Development and characterization of refractory high-entropy alloys for high temperature applications
Motivation
Ni-base superalloys currently are the preferred materials for high temperature applications in gas turbines. However, the applicable temperature range is limited by the melting points of the alloys (approx. 1450 °C), despite of cooling and thermal isolation. Refractory high-entropy alloys are expected to exceed the applicable temperature range of Ni-base superalloys.
Goals
- conventional metallurgical production of Ta-Mo-Cr-Ti-Al-X high entropy alloys with uniformly distributed microstructure
- stabilization a single phase, homogeneous solid solution or two-phase compositionally complex alloys by specific heat treatments
- determination of reproducible, characteristic values for evaluating mechanical properties regarding high temperature applications
- understanding of the deformation behavior by the distorted solid solution and ordered precipitates
Investigations
- evaluation of the alloy quality by O-/N-analysis for investigating the material purity and by wet chemical analysis for exactly determining the alloy composition
- thermal analysis to determine and characterize phase transitions
- tensile, compression and creep tests as well as hardness measurements for determining mechanical properties
- investigation on the microstructure in as cast, as heat treated and as deformed condition by diffractometric and microscopic characterization methods