Effect of microstructural evolution on the measured creep parameters of yttria-stabilized tetragonal zirconia polycrystals

Journal Article · Wed Dec 15 04:00:00 EST 1993 · Scripta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-716X(93)90291-Y· OSTI ID:5788312

Bravo-Leon, A; Ye, J; Jimenez-Melendo, M; Dominguez-Rodriguez, A ^[1]

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1. Univ. de Sevilla (Spain). Dept. de Fisica de la Materia Condensada

From the early work of Wakai et al., many studies have been devoted to the structural superplasticity on fine-grained zirconia-based polycrystals, especially when doped with yttria. Superplastic deformation is provided by grain boundary sliding without appreciable deformation of the grains themselves; the strain rate [var epsilon] is usually controlled by diffusion necessary to accommodate the motion of the grains one each other. High temperature deformation data are analyzed through the standard equation for steady state deformation: [var epsilon] [equals] A/T [center dot] [sigma][sup n] [center dot] d[sup [minus]p] [center dot] exp([minus]Q/RT) where A is a constant, [sigma] the stress, d the grain size and T the temperature. The parameters n, p and Q are characteristic of the deformation and diffusion mechanisms. The dependence of [var epsilon] on the oxygen partial pressure (PO[sub 2]) has not been taken into account in eq. (1) because a PO[sub 2] exponent m [equals] 0 was found in the creep of Y[sub 2]O[sub 3]-stabilized ZrO[sub 2] single and polycrystals between 0.21 and 10[sup [minus]9] atm at 1,200--1,600 C [4,5], and also in this work between 0.21 and 10[sup [minus]5] atm at 1,200--1,400 C. The stress and temperature exponents can be measured by two different techniques, which are not equivalent when the microstructure evolves during the tests. In the conventional method, experiments are performed on different specimens changing only one variable and keeping the others constant; on the contrary, in the differential method, one variable is changing during the test on the same sample.

• OSTI ID: 5788312
• Journal Information: Scripta Metallurgica et Materialia; (United States), Journal Name: Scripta Metallurgica et Materialia; (United States) Vol. 29:12; ISSN 0956-716X; ISSN SCRMEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
360103 -- Metals & Alloys-- Mechanical Properties
ALLOYS
CREEP
DEFORMATION
GRAIN BOUNDARIES
GRAIN SIZE
MECHANICAL PROPERTIES
MICROSTRUCTURE
SIZE
YTTRIUM ADDITIONS
YTTRIUM ALLOYS
ZIRCONIUM ALLOYS
ZIRCONIUM BASE ALLOYS