Synthesis and characterization of a Pt–Al–Cr–Ni γ/γ′-coating on the Ni-based superalloy CMSX‐4

The reduction of wall thickness of turbine blades brings coating systems into focus with a high oxidation resistance and mechanical strength at high temperatures. Therefore a multi-layer coating with a nominal composition of 77Pt–12Al–6Cr–5Ni (at.%) was applied to single crystal Ni-based superalloy CMSX-4 substrates by electron beam physical vapor deposition. The multi-layer structures were homogenized at 800–1000 °C under continuous argon/2%-hydrogen gas flow for various times. Microstructures were investigated using scanning electron microscopy and transmission electron microscopy. Phase compositions were determined using energy dispersive X-ray spectroscopy in scanning and transmission electron microscopy. The coatings transformed into two phase microstructure with a fcc γ-phase and a L12 ordered γ′-phase during annealing.