Fe30Mn5Al合金氧化改性层的电化学腐蚀性能

将Fe30Mn5Al合金在800℃空气中循环氧化160h,在氧化层与基体之间获得厚度约为15μm的贫Mn,富Fe铁素体层,研究氧化改性贫Mn层对Fe30Mn5Al合金电化学腐蚀性能的影响。结果表明:在1mol·L-1 Na2SO4溶液中,与原始合金相比,贫Mn层的阳极极化曲线呈自钝化,自腐蚀电位Evs SCE从-750mV提高至-130mV,钝化电流密度ip从310μA/cm2下降至29μA/cm2;电化学交流阻抗谱(EIS)的容抗弧直径及|Z|值增加,相位角平台变宽,利用等效电路Rs-(Rt//CPE)拟合的极化电阻Rt由2.7kΩ·cm2增至9.9kΩ·cm2;贫Mn层比合金基体具有更好的抗蚀性能。

Electrochemical Corrosion Behavior of Oxidation Layer on Fe30Mn5Al Alloy

The Fe30Mn5Al alloy was oxidized at 800℃ in air for 160h,the oxidation-induced layer about 15μm thick near the scale-metal interface was induced to transform to ferrite and become enriched in Fe and depletion in Mn.The effect of the oxidation-induced Mn depletion layer on the electrochemical corrosion behavior of Fe30Mn5Al alloy was evaluated.The results show that in 1mol · L-1 Na2SO4 solution,the anodic polarization curve of the Mn depletion layer exhibits self-passivation,compared with Fe30Mn5Al austenitic alloy,and the corrosion potential Evs SCE is increased to-130mV from-750mV and the passive current density ip is decreased to 29μA/cm2from 310μA/cm2.The electrochemical impedance spectroscopy(EIS) of the Mn depletion layer has the larger diameter of capacitive arc,the higher impedance modulus |Z|,and the wider phase degree range,and the fitted polarization resistant Rt is increased to 9.9kΩ · cm2 from 2.7kΩ · cm2 by using an equivalent electric circuit of Rs-(Rt//CPE).The high insulation of the Mn depletion layer leads to an improved corrosion resistance of Fe30Mn5Al austenitic alloy.