Critical role of minor element constituents on the lifetime oxidation behaviour of FeCrAl(RE) alloys

In the present study the effect of a number of common alloying additions and impurities, i.e. Zr, Ti, V, Ca, P on the oxidation limited lifetime of FeCrAlY alloys in the temperature range of 1100-1300degreesC has been studied. The elements in concentrations ranging from 5 to 300 ppm were added to an alloy with a base composition of (mass%) Fe-20Cr-5Al-0.05Y with a sulfur content below 10 ppm. The long term tests revealed that P had a detrimental effect on the oxidation resistance, especially at 1300 C. It has also been found that minor additions of carbide forming elements such as Ti and Zr to Y-containing FeCrAl alloys are of vital importance for improved long term cyclic oxidation performance. Comparison of the obtained results with data from commercial materials of similar composition revealed that the fundamental findings derived for high purity alloys can be substantially changed by interaction of the mentioned minor alloying additions with common alloy impurities such as C and N.