This study assesses the oxidation resistance of a MAX-Phase coating based on Cr2AlC applied to the Ti–48Al–2Cr–2Nb (at. %) alloy at temperatures of 700 °C and 800 °C in air. The coatings were produced through a combination of DC magnetron sputtering and subsequent annealing. Notably, the oxidation resistance of the TiAl alloy exhibited significant enhancement, attributed to the formation of a protective Al2O3/Cr2O3-scale at both temperatures.
Throughout the oxidation process, Al diffused from the coating into the substrate, driven by the higher Al activity of the Cr2AlC-phase compared to the TiAl substrate. This led to a depletion of Al, resulting in the emergence of Cr7C3, Cr23C6, and Cr2Al as the predominant phases in the coating. The mechanical properties of the coated samples, investigated via four-piont bending tests, were initially very promising, but were adversely affected by the degradation due to interdiffusion. This decrease in the mechanical properties and especially the fracture strain of the coatings was related to the brittle nature of the newly evolving phases. Finally an outlook on the substitution of Cr by titanium in the MAX-phase in the form of Ti2AlN and Ti2AlC MAX-phase is given. These are predicted to be thermodynamically more stable in the presence of the γ-TiAl phase.