Evolution of γ/γ\u27 phases, their misfit and volume fractions in Al10Co25Cr8Fe15Ni36Ti6 compositionally complex alloy

Recently introduced Al10Co25Cr8Fe15Ni36Ti6 compositionally complex alloy has been investigated in the as-cast state and after heat treatment in a thorough characterization. The combination of optical, scanning and transmission electron microscopy, three dimensional atom probe and x-ray diffraction, both at lab and synchrotron level provides precise information of the microstructural evolution. After the typical dendritic solidification the alloy reveals dendritic cores consisting of γ and γ\u27 phases and interdendritic regions consisting of η and Heusler type phases. Homogenization removes the interdendritic regions and their phases and subsequent annealing produces a microstructure similar to Ni based superalloys consisting of γ/γ\u27 phases. In addition, about 50 μm sized Al-Ni rich needle-shaped precipitates of Heusler type structure can be observed. The four phases and their evolution with heat treatment are investigated in detail. Special focus lies on the γ/γ\u27 misfit determination and the determination of volume fractions by different methods