PREPARATION, MICROSTRUCTURE AND MECHANICAL-PROPERTIES OF METAL-PARTICULATE GLASS-MATRIX COMPOSITES/

Composites with a borosilicate glass matrix containing different conce ntrations of vanadium particles were fabricated by powder metallurgy a nd hot-pressing. The mechanical properties and fracture behaviour of t he composites were assessed by a range of techniques. Young's modulus, fracture strength in bending, and fracture toughness increased with v anadium content. By virtue of the good interfacial bonding and low res idual internal stresses, an effective crack-particle interaction durin g fracture was achieved. The fracture toughness of composites containi ng 30 vol.% of vanadium inclusions was approximately 65% higher than t hat of the unreinforced glass. Experimental values for the fracture to ughness increment were in good qualitative agreement with the predicti ons of theoretical models in the literature. Extensive plastic deforma tion of the vanadium inclusions was not found, however. This was attri buted mainly to the constraint imposed by the rigid matrix surrounding the particles and to possible embrittlement of the particles during c omposite fabrication at high temperatures. The brittleness index (B) o f the composites was calculated and its relevance for characterisation of the ductile versus brittle behaviour of brittle-matrix composites is discussed. (C) 1997 Elsevier Science Limited.