Oxidation of alumina formers at 1173 K: effect of yttrium ion implantation and yttrium alloying addition

Abstract

The oxidation behaviour of three alumina forming FeCrAl alloys has been investigated during isothermal exposures in air at 1173 K. Two of them were Kanthal A1, differing by the presence or not of implanted yttrium. The third one, Kanthal AF contains alloying additions of yttrium. Kinetic results indicate that only yttrium implantation significantly reduces the growth rate of the oxide scale during the early oxidation stage. For longer oxidation times, the reactive element markedly influences the oxidation rate and the composition of the oxide scale, whatever its introduction mode in the alloy. In situ X-ray diffraction shows that yttrium suppresses the formation of transition alumina and promotes the growth of α-Al 2O 3, thereby leading to the earlier formation of a protective oxide scale.