YOUNGS MODULUS OF CAST HMS 2112-C-F COMPOSITE-PREDICTION AND ULTRASONIC EVALUATION

Various models for the prediction of strengthening mechanism of metal matrix composites (MMCs) containing either fibres or particulates are analysed. Assuming that the matrix strengthening by dislocations could be treated as equivalent to the effect of different volume fraction o f dispersoids, as well as by considering the effect of morphology of r einforcement on the Young's modulus, an expression for Young's modulus for MMCs has been derived. The Young's modulus values thus predicted, using this model, have been validated by ultrasonically-derived value s of Young's modulus of an Al-alloy matrix composite containing 5, 8 a nd 12 wt% chopped carbon fibre (C-f) dispersoids, in as cast and extru ded conditions. Further, the theoretically- and ultrasonically-derived Young's modulus of cast Al-alloy-C-f composites with 5 and 8 wt% C-f have been found to be comparable with the reported values of Young's m odulus for these weight fractions.