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

The fatigue and fracture characteristics of a partially-stabilized fine-grained zirconia with spinel additions, (Mg, Y)-PSZ, were studied. Fracture toughness, crack growth resistance curves and fatigue crack growth (FCG) behavior, under both sustained and cyclic loading, were evaluated. Mechanical fatigue effects were clearly evidenced by (1) remarkable crack growth rate differences under cyclic and static loading and (2) significant loading Patio effects. Comparing the cyclic and the static FCG behavior allows to deduce 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 in situ observation of crack extension under cyclic loading, the fatigue mechanisms 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 of the (Mg, Y)-PSZ is the interaction between crack faces and hard spinel particles. The sensitivity of (Mg, Y)-PSZ and Mg-PSZ to cyclic fatigue is discussed in terms of the respective microstructures, prevalence and operativity of distinct mechanical fatigue mechanisms. (C) 1999 Elsevier Science Limited. All rights reserved.