Topic：High Entropy Alloys - Materials for High Temperature Applications? and Introduction to the new German Priority Programme
"Compositionally Complex Alloys - High Entropy Alloys (CCA - HEA)"

Speaker：Prof. Uwe Glatzel
　　　　　　Metals and Alloys, University Bayreuth, Germany

Time：10:00-11:30,am., (Tuesday)Apr.10, 2018

Venue：Room 403, Shi Changxu Building

By setting the maximum content of an element to 35 at.%, high temperature tensile and oxidation behavior up to 1000°C using the elements Al, Co, Cr, Cu, Fe, Ni and Ti in various mixtures is determined. The alloy development is aiming to balance high temperature tensile strength and ductility with good oxidation resistance. The alloys are in a first step optimized by microstructural observations. One of the goals was to achieve an fcc matrix with precipitate hardening. This goal deviates from the initial high entropy alloy (HEA) concept, which should yield to a simple, single-phase structure. For best high temperature properties, the precipitates should be stable up to at least 800°C. By this optimization route, supported by the CALPHAD method, the composition moves towards known Ni-base superalloys. Temperature dependent mechanical properties and oxidation resistance of the obtained alloys is compared with commercially available alloys (Inconel 617 and Alloy 800H).

The resulting optimized alloy Al₁₀Co₂₅Cr₈Fe₁₅Ni₃₆Ti₆ (in at.%) is in a follow-up project further improved by adding additional elements of concentrations < 2 at.%.

A brief overview of a Priority Programme funded by the German Research Foundation (DFG) entitled "Compositionally Complex Alloys - High Entropy Alloys (CCA-HEA)" will be presented. For further details see www.sppccahea.de. The programme has started in October 2017 for initially 3 years with a possible extension of up to 6 years in total. Financial support of more than 20 PhD students distributed all-over Germany has been granted. Two projects, successfully applied for by my group, will be briefly presented.