How TCP particles affect the high temperature strength of the polycrystalline Ni-base superalloy C-265 (T06*)

• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 190389738

Ni-base superalloys contain up to ten alloy elements. They show an excellent resistance against mechanical deformation and corrosion at temperatures up to 1000°C. For these alloy systems one aims at establishing microstructures which consist of a cubic face centered solid solution (γ-phase; matrix) and the ordered L12-phase (γʼ-phase; strengthening particles). However, the complex alloy composition also leads to the formation of so called TCP phases, like the σ-phase. Its formation is often associated with long thermal exposures at intermediate temperatures. It has been claimed that stresses and strains promote its formation. The formation of σ-phase particles is considered as being detrimental, because the particles change local alloy compositions and are thought of as representing nucleation sites for micro cracks. However, there is little scientific evidence which clearly proves these points. The research project explores how σ-phase particles nucleate and grow in the new polycrystalline Ni-bases superalloy C-265. Their effect on high temperature strength (creep and high temperature fatigue) will be explored. High resolution characterization methods will be used to characterize their chemical, physical and microstructural properties. Special emphasis will be placed on elementary processes at matrix/particle interfaces. It will be documented how different volume fractions, particle size distributions and particle shapes affect high temperature strength. The transfer project also aims at promoting the new poly crystalline Ni-base superalloy C-265.

• DFG Programme: CRC/Transregios (Transfer Project)
• Subproject of: TRR 103: From Atoms to Turbine Blades - A Scientific Approach for Developing the Next Generation of Single Crystal Superalloys
• Applicant Institution: Ruhr-Universität Bochum
• Business and Industry: VDM Metals International GmbH
• Project Head: Professor Dr.-Ing. Gunther Eggeler