The oxidation behavior of some FeCrAlY, FeCrAl, and yttrium ion‐implanted FeCrAl alloys compared and contrasted

Abstract

The 1050 °C oxidation behavior of an iron–25 wt. % chromium–4 wt. % aluminum alloy modified by yttrium additions was studied. Yttrium was added to this alloy in the form of (1) a metallic addition; (2) an ion implant; and (3) as yttrium sulfide. In agreement with other investigators, metallic yttrium additions effected thin, essentially flat adherent scales. As compared with the base line alloy without any yttrium, implantation did improve the resistance of the scale to cracking. However, highly convoluted scales resulted with the yttrium implants. When yttrium was added as the sulfide, scales were produced similar to those found when no yttrium was added to the alloy. For the base line alloy without yttrium additions, aluminum oxide protrusions (or pegs) developed at the base of the alumina scales. Despite this, the scales were clearly cracked and poorly adherent. In the yttrium‐containing alloy, indigenous sulfur was present in the form of precipitates associated with yttrium.