GRAIN-SIZE EFFECTS ON CYCLIC FATIGUE AND CRACK-GROWTH RESISTANCE BEHAVIOR OF PARTIALLY-STABILIZED ZIRCONIA

Cyclic fatigue crack growth and crack-resistance behaviour was studied in partially stabilized zirconia (PSZ) with three different cubic-pha se grain sizes following sub-eutectoid heat treatments. Raman spectros copy was used to determine the extent of phase transformation around t he cracks for both cyclic and monotonic roading conditions. All tests were on ''long'', through thickness cracks using compact-tension speci mens. Predictions of crack-tip shielding were made following determina tion of toughening parameters using crack-resistance data. It was foun d that the dominant factors affecting cyclic fatigue-crack growth were the level of crack-tip shielding, as a result of phase transformation , and the intrinsic toughness of the material. Grain size did not appe ar to significantly affect fatigue crack-growth behaviour.