From the ReRu-rich δ Phase to the Intergrowth of the P and the σ Phases in Ru-bearing Ni-base Superalloys

7th Annual International Conference on Materials Science and Engineering

Wang, Chunhui^1 ; Chen, Yanhui^1 ; Chen, Jingyang^2 ; Xue, Fei^2 ; Li, Wei^1 ; Yang, Luyan^1

Institute of the Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing

100124, China^1

Science and Technology of Advanced High-Temperature Structural Materials Laboratory, Beijing Institute of Aeronautical Materials, Beijing

100095, China^2

关键词: Formation mechanism;    Hexagonal structures;    Low-cr alloys;    Ni-base single crystal superalloy;    Ni-base superalloys;    Orientation relationship;    Primary phase;    Short periods;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/562/1/012021/pdf
DOI  :  10.1088/1757-899X/562/1/012021

来源: IOP

【 摘 要 】

The morphology, composition, structure and formation mechanisms of precipitates in three Ni-base single crystal superalloys containing 3.2 at. % Ru by adding Cr (0 to 6.5 at. %) were investigated. The precipitation speed in the Low-Cr alloy was low at a temperature of 1100 °C. The ReRu-rich δ phase, with a hexagonal structure, was the primary phase. A high quantity of precipitates appeared in the high Cr alloy after 50 h of heat treatment. The quantity increased rapidly from that time. The σ phases dominated the precipitate after a short period of heating at 1100 °C, with the orientation relationship corresponding to [111] γ/γ′ // [111] σ and (110) γ/γ′ // (110) σ. The σ phase transformed into the intergrowth of the σ and the P phases discontinuously through the σ needle as the exposure time increased. The large elemental γ/γ′ partitioning ratio of Re in 6.5 at. % Cr was the key factor that promoted nucleation in the σ phase.