Deformation behaviour and failure mechanisms of Al–TiB 2 in situ composites

Abstract

The deformation behaviour and failure mechanisms of Al–TiB₂ in situ metal matrix composites were examined through uniaxial tension and compression tests. The influence of particle size and holding time was found to have stronger influence. Elastic modulus of the composite during tension and compression was higher than that of the unreinforced matrix. Fractographic morphology studies were done using optical and scanning electron microscopy. Results reveal that the primary failure was due to matrix yielding initiated by the slip lines. A dimpled structure of the matrix is observed indicating that the failure occurred by microvoid coalescence. The specimens also exhibit plastic microbuckling phenomena at the circumference, followed by particle fracture adding up to the failure mechanisms during compression. Compressive strength and tensile elastic modulus were very sensitive to change in the percentage reinforcement. During compression, majority of the samples failed by splitting or splaying mode. In tension, the particles influence the failure mechanism, whereas in compression they act as barriers to the matrix flow.