Statistical fatigue strength evaluation and inelastic deformation generated during static and cyclic loadings in Ce-TZP/alumina nanocomposite: part 2 - in water environment

The statistical fatigue strength evaluations in water of an intragranular type Ce-TZP/Al2O3 nanocomposite (Ce-TZP/A-N) were investigated in comparison to 3Y-TZP. The isothermal t-m transformation which causes low temperature aging degradation (LTAD) did not occur during fatigue tests for both materials. The strength degradations under static and cyclic loadings of Ce-TZP were fairly small compared to those of 3Y-TZP. The life shortening in water of 3Y-TZP was slight, and Ce-TZP/A-N maintained comparable fatigue lives found in air. Large inelastic deformations (converted strain = 0.06-0.23%) were observed in the non-failure fatigued specimens after static and cyclic loadings. The amount of inelastic deformations and relevant transformed monoclinic contents in water were smaller than those in air at equivalent stress level. In contrast, the volume fractions of the monoclinic phase in water were slightly higher than those in air at equivalent strain level. For 3Y-TZP, no inelastic deformation was identified.