Optimizing the mechanical properties of variations of Al10Co25Cr8Fe15Ni36Ti6 compositionally complex alloy

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"Compositionally complex alloy/high entropy alloy" Al10Co25Cr8Fe15Ni36Ti6 and its variations with trace elements Hf, Zr, W, Mo, Y and B have been found to be good candidates for a long-term application in turbines. After an optimized heat treatment they are characterized mainly by a two phase microstructure consisting of cuboid precipitates of ordered crystal structure and a matrix of disordered structure. Additionally, a third phase has been detected. Depending on the trace element it has different shapes, i.e. needles or ellipsoids, and influences the mechanical properties massively.Tensile tests at room temperature and around 600-800°C show excellent mechanical properties, comparable to commercial Ni-based superalloy such as Inconel 617 or Fe-Ni based alloys like Alloy 800. The best trace element concerning mechanical properties has been found to be Hf. The alloy with Hf shall now be optimized further, e.g. by adding small amounts of interesting trace elements W and/or Zr which excel in the domains of microstructure and oxidation.