The oxidation of Ni3Al containing decomposed SiC-particles

Alloys of Ni3Al–(0, 1, 3, 5 vol.%)SiC were prepared via powder metallurgical routes and their oxidation kinetics were studied between 1273 and 1473 K in air. The initially added SiC particles were unstable and decomposed within the matrix. It was found that initially added SiC increased the isothermal oxidation resistance to a certain extent, but adversely decreased the cyclic oxidation resistance because silica made the Al2O3-rich oxide layer more susceptible to spallation. For SiC-added alloys, the oxide scales consisted primarily of α-Al2O3 and SiO2 with and without NiAl2O4. During oxidation, Al, Si and a bit of Ni diffused outwardly to form the oxide scale, while oxygen and most of Ni transported inwardly.