R-curve behavior of 3Y-TZP at cryogenic temperatures

We reported, for the first time, the R-curve behavior of zirconia ceramic stabilized with 3 mol% Y₂O₃ (3Y-TZP) at cryogenic temperatures down to liquid nitrogen temperature of 77 K, measured using direct indentation method and analyzed together with the Weibull statistical analysis of fracture strength data. The results provided a detailed understanding on the effect of decreasing temperature to the steady-state fracture toughness K _â that only the increase in the transformation toughening shielding term ΔK_T contributed to the K_â value at cryogenic temperatures, whereas the intrinsic fracture toughness K ₀ is independent of temperature. A more pronounced R-curve behavior unanticipated by the conventional interpretation was found at cryogenic temperatures, which could be of great significance to the concomitant increment of the fracture strength and toughness. Therefore, it is believed that 3Y-TZP could be one of the most promising materials in cryogenic structural applications.