Elevated temperature creep of polycrystalline uranium dioxide: from microscopic mechanisms to macroscopic behaviour

Creep of polycrystalline UO2 at intermediate temperatures is studied by compression experiments and microstructural observations at different dimensional scales. Creep data exhibit two different stress regimes in the classical power law representation, but can be described on a more physical basis by a unique hyperbolic sine creep law on the whole range of stresses explored here, which is shown to account for both bulk grain deformation and accommodated grain boundary sliding. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.