Electrochemical Behavior Assessment of As-Cast Mg-Y-RE-Zr Alloy in Phosphate Buffer Solutions (X Na3PO4 + Y Na2HPO4) Using Electrochemical Impedance Spectroscopy and Mott–Schottky Techniques

Article
  • 11 Downloads

Abstract

In the present study, electrochemical behavior of as-cast Mg-Y-RE-Zr alloy (RE: rare-earth alloying elements) was investigated using electrochemical tests in phosphate buffer solutions (X Na3PO4 + Y Na2HPO4). X-ray diffraction techniques and Scanning electron microscopy equipped with energy dispersive x-ray spectroscopy were used to investigate the microstructure and phases of the experimental alloy. Different electrochemical tests such as potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) and Mott–Schottky (M–S) analysis were carried out in order to study the electrochemical behavior of the experimental alloy in phosphate buffer solutions. The PDP curves and EIS measurements indicated that the passive behavior of the as-cast Mg-Y-RE-Zr alloy in phosphate buffer solutions was weakened by an increase in the pH, which is related to formation of an imperfect and less protective passive layer on the alloy surface. The presence of the insoluble zirconium particles along with high number of intermetallic phases of RE elements mainly Mg24Y5 in the magnesium matrix can deteriorate the corrosion performance of the alloy by disrupting the protective passive layer that is formed at pH values over 11. These insoluble zirconium particles embedded in the matrix can detrimentally influence the passivation. The M–S analysis revealed that the formed passive layers on Mg-Y-RE-Zr alloy behaved as an n-type semiconductor. An increase in donor concentration accompanying solutions of higher alkalinity is thought to result in the formation of a less resistive passive layer.

Keywords

EIS Mg-Y-RE-Zr alloy Mott–Schottky analysis polarization 

References

  1. 1.
    J.E. Gray and B. Luan, Protective Coatings on Magnesium and Its Alloys—A Critical Review, J. Alloy. Compd., 2002, 336, p 88–113CrossRefGoogle Scholar
  2. 2.
    T. Rzychoń and A. Kiełbus, Microstructure of WE43 Casting Magnesium Alloy, J. Achiev. Mater. Manuf. Eng., 2007, 21, p 31–34Google Scholar
  3. 3.
    J.W. Chang, X.W. Guo, S.M. He, P.H. Fu, L.M. Peng, and W.J. Ding, Effect of Heat Treatment on Corrosion and Electrochemical Behaviour of Mg–3Nd–0.2Zn–0.4Zr (wt%) Alloy, Electrochim. Acta, 2007, 52, p 3160–3167CrossRefGoogle Scholar
  4. 4.
    R. Arrabal, E. Matykina, F. Viejo, P. Skeldon, and G.E. Thompson, Corrosion Resistance of WE43 and AZ91D Magnesium Alloys with Phosphate PEO Coatings, Corros. Sci., 2008, 50, p 1744–1752CrossRefGoogle Scholar
  5. 5.
    G.L. Song and A. Atrens, Understanding Magnesium Corrosion—A Framework for Improved Alloy Performance, Adv. Eng. Mater., 2003, 5, p 837–858CrossRefGoogle Scholar
  6. 6.
    G.L. Song and A. Atrens, Corrosion Mechanisms of Magnesium Alloys, Adv. Eng. Mater., 1999, 1, p 11–33CrossRefGoogle Scholar
  7. 7.
    X. Zhang, K. Zhang, X.-G. Li et al., Corrosion and Electrochemical Behavior of As-cast Mg-5Y-7Gd-1Nd-0.5Zr Magnesium Alloys in 5% NaCl Aqueous Solution, Prog. Nat. Sci. Mater. Int., 2011, 21, p 314–321CrossRefGoogle Scholar
  8. 8.
    T. Rzychoń, J. Michalska, and A. Kiełbus, Corrosion Resistance of Mg-RE-Zr Alloys, J. Achiev. Mater. Manuf. Eng., 2007, 21, p 51–54Google Scholar
  9. 9.
    H. Kalb, A. Rzany, and B. Hensel, Impact of Microgalvanic Corrosion on the Degradation Morphology of WE43 and Pure Magnesium Under Exposure to Simulated Body Fluid, Corros. Sci., 2012, 57, p 122–130CrossRefGoogle Scholar
  10. 10.
    H. Ardelean, A. Seyeux, S. Zanna et al., Corrosion Processes of Mg–Y–Nd–Zr Alloys in Na2SO4 Electrolyte, Corros. Sci., 2013, 73, p 196–207CrossRefGoogle Scholar
  11. 11.
    A.E. Coy, F. Viejo, P. Skeldon, and G.E. Thompson, Susceptibility of Rare-Earth-Magnesium Alloys to Micro-galvanic Corrosion, Corros. Sci., 2010, 52, p 3896–3906CrossRefGoogle Scholar
  12. 12.
    M. Pourbaix, Atlas of Electrochemical Equilibria in Aqueous Solutions, 2nd ed., NACE, Houston, 1974Google Scholar
  13. 13.
    R. Pinto, M.G.S. Ferreira, M.J. Carmezim, and M.F. Montemor, Passive Behavior of Magnesium Alloys (Mg–Zr) Containing Rare-Earth Elements in Alkaline Media, Electrochim. Acta, 2010, 55, p 2482–2489CrossRefGoogle Scholar
  14. 14.
    Y. Mizutani, S.J. Kim, R. Ichino, and M. Okido, Anodizing of Mg Alloys in Alkaline Solutions, Surf. Coat. Technol., 2003, 169–170, p 143–146CrossRefGoogle Scholar
  15. 15.
    Y. Song, E.H. Han, K. Dong et al., Microstructure and Protection Characteristics of the Naturally Formed Oxide Films on Mg–xZn Alloys, Corros. Sci., 2013, 72, p 133–143CrossRefGoogle Scholar
  16. 16.
    H. Duan, Ch Yan, and F. Wang, Effect of Electrolyte Additives on Performance of Plasma Electrolytic Oxidation Films Formed on Magnesium Alloy AZ91D, Electrochim. Acta, 2007, 52, p 3785–3793CrossRefGoogle Scholar
  17. 17.
    S.O. Gashti, A. Fattah-alhosseini, Y. Mazaheri, and M.K. Keshavarz, Microstructure, Mechanical Properties and Electrochemical Behavior of AA1050 Processed by Accumulative Roll Bonding (ARB), J. Alloy. Compd., 2016, 688, p 44–55CrossRefGoogle Scholar
  18. 18.
    A. Fattah-alhosseini, M. Vakili-Azghandi, M. Sheikhi, and M.K. Keshavarz, Passive and Electrochemical Response of Friction Stir Processed Pure Titanium, J. Alloy. Compd., 2017, 704, p 499–508CrossRefGoogle Scholar
  19. 19.
    Y. Li, T. Zhang, and F. Wang, Effect of Microcrystallization on Corrosion Resistance of AZ91D Alloy, Electrochim. Acta, 2006, 51, p 2845–2850CrossRefGoogle Scholar
  20. 20.
    R. Walter and M. Bobby Kannan, In-vitro Degradation Behaviour of WE54 Magnesium Alloy in Simulated Body Fluid, Mater. Lett., 2011, 65, p 748–750CrossRefGoogle Scholar
  21. 21.
    R. Pinto, M.G.S. Ferreira, M.J. Carmezim, and M.F. Montemor, The Corrosion Behaviour of Rare-Earth Containing Magnesium Alloys in Borate Buffer Solution, Electrochim. Acta, 2011, 56, p 1535–1545CrossRefGoogle Scholar
  22. 22.
    M. Sun, G. Wu, W. Wang, and W. Ding, Effect of Zr on the Microstructure, Mechanical Properties and Corrosion Resistance of Mg–10Gd–3Y Magnesium Alloy, Mater. Sci. Eng. A, 2009, 523, p 145–151CrossRefGoogle Scholar
  23. 23.
    G. Ben-Hamu, D. Eliezer, K.S. Shin, and S. Cohen, The Relation Between Microstructure and Corrosion Behavior of Mg–Y–RE–Zr Alloys, J. Alloy. Compd., 2007, 431, p 269–276CrossRefGoogle Scholar
  24. 24.
    J. Chang, X. Guo, Sh He et al., Investigation of the Corrosion for Mg–xGd–3Y–0.4Zr (x = 6,8, 10,12 wt%) Alloys in a Peak-Aged Condition, Corros. Sci., 2008, 50, p 166–177CrossRefGoogle Scholar
  25. 25.
    G.L. Song and D. StJohn, The Effect of Zirconium Grain Refinement on the Corrosion Behaviour of Magnesium-Rare Earth Alloy MEZ, J. Light Met., 2002, 2, p 1–16CrossRefGoogle Scholar
  26. 26.
    J.P. Li, P. Wang, Y.C. Guo et al., Microstructure and Microgalvanic Corrosion of an Extruded Mg-10Gd-2Y-0.5Zr Magnesium Alloy, Mater. Sci. Forum, 2013, 765, p 683–687CrossRefGoogle Scholar
  27. 27.
    W.C. Neil, M. Forsyth, P.C. Howlett, C.R. Hutchinson, and B.R.W. Hinton, Corrosion of Magnesium Alloy ZE41—The Role of Microstructural Features, Corros. Sci., 2009, 51, p 387–394CrossRefGoogle Scholar
  28. 28.
    D.S. Gandel, M.A. Easton, M.A. Gibson, T. Abbott, and N. Birbilis, The Influence of Zirconium Additions on the Corrosion of Magnesium, Corros. Sci., 2014, 81, p 27–35CrossRefGoogle Scholar
  29. 29.
    A. Fattah-alhosseini, M. Vakili-Azghandi, and M.K. Keshavarz, Influence of Concentrations of KOH and Na2SiO3 Electrolytes on the Electrochemical Behavior of Ceramic Coatings on 6061 Al Alloy Processed by Plasma Electrolytic Oxidation (PEO), Acta Metallurgica Sinica (Engl Lett), 2016, 29, p 274–281CrossRefGoogle Scholar
  30. 30.
    S. Vafaeian, A. Fattah-alhosseini, M.K. Keshavarz, and Y. Mazaheri, The Influence of Cyclic Voltammetry Passivation on the Electrochemical Behavior of Fine and Coarse-Grained AISI, 430 Ferritic Stainless Steel in an Alkaline Solution, J. Alloy. Compd., 2016, 677, p 42–51CrossRefGoogle Scholar
  31. 31.
    A. Fattah-alhosseini and M. Sabaghi, Joni, Effect of Immersion Time on the Electrochemical Behaviour of AZ31B Alloy, J. Alloy. Compd., 2015, 646, p 685–691CrossRefGoogle Scholar
  32. 32.
    S.J. Xia, R. Yue, R.G. Rateick, Jr., and V.I. Birss, Electrochemical Studies of AC/DC Anodized Mg Alloy in NaCl Solution, J. Electrochem. Soc., 2004, 151, p B179–B187CrossRefGoogle Scholar
  33. 33.
    F.F. Eliyan and A. Alfantazi, Corrosion of the Heat-Affected Zones (HAZs) of API-X100 Pipeline Steel In Dilute Bicarbonate Solutions at 90 C—An Electrochemical Evaluation, Corros. Sci., 2013, 74, p 297–307CrossRefGoogle Scholar
  34. 34.
    X. Ma, Q. Jiang, Y. Li, and B.R. Hou, Effect of Heat Treatment on Corrosion Behaviors of Mg-5Y-1.5Nd Alloys, Int. J. Electrochem., 2016, 2016, p 1–9CrossRefGoogle Scholar
  35. 35.
    G.L. Song, Recent progress in corrosion and protection of magnesium alloys, Adv. Eng. Mater., 2005, 7, p 563–586CrossRefGoogle Scholar

Copyright information

© ASM International 2018

Authors and Affiliations

  1. 1.Department of Materials EngineeringBu-Ali Sina UniversityHamedanIran

Personalised recommendations