Room temperature fracture and high temperature creep deformation properties of alumina reinforced with 20 vol % particulate niobium

摘要

For this material, an increase in RT crack growth resistance of (ge) 300% was achieved; this property increases with increasing Nb particle size. SEM and in-situ crack growth observations show that crack bridging is the primary toughening mechanism for the increased crack growth resistance. A model was presented which uses existing models to determine the steady state bridging length given a stress intensity due to crack bridging. This model showed that the specimen size used for determining the RT fracture toughness was too small. It was also determined that the creep strain rate is in the same range as and comparable to existing studies of Al(sub 2)O(sub 3) and Al(sub 2)O(sub 3) systems. The creep mechanism of the composite material was found to be similar to that of unreinforced Al(sub 2)O(sub 3) with a stress redistribution to the particle/matrix interface.