The effect of creep deformation of a β sialon on Vickers hardness, fracture toughness and Weibull modulus

The influence of creep deformation of a beta sialon with Sm-melilite solution (denoted as M') as intergranular phase on Vickers hardness, indentation fracture toughness and Weibull modulus was investigated in this article. For samples crept at different temperatures and stresses, Vickers hardness and fracture toughness fell in the range of 14.1-15.5 GPa and 5.73-7.04 MPa m(1/2), respectively. For virgin sample, the Vickers hardness and toughness were 15.8 GPa and 6.08 MPa m(1/2), respectively. Weibull moduli on Vickers hardness were 36 and 39 for the samples crept at 1300 degreesC (sample 5, see Table 1) and 1350 degreesC (sample 9, see Table 1), respectively, compared to 23 for the virgin sample. Weibull moduli on fracture toughness were 18 and 21 for sample 5 and sample 9, respectively, compared to 19 for the virgin sample. The discrepancy of Vickers hardness, fracture toughness and Weibull modulus between the virgin and crept samples was due to the more compact microstructure, the decrease in the amount and devitrification of intergranular phase and cavities during creep. Aging effect study shows that Vickers hardness values on the ends of crept specimens are lower than those within the deformation zones. (C) 2001 Elsevier Science B.V. All rights reserved.