Microstructures et Recristallisation
J. Phys. IV 05 (1995) C3-225-C3-235
Etude Expérimentale et Simulation Numérique de la Cinétique de Précipitation γ' et de l'Evolution Microstructurale dans le Superalliage N18 au cours de la TrempeN. Gayraud1, F. Moret1 and Y. Desvalley2
1 Section de Génie des Matériaux, CEREM, CENG, 38054 Grenoble, France
2 SNECMA, 291 avenue d'Argenteuil, 92230 Gennevilliers, France
The high temperatures and stresses experienced within turbine discs require high temperature resistant Ni-base superalloys produced by Powder Metallurgy techniques. The alloy N18 we study has good overall mechanical properties at temperatures up to 700°C after appropriate heat treatment. These properties are derived from the precipitation of ordered γ' phase and are strongly dependent upon the microstructure produced during thermal treatments. The γ' precipitation kinetics is experimentally studied by dilatometry and transmission electron microscopy. The microstructural evolution of γ'precipitates during quenching is followed in a high quenching rate apparatus that permits to preserve the high temperature microstructure at room temperature. In the present work, a model is being developped and is experimentally verified in order to describe the intragranular γ' precipitation during quenching.
© EDP Sciences 1995