No abstract

No abstract

No abstract

The discovery of high entropy alloys at the turn of the millennium lead to a multitude of investigations of different types, focus and aims. With an increased knowledge of the new family of materials, it was possible to make a separation into true single phase high entropy alloys (HEA) and multi-phase compositionally complex alloys (CCA), which both fulfil the initial definition criteria. This review focuses on CCA that have been investigated and developed with a mechanical application in mind. A special importance is attributed to the mechanical testing methods, and priority is given to tensile testing at both room temperature and up to 700°C. Precise microstructural characterization techniques like transmission electron microscopy and/or atom probe tomography ensure the determination of small scale phases, which could be overlooked when using only scanning electron microscopy and/or X-ray diffraction. Comparison of the investigations that meet these criteria are summarized in several tables and figures.

Abstract:The most commonly investigated high entropy alloy, AlCoCrCuFeNi, has been chosen for optimization of its microstructural and mechanical properties by means of compositional changes and heat treatments. Among the different available optimization paths, the decrease of segregating element Cu, the increase of oxidation protective elements Al and Cr and the approach towards a γ-γ 1 microstructure like in Ni-based superalloys have been probed and compared.