Investigation on corrosion and galvanic corrosion in LaFe11.6Si1.4 alloy

The corrosion and galvanic corrosion of LaFe11.6Si1.4 alloy were investigated. The microstructure showed the presence of three phases: La(Fe,Si)13, α-Fe and La–Fe–Si. Experiments indicated that the corrosion of each phase increase in the order: La–Fe–Si > La(Fe,Si)13 > α-Fe in the alkaline water and 0.05 M BTA/0.05 M sodium benzoate inhibitor solution. Galvanic corrosion measurement gave corrosion current densities of 37 μA cm−2 for α-Fe/La–Fe–Si and 4.3 μA cm−2 for α-Fe/LaFe11.6Si1.4 coupled electrodes in the alkaline water. The corresponding values were 5.3 μA cm−2 and 0.5 μA cm−2 in 0.05 M BTA/0.05 M sodium benzoate mixed solution. However, in the case of LaFe11.6Si1.4/La–Fe–Si coupled electrode, galvanic corrosion current density remains nearly constant although the potential difference is not the same in the two solutions.