Troisiéme Conférence Européenne sur les Matériaux et les Procédés Avancés
J. Phys. IV France 03 (1993) C7-519-C7-522
Microstructural evolution of α or β quenched zirconium alloys during isothermal agings, between 20 °C and 750 °CP. MERLE, K. LOUCIF and R. BORRELLY
Groupe d'Etudes de Métallurgie Physique et de Physique des Matériaux, URA 341, Bat. 502, INSA, 69621 Villeurbanne cedex, France
In Zircaloy and zirconium alloys, after quench from the upper limit of the α domain a small quantity of iron, chromium or nickel remains in solid solution and then precipitates during further isothermal aging. This precipitation is studied between 450°C and 600°C, using thermoelectric power (TEP) and resistivity measurements. It is shown that precipitation kinetic is strongly reduced by the presence of oxygen and tin. After quench from the β domain (1030°C) five stages of evolution are detected by TEP measurements in Zircaloy-4, the more important being : - a low temperature evolution (<400°C) attributed to local atomic rearrangements - the precipitation of iron and chromium initially dissolved. The amplitude of TEP variation shows that β quench do not permit to allow larger amount of iron and chromium in solution tha for α quench - the recrystallization of the initial martensitic structure.
© EDP Sciences 1993