Characterization of dislocation structures in Zr-2.5 Nb pressure tube alloys

The nature of the dislocation substructure formed at α:α and α:β boundaries in Zr-Nb pressure tube alloys has been studied by electron microscopy. The character of the boundaries is established by the extrusion operation, and subsequent cold working and/or annealing treatments modify only the misorientation and nature of the boundaries but not the scale of the substructure. The dominant boundary structure introduced by extrusion contains arrays of both [a] and [c] dislocations. The importance of these dislocation arrays in understanding the strengthening mechanisms and irradiation growth behaviour of the alloy is emphasized