Corrosion performance of a rapidly solidified NiAl intermetallic macroallolled with Fe in 0.5M H2SO4

The effect of Fe contents on the corrosion resistance of NiAl intermetallic rapidly solidified in 0.5 M H2SO4 at room temperature has been evaluated using electrochemical techniques. Iron contents included 15, 18 and 20 wt.% and techniques included potentiodynamic polarization curves, linear polarization resistance and potentiostatic tests. For comparison, the same tests were performed on a 316L type stainless steels. The results showed that all the intermetallics, except the alloy containing 18 Fe, exhibited a better corrosion resistance than the 316L type stainless steel for at least five times. Additions of Fe to the NiAl alloy always increased the corrosion current density, I-corr. except by adding 20 Fe, which decreased the I-cor value only for long times. The pitting potential, E-pit, passivation potential, E-pass and passive current density values were higher for all the NiAL intermetallics than those values for the 316 stainless steel. Additions of Fe to the NiAl alloy always decreased these values with. Corrosion morphologies showed a preferential dissolution of a phase respect to another due to the formation of micro galvanic cells due to the addition of Fe.