Development and characterization of refractory high-entropy alloys for high temperature applications
Currently, Ni-based superalloys are the preferred materials for high-temperature gas turbine applications. However, their melting point of approximately 1450°C limits the temperature range in which they can be used, even with cooling and thermal insulation.
Refractory Compositionally Complex Alloys (RCCA) and Refractory High Entropy Alloys (RHEA) consist of a combination of mutually soluble refractory metals, typically resulting in a disordered or ordered body-centered cubic crystal structure. The latter is defined as forming a single-phase microstructure, while the former can exhibit a multi-phase microstructure. Some of these alloys have been shown to outperform Ni-based superalloys in certain key structural properties, such as high-temperature strength or density.
Conventional metallurgical production of equiatomic and non-equiatomic Ta-Mo-Cr-Ti-Al alloys with uniformly distributed microstructure
Stabilization of a single-phase, homogeneous solid solution or two-phase compositionally complex alloys by tailoring the composition and specific heat treatments
Determination of reproducible, characteristic values for evaluating mechanical properties regarding high-temperature applications
Understanding of the deformation behavior of single-phase and multi-phase alloys with varying ordering states
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 and high-resolution atom probe tomography to determine and characterize phase transitions
Compression tests as well as hardness measurements on different length scales for determining mechanical properties
Investigation of the microstructure in the heat treated and the deformed condition by diffractometric and microscopic characterization methods
SPP 2006 "Compositionally Complex Alloys – High Entropy Alloys" by Deutsche Forschungsgemeinschaft