High-temperature electrochemical testing of spray atomized and deposited iron aluminides alloyed with boron and reinforced with alumina particulate

The corrosion behavior of FeAl40 at.%, FeAl40 + 0.1 at.% B and FeAl40 0.1 at.% B 10 at.% Al2O3 in a mixture of molten salts of 80% V2O5 + 20% Na2SO4 (wt.%) from 600°C to 900°C was studied using a potentiodynamic polarization technique. Experiments were conducted in a typical three-electrode cell immersed in the fused salt. Curves of corrosion current density (Icorr) as a function of molten salt temperature were obtained and discussed in terms of the passive layer and corrosion products formed during the electrochemical tests. The corrosion resistance of the FeAl40 + 0.1 at.% B + 10 at.% Al2O3 samples was superior at all temperatures in the interval between 600°C and 900°C. It is apparent that the alumina is playing an important role in corrosion protection. The log i vs. potential polarization curves indicate that corrosion in the FeAl40 at.% and FeAl40 + 0.1 at.% B samples may be associated with the formation and spalling of oxide layers rich in vanadium.