63857 2023 eng lecture 0 -- -- -- The chemically complex alloys that contain mostly refractory elements (rCCAs), may be highly resistant to heat and load, which makes them attractive candidates for use at extremely high temperatures associated with technological applications such as aeroengine turbines. However, the oxidation behavior remains an emerging field within the CCA community. The fully heat treated AlMo0.5NbTa0.5TiZr rCCA contains a dual-phase microstructure that resembles the γ/ γ’ pattern of the well-known Ni-base superalloys, however with a continuous Al-Zr-Ti-rich B2 ordered matrix embedding Mo-Nb-Ta-rach bcc precipitates. The question thus arises what is the oxidation behavior of this rCCA alloy? In this study, this question is addressed via in situ and ex situ X-ray diffraction (XRD) in dry and humid air in the 800–1000 °C regime. Electron microscopic investigations complement the findings. In situ synchrotron experiments were carried out at the KMC2 beamline of the Helmholtz Zentrum Berlin (HZB), with a wavelength of 1.5418 Å at 800 and 950 °C under dry and humid (≈ 40% rH, laboratory air) air for 12 h. Scanning and transmission electron microscopy was performed before and after exposure to spatially resolve the scale development ex situ. In general, 12 h exposure led to an oxide scale which internal oxidation reaches several tens of microns, and which is dominated by Zr-, Ti- and Mo-containing oxides although aluminum oxide was also always present. Main differences are observed between temperatures, while the humidity played a lesser role. International Conference on High Entropy Materials (ICHEM) 2023 Knoxville, TN, USA 18.06.2023 22.06.2023 0 publish false true Patricia Suárez Ocaño Leonardo Agudo Jácome eng uncontrolled High entropy superalloy eng uncontrolled High temperature oxidation eng uncontrolled In situ synchrotron diffraction eng uncontrolled Electron microscopy Ingenieurwissenschaften und zugeordnete Tätigkeiten 5 Werkstofftechnik 5.1 Mikrostruktur Design und Degradation Material Degradationsmechanismen Datei im Netzwerk der BAM verfügbar ("Closed Access") Präsentation