Abstract: This paper describes the key role played by superalloys in aerospace propulsion. Turbopump blades in liquid rocket engines operating under severe thermal and environmental conditions require the development of specific materials.A new superalloy,THYMONEL 8, developed by ONERA in collaboration with SEP is shown to possess a set of properties required for advanced rocket engines. For future civil aircraft engines, the development of compressor and turbine disk materials operating at still higher temperatures requires a greater contrul of the grain size,which has to be increased for improved creep resistance and higher damage tolerance. Work carried out at ONERA emphasizes the importance of high temperature deformation conditions, especially the strain rate, for obtaining a uniform grain growth.

Key words: superalloy, stngle crystal, turbopump, THYMONEL 8, disc