Fatigue and fracture characteristics of a fine-grained (Mg,Y)-PSZ zirconiaceramic

The fatigue and fracture characteristics of a partially-stabilized fine-gra ined zirconia with spinel additions, (Mg, Y)-PSZ, were studied. Fracture to ughness, crack growth resistance curves and fatigue crack growth (FCG) beha vior, under both sustained and cyclic loading, were evaluated. Mechanical f atigue effects were clearly evidenced by (1) remarkable crack growth rate d ifferences under cyclic and static loading and (2) significant loading Pati o effects. Comparing the cyclic and the static FCG behavior allows to deduc e a higher cyclic fatigue sensitivity of the fine-grained (Mg, Y)-PSZ with respect to a commercial peak-aged Mg-PSZ used as a reference material. By i n situ observation of crack extension under cyclic loading, the fatigue mec hanisms could be resolved. Mechanical degradation of bridging ligaments, as already known for coarse-grained Mg-PSZ, is one sour ce of cyclic fatigue. An additional source attributed to the particle dispersed microstructure o f the (Mg, Y)-PSZ is the interaction between crack faces and hard spinel pa rticles. The sensitivity of (Mg, Y)-PSZ and Mg-PSZ to cyclic fatigue is dis cussed in terms of the respective microstructures, prevalence and operativi ty of distinct mechanical fatigue mechanisms. (C) 1999 Elsevier Science Lim ited. All rights reserved.