High temperature oxidation behavior of Cr₂O₃-forming heat-resisting alloys with small amounts of rare earth elements (Y, Lu) at 1473 and 1573K

Abstract

High temperature oxidation behavior of Ni-20Cr and Ni-20Cr-1Si alloys with small amounts of rare earth elements (Y, Lu) was studied in oxygen for 18ks at 1473 and 1573K, by mass gain measurements, observation of surface appearance, X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). The mass gains of the Ni-20Cr alloys with 0.5% rare earths (Y, Lu) and/or 1%Si decreased at both the oxidation temperatures. Granular Cr₂O₃ particles on Ni-20Cr-(0.05, 0.1, 0.2, 0.5)Y(Lu) and Ni-20Cr-1Si-(0.05, 0.1, 0.2, 0.5)Y(Lu) alloys decreased in size with increasing Y(Lu) and increased with increasing oxidation temperature.