  FeCrAl alloys are proposed and being intensively investigated as alternative
accident tolerant fuel (ATF) cladding for nuclear fission application. Herein,
the influence of major alloy elements (Cr and Al), reactive element effect and
heating schedules on the oxidation behavior of FeCrAl alloys in steam up to
1500{\deg}C was examined. In case of transient ramp tests, catastrophic
oxidation, i.e. rapid and complete consumption of the alloy, occurred during
temperature ramp up to above 1200{\deg}C for specific alloys. The maximum
compatible temperature of FeCrAl alloys in steam increases with raising Cr and
Al content, decreasing heating rates during ramp period and doping of yttrium.
Isothermal oxidation resulted in catastrophic oxidation at 1400{\deg}C for all
examined alloys. However, formation of a protective alumina scale at
1500{\deg}C was ascertained despite partial melting. The occurrence of
catastrophic oxidation seems to be controlled by dynamic competitive mechanisms
between mass transfer of Al from the substrate and transport of oxidizing gas
through the scale both toward the metal/oxide scale interface.
