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Dependence of Flow Stress on Nonstoichiometry in Oxygen‐Rich Uranium Dioxide at High Temperatures
Author(s) -
Nadeau J. S.
Publication year - 1969
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.1151-2916.1968.tb11863.x-i1
Subject(s) - stoichiometry , uranium dioxide , materials science , anisotropy , oxygen , stress (linguistics) , flow stress , uranium , deformation (meteorology) , thermodynamics , mineralogy , composite material , chemistry , metallurgy , strain rate , linguistics , philosophy , organic chemistry , physics , quantum mechanics
The compressive flow stresses of UO 2+x polycrystals and single crystals were measured between 900° and 16000°C. The stoichiometry was controlled by CO 2 /CO gas mixtures during the tests. The functional dependence of strength on stoichiometry was:where C and m are constant at a constant temperature and 0.001 ≤ x ≤ 0.25. In stoichiometry crystals there was a marked anistrophy in strength. The {100} (110) systems were much softer than the {110} (110) systems, and the latter seemed to determine the strength of polycrystals. The harder systems {110} (110) displayed a softer ones. Nonstoichiometry largely removed the anisotrophy in strength and temperature dependence. It is suggested that the rate‐controlling deformation mechanism for polycrystals may be the thermally activated surmounting of the peierls barrier.