Oxidation Behavior of a Disk Powder Metallurgy Superalloy
Oxidation behaviors of a spray-forming disk superalloy LSHR were investigated in the temperature range of 750-900°C. The composition and morphology of oxidation scales were investigated by X-ray diffraction (XRD), scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS), and electron probe microanalysis (EPMA). Oxidation kinetics was studied by the means of isothermal oxidation testing in air and weight gain measurement. The oxide scales were composed of Cr2O3, TiO2, Al2O3 and a small amount of NiCr2O4. The experiment results showed that oxidation kinetics and oxide layers followed a square power law as time extended from 750 to 900°C. With the oxidation temperature increasing, external scale thickness, and internal oxidation zone increased. The oxidation behavior was controlled by the diffusion of oxygen, chromium, titanium, and aluminum ions, as chromium, titanium, and aluminum ions diffused outward and oxygen diffused inward. Based on the standard HB5258-2000 spray-forming LSHR exhibited an excellent oxidation resistance in the whole test temperature range.
K. X. Dong et al., "Oxidation Behavior of a Disk Powder Metallurgy Superalloy", Materials Science Forum, Vol. 898, pp. 467-475, 2017