The effect of oxygen partial pressure on dislocation creep in polycrystalline uranium dioxide. Issue 3 (March 2021)

• Record Type: Journal Article
• Authors: Garcia, Philippe; Miard, Audrey; Helfer, Thomas; Parise, Jean-Baptiste; Iltis, Xavière; Antou, Guy
• Is Part Of: Journal of the European Ceramic Society. Volume 41:Issue 3(2021)
• Page Start: 2124
• Page End: 2133
• Publication Date: 2021-03
• Subjects: Uranium dioxide -- Non-stoichiometry -- Creep -- Self-diffusion -- Defect behaviour; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2020.09.005
• Languages: English
• ISSNs: 0955-2219

Abstract

Abstract: We report a set of compression test experiments carried out on sintered uranium dioxide at 1500 ° C, at constant strain rates and under controlled oxygen partial pressures. The macroscopic data indicate an initial strain hardening stage followed by a quasi steady-state period during which changes in the stress level are sluggish. The data are further interpreted in a continuum mechanics, finite strain framework, in both one and two-dimensional geometries, whence stress and oxygen partial pressure exponents of the creep law are estimated. The stress exponent is indicative of power-law creep. The oxygen partial pressure exponent is consistent with a strain-rate limited by vacancy mediated self-diffusion of the slowest moving ion, suggesting a climb-controlled recovery process. Some samples are further characterized using SEM/EBSD which reveals signs of plastic deformation typical of recovery creep. The effect of oxygen pressure upon microstructure is discussed.