Abstract
The creep data for stoichiometric polycrystalline uranium dioxide (UO
2) obtained in several compression investigations are analyzed using the Dorn equation together with deformation mapping, and it is shown that the data are divisible into three regions of deformation, depending on the value of the normalized stress. At high normalized stresses (
σ/
G > 10
−3 where σ is the applied stress and G is the shear modulus), the stress exponent is greater than 5 and the creep behavior seems to be consistent with the breakdown of the creep power law. At intermediate normalized stresses (5 × 10
−4 <
σ/
G < 10
−3), the stress exponent is about 4.5 and the creep behavior is in accord with that attributed to dislocation creep. At low normalized stresses (
σ/
G < 5 × 10
−4), the stress exponent is about 1, but the creep characteristics are not entirely compatible with the Nabarro-Herring process as originally documented in the literature on creep.