The role of liquid phase formation during thermal processing of Ni base superalloys

• Applicant: Dr.-Ing. Inmaculada López Galilea, Ph.D.
• Subject Area: Metallurgical, Thermal and Thermomechanical Treatment of Materials
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 503229465

The undisputable high-temperature properties of single crystal (SX) Ni base superalloys are the result of a complex alloying system coupled with a complex manufacturing process. In order to achieve the best performance of the SX superalloys, demanding heat treatment and hot isostatic pressing (HIP) are always required as characteristic process steps. There is an enormous scientific and industrial interest in mastering them in the best possible way. This project proposes for the first time an innovative route to process SX Ni base superalloys, which consists of a heat treatment under pressure at super-solidus temperatures with the presence of a liquid phase. The main objective of this research project is to understand the role of liquid phase formation during thermal processing at super-solidus temperatures on the microstructure and mechanical properties of three commercial SX Ni base superalloys. Super-solidus HIP heat treatments are considered very attractive because the extremely long solution treatment times of complex commercial SX superalloys can be significantly shortened, resulting in homogeneous structures with good mechanical properties. The commercial casted SX Ni-base superalloys CMSX-4, CMSX-4Plus and CMSX-10K are investigated in this project. The key to the success of this heat treatment is based on the control of the amount of melted material at super-solidus temperatures in order to prevent the resolidification of misoriented grains. This innovative, economically interesting and sustainable approach has not yet been found in the scientific literature. The project has ambitious and innovative scientific objectives that will be achieved through the execution of the demanding work program detailed in it.

• DFG Programme: Research Grants