The cyclic oxidation behaviour of PM Ni3Al in air at elevated temperatures: the effect of Cr- and Y-implantation

Abstract

Abstract The effect of Cr- and Y-implantation on the cyclic oxidation behaviour of a boron-doped Ni 3 Al alloy at 585, 730, and 900 °C in air has been studied. Compared with non-implanted material, Y-implantation caused slightly higher oxidation rates from the earliest oxidation stage. Furthermore, the scale was prone to significant spallation at 900 °C, at least to a much higher extent than for the non-implanted material. Upon exposure at 585 and 730 °C a scale is formed consisting of an outer NiO layer, an intermediate layer of pure Ni and an internal oxidation zone (IOZ). At 900 °C the scale consisted of an outer NiO layer, an intermediate Ni- and Al-rich oxidation zone, and an inner thin alumina layer. Similar results were obtained with the non-implanted material. Cr-implantation, however, considerably decreased the cyclic oxidation rate, through the formation of a thin alumina layer, induced by the presence of chromium. No spallation of the oxide scale occurred even at 900 °C.