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Enhancing superplasticity of Zr02 (Y2030)-Al203 composites

Suffner, J. and Wang, D. and Hahn, H. (2010):
Enhancing superplasticity of Zr02 (Y2030)-Al203 composites.
In: Materials Science and Engineering: A, 527 (29-30), pp. 7885-7892. Elsevier Science Publishing Company, [Article]

Abstract

Dense ZrO2 (5 wt% Y2O3)–20 wt% Al2O3 composites with an average grain size of the zirconia matrix of about 450nm were prepared by means of spark plasma sintering of a metastable powder. The powder, consisting of a supersaturated solid solution of Al3+ in a stabilized cubic ZrO2(Y) matrix, was prepared by atmospheric plasma spraying using liquid nitrogen cooled substrates. During sintering, phase separation and precipitation of Al2O3 in a tetragonal ZrO2(Y) matrix occurred. Due to the rapid sintering, thermodynamic equilibrium was not fully achieved and part of the metastable nature was retained in the form of Al3+, Y3+ co-doped ZrO2 grains. High temperature Vickers indentations and creep tests in uniaxial compression were performed to characterize the deformation behavior. Arrhenius plots of the high temperature hardness indicated a transition of the deformation process at 1080 ◦C. Creep tests above the transition temperature yielded superplastic deformation. The stress exponent n, the grain size exponent p and the activation energy Q of the deformation process were calculated and discussed with respect to the microstructure evolution during deformation. Grain boundary sliding was assumed to be the deformation mechanism accompanied by cation diffusion through the lattice. A strain rate of 3×10−3 s−1 at a temperature of 1350 ◦C was achieved in the absence of a glassy grain boundary phase. Normalized stress–strain rate plots indicated that the alumina doping successfully increases the deformability of this composite with respect to a conventionally processed ZrO2(Y)–Al2O3 material.

Item Type: Article
Erschienen: 2010
Creators: Suffner, J. and Wang, D. and Hahn, H.
Title: Enhancing superplasticity of Zr02 (Y2030)-Al203 composites
Language: English
Abstract:

Dense ZrO2 (5 wt% Y2O3)–20 wt% Al2O3 composites with an average grain size of the zirconia matrix of about 450nm were prepared by means of spark plasma sintering of a metastable powder. The powder, consisting of a supersaturated solid solution of Al3+ in a stabilized cubic ZrO2(Y) matrix, was prepared by atmospheric plasma spraying using liquid nitrogen cooled substrates. During sintering, phase separation and precipitation of Al2O3 in a tetragonal ZrO2(Y) matrix occurred. Due to the rapid sintering, thermodynamic equilibrium was not fully achieved and part of the metastable nature was retained in the form of Al3+, Y3+ co-doped ZrO2 grains. High temperature Vickers indentations and creep tests in uniaxial compression were performed to characterize the deformation behavior. Arrhenius plots of the high temperature hardness indicated a transition of the deformation process at 1080 ◦C. Creep tests above the transition temperature yielded superplastic deformation. The stress exponent n, the grain size exponent p and the activation energy Q of the deformation process were calculated and discussed with respect to the microstructure evolution during deformation. Grain boundary sliding was assumed to be the deformation mechanism accompanied by cation diffusion through the lattice. A strain rate of 3×10−3 s−1 at a temperature of 1350 ◦C was achieved in the absence of a glassy grain boundary phase. Normalized stress–strain rate plots indicated that the alumina doping successfully increases the deformability of this composite with respect to a conventionally processed ZrO2(Y)–Al2O3 material.

Journal or Publication Title: Materials Science and Engineering: A
Journal volume: 527
Number: 29-30
Publisher: Elsevier Science Publishing Company
Uncontrolled Keywords: Spark plasma sintering, Atmospheric plasma spraying, Metastability, Superplasticity, Supersaturated solid solution
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Joint Research Laboratory Nanomaterials
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 15 Feb 2013 09:01
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