone of the fibre is thin, and the strength of the fibre is controlled by inherent defects so that the fibre retains its original strength. After the early stages, notches are formed in the reaction zone of the fibre on loading at a small strain and the fibre fractures when a notch extends into the fibre. In this stage the fibre strength is dependent on the thickness of the reaction zone. An alloying addition of 1 or 5 at % Si to the aluminium matrix was found to be effective in retarding the growth rate of the reaction zone. © 1990 Chapman and Hall Ltd.