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Effect of Oxygen Potential on the Thermal Creep of Niobia Doped UO 2
Author(s) -
AINSCOUGH J. B.,
RIGBY F.,
MORROW S. A.
Publication year - 1981
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1981.tb09609.x
Subject(s) - creep , activation energy , oxygen , materials science , atmospheric temperature range , doping , microstructure , ultimate tensile strength , strain (injury) , kinetics , strain rate , analytical chemistry (journal) , thermodynamics , chemistry , composite material , medicine , physics , optoelectronics , organic chemistry , chromatography , quantum mechanics
Compressive and tensile creep were measured on UO 2 doped with 0.4 wt % niobia at controlled oxygen potentials. Kinetic results were almost identical, irrespective of the nature of the applied stress, but differences in after‐test microstructures were observed. Formation of “plastic” UO 2 with increases in strain rate of more than two orders of magnitude were recorded when oxygen potential changed from −560 to −410 kJ/mol; this was associated, primarily, with the formation of the Nb 4+ ion. Over the same range of oxygen potential, creep activation energy decreased linearly from −425 to −225 kJ/ mol. In contrast, strain rate and activation energy for undoped UO 2 remain almost constant under these conditions.