本研究以鎳基合金C-276為基礎，探討不同Mo含量對合金在20wt. % HCl添加1000 ppm三價鐵離子的環境中之耐蝕性的影響。除浸泡試驗外，亦利用動電位極化試驗與循環動電位極化試驗進行的耐蝕性分析，最後以所得之結果、質量損失、表面微觀狀況與腐蝕程度進行綜合性的討論，並探討腐蝕機制與Mo元素之影響。
　　實驗結果顯示，合金熔煉後所產生之富Mo與富Nb之析出相與周圍底材之電動勢不同，相較於底材的其它主要合金元素(Ni, Cr, Fe)，富Mo與富Nb的析出相擁有更高的電位，容易形成陰極反應電位，進而觸發相鄰底材的陽極溶解，造成加凡尼腐蝕。當合金添加之Mo含量下降時，會使底材的抗蝕性下降，使腐蝕加劇；當合金添加Nb時，會使合金析出富Nb相，富Nb相較高的電位會使相鄰的底材產生陽極溶解，使腐蝕加劇。

　　This study is based on the nickel-based alloy C-276 and explores the effect of different Mo contents on the corrosion resistance in an environment with 20 wt.% HCl and 1000 ppm ferric ions. In addition to immersion test, the corrosion resistance analysis by the potentiodynamic polarization test and the cyclic potentiodynamic polarization test were also carried out. Finally, a comprehensive discussion is carried out based on the results, including mass loss, surface microscopic conditions and corrosion degree, and the corrosion Mechanism and influence of Mo element.
　　The experimental results show that the Mo-rich and Nb-rich precipitates formed after alloy smelting have different electromotive forces with the surrounding substrate. Compared with the other major alloying elements of the substrate (Ni, Cr, Fe), the Mo-rich and Nb-rich precipitates have a higher potential, which is benefucial for the formation of a cathode reaction potential, while the anode dissolution of the adjacent substrate, occurred Gavanic corrosion was caused When the Mo content decreases, the corrosion resistance would will decrease, the alloy added with Nb would cause the formation of Nb-rich phase, and the higher potential of the Nb-rich phase will make the adjacent material dissolves in the anode, which aggravates the corrosion.

[1] C. P. Dillon and W. I. Pollock, "Materials selector for hazardous chemicals : vol 3:hydrochloric acid, hydrogen chloride and chlorine", Materials Technology Institute, 1999.
[2] H. Alves and U. Heubner, "Aqueous Corrosion of Nickel and its Alloys", Reference Module in Materials Science and Materials Engineering, 2010.
[3] T. Yonezawa, "Nickel Alloys: Properties and Characteristics", Comprehensive Nuclear Materials, vol. 2, 2012.
[4] 李名言，"鎳基合金材質特性介紹"，中工高雄會刊，第21卷第1期，p.23-66，2013。
[5] P. Crook, "Corrosion of Nickel and Nickel-Base Alloys", Corrosion Materials vol. 13B, ASM International, 2005.
[6] M. Bauccio and American Society for matal, ASM metals reference book. Materials Park, Ohio: ASM International, 1993.
[7] T. F. A. Santos, R. R. Marinho, M. T. P. Paes, and A. J. Ramirez, "Microstructure evaluation of UNS S32205 duplex stainless steel friction stir welds," Rem: Revista Escola de Minas, vol. 66, pp. 187-191, 2013.
[8] T. M. Pollock and S. Tin, Nickel-Based Superalloys for Advanced Turbine Engines: Chemistry, Microstructure and Properties vol. 22, 2006.
[9] E. O. Ezugwu, Z. M. Wang, and A. R. Machado, "The machinability of nickel-based alloys: a review," Journal of Materials Processing Technology, vol. 86, pp. 1-16, 1999.
[10] 柯賢文、王朝正，"腐蝕及其防制"，全華圖書，2014。
[11] 王朝正，"中鋼耐蝕合金開發專案"，國立臺灣科技大學機械工程研究所計畫，2019。
[12] 羅有庭，"C-276合金熔煉與成分改質於鹽酸環境下之性價比評估"，國立臺灣科技大學機械工程研究所碩士論文，2019。
[13] 林本源，"合金元素對球墨鑄鐵沃斯回火相轉變的影響"，國立臺灣科技大學機械工程研究所博士論文，1995。
[14] P. E. A. Turchi, L. Kaufman, and Z. K. Liu, "Modeling of Ni–Cr–Mo based alloys: Part I-phase stability," Calphad, vol. 30, pp. 70-87, 2006.
[15] F. G. Hodge, "The history of solid-solution-strengthened Ni alloys for aqueous corrosion service," JOM, vol. 58, pp. 28-31, 2006.
[16] A. K. Mishra, N. Ebrahimi, D. W. Shoesmith, and P. E. Manning, "Materials Selection for Use in Hydrochloric Acid," presented at the CORROSION 2016, Vancouver, British Columbia, Canada, 2016.
[17] T. Bellezze, G. Giuliani, and G. Roventi, "Study of stainless steels corrosion in a strong acid mixture. Part 1: cyclic potentiodynamic polarization curves examined by means of an analytical method," Corrosion Science, vol. 130, pp. 113-125, 2018.
[18] J. R. Hayes, J. J. Gray, A. W. Szmodis, and C. A. Orme, "Influence of Chromium and Molybdenum on the Corrosion of Nickel-Based Alloys," CORROSION, vol. 62, pp. 491-500, 2006.
[19] B. Craig and D. Anderson, Handbook of corrosion data, ASM International, 2nd edition, 2019.
[20] R. Rebak and P. Crook, "Nickel alloys for corrosive environments" Advanced Materials and Processes, vol. 157, pp. 37-42, 2000.
[21] M. Davies, "Alloy selection for service in chlorine, hydrogen chloride and hydrochloric acid" Nickel Institute, 2018.
[22] A. K. Mishra and D. W. Shoesmith, "Effect of Alloying Elements on Crevice Corrosion Inhibition of Nickel-Chromium- Molybdenum-Tungsten Alloys Under Aggressive Conditions: An Electrochemical Study," CORROSION, vol. 70, pp. 721-730, 2014.
[23] S. C. Yoo, K. J. Choi, T. Kim, S. H. Kim, J. Y. Kim, and J. H. Kim, "Microstructural evolution and stress-corrosion-cracking behavior of thermally aged Ni-Cr-Fe alloy," Corrosion Science, vol. 111, pp. 39-51, 2016.
[24] Y. X. Xu, W. Y. Li, and X. W. Yang, "Influence of alloyed Fe on corrosion of Ni-Cr alloys in molten silicates and the effects of pre-oxidation treatment," Corrosion Science, vol. 134, pp. 179-188, 2018.
[25] R. S. Lillard, J. R. Scully, and M. P. Jurinski, "Crevice Corrosion of Alloy 625 in Chlorinated ASTM Artificial Ocean Water," vol. 50, 1994.
[26] M. Ht, N. L. Richards, and W. F. Caley, ''Isothermal Oxidation Comparison of Three Ni-Based Superalloys,'' vol. 26, 2017.
[27] X. Y. Li, E. Akiyama, H. Habazaki, A. Kawashima, K. Asami, and K. Hashimoto, "Electrochemical and XPS studies of the passivation behavior of sputter-deposited Cr–Ta alloys in 12 M HCl," Corrosion Science, vol. 40, pp. 1587-1604, 1998.
[28] P. Y. Park, E. Akiyama, H. Habazaki, A. Kawashima, K. Asami, and K. Hashimoto, "The corrosion behavior of sputter-deposited Mo-Nb alloys in 12 M HCl solution," Corrosion Science, vol. 38, pp. 1731-1750, 1996.
[29] A. A. N. Németh, D. J. Crudden, D. M. Collins, V. Kuksenko, C. H. Liebscher, D. E. J. Armstrong, A. J. Wilkinson and R. C. Reed, "On the Influence of Nb/Ti Ratio on Environmentally-Assisted Crack Growth in High-Strength Nickel-Based Superalloys" Metallurgical and Materials Transactions A, vol. 49, pp. 3923-3937, 2018.
[30] 鄭沂聖，"商用鎳基超合金之電化學腐蝕行為研究"，中國文化大學材料科學與奈米科技研究所碩士論文，2011。
[31] 枋明輝，"無磨料電化學機械加工在銅薄膜平坦化製程之研究"，國立臺灣科技大學機械工程系碩士論文，2009。
[32] D. R. Crow, "Principles and Applications of Electrochemistry, 4th Edition" CRC Press, 1994.
[33] ASTM G61-86 (Reapproved 2018), "Standard Test Method for Conducting Cyclic Potentiodynamic Polarization Measurements for Localized Corrosion Susceptibility of Iron-, Nickel-, or Cobalt-Based Alloys."
[34] ASTM G48-11 "Standard Test Methods for Pitting and Crevice Corrosion Resistance of Stainless Steels and Related Alloys by Use of Ferric Chloride Solution"
[35] ASTM G78-15 "Standard Guide for Crevice Corrosion Testing of Iron-Base and Nickel-Base Stainless Alloys in Seawater and Other Chloride-Containing Aqueous Environments."
[36] Davide Prando, Andrea Brenna, Maria Vittoria Diamanti, Silvia Beretta, Fabio Bolzoni, Marco Ormellese, and MariaPia Pedeferri, "Corrosion of titanium : aggressive environments and main forms of degradation" JABFM, vol. 15, pp. e291-e302, 2017
[37] X. Ren, K. Sridharan, and T.R. Allen, "Corrosion Behavior of Alloys 625 and 718 in supercritical Water" Corrosion Science Section, Vol. 63, No. 7, 2007
[38] A. E. Danon, O. Muransky, I. Karatchevtseva, Z. Ahang, Z. J. Li, N. Scales, J. J. Kruzic, and L. Edwards, "Molten salt corrosion (FLINaK) of a Ni-Mo-Cr alloy and its welds for application in energy-generation and energy-storage systems" Corrosion Science 164 (2020)
[39] Madan Patnamsetty, Ari Saastamoinen, and Pasi Peura, "Annealing Effects on the Microstructure and Properties of Vanadium and Molybdenum Rich FCC High Entropy Alloy" Key Engineering Materials, Vol. 799, pp.109-115, 2019.
[40] Michael A. Streicher, "Effect of Composition and Structure on Crevice, Intergranular and Stress Corrosion of Some Wrought Ni-Cr-Mo Alloy" Corrosion NACE, Vol. 32, No. 3, March, 1976.
[41] Marisa Aparecida de Souza, Tomaz Manabu Hashimoto, and Ana Paula Rosifini, "Influence of Niobium or Molybdenum Addition on Microstructure and Tensile Properties of Nickel-Chromium Alloys" MDPI, Metals 2019.
[42] Heon-Young Ha, Tae-Ho Lee, Jee-Hwan Bae, and Dong Won Chun, "Molybdenum Effects on Pitting Corrosion Resistance of FeCrMnMoNC Austenitic Stainless Steels" MDPI, Metals 2018.
[43] Shuncun Luo, Wenpu Huang, Huihui Yang, Jingjing Yang, Zemin Wang, and Xiaoyan Zeng, "Microstructural evolution and corrosion behaviors of Inconel 718 alloy produced by selective laser melting following different heat treatments" Additive Manufacturing 30 (2019)
[44] 侯文星，"718鎳基超合金細晶製程之研究" 國立成功大學機械工程學系碩士論文，2012
[45] 陳旭俊、王海林、陳振家，"鉬酸鹽對不銹鋼孔蝕抑制作用機理的研究" 中國腐蝕與防護學報，第12卷第3期，p.213-220，1992。