It is shown that the tetragonal phase can be stabilized in the sintered body of a partially stabilized zirconia (PSZ) containing low concentrations of yttria. Such sintered body containing the metastable phase undergoes stress-induced phase transformation by the absorption of thermal or mechanical stress and exhibits strengths in excess of 690 MPa (100ksi).
"Phase transformations in ceramics such as martensitic metamorphoses can involve spontaneous strain, and ferroelastic response occurs when such spontaneous strains are modified by, for example, exchange of twin variants (see, e.g.,             ). Such permanent strain, if heterogeneous, gives rise to self-equilibrating residual stresses within the object. "
[Show abstract][Hide abstract] ABSTRACT: In this paper the problem of transformation toughening in anisotropic solids is addressed in the framework of Stroh formalism. The fundamental solutions for a transformed strain nucleus located in an infinite anisotropic elastic plane are derived first. Furthermore, the solution for the interaction of a crack tip with a residual strain nucleus is obtained. On the basis of these expressions, fundamental formulations are presented for the toughening arising from transformations using the Green's function method. Finally, a representative example is studied to demonstrate the relevance of the fundamental formulation.
"There are two ways to stabilize t-and c-ZrO 2 at ambient temperature: (i) doping (e.g. with yttrium or other oversized dopant cations to obtain t-ZrO 2 (YSZ) or c-ZrO 2 )  and (ii) reducing the grain size down to the nanometer scale  . While t-ZrO 2 grains have been observed to be size-stabilized below 200 nm , c-ZrO 2 was reported to become size-stabilized only for grains of a few nanometers diameter . "
[Show abstract][Hide abstract] ABSTRACT: Zr-L2,3 XANESs of tetravalent zirconium oxides with different coordination numbers and local symmetries are systematically investigated by ab initio multiplet calculations using fully relativistic molecular spinors for model clusters. Experimental Zr-L2,3 XANESs are obtained for SrZrO3, m-ZrO2 (monoclinic) and t-ZrO2 (tetragonal). The theoretical spectra are in good agreement with the experimental data. The multiplet effects are found to play essential roles in determining the peak shape. The shapes of L3- and L2-edges are systematically different. The intensity ratios of the doublet peaks at both L3- and L2-edges are found to be sensitive to the coordination number of Zr. The ratio can therefore be used to estimate the coordination number of Zr in such oxides.
"Typical grain sizes of the sintered materials were by 0.5–2.0 mm, depending on sintering temperature, holding time, and physicochemical properties of the starting powders    . Fracture toughness as high as 12–14 MPa m À1/2 were obtained and hardness values were by 12–14 GPa. "
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