Institute for Applied Materials – Materials Science and Engineering

Development and characterization of refractory high-entropy alloys for high temperature applications

M.Sc. Stephan Laube

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