Influence of microstructure on the oxidation behaviour of the Ni-based single crystal superalloy AM1 between 850 and 1050 °C in air

Abstract

The influence of the as-cast and fully heat-treated microstructures on the isothermal behaviour of the Ni-based single crystal superalloy AM1 was investigated at 8501050 °C. It appears that the kinetics transition regime is a function of time, temperature and also of bulk microstructure. The various characterisation techniques allowed elucidating that the growth of a continuous inner layer of α-Al2O3 governs the oxidation mechanisms, irrespective of the microstructure. Such a layer is favoured for high oxidation temperatures, long exposure times and high γ' precipitate surface fraction. However, the chemical segregation of the as-cast state is responsible for the growth of inhomogeneous oxide layers.