Fracture toughness tests were performed on two aluminium alloy matrices, 2014-0 and 2024-0 reinforced with alumina particulates of different volume fractions and particulate sizes so as to investigate the fracture mechanisms operative in such composites and to determine how microstructural parameters such as volume fraction, particulate size and interparticle spacing affect the fracture toughness. The results indicate that fracture occurred by a locally ductile mechanism. The fracture toughness increased with increasing particle spacing provided that the particle size was less than a limiting value, above which unstable crack growth occurred and the toughness lowered.

Engineering structures experience impulsive loads during the time of natural disasters like earthquakes, cyclones and collisions. The design of structures resistant to such natural disasters requires an understanding of the deformation and fracture behaviour of the materials constituting the structure under impulsive loading conditions. In this paper the various aspects of dynamic plastic deformation and fracture of common engineering materials are reviewed and contrasted with their behaviour under static loading conditions.

The effect of alloying additions viz. cobalt, molybdenum, cerium and a combination of cobalt and molybdenum, on theK_ISCC of NiSiCr steel in 3·5% NaCl aqueous solution was studied. Addition of cobalt to NiSiCr steel resulted in an increase in theK_ISCC whereas molybdenum addition decreased theK_ISCC. Cerium addition did not affect theK_ISCC while the combination of cobalt and molybdenum resulted in an increase in theK_ISCC although not as much as in the case of cobalt addition. The effect of alloying elements onK_ISCC could be attributed to their effect on the critical fracture stress and yield strength.