Abstract:
Widely investigated Al-Co-Cr-Cu-Fe-Ni-Ti high entropy alloys have been chosen for optimization of the microstructural and mechanical properties. The starting alloy is the equiatomic AlCoCrCuFeNi alloy which has been most studied since the HEA’s introduction in the early 2000’s. Different paths have been chosen for optimization, namely the decrease of segregating element Cu, the increase of oxidation protective elements Al and Cr and the approach towards a γ-γ’ microstructure as can be found in Ni-based superalloys. Microscopical observation at differerent levels (optical microscopy, scanning electron microscopy, transmission electron microscopy and three dimensional atom probe) have been made for each optimization step and compared with results obtained by Vickers microhardness measurements. Out of five derivate alloys, i.e. AlCoCrFeNi, Al23Co15Cr23Cu8Fe15Ni16, Al8Co17Cr17Cu8Fe17Ni33, Al8Co17Cr14Cu8Fe17Ni33Mo1Ti1W1 and Al10Co25Cr8Fe15Ni36Ti6 the most promising one has been chosen for further investigation.
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Institut für Angewandte Materialforschung EM-IAM Mikrostruktur