| The oxidation behaviours, such as kinetics, surface morphology, structure and compositions, and electrochemical corrosion resistance of oxidizing layer of Fe-Mn base alloys and Fe-0.15C alloy in air in the temperature range of 700 ℃~950 ℃ have been studied by using weight-chang/time curves of cyclic oxidation, scanning electron microscope, x-ray diffraction, electron probe micro-analysis and electrochemical polarization. Results showed that the property of resistance to high temperature oxidation at 700 ℃ of Fe-Mn base alloy is greatly improved due to the formation of Al2O3, SiO2, Cr2O3 and the compound oxide of MnAkO4. The oxidation kinetics transform from square parabolic for alloys containing single elements such as Al, Cr or Si to cubic parabolic of alloys containing Al and Cr and to logarithmic law for alloy containing Al, Cr and Si. With the increase of temperature from 700 ℃ to 800 ℃, oxidation kinetics of the alloys become sub-square parabolic to square parabolic duo to the decrease in continuance and compacity of oxidic layers. At 950 ℃, the resistance of Fe-Mn base alloys to high temperature oxidation is sharply decreased because of the inner oxidation, and the oxidation kinetics of all alloys obey the near linearity to sub-square parabolic. As oxidized at 800 ℃, the selective oxidation of Mn in austenitic Fe-30Mn-9Al and Fe-32Mn-3Al-8Cr-2Si alloys results in the formation of a Mn-depleted ferrite layer and an Al-enrich oxide layer, which can increase the resistance to high temperature oxidation and electrochemical corrosion of the alloys. The corrosion resistance of the modified layer formed on Fe-30Mn-9Al alloy and Fe-32Mn-3Al-8Cr-2Si alloys, characterized by polarization curves in Imol I"1 Na2SC>4 aqueous solution is superior and equivalent to ICrB stainless steel, respectively.The results of the work imply that it probably presents the potentiality of developing a new method of surface modification.
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