Experimental Assessment of Plasticity of Nanocrystalline 1.7 mol% Yttria Tetragonal Zirconia Polycrystals

Abstract

High temperature mechanical behavior of nanocrystalline 1.7 mol% (3 wt%) yttria tetragonal zirconia polycrystals (nc‐YTZP) was characterized by compression creep tests. The hot isostatically pressed nc‐YTZP with mean grain size of 120 nm was subjected to grain growth to obtain grain sizes in the range of 120–310 nm. Direct measurements of the creep parameters were performed in the temperature range 1150°–1300°C and stress range 5–400 MPa. The strain rates at 1150°C ranged between 2 × 10−7 and 9 × 10−5 s−1 when increasing the stress from 15 to 400 MPa. Values of the stress exponent, n=2.0±0.3, and the activation energy, Q=630±40 kJ/mol, were obtained for all test conditions. A value of the grain size exponent, p=1.5±0.3, was obtained at 1150°C in the stress range studied. Detailed microstructural observations revealed the absence of glassy phase at the grain boundaries. The creep parameters were compared with those from the literature, and the results were discussed in terms of the model recently developed by the authors, with a reasonable agreement.

High‐Temperature Deformation Mechanisms in Monolithic 3YTZP and 3YTZP Containing Single‐Walled Carbon Nanotubes

“…Gutierrez‐Mora et al . also reported activation energy values close to 700 kJ/mol in nanocrystalline Y‐TZP crept at temperatures between 1150°C and 1250°C, and stresses ranging between 5 and 200 MPa.…”

Diffusion and Creep in Silica‐Doped Tetragonal Zirconia

“…23 It is interesting to note that there have been other recent studies that have also revealed that the threshold stress approach is unable to rationalize the experimental observations in a 4 mol% yttria-stabilized tetragonal zirconia 35 as well as some nanocrystalline zirconias. 36 Although some studies have noted intragranular dislocations, 18 several other studies on superplastic zirconias have noted the lack of intragranular dislocations. 35,37 A recent study by Dominguez-Rodriguez et al 38 concluded that observation of intergranular dislocation in deformed 3YTZ samples were experimental artifacts.…”

High temperature plasticity in yttria stabilised tetragonal zirconia polycrystals (Y-TZP)

“…Improved creep resistance has been reported in 50-70 nm Y-TZP deformed at 1200uC, in agreement with model predictions. [58][59][60][61][62][63] In this regard, it has been shown that the effect of segregation becomes increasingly important as the grain size becomes smaller. Indirect experimental evidence for this is shown in Fig.…”