Microstructural study of oxide layers formed on Zircaloy-4 in autoclave and in reactor Part i: Impact of irradiation on the microstructure of the zirconia layer

Abstract

This study is devoted to assessing the repercussions of irradiation-induced microstructural changes in a Zircaloy-4 type alloy on the zirconia microstructure. It also deals with the study of microstructural features associated with the growth of the oxide layer under neutron irradiation. For this purpose, comparative analytical electron microscopy examinations are conducted on oxide layers formed in autoclave and in reactor. This first part of the study deals with the results relating to the oxidised matrix microstructure. Microstructural differences are shown up between layers formed with and without irradiation exposure. These are related to the zirconia crystallites nucleation and growth process from the metal-oxide interface and to the grain growth process in the thickness of the layer.