Experimental evidence for diffusion creep in the superplastic 3 mol% yttria-stabilized tetragonal zirconia

• Published in: Acta materialia Vol. 49; no. 12; pp. 2239 - 2249
• Main Authors: Charit, I, Chokshi, A.H
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 17.07.2001; Elsevier Science
• Subjects: Applied sciences; Condensed matter: structure, mechanical and thermal properties; Creep; Diffusion; Exact sciences and technology; Interface; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Metals. Metallurgy; Physics; Superplasticity; Superplasticity; Creep; Diffusion; Interface; Interfaces; Zirconia; Diffusion creep; Superplastic deformation; Stabilized zirconia; Experimental study; Microstructure; Flow stress
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/S1359-6454(01)00131-8

Although there have been numerous studies on the high temperature deformation characteristics of the superplastic 3 mol% yttria stabilized tetragonal zirconia (3YTZ), the rate controlling deformation mechanism has not been identified unambiguously. In the present study, experiments were conducted on 3YTZ at high stresses and at coarser grain sizes than used conventionally for superplasticity. The experimental results reveal, for the first time, an intragranular dislocation motion controlled high stress regime that is independent of the grain size. With a decrease in stress, there is a transition to a Newtonian viscous deformation regime consistent with Coble grain boundary diffusion creep. At sufficiently low stresses, or in materials with finer grain sizes, there is a further transition to a grain size dependent interface controlled deformation regime. Analysis of the experimental data suggests strongly that superplastic flow in 3YTZ occurs by an interface controlled deformation mechanism.