Filtern
Dokumenttyp
Sprache
- Englisch (2)
Schlagworte
- Carbide phase NbC (1)
- Creep under thermal cycling (1)
- Electron backscatter diffraction (1)
- Hardening (1)
- High temperature nickel-based eutectic alloys (1)
- In-situ composites (1)
- Microstructure (1)
- Superalloy (1)
- TEM (1)
- γ/γ' matrix (1)
Organisationseinheit der BAM
The thermal stability of the microstructure of a heat-resistant cobalt alloy, which consists of a γ solid solution strengthened with γ'-phase precipitates, has been studied. The temperature behavior of the dissolution of the hardening γ' phase and the kinetics of its coarsening at 700 and 800°C have been determined. It is found that, during prolonged annealing at 800°C, the γ' → β phase transformation occurs.
A nickel-based eutectic alloy with a γ/γ'-NbC structure was directionally solidified with a planar front. The specimens were tested for creep under sawtooth thermal cycling in the temperature range from 600 to 1100°C. It has been established that the lifetime under the conditions of thermal cycling is about five times shorter than it is predicted by the linear damage accumulation rule on the basis of results of isothermal creep tests. Faster creep under thermal cycling is caused by the rapid coarsening of the γ/γ' microstructure due to the periodic partial dissolution and reprecipitation of the γ' phase in heating and cooling half-cycles.