Effect of Combined Yttrium and Zirconium Additions on Protective Alumina Scale Formation on High Purity FeCrAl Alloys During Oxidation in the Temperature Range of 1200 to 1300°C

摘要

The oxidation behaviour of high purity FeCrAl alloys containing minor additions (in the 100 ppm range) of Y and a combination of Y+Zr has been studied at temperatures between 1200 and 1300°Cin Ar/O{sub}2. Higher oxidation rates of the Y+Zr-doped alloy compared to those of the Y-doped alloy were found. Yttrium incorporation into the alumina scale followed by formation of Y/Al-mixed oxide compounds was observed in case of the Y-doped alloy. The Y incorporation into the scale tended to be suppressed in the Y+Zr-doped alloy. Instead, substantial Zr incorporation occurred which resulted in numerous zirconia inclusions and a rather high degree of microporosity. This leads to an enhanced contribution of molecular oxygen transport to the overall scale growth process resulting in an enhanced oxidation rate.