Study of defects in welded zircaloy-4 using transmission electron microscopy

Zircaloy-4 is used as a cladding material in CANDU type nuclear power reactors. The technique of electron microscopy has been used for the investigation of microstructural defects produced in zircaloy-4 due to the quenching treatment received during welding. This report describes the experimental results on the determination of Burgers vector of the dislocation loops. Identification of the nature of the defects, i.e., whether these are vacancy loops or hydride precipitates using electron diffraction analysis is discussed. Quantitative measurements of loop size distributions and density of loops are reported. Variation of vacancy concentration with distance from the molten zone is also presented. (author). 9 figs, 17 refs