High-Entropy Alloys

The classical concept for tailoring properties of metallic materials compromises alloying of a single, metallic principle element with typically minor alloying elements. In contrast, high entropy alloys contain at least five elements in significant amounts - in many cases an almost equimolar composition is used. Here, CoCrFeMnNi or HfNbTaTiZr as well as our newly developed NbMoCrTiAl can be mentioned since these alloys exhibit rather simple disordered, face centered cubic or body centered cubic crystal structures which contradicts the metallurgical expectations. Since the expected, usually brittle intermetallic phases do not form, a rather high ductility even at low temperature is observed or a combination of rather contradictory properties like high melting point by refractory metals and good oxidation resistance by passivating elements can be achieved.

Following topics are currently under investigation:

• M.Sc. Stephan Laube:
  Development and characterization of refractory high-entropy alloys for high temperature applications
• M.Sc. Liu Yang:
  Creep behavior and deformation mechanisms of precipitation-strengthened Ta-Mo-Cr-Ti-Al alloys