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Microstructure and high-temperature deformation behavior of Al2O3–TiO2 obtained from ultra-high-pressure densification of metastable powders

Suffner, J. and Scherer, T. and Wang, D. and Fasel, C. and Jaworska, L. and Hahn, H. (2011):
Microstructure and high-temperature deformation behavior of Al2O3–TiO2 obtained from ultra-high-pressure densification of metastable powders.
In: Acta Materialia, 59 (20), Elsevier Science Publishing Company, pp. 7592-7601, ISSN 13596454,
[Online-Edition: http://dx.doi.org/10.1016/j.actamat.2011.09.025],
[Article]

Abstract

Metastable alumina composite powders with 13 wt.% titania were produced by plasma spraying using liquid nitrogen quenched substrates. The material consisted of a mixture of Al2O3 in a distorted spinel structure and a large amount of amorphous phases. High-pressure–high-temperature sintering below the crystallization temperature of the amorphous phase yielded a crystalline/amorphous composite that was used for creep experiments. During heating to the desired testing temperature, crystallization occurred and an in situ composite composed of corundum and rutile was obtained. This material exhibited superior deformation behavior compared to conventionally processed alumina materials. Comparably low temperatures of 1100 °C could be utilized to achieve plastic deformation of the material under a pressure of 50 MPa. Coble grain boundary creep with n = 1 and a low activation energy for diffusion of 390 kJ mol−1 was assumed to be the deformation mechanism.

Item Type: Article
Erschienen: 2011
Creators: Suffner, J. and Scherer, T. and Wang, D. and Fasel, C. and Jaworska, L. and Hahn, H.
Title: Microstructure and high-temperature deformation behavior of Al2O3–TiO2 obtained from ultra-high-pressure densification of metastable powders
Language: English
Abstract:

Metastable alumina composite powders with 13 wt.% titania were produced by plasma spraying using liquid nitrogen quenched substrates. The material consisted of a mixture of Al2O3 in a distorted spinel structure and a large amount of amorphous phases. High-pressure–high-temperature sintering below the crystallization temperature of the amorphous phase yielded a crystalline/amorphous composite that was used for creep experiments. During heating to the desired testing temperature, crystallization occurred and an in situ composite composed of corundum and rutile was obtained. This material exhibited superior deformation behavior compared to conventionally processed alumina materials. Comparably low temperatures of 1100 °C could be utilized to achieve plastic deformation of the material under a pressure of 50 MPa. Coble grain boundary creep with n = 1 and a low activation energy for diffusion of 390 kJ mol−1 was assumed to be the deformation mechanism.

Journal or Publication Title: Acta Materialia
Volume: 59
Number: 20
Publisher: Elsevier Science Publishing Company
Uncontrolled Keywords: Sintering, Nanocomposite, Superplasticity, Ceramics, Crystallization
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Dispersive Solids
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: 19 Feb 2013 09:56
Official URL: http://dx.doi.org/10.1016/j.actamat.2011.09.025
Identification Number: doi:10.1016/j.actamat.2011.09.025
Funders: Supported by the EU within the 6th framework program STRP NMP3-CT-2004-001470 NAMAMET (NAnostructured Materials through Metastable Transformations)., Financial support by the state of Hessen is gratefully acknowledged.
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