Electrochemical corrosion performance of continuous columnar-grained BFe10-1-1 alloy

The corrosion resistance of BFe10-1-1 alloy with continuous columnar-grained microstructure in a 3.5% NaCl solution was investigated by means of polarization tests and electrochemical impedance spectroscopy(EIS),and compared with that of BFe10-1-1 alloy with conventional polycrystalline microstructure fabricated by conventional casting.Polarization test results show that both BFe10-1-1 alloys have similar electrochemical behavior,and their polarization curves include three distinct regions,that is,the active dissolution region,the active-passive transition region and the limiting current region.However the corrosion rate of BFe10-1-1 alloy with continuous columnar-grained microstructure is lower than that of the one with conventional polycrystalline microstructure,as less microsegregation in BFe10-1-1 alloy with continuous columnar-grained microstructure can effectively avoid interdendritic corrosion.EIS spectra indicate that BFe10-1-1 alloy with continuous columnar-grained microstructure has a higher charge transfer resistance and a higher corrosion product film resistance compared with BFe10-1-1 alloy with conventional polycrystalline microstructure.The results further demonstrate that BFe10-1-1 alloy with continuous columnar-grained microstructure has a better corrosion resistance.