Evolution of microstructure, microtexture and texture in dilute zirconium based structural components of pressurized heavy water reactors

Abstract

Microstructure and texture of Zr alloys plays a significant role in deciding the material properties and its performance in nuclear reactor. In order to understand the development of microstructure, it is important to know the phase transformations mechanism in these alloys. Dilute Zr-Nb alloys exhibit a range of diffusional, diffusion less and hybrid phase transformations which includes martensitic omega and hydride transformation. With these points in view detail studies on the physical metallurgy aspects of the binary, ternary and quaternary Zirconium base alloys has been carried out in this study. Electron Diffraction and X-ray diffraction techniques have been used to determine the phases, defects and their crystallographic features. Hydriding is most important corrosion problem in the Zirconium cladding alloys. The mechanism of hydride phase transformation and their crystallographic and microstructural aspects has been presented in detail in some Zirconium alloys. Zirconium alloys being crystallographically asymmetric it shows deformation and annealing texture. Result of the studies on bulk and micro texture in some zirconium alloys and some micro-textural aspects on hydride formation is presented in this paper.