Abstract: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/cm2 from 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.
[1] GEBHARDT T, MUSIC D, KOSSMANN D, et al. Elastic properties of fcc Fe-Mn-X (X=Al, Si) alloys studied by theory and experiment[J]. Acta Mater, 2011, 59(8):3145-3155.
[2] LEE S, LEE C Y, LEE Y K. Schaeffler diagram for high Mn steels[J]. Journal of Alloys and Compounds, 2015, 628(1):46-49.
[3] WU Z Q, DING H, AN X H, et al. Influence of Al content on the strain-hardening behavior of aged low density Fe-Mn-Al-C steels with high Al content[J]. Materials Science and Engineering:A, 2015, 639(5):187-191.
[4] TUAN Y H, WANG C S, TSAI C Y. Corrosion behaviors of austenitic Fe-30Mn-7Al-xCr-1C alloys in 3.5% NaCl solution[J].Materials Chemistry and Physics, 2009, 114(2-3):595-598.
[5] ZHU X M, ZHANG Y S. Investigation of the electrochemical corrosion behaviour and passive film for Fe-Mn, Fe-Mn-Al, and Fe-Mn-Al-Cr alloys in aqueous solutions[J]. Corrosion, 1998, 54(1):3-12.
[6] LEE J W, DUH J G, WANG J H. Mechanical property evaluation of cathodic arc plasma-deposited CrN thin films on Fe-Mn-Al-C alloys[J]. Surf Coat Technol, 2003, 168(2-3):223-230.
[7] JAW J H, CHENG W C, WANG C J. The formation of AlN crystals in an Fe-Mn-Al-C alloy during the nitriding process[J]. Metall Mater Trans A, 2005, 36A(9):2289-2296.
[8] SU C W, LEE J W, WANG C S, et al. The effect of hot-dipped aluminum coatings on Fe-8Al-30Mn-0.8C alloy[J]. Surf Coat Technol, 2008, 202(9):1847-1852.
[9] WANG C H, LUO C W, HUANG C F, et al. Biocompatibility of metal carbides on Fe-Al-Mn-based alloys[J]. J Alloy Comp, 2011, 509(3):691-696.
[10] ZHU X M, LIU M, ZHANG Y S. Electrochemistry and surface investigations of anodically passivated layer formed on Fe-Mn-Al-Cr alloy in Na2SO4 solution[J].Corro Eng Sci Technol, 2007, 42(1):22-28.
[11] OH J M, MCNALLAN M J. Microstructural development in the surface region during oxidation of iron-manganese-nickel-silicon alloys[J]. J Electrochem Soc, 1986,133(5):1042-1048.
[12] PARK S H, CHUNG I S, KIM T W. Characterization of the high -temperature oxidation behavior in Fe-25Mn-1.5Al-0.5C alloy[J].Oxid Met, 1998, 49(3-4):349-371.
[13] PEREZ P, PEREZ F J, GOMEZ C, et al. Oxidation behaviour of an austenitic Fe-30Mn-5Al-015C alloy[J].Corro Sci, 2002, 44(1):113-127.
[14] PEREZ P, GARCES G, PEREZ F J, et al. Influence of chromium additions on the oxidation resistance of an austenitic Fe-30Mn-5Al alloy[J]. Oxid Met, 2002,57(3-4):339-361.
[15] OH J M, MCNALLAN M J. The effect of oxidation-induced surface transformations on the anodic polarization characteristics of FeMnSi alloys[J]. Corrosion, 1987, 43(9):561-566.
[16] COCCIA L G, LENARDI C, SABATINI A. The effect of Mn-depleted surface layer on the corrosion resistance of shape memory Fe-Mn-Si-Cr alloys[J]. Metall Mater Trans A, 1997, 28A(5):1219-1222.
[17] 张林伟,王鲁,王全胜,等. 冷喷涂CoNiCrAlY涂层在Na2SO4熔盐中的热腐蚀行为[J]. 材料工程, 2016, 44(11):45-50. ZHANG L W, WANG L, WANG Q S, et al. Hot corrosion behavior of cold-sprayed CoNiCrAlY coating in Na2SO4 salt[J]. Journal of Materials Engineering, 2016, 44(11):45-50.
[18] 戴建伟, 易军, 王占考, 等. 单晶高温合金铂改性铝化物涂层的高温氧化行为[J]. 航空材料学报, 2015, 35(5):32-38. DAI J W, YI J, WANG Z K, et al. High temperature oxidation behavior of Pt modified aluminide coating on single crystal superalloy[J]. Journal of Aeronautical Materials, 2015, 35(5):32-38.