高熵合金是一種由五個以上主元素相混合所組成的多元合金。這類合金具有高度原子無序排列的特性，造成許多獨特的磁性、機械及電化學性質。先前的研究指出Co1.5CrFeNi1.5Ti0.5 合金為單一 FCC固溶體結構、高硬度、耐高溫氧化及大氣腐蝕能力。另一方面，鉬 (Mo) 具有固溶強化、抗氯鹽孔蝕的作用，因此添加Mo於高熵合金內。本研究利用動態極化試驗於室溫及稍高的水溶液，評估不同Mo成分莫耳比的高熵合金Co1.5CrFeNi1.5Ti0.5Mox (x = 0, 0.1, 0.2, 0.5, 0.8) 之腐蝕行為。
首先評估Mo的添加對Co1.5CrFeNi1.5Ti0.5Mox合金分別在酸性、鹼性和中性環境下的腐蝕阻抗影響(25 ℃)。由極化曲線清楚顯示在氫氧化鈉及硫酸溶液中，隨著Mo含量的增加，高熵合金的抗均勻腐蝕能力隨之下降；另一方面，由循環極化掃瞄及SEM表面腐蝕型態結果得知在Co1.5CrFeNi1.5Ti0.5 合金中添加Mo有助於提升孔蝕阻抗。
接著探討Mo含量對Co1.5CrFeNi1.5Ti0.5Mox合金在氯鹽水溶液中(由25 ℃升至80 ℃)的孔蝕行為。結果顯示Co1.5CrFeNi1.5Ti0.5 合金分別在0.001、0.01、0.1 與1 M 氯化鈉之臨界孔蝕溫度為80 ℃、 50 ℃、30 ℃及低於 25 ℃。合金的孔蝕電位隨著氯鹽濃度上升而下降、臨界孔蝕溫度隨著Mo含量的增加而上升。
最後評估無機/有機腐蝕抑制劑添加於氯鹽中對Co1.5CrFeNi1.5Ti0.5Mo0.1 合金的孔蝕電位及臨界孔蝕溫度影響。結果顯示該合金分別在0.1、0.5和 1 M 氯化鈉之臨界孔蝕溫度為70 ℃、60 ℃和60 ℃; 孔蝕電位與氯鹽濃度成線性關係。當硫酸鹽與氯鹽比超過0.5，硫酸鹽對合金孔蝕電位及臨界孔蝕溫度有正面效應。孔蝕抑制能力依序為硝酸鹽≒苯甲酸鹽＞醋酸鹽≒過氯酸鹽＞草酸鹽＞鉬酸鹽。

A high-entropy alloy (HEA) is a multi-component alloy containing n major alloying elements (n≧5), which has a high degree of atomic disorder that leads to various unique magnetic, mechanical and electrochemical properties. The Co1.5CrFeNi1.5Ti0.5 HEA, evaluated previously, possessed a single FCC structure, high hardness, excellent resistance to oxidation and atmospheric corrosion. Molybdenum is an element known to enhance the resistance to pitting corrosion in chloride-containing solutions. Another important contribution of molybdenum to a given alloy is its solid-solution strengthening effect, due to its large atomic volume in the matrix to pin dislocation. Therefore, the purpose of this thesis is to investigate the corrosion behavior of the Co1.5CrFeNi1.5Ti0.5Mox (x = 0, 0.1, 0.2, 0.5, 0.8) HEA in aqueous environments at room and elevated temperatures using the potentiodynamic polarization technique.
First, the corrosion resistance of Co1.5CrFeNi1.5Ti0.5Mox alloys was conducted in three different environmental conditions；1 M NaOH, 0.5 M H2SO4 and 1 M NaCl, which will be referred to as base, acid and salt solution, respectively henceforth at 25 ℃ under atmospheric pressure. The potentiodynamic polarization curves of the Co1.5CrFeNi1.5Ti0.5Mox alloys, obtained in aqueous solutions of H2SO4 and NaOH, clearly revealed that the corrosion resistance of the Mo-free alloy was superior to that of the Mo-containing alloys. On the other hand, the lack of hysteresis in cyclic polarization tests and SEM micrographs confirmed that the Mo-containing alloys are not susceptible to pitting corrosion in NaCl solution.
Second, we report the effect of molybdenum from 25 to 80 ℃ on the pitting corrosion of the Co1.5CrFeNi1.5Ti0.5Mox high-entropy alloys in chloride solutions. The values of critical pitting temperature (CPT) for the Mo-free alloy in 0.001, 0.01, 0.1 and 1 M NaCl are 80, 50, 30 and below 25 ℃, respectively. The values of pitting potential (Epit) decrease with increasing chloride concentrations and the values of CPT increase with the increase of Mo content.
Finally, we investigate the effect of inorganic/organic inhibitors on the Epit and CPT of the high-entropy alloy Co1.5CrFeNi1.5Ti0.5Mo0.1 in chloride solutions. The results indicate that the values of CPT for the alloy in 0.1, 0.5, and 1 M NaCl are 70, 60 and 60 ℃, respectively; the values of Epit are linear with the logarithm of chloride concentrations at 70 and 80 ℃; and the addition of SO42- ions to chloride solutions has a positive effect on both Epit and CPT as the ratio of SO42-/Cl- is higher than 0.5. Six anions all retard the occurrence of pitting corrosion; the inhibitive effect decreases in the order: nitrates≒benzonates＞acetates≒perchlorates＞citrates＞molybdates.

[1] J. R. Davis (Ed.), Metals Handbook, tenth ed., Vol. 1, ASM International, Metals Park, Ohio, 1990.
[2] J. R. Davis (Ed.), Metals Handbook, tenth ed., Vol. 2, ASM International, Metals Park, Ohio, 1990.
[3] C. T. Sims, W. C. Hagel, The superalloys, John Wiley and Sons, New York, 1972.
[4] S. Ranganathan, Alloyed pleasures: multimetallic cocktails, Curr. Sci. 85 (2003) 1404-1406.
[5] W. Klement, R. H. Willens, P. Duwez, Non-crystalline structure in solidified gold-silicon alloys, Nature 187 (1960) 869-870.
[6] H. W. Kui, A. L. Greer, D. Turnbull, Formation of bulk metallic glass by fluxing, Appl. Phys. Lett. 45 (1984) 615-616.
[7] A. Inoue, K. Ohtera, K. Kita, T. Masumoto, New amorphous Mg-Ce-Ni alloys with high strength and good ductility, Jpn. J. Appl. Phys. 27 (1988) L2488-L2251.
[8] A. Inoue, T. Zhang, T. Masumoto, Al-La-Ni amorphous alloys with a wide suoercooled liquid region, Mater. Trans. JIM 30 (1989) 965-972.
[9] A. Inoue, T. Zhang, M. W. Chen, T. Sakurai, J. Saida, M. Matsushita, Ductile quasicrystalline alloys, Appl. Phys. Lett. 76 (2000) 967-969.
[10] T. Zhang, A. Inoue, T. Masumoto, The effect of atomic size on the stability of supercooled liquid for amorphous (Ti, Zr, Hf)65Ni25Al10 and (Ti, Zr, Hf)65Cu25Al10 alloys, Mater. Lett. 15 (1993) 379-382.
[11] A. Inoue, N. Nishiyama, K. Amiya, T. Zhang, T. Masumoto, Ti-based amorphous alloys with a wide supercooled liquid region, Mater. Lett. 19 (1994) 131-135.
[12] T. Zhang, A. Inoue, New bulk glassy Ni-based alloys with high strength of 3000 MPa, Mater. Trans. JIM 43 (2002) 708-711.
[13] K. Asami. S. J. Pang, T. Zhang, A. Inoue, Preparation and corrosion of resistance of Fe-Cr-Mo-C-B-P bulk glassy alloys. J. Electrochem. Soc. 149 (2002) B366-B369.
[14] T. D. Shen, Y. He, R. B. Schwarz, Bulk amorphous Pd-Ni-Fe-P alloys: Preparation and characterization, J. Mater. Res. 14 (1999) 2107-2115.
[15] A. Inoue, M. Koshiba, T. Itoi, A. Makino, Ferromagnetic Co-Fe-Zr-B amorphous alloys with glass transition and good high-frequency permeability, Appl. Phys. Lett. 73 (1998) 744-746.
[16] A. Inoue, W. Zhang, Bulk glassy Cu-based alloys with a large supercooled liquid region of 110 K, Appl. Phys. Lett. 83 (2003) 2351-2353.
[17] H. S. Chen, Glassy metals, Rep. Prog. Phys. 43 (1980) 464-467.
[18] A. Inoue, Bulk amorphous and nanocrystalline and alloys with high functional properties, Mater. Sci. Eng. A 304-306 (2001) 1-10.
[19] A. Greer, Confusion by design, Nature 366 (1993) 303-304.
[20] S. J. He, L. R. Gao, Amorphous Material and its Application, China Machine, Press, Beijing, 1987.
[21] F. E. Luborsky, in: C. Ke, Y. C. Tang, Y. Luo, K. Y. He, Amorphous Metallic Alloys, Metallurgical Industry Press, Beijing, 1989.
[22] G. Rife, P. C. C. Chan, K. T. Aust, Corrosion of iron, nickel, and cobalt-based metallic glasses containing boron and silicon metalloids, Mater. Sci. Eng. 48 (1981) 73-79.
[23] B. Shen, M. Akiba, A. Inoue, Effect of Cr addition on the glass-forming ability, magnetic properties, and corrosion resistance in FeMoGaPCBSi bulk glassy alloys, J. Appl. Phys. 100 (2006) 043523.
[24] S. J. Pang, T. Zhang, K. Asami, A. Inoue, Bulk glassy Fe–Cr–Mo–C–B alloys with high corrosion resistance, Corros. Sci. 44 (2002) 1847-1856.
[25] I. Chattoraj, S. Baunack, M. Stoica, A. Gebert, Electrochemical response of Fe65.5Cr4Mo4Ga4P12C5B5.5 bulk amorphous alloy in different aqueous media, Mater. Corros. 55 (2004) 36-42.
[26] D. Y. Liu, H. F. Zhang, Z. Q. Hu, W. Gao, Magnetic and corrosion properties of Fe56Co7M2Mo5Zr10B20 (M = W or Ni) bulk metallic glasses, J. Alloys and Compounds 422 (2006) 28–31.
[27] H. Habazaki, A. Kawashima, K. Asami, K. Hashimoto, The corrosion behavior of amorphous Fe-Cr-Mo-P-C and Fe-Cr-W-P-C alloys in 6 M HCl solution, Corros. Sci. 33 (1992) 225-236.
[28] M. W. Tan, E. Akiyama, A. Kawashima, K. Asami, K. Hashimoto, The effect of air exposure on the corrosion behavior of amorphous Fe-8Cr-Mo-13P-7C alloys in 1 M HCl solution, Corros. Sci. 37 (1995) 1289-1301.
[29] M. W. Tan, E. Akiyama, A. Kawashima, K. Asami, K. Hashimoto, The influence of Mo addition and air exposure on the corrosion behavior of amorphous Fe-8Cr -13P-7C alloys in de-aerated 1 M HCl, Corros. Sci. 38 (1996) 349-365.
[30] H. Katagiri, S. Meguro, M. Yamasaki, H. Habazaki, T. Sato, A. Kawashima, K. Asami, K. Hashimoto, Synergistic effect of three corrosion-resistant elements on corrosion resistance in concentrated hydrochloric acid, Corros. Sci. 43 (2001) 171-182.
[31] H. Habazaki, T. Sato, A. Kawashima, K. Asami, K. Hashimoto, Preparation of corrosion-resistant amorphous Ni–Cr–P–B bulk alloys containing molybdenum and tantalum, Mater. Sci. Eng. A 304-306 (2001) 696-700.
[32] M. L. Morrison, R. A. Buchanan, A. Peker, W. H. Peter, J. A. Horton, P. K. Liaw, Cyclic-anodic-polarization studies of a Zr41.2Ti13.8Ni10Cu12.5Be22.5, Intermetallics 12 (2004) 1177-1181.
[33] A. Dhawan, S. Roychowdhury, P. K. De, S. K. Sharma, Potentiodynamic polarization studies on bulk amorphous alloys and Zr46.75Ti8.25Cu7.5Ni10Be27.5 and Zr65Cu17.5Ni10Al7.5, J. Non-Cryst. Solids 351 (2005) 951–955.
[34] K. Mondal, B. S. Murty, U. K. Chatterjee, Electrochemical behavior of multicomponent amorphous and nanocrystalline Zr-based alloys in different environments, Corros. Sci. 48 (2006) 2212–2225.
[35] L. Liu, B. Liu, Influence of the micro-addition of Mo on glass forming ability and corrosion resistance of Cu-based bulk metallic glasses, Electrochim. Acta 51 (2006) 3724–3730.
[36] L. Liu, B. Liu, Improvement of corrosion resistance of Cu-based bulk metallic glasses by the microalloying of Mo, Intermetallics 15 (2007) 679-682.
[37] L. Liu, B. Liu, The effect of microalloying on thermal stability and corrosion resistance of Cu-based bulk metallic glasses, Mater. Sci. Eng. A 415 (2006) 286–290.
[38] K. Asami, C. L. Qin, T. Zhang, A. Inoue, Effect of additional elements on the corrosion behavior of a Cu–Zr–Ti bulk metallic glass, Mater. Sci. Eng. A 375–377 (2004) 235–239.
[39] D. Zander, B. Heisterkamp, I. Gallino, Corrosion resistance of Cu–Zr–Al–Y and Zr–Cu–Ni–Al–Nb bulk metallic glasses, J. Alloys and Compounds 434–435 (2007) 234–236.
[40] S. Pang, C. H Shek, C. Ma, A. Inoue, T. Zhang, Corrosion behavior of a glassy Ti–Zr–Hf–Cu–Ni–Si alloy, Mater. Sci. Eng. A 449–451 (2007) 557–560.
[41] J. Jayaraj, K. B. Kim, H. S. Ahn, E. Fleury, Corrosion mechanism of N-containing Fe–Cr–Mo–Y–C–B bulk amorphous alloys in highly concentrated HCl solution, Mater. Sci. Eng. A 449–451 (2007) 517–520.
[42] A. Dhawan, K. Sachdev, S. Roychowdhury, P. K. De, S. K. Sharma, Potentiodynamic polarization studies on amorphous Zr46.75Ti8.25Cu7.5Ni10Be27.5, Zr65Cu17.5Ni10Al7.5, Zr67Ni33 and Ti60Ni40 in aqueous HNO3 solutions, J. Non-Cryst. Solids 353 (2007) 2619–2623.
[43] M. W. Tan, E. Akiyama, H. Habazaki, A. Kawashima, K. Asami, K. Hashimoto, The role of chromium and molybdenum in passivation of amorphous Fe-Cr–Mo-P-C alloys in de-aerated 1 M HCl, Corros. Sci. 38 (1996) 2137-2151.
[44] H. Katagiri, S. Meguro, M. Yamasaki, H. Habazaki, T. Sato, A. Kawashima, K. Asami, K. Hashimoto, An attempt at preparation of corrosion-resistant bulk amorphous Ni-Cr-Ta-Mo-P-B alloys, Corros. Sci. 43 (2001) 183-191.
[45] S. Hiromoto, A. P. Tsai, M. Sumita, T. Hanawa, Effect of chloride ion on the anodic polarization behavior of the Zr65Al7.5Ni10Cu17.5 amorphous alloy in phosphate buffered solution, Corros. Sci. 42 (2000) 1651-1660.
[46] T. C. Chieh, J. Chu, C. T. Liu, J. K. Wu, Corrosion of Zr52.5Cu17.9Ni14.6Al10Ti5 bulk metallic glasses in aqueous solutions, Mater. Lett. 57 (2003) 3022–3025.
[47] T. Saito, T. Furuta, H. Hwang, S. Kuramoto, K. Nishino, N. Suzuki, R. Chen, A. Yamaha, K. Ito, Y. Seno, T. Nonaka, H. Ikehata, N. Nagasako, C. Iwamoto, Y. Ikuhara, T. Sakuma, Multifunctional alloys obtained via a dislocation-free plastic deformation mechanism, Science 300 (2003) 464-467.
[48] K. H. Huang, J. W. Yeh, A study on the multicomponent alloy systems containing equal-mole elements, Master’s thesis of National Tsing Hua University, Taiwan, 1996.
[49] A. L. Mackay. Crystallographic symmetry, Crystallogr. Rep. 46 (2001) 524-526.
[50] R. A. Swalin, Thermodynamics of Solids, second ed., Wiley, New York, 1991.
[51] F. R. de Bohr, R. Boom, W. C. M. Mattens, A. R. Miedema, A. K. Niessen, Ch. 1 and Ch. 2 in Cohesion in Metals: Transition Metal Alloys, Elsevier, New York, 1988.
[52] J. W. Yeh, A. K. Chen, J. Y. Gan, A. J. Lin, T. S. Chin, T. T. Shun, C. H. Tsau, S. Y. Chang, Formation of simple crystal structures in Cu-Co-Ni-Cr-Al-Fe-Ti-V alloys with multiprincipal metallic elements, Metall. Mater. Trans. 35A (2004) 2533-2536.
[53] J. W. Yeh, S. K. Chen, S. J. Lin, J. Y. Gan, T. S. Chin, T. T. Shun, C. H. Tsau, S. Y. Chang, Nanostructured high-entropy alloys with multiple principal elements: novel alloy design concepts and outcomes, Adv. Eng. Mater. 6 (2004) 299-303.
[54] C. W. Chen, S. K. Chen、T. Hsu, Microstructure and properties of as-cast 10-component nanostructured AlCoCrCuFeMoNiTiVZr high-entropy alloy, Master’s thesis of National Tsing Hua University, Taiwan, 2004.
[55] T. Zhang, A. Inoue, Density, thermal stability and mechanical properties of Zr-Ti-Al-Cu-Ni bulk amorphous alloys with high Al plus Ti concentrations, Mater. Trans. JIM 39 (1998) 857-862.
[56] C. Fan, A. Takeuchi, A. Inoue, Preparation and mechanical properties of Zr-based bulk nanocrystalline alloys containing compound and amorphous phases, Mater. Trans. JIM 40 (1999) 42-51.
[57] T. K. Chen, T. T. Shun, J. W. Yeh,, M. S. Wong, Nanostructured nitride films of multi-element high-entropy alloys by reactive DC sputtering, Surf. Coat. Tec. 188-189 (2004) 193-200.
[58] H. Bakker, in: Enthalpies in alloys, Materials Science Foundations, Vol. 1, Trans. Tech. Publications, Netherlands, 1998.
[59] International Union of Crystallography, International Tables for X-ray Crystallography, Kynock Press, Birmingham, 1968.
[60] J. L. C. Daams, P. Villars, j. H. N. Vucht, in: Atlas of crystal structure types for intermetallic phases, Vol. 1, ASM international, Metals Park, OH, 1991.
[61] J. M. Wu, S. J. Lin, J. W. Yeh, S. K. Chen, Y. S. Huang, Adhesive wear behavior of AlxCoCrCuFeNi high-entropy alloys as a function of aluminum content, Wear 261 (2006) 513-519.
[62] C. Y. Hsu, J. W. Yeh, S. K. Chen, T. T. Shun, Wear resistance and high-temperature compression strength of FCC CuCoNiCrAl0.5Fe alloy with boron addition, Metall. Mater. Trans. 35A (2004) 1465-1469.
[63] Y. Y. Chen, U. T. Hong, J. W. Yeh. H. C. Shih, Mechanical properties of a bulk Cu0.5NiAlCoCrFeSi glassy alloy in 288 ℃ high-purity water, Appl. Phys. Lett. 87 (2005) 261918.
[64] Y. Y. Chen, T. Duval, U. D. Hung, J. W. Yeh, H. C. Shih, Microstructure and electrochemical properties of high entropy alloys—a comparison with type-304 stainless steel, Corros. Sci. 47 (2005) 2257-2279.
[65] Y. Y. Chen, U. T. Hong, H. C. Shih, J. W. Yeh, T. Duval, Electrochemical kinetics of the high entropy alloys in aqueous environments—a comparison with type 304 stainless steel, Corros. Sci. 47 (2005) 2679-2699.
[66] Y. Y. Chen, U. T. Hong, J. W. Yeh, H. C. Shih, Selected corrosion behaviors of a Cu0.5NiAlCoCrFeSi bulk glassy alloy in 288 ℃ high-purity water, Scr. Mater. 54 (2006) 1997-2001.
[67] Y. J. Hsu, W. C. Chiang, J. K. Wu, Corrosion behavior of FeCoNiCrCux high-entropy alloys in 3.5 % sodium chloride solution, Mater. Chem. Phys. 92 (2005) 112-117.
[68] ASTM standard G31-72, Practice for laboratory immersion corrosion testing of metals, 2003.
[69] C. P. Lee, Y. Y. Chen, C. Y. Hsu, J. W. Yeh, H. C. Shih, The effect of boron on the corrosion resistance of the high entropy alloys Al0.5CoCrCuFeNiBx, J. Electrochem. Soc., 154 (2007) C424-C430.
[70] C. P. Lee, C. C. Chang, Y. Y. Chen, J. W. Yeh, H. C. Shih, Effect of the aluminum content of AlxCrFe1.5MnNi0.5 high-entropy alloys on the corrosion behavior in aqueous environments, Corros. Sci. 50 (2008) 2053-2060.
[71] C. P. Lee, Y. Y. Chen, C. Y. Hsu, J. W. Yeh, H. C. Shih, Enhancing pitting corrosion resistance of AlxCrFe1.5MnNi0.5 high-entropy alloys by anodic treatment in sulfuric acid, Thin Solid Films 517 (2008) 1301–1305.
[72] P. K. Huang, J. W. Yeh, T. T. Shun, S. K. Chen, Multiprincipal element alloys with improved oxidation and wear resistance for thermal spray coating, Adv. Eng. Mater. 6 (2004) 74-78.
[73] J. W. Yeh, S. K. Chen, S. J. Lin, J. Y. Gan, T. S. Chin, T. T. Shun, C. H. Tsau, S. Y. Chang, Nanostructured high-entropy alloys with multiple principal elements: novel alloy design concepts and outcomes, Adv. Eng. Mater. 6 (2004) 299-303.
[74] J. W. Yeh, S. K. Chen, J. Y. Gan, S. J. Lin, T. S. Chin, T. T. Shun, C. H. Tsau, S. Y. Chang, Formation of simple crystal structures in Cu-Co-Ni-Cr-Al-Fe-Ti-V alloys with multiprincipal metallic elements, Metall. Mater. Trans. 35 (2004) 2533-2536.
[75] H. F. Kuo, W. Chin, T. W. Cheng, W. K. Hsu, J. W. Yeh, Hyperfine splitting from magnetic boride domains embedded in Fe-Co-Ni-Al-B-Si alloy, Appl. Phys. Lett. 89 (2006) 182503.
[76] Y. C. Wang, J. W. Yeh, Microstructure and Mechanical Properties of AlXCo1.5CrFeMoYNi1.5Ti0.5, Master’s thesis of National Tsing Hua University, Taiwan, 2007.
[77] Y. L. Chou, J. W. Yeh, H. C. Shih, The effect of molybdenum on the corrosion behaviour of the high-entropy alloys Co1.5CrFeNi1.5Ti0.5Mox in aqueous environments, Corros. Sci. 52 (2010) 2571-2581.
[78] R. J. Brigham, E. W. Tozer, Effect of alloying additions on the pitting resistance of 18 % Cr austenitic stainless steel, Corrosion 30 (1974) 161-166.
[79] R. J. Brigham, E. W. Tozer, Pitting resistance of 18 % Cr ferritic stainless steels containing molybdenum, J. Electrochem. Soc., 121 (1974) 1192-1193.
[80] K. Lorenz, G. Medawar, Über das Korrosionsverhalten austenitischer Chrom– Nickel–(Molybdan)–Stahle mit und ohne Stickstoffzusatz unter besonderer Berücksichtigung ihrer Beanspruchung in chloridhaltigen Lösungen, Thyssenforschung 1 (1969) 97-108.
[81] H. P. Leckie, H. H. Uhlig, Environmental factors affecting the critical potential for pitting in 18-8 stainless steel, J. Electrochem. Soc. 113 (1966) 1262-1267.
[82] P. C. Pistorius, G. T. Burstein, Growth of corrosion pits on stainless steel in chloride solution containing dilute sulphate, Corros. Sci. 33 (1992) 1885-1897.
[83] Y. Zuo, H. Wang, J. Zhao, J. Xiong, The effects of some anions on metastable pitting of 316L stainless steel, Corros. Sci. 44 (2002) 13-24.
[84] M. H. Moayed, R. C. Newman, Aggressive effects of pitting inhibitors on highly alloyed stainless steels, Corros. Sci. 40 (1998) 519-522.
[85] B. Deng, Y. Jiang, J. Liao, Y. Hao, C. Zhong, J. Li, Dependence of critical pitting temperature on the concentration of sulphate ion in chloride-containing solutions, Appl. Surf. Sci. 253 (2007) 7369-7375.
[86] H. Böhni, H. H. Uhlig, Environmental factors affecting the critical pitting potential for aluminum, J. Electrochem. Soc. 116 (1969) 906-910.
[87] J. C. Scully, W. J. Rudd, The role of corrosion product in the inhibition of pitting corrosion on aluminum, NACE, Houston, Texas, 1979.
[88] K. Sugimoto, Y. Sawada, The role of alloyed molybdenum in austenitic stainless steels in the inhibition of pitting in neutral halide solutions, Corrosion 32 (1976) 347-352.
[89] E. Wallis, Influence of the molybdenum content of high-alloy stainless steels and of the precipitation of intermetallic phases on pitting resistance in chloride-containing media, Mater. Corros. 41 (1990) 155-162.
[90] D. A. Jones, Principles and prevention of corrosion second ed., Prentice Hall, New Jersey, 1996.
[91] W. S. Tait, An introduction to electrochemical corrosion testing for practicing engineers and scientists, Racine, Wisconsin, 1994.
[92] H. H. Uhlig, R. W. Revie, Corrosion and corrosion control, John Wiley and Sons, New York, 1991.
[93] M. A. Ameer, A. M. Fekry, F. El-Taib Heakal, Electrochemical behavior of passive films on molybdenum-containing austenitic stainless steels in aqueous solutions, Electrochim. Acta 50 (2004) 43-49.
[94] H. C. Shih, J. C. Oung, J. T. Hsu, J. Y. Wu, F. I. Wei, Applications of electrochemical hysteresis for constructing the experimental potential-pH diagram for steels in seawater, Mater. Chem. Phys. 37 (1994) 230-236.
[95] H. Kaesche, Korrosion der Metalle, Springer Verlag, Berlin, 1966.
[96] S. Brennert, Met. Prog. 31 (1937) 641.
[97] Z. Szklarska-Smialowska, Review of literature on pitting corrosion published since 1960, Corrosion 27 (1971) 223-233.
[98] Z. Szklarska-Smialowska, M. Janik-Czachor, The analysis of electrochemical methods for the determination of characteristic potentials of pitting corrosion, Corros. Sci. 11 (1971) 901-914.
[99] N. Pessal, C. Liu, Determination of critical pitting potentials of stainless steels in aqueous chloride environments, Electrochim. Acta 16 (1971) 1987-2003.
[100] B. C. Syrett, PPR curves–a new method of assessing pitting corrosion resistance, Corrosion 33 (1977) 221-224.
[101] I. L. Rozenfeld, I. S. Danilov, Electrochemical aspects of pitting corrosion, Corros. Sci. 7 (1967) 129-142.
[102] H. S. Isaacs, Potential scanning of stainless steel during pitting corrosion, NACE, Houston, Texas, 1974.
[103] H. S. Isaacs, G. Kissel, Surface preparation and pit propagation in stainless steels, J. Electrochem. Soc. 119 (1972) 1628-1632.
[104] R. J. Brigham, Pitting of molybdenum bearing austenitic stainless steel, Corrosion 28 (1972) 177-179.
[105] R. J. Brigham, E. W. Tozer, Temperature as a pitting criterion, Corrosion 29 (1973) 33-36.
[106] R. Qvarfort, Critical pitting temperature measurements of stainless steels with an improved electrochemical method, Corros. Sci. 29 (1989) 987-993.
[107] N. J. Laycock, Effects of temperature and thiosulphate on chloride pitting of austenitic stainless steels, Corrosion 55 (1999) 590-595.
[108] P. Ernst, M. H. Moayed, N. J. Laycock, R. C. Newman, in: M.B. Ives, B.R. Macdovgall, J. Bardwell (Eds.), Passivity of Metals and Semiconductors VIII, PV 99-42, The Electrochemical Society, Pennington NJ, USA, (1999) 665.
[109] K. Vu Quang, P. L. Guevel, N. Jallerat, Fast method for determination of critical pitting temperature, Corros. Sci. 28 (1988) 423-424.
[110] V. M. Salinas-Bravo, R. C. Newman, An alternative method to determine critical pitting temperature of stainless steels in ferric chloride solution, Corros. Sci. 36 (1994) 67-77.
[111] Standard test methods for pitting and crevice corrosion Resistance of stainless steels and related alloys by use of ferric chloride solution, Designation: G 48–03.
[112] B. Deng, Y. Jiang, J. Gong, C. Zhong, J. Gao, J. Li, Critical pitting and repassivation temperatures for duplex stainless steel in chloride solutions, Electrochim. Acta 53 (2008) 5220-5225.
[113] Standard test method for electrochemical critical pitting temperature testing of stainless steels, Designation: G 150–99.
[114] L. F. Garfias-Mesias, J. M. Sykes, Metastable pitting in 25 Cr duplex stainless steel, Corros. Sci. 41 (1999) 959-987.
[115] H. H. Uhlig, Absorbed and reaction-product films on metals, J. Electrochem. Soc. 97 (1950) 215C-220C.
[116] Ya. M. Kolotyrkin, Effects of anions on the dissolution kinetics of metals, J. Electrochem. Soc. 108 (1961) 209-216.
[117] Ya. M. Kolotyrkin, Pitting corrosion of metals, Corrosion. 19 (1963) 261-268.
[118] J. Zahavi, M. Metzger, Breakdown of films and initiation of pits on aluminum during anodizing, NACE, Houston, Texas, 1974.
[119] B. MacGougall, Effect of chloride ion on the localized breakdown of nickel oxide films, J. Electrochem. Soc. 126 (1979) 919-925.
[120] K. Videm, Kjeller Report KR-140, Institutt for Atomenergi, Kjeller, Norway, 1974.
[121] K. G. Weil, D. Menzel, Z. Elektrochem. 63 (1959) 669.
[122] I. L. Rozenfeld, I. K. Marshakov, Mechanism of crevice corrosion, Corrosion 20 (1964) 115-125.
[123] G. Okamoto, Passive film of 18-8 stainless steel structure and its function, NACE, Houston, Texas, 1969.
[124] G. Okamoto, Passive film of 18-8 stainless steel structure and its function, Corros. Sci. 13 (1973) 471-489.
[125] K. Schwabe, Investigation into the nature of anodic passive and barrier coatings, J. Electrochem. Soc. 110 (1963) 667-670.
[126] K. Kudo, T. Shibata, G. Okamoto, N. Sato, Ellipsometric and radiotracer measurements of the passive oxide film on Fe in neutral solution, Corros. Sci. 8 (1968) 809-814.
[127] Z. Szklarska-Smialowska, Pitting Corrosion of Metals, NACE, Houston Texas, 1986.
[128] R. Nishimura, K. Kudo, Effect of thickness and composition of films on the breakdown of passivity of iron, Proc. 8th Int. Met. Corros., Mainz, DECHEMA, Frankfurt am Main, 1981.
[129] A. K. Vijh, A possible interpretation of the influence of chloride ions on the anodic behaviour of some metals, Corros. Sci. 11 (1971) 161-167.
[130] A. K. Vijh, The influence of solid state cohesion of metals on their pitting potentials, Corros. Sci. 12 (1972) 935-938.
[131] T. P. Hoar, The production and breakdown of the passivity of metals, Corros. Sci. 7 (1967) 341-355.
[132] J. Yahalom, On the initiation of and of propagation of pits, NACE, Houston, Texas, 1976.
[133] N. Sato, A theory for breakdown of anodic oxide films on metals, Electrochim. Acta 19 (1971) 1683-1692.
[134] N. Sato, Anodic breakdown of passive films on metals, J. Electrochem. Soc. 129 (1982) 255-260.
[135] L. F. Lin, C. Y. Chao, D. D. Macdonald, A point defect model for anodic passive films, J. Electrochem. Soc. 128 (1981) 1194-1198.
[136] J. R. Galvele, Transport processes and the mechanism of pitting of metals, J. Electrochem. Soc. 123 (1976) 464-474.
[137] E. A. Lizlovs, A. P. Bond, An evaluation of some electrochemical techniques for the determination of pitting potentials of stainless steel, Corrosion 31 (1975) 219-222.
[138] K. Osozawa, N. Okato, Effect of alloying elements, especially nitrogen, on the initiation of pitting in stainless steel, NACE, Houston, Texas, 1976.
[139] S. E. Traubenberg, R. T. Foley, The influence of chloride and sulfate ions on the corrosion of iron in sulfuric acid, J. Electrochem. Soc. 118 (1971) 1066-1070.
[140] T. P. Hoar, W. R. Jacob, Nature 216 (1967) 1209.
[141] H. Kaeche, Proc. 4th Int. Symp. Passivity, Airlie, West Virginia, 1977.
[142] M. Janik-Czachor, A Szummer, Z. Szklarska-Smialowska, Electrochemical equilibria of cadmium and water and the dissolution of cadmium as a function of pH, Corros. Sci. 15 (1973) 663-665.
[143] M. Seo, Y. Matsumura, N. Sato, Titanium enrichment in anodic oxide films on Fe-3 % Ti alloy, Proc. 8th Int. Cong. Met. Corros., Mainz, DECHEMA, Frankfurt am Main, 1981.
[144] Z. Szklarska-Smialowska, Nucleation and development of pitting corrosion in iron and steel, Proc. 7th Int. Cong. Met. Corros., Rio de Janeiro, Associacao Brasileira de Corrosao, Rio de Janeiro, 1978.
[145] S. Matsuda, H. H. Uhlig, Effect of pH. sulfates, chlorides on behavior of sodium chromate and nitrite as passivators for steel, J. Electrochem. Soc. 111 (1964) 156-161.
[146] H. H. Strehblow, B Titze, Pitting potentials and inhibition potentials of iron and nickel for different aggressive and inhibiting anions, Corros. Sci. 17 (1977) 461-472.
[147] G. H. Awad, T. P. Hoar, The role of phosphates in inhibiting pitting of commercial mild steel in chloride-containing media, Corros. Sci. 15 (1975) 581-588.
[148] K. Venu, K. Balakrishnan, K. S. Rajagopalan, A potentiokinetic polarization study of the behaviour of steel in NaOH-NaCl system, Corros. Sci. 5 (1965) 59-69.
[149] H. C. Man, D. R. Gabe, The study of pitting potentials for some austenitic stainless steels using a potentiodynamic technique, Corros. Sci. 21 (1981) 713-721.
[150] H. H. Uhlig, J. R. Gilman, Pitting of 18-8 stainless steel in ferric chloride inhibited by nitrates, Corrosion 20 (1964) 289-292.
[151] K. Sugimoto, Y. Sawada, The role of molybdenum additions to austenitic stainless steels in the inhibition of pitting in acid chloride solutions, Corros. Sci. 17 (1977) 425-445.
[152] S. I. Ali, G. J. Abbaschian, The chloride corrosion of austenitic stainless steels and of an inconel alloy in hot acidic media, Corros. Sci. 18 (1978) 15-19.
[153] Z. Szklarska-Smialowska, Effect of the ratio of Cl−/SO42− in solution on the pitting corrosion of Ni, Corros. Sci. 11 (1971) 209-221.
[154] W. Bogaerts, A. Van Haute, M. Brabers, P. Vanslembrouck, D. Kennis, Influence of Cl-, HCO3-, and SO42- on the corrosion of Fe-Cr-Ni alloys in hot water systems, Proc. 8th Int. Cong. Met. Corros., Mainz, DECHEMA, Frankfurt am Main, 1981.
[155] M. H. Moayed, N. J. Laycock, R. C. Newman, Dependence of the critical pitting temperature on surface roughness, Corros. Sci. 45 (2003) 1203-1216.
[156] B. D. Cullity, Elements of X-ray Diffraction, Addison-Wesley, Massachusetts, 1978.
[157] A. Takeuchi, A. Inoue, Calculations of mixing enthalpy and mismatch entropy for ternary amorphous alloys, Mater. Trans. 41 (2000) 1372-1378.
[158] A. Takeuchi, A. Inoue, Calculations of amorphous-forming composition range for ternary alloy systems and analyses of stabilization of amorphous phase and amorphous-forming ability, Mater. Trans. 42 (2001) 1435.
[159] R. Boom, A. R. Miedema, A. K. Niessen, F. R. de Boer, W. C. Mattens, Cohesion in Metals: Transition Metal Alloys, Elsevier Applied Science, Amsterdam, Netherlands, 1988.
[160] H. S. Khatak, B. Raj, Corrosion of austenitic stainless steels: mechanism mitigation and monitoring. Woodhead publishing, 2002.
[161] O. Conejero, M. Palacios, S. Rivera, Premature corrosion failure of a 316L stainless steel plate due to the presence of sigma phase, Eng. Fail. Anal. 16 (2009) 699-704.
[162] A. J. Sedriks, Effects of alloy composition and microstructure on the passivity of stainless steels, Corrosion 42 (1986) 376-389.
[163] T. Laitinen, M. Bojinov, I. Betova, K. Mäkelä, T. Saario, The properties of and transport phenomena in oxide films on iron, nickel, chromium and their alloys in aqueous environments, STUK-YTO-TR150. ISBN 951-712-286-1, January 1999 (Helsinki).
[164] K. Hashimoto, K. Asami, K. Teramoto, An x-ray photo-electron spectroscopic study on the role of molybdenum in increasing the corrosion resistance of ferritic stainless steels in HCl, Corros. Sci. 19 (1979) 3–14.
[165] H. Ogawa, H. Omata, I. Itoh, H. Okada, Auger electron spectroscopic and electrochemical analysis of the effect of alloying elements on the passivation behavior of stainless steels, Corrosion 34 (1978) 52–60.
[166] Y. C. Lu, C. R. Clayton, Evidence for a bipolar mechanism of passivity in Mo bearing stainless steels, J. Electrochem. Soc. 132 (1985) 2517–2518.
[167] A. R. Brooks, C. R. Clayton, K. Doss, Y. C. Lu, On the role of Cr in the passivity of stainless steel, J. Electrochem. Soc. 133 (1986) 2459-2464.
[168] C. R. Clayton, Y. C. Lu, A bipolar model of the passivity of stainless steel: The role of Mo addition, J. Electrochem. Soc. 133 (1986) 2465-2473.
[169] T. Kodama, J. R. Ambrose, Effect of molybdate ion on the repassivation kinetics of iron in solutions containing chloride ions, Corrosion 33 (1977) 155-161.
[170] K. Ogura, T. Ohama, Pit formation in the cathodic polarization of passive iron IV. Repair mechanism by molybdate, chromate and tungstate, Corrosion 40 (1984) 47-51.
[171] M. Pourbaix, Atlas of electrochemical equilibria in aqueous solutions, NACE, Houston, Texas, 1974.
[172] K. Hashimoto, K. Asami, A. Kawashima, H. Habazaki, E. Akiyama, The role of corrosion-resistant alloying elements in passivity, Corros. Sci. 49 (2007) 42–52.
[173] M. Bojinov, G. Fabricius, T. Laitinen, K. Mäkelä, T. Saario, G. Sundholm, Influence of molybdenum on the conduction mechanism in passive films on iron–chromium alloys in sulphuric acid solution, Electrochim. Acta 46 (2001) 1339–1358.
[174] J. O. Nilsson, T. Huhtala, P. Jonsson, L. Karlsson, A. Wilson, Structural stability of super duplex stainless weld metals and its dependence on tungsten and copper, Metall. Mater. Trans. A 27A (1996) 2196-2208.
[175] Y. Maehara, Y. Ohmori, J. Murayama, N. Fujino, T. Kunitake, Effects of alloying elements on sigma phase precipitation in delta-gamma duplex phase stainless steels, Metal. Sci. 17 (1983) 541-547.
[176] D. M. E. Villanueva, F. C. P. Junior, R. L. Plaut, A. F. Padilha, Comparative study on sigma phase precipitation of three types of stainless steels: austenitic, superferritic and duplex. Mater. Sci. Technol. 22 (2006) 1098-1104.
[177] B. E. Wilde, A critical appraisal of some popular laboratory electrochemical tests for predicting the localized corrosion resistance of stainless alloys in sea water, Corrosion 28 (1972) 283-291.
[178] J. D. Bumgardner, L. C. Lucas, Surface analysis of nickel chromium dental alloys, Dent. Mater. 9 (1993) 252-259.
[179] M. Roach, D. Parsell, S. Gardner, J. D. Bumgardner, Correlation of corrosion and surface analyses for Ni-Cr alloys, Crit. Rev. Biomed. Eng. 26 (1998) 391-392.
[180] M. B. Rockel, M. Renner, Pitting, crevice and stress corrosion resistance of high chromium and molybdenum alloy stainless steels, Mater. Corros. 35 (1984) 537-542.
[181] T. J. Glover, Recent developments in corrosion-resistant metallic alloys for construction of seawater pumps, Mater. Performance 27 (1988) 51-56.
[182] J. S. Kim, H. S. Kwon, Effects of Tungsten on corrosion and kinetics of sigma phase formation of 25 % chromium duplex stainless steels, Corrosion 55 (1999) 512-521.
[183] Z. Cvijović, G. Radenković, Microstructure and pitting corrosion resistance of annealed duplex stainless steel, Corros. Sci. 48 (2006) 3887–3906.
[184] J. H. Wang, C. C. Su, Z. Szklarska-Smialowska, Effects of Cl- concentration and temperature on pitting of AISI 304 stainless steel, Corrosion 44 (1988) 732-737.
[185] P. E. Manning, D. J. Duquette, The effect of temperature (25°–289 ℃) on pit initiation in single phase and duplex 304L stainless steels in 100 ppm Cl− solution, Corros. Sci. 20 (1980) 597-609.
[186] E. A. Abd El Meguid, N. A. Mahmoud, S. S. Abd El Rehim, The effect of some sulphur compounds on the pitting corrosion of type 304 stainless steel, Mater. Chem. Phys. 63 (2000) 67-74.
[187] E. A. Abd El Meguid, A. A. Abd El Latif, Critical pitting temperature for type 254 SMO stainless steel in chloride solutions, Corros. Sci. 49 (2007) 263-275.
[188] E. A. Abd El Meguid, N. A. Mahmoud, V.K. Gouda, Pitting corrosion behaviour of AISI 316L steel in chloride containing solutions, Br. Corros. J. 33 (1998) 42-48.
[189] R. C. Newman, 2001 W.R. Whitney award lecture: Understanding the corrosion of stainless steel, Corrosion 57 (2001) 1030-1041.
[190] G. C. Palit, V. Kain, H. S. Gadiyar, Electrochemical investigations of pitting corrosion in nitrogen-bearing type 316LN stainless steel, Corrosion 49 (1993) 977-991.
[191] R. F. A. Jargelius-Petterson, Electrochemical investigation of the influence of nitrogen alloying on pitting corrosion of austenitic stainless steels, Corros. Sci. 41 (1999) 1639-1664.
[192] R. C. Newman, The dissolution and passivation kinetics of stainless alloys containing molybdenum—II. Dissolution kinetics in artificial pits, Corros. Sci. 25 (1985) 341-350.
[193] R. F. A. Jargelius-Petterson, Application of the pitting resistance equivalent concept to some highly alloyed austenitic stainless steels, Corrosion 54 (1998) 162-168.
[194] A. Igual Muñoz, J. García Antón, J.L. Guiñón, V. Pérez Herranz, Effects of solution temperature on localized corrosion of high nickel content stainless steels and nickel in chromated LiBr solution, Corros. Sci. 48 (2006) 3349-3374.
[195] A. Pardo, E. Otero, M. C. Merino, M. D. López, M. V. Utrilla, F. Moreno, Influence of pH and chloride concentration on the pitting and crevice corrosion behaviour of high-alloy stainless steels, Corrosion 56 (2000) 411–418.
[196] R. Guo, M. B. Ives, Pitting susceptibility of stainless steels in bromide solutions at elevated temperatures, Corrosion 46 (1990) 125–129.
[197] N. J. Laycock, Effects of temperature and thiosulphate on chloride pitting of austenitic stainless steels, Corrosion 55 (1999) 590–595.
[198] M. H. Moayed, R. C. Newman, Deterioration in critical pitting temperature of 904L stainless steel by addition of sulphate ions, Corros. Sci. 48 (2006) 3513-3530.
[199] P. C. Pistorius, G. T. Burstein, Growth of corrosion pits on stainless steel in chloride solution containing dilute sulphate, Corros. Sci. 33 (1992) 1885-1897.
[200] N. J. Laycock, M. H. Moayed, R. C. Newman, Metastable pitting and the critical pitting temperature, J. Electrochem. Soc. 148 (1998) 2622-2628.
[201] P. Ernst, R. C. Newman, Pit growth studies in stainless steel foils. II. Effect of temperature, chloride concentration and sulphate addition, Corros. Sci. 44 (2002) 943-954.
[202] D. W. DeBarry, in: A. Raman, P. Labine (Eds.), Reviews on Corrosion Inhibitor Science and Technology, NACE, Houston, TX, 1993, p. II-19-1.
[203] E. H. Hamner, in: C. C. Nathan (Ed.), Corrosion Inhibitors, NACE, Houston, TX, 1973, p. 1.
[204] E. Mattsson, Basic Corrosion Technology for Scientists and Engineers, Ellis Harwood Ltd., Chichester, 1989.
[205] A. D. Mercer, in: 7th European Symposium on Corrosion Inhibitors (7SEIC), Ann. Univ., Ferrara, Italy, Suppl. no. 9, 1990, p. 449.
[206] R. C. Newman, M. A. A. Ajjawi, A micro-electrode study of the nitrate effect on pitting of stainless steels, Corros. Sci. 26 (1986) 1057-1063.
[207] R. C. Newman, T. Shahrabi, The effect of alloyed nitrogen or dissolved nitrate ions on the anodic behaviour of austenitic stainless steel in hydrochloric acid, Corros. Sci. 27 (1987) 827-838.
[208] J. E. Huheey, Inorganic Chemistry: Principles, Structure and Reactivity, second ed., Harper and Row, New York, 1978.
[209] J. E. Huheey, E. A. Keiter, R. L. Keiter, Principles, Structure and Reactivity, fourth ed., Harper and Row, New York, 1993.
[210] G. O. Ilevbare, G. T. Burstein, The inhibition of pitting corrosion of stainless steels by chromate and molybdate ions, Corros. Sci. 45 (2003) 1545-1569.
[211] N. Hackerman, in: A. Raman, P. Labine (Eds.), Reviews on Corrosion Inhibitor Science and Technology, NACE, Houston, TX, 1993, p. I-1-1.
[212] G. Trabanelli, in: A. Raman, P. Labine (Eds.), Reviews on Corrosion Inhibitor Science and Technology, NACE, Houston, TX, 1993, p. I-2-1.
[213] M. V. Pospelov, A. V. Fokin, in: A. Raman, P. Labine (Eds.), Reviews on Corrosion Inhibitor Science and Technology, NACE, Houston, TX, 1993, p. I-4-1.