Determination of Fracture Toughness and Fracture Probability of LPS Aluminas by Hertzian Indentation
The Hertzian indentation technique has been evaluated as a possible means of assessing the surface fracture behaviour of a set of qualitatively similar liquid phase sintered polycrystalline aluminas with systematically varied composition, and a range of grain sizes. The method provides a better correlation between microstructure characteristics and surface fracture behaviour than does Vickers indentation. The fracture toughness determined from Hertzian indentations was found to be a function of grain size, irrespective of the composition of the material. The cumulative probabilities of formation of ring cracks at specific loads during indentation with a spherical indenter were determined for each material from the set of 25 measurements, and the parameters of distribution of the probability of fracture were calculated. A statistical correlation between the failure probability distribution and the size distribution of alumina grains was detected.
J. Dusza, R. Danzer and R. Morrell
D. Galusek et al., "Determination of Fracture Toughness and Fracture Probability of LPS Aluminas by Hertzian Indentation", Key Engineering Materials, Vol. 290, pp. 308-311, 2005