Plastic deformation in nonstoichiometric UO2+ x single crystals—I. Deformation at low temperatures

Abstract

Single crystals of UO 2 + x (5 × 10 −6 ⩽ x ⩽ 10 −2) have been deformed in equilibrium CO CO 2 mixtures at 873 K in compression and at 300 K under microhardness indents. The primary glide plane is {111} under all conditions, and the yield stress is independent of x at 873 K but increases slightly with increasing x at 300 K. Dislocation substructures consist largely of screw dislocations, indicating that the motion of screw dislocations controls deformation; it is likely that dislocation mobility is controlled by interactions between dislocations and extrinsic defects.