Nickel-based superalloys are widely used in aircraft and helicopter engines for their outstanding mechanical properties at operating temperatures around 750°C. To allow for ever higher temperature operations, new alloys are being developed. Their use imposes a fine understanding of the mechanisms of deformation. This is made possible by the investigation methods available at CEMES.
To answer this question, experiments were carried out on the new AD730 superalloy developed by Aubert & Duval, using different transmission electron microscopes, in order to explain the totally different lifetimes that result from the different heat treatments. Following the analysis of local chemical compositions of the various phases (matrix and precipitates), an evolution has been evidenced when the alloy is heat-treated at 790°C. This evolution of chemical composition has been related to the physical parameters that control the micromechanisms of deformation and thus allowed to explain the decrease of lifetime of the alloy when heat-treated at such temperature.
This work proves the need to carry out fine analyzes of local chemistry coupled with identification of the deformation micromechanisms to improve the understanding of the mechanical behavior of these efficient materials.
This work take part in the cross study INCA INfluence of local Chemistry on the mechanical behavior of metallic Alloys
Creep behavior in the new AD730TM nickel-based disk superalloy – Influence of aging heat treatment and local chemical fluctuations
F. Pettinari-Sturmel, W. Vultos, M. Hantcherli, B. Warot-Fonrose, C. Marcelot, Joël Douin, J. Cormier, P. Villechaise, A. Devaux
Materials Science and Engineering: A, Elsevier, 2019.
DOI : 10.1016/j.msea.2019.02.088.
Dr. Florence PETTINARI, CEMES (CNRS)