Characterization of Dislocation Substructures in Zr-2.5 Nb Pressure Tube Alloys

Abstract

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.