Fe <sub> 3 </ Sub> Al Fund Intermetallic Compound In Seawater Corrosion Behavior

Marine corrosion is the quesion which ocean exploitation must face and resolve. Fe₃Al intermetallics,with good capability,is a new kind of cheap material.It is meaningful for studying the corrosion behavior of Fe₃Al in marine and developing new marine materials.By using metallography ,polarization measurement, electrochemical impedance spectrum(EIS),scanning electron microscopy(SEM)to reveal the electrochemical behavior of Fe₃Al intermetallics in natural sea-water.B2 and DO3 Fe₃Al is got by annealed at 500℃and 900℃.Compared with 316L stainless steel, the corrosion behavior in marine is studied.The result shows that:Pitting-corrosion is the major form,and average corrosion exists.In the center was the white floccule with wine rust surrounding it. Fe₃Alof as-cast has poor ability of pitting-corrosion resistance.It can be proved by ordering. The corrosion resistance of Fe₃Alof ordering can match with the 316L stainless steel, but it has poorer pitting-corrosion resistance than the 316L stainless steel.In this paper, the corrosion behavior of pre-oxided Fe₃Al which oxided at difFerent tempreture is also studied. It indicate that the main composition of the pre-oxided film isα-Al2O3 which can improve the corrosion resistance ability highly.But the oxide film which got at the lower temperature has a high sensitivity for containing lessγ–A12O3 andα–Fe2O3.The corrosion products of Fe₃Al in marine are studied by using X-ray Diffraction (XRD) and scanning electron microscopy(SEM). It shows that The corrosion products of Fe₃Al in the sea-water contain FeO(OH)which exists as Lepidocrocite Iron Oxide HyDroxide. Some products containing aluminium maybe exist. The mechanism of Fe₃Al in marine is that When corrosion happens, aluminium and iron are dissolved at the same time. Then iron is replaced by aluminium and deposits on the surface of Fe₃Al.