The tensile failure modes of metal-matrix composite materials

The strengths of individual boron fibers extracted from various as-received and thermally-fatigued aluminum alloy matrix materials were measured. The results are described in terms of a Weibull distribution, and strengths of composites fabricated from these fibres are calculated in terms of lower and upper bounds. Tests conducted on composites specimens indicated that strengths approaching the upper bounds can be achieved in composites fabricated by normal diffusion bonding techniques. Cyclic temperature changes effectively reduced the strength values towards the lower bounds. It was concluded that this effect resulted from the degradation of the strength of the fiber-matrix bond.