J. Phys. Colloques
Volume 50, Numéro C8, Novembre 198936th International Field Emission Symposium
|Page(s)||C8-429 - C8-434|
J. Phys. Colloques 50 (1989) C8-429-C8-434
AN APFIM STUDY OF THE AGEING BEHAVIOUR OF U-6.0 wt% NbG. BEVERINI et D.V. EDMONDS
Department of Metallurgy and Science of Materials, University of Oxford, Parks Road, GB-Oxford 0X1 3PH, Great-Britain
Atom Probe Field Ion Microscopy (APFIM) in conjunction with Transmission Electron Microscopy is being used to determine the mechanisms responsible for the strength increase observed upon ageing U-6.0wt% Nb. Analysis of composition profiles obtained from the APFIM show that two distinct types of phase separation reactions are taking place during ageing. At present no conclusive evidence exists to identify the reaction mechanisms. However, electron diffraction and APFIM results suggest that at ageing temperatures below 400°C a fine sale segregation reaction takes place, possibly spinodal decomposition, whilst at temperatures above 400°C strengthening is probably due to precipitation of a Nb-rich phase.