Deoxidation of Titanium Using Mg as Deoxidant in MgCl2-YCl3 Flux

  • Chenyi Zheng
  • Takanari OuchiEmail author
  • Akihiro Iizuka
  • Yu-ki Taninouchi
  • Toru H. Okabe


To reduce the oxygen level in titanium (Ti) to less than 1000 mass ppm O, using magnesium as the deoxidant at 1300 K (1027 °C), the activity of the deoxidation product (MgO), i.e., aMgO, in the system must be reduced to less than 0.04, from a thermodynamic viewpoint. In this study, we developed a new deoxidation technique for Ti, by adding yttrium chloride (YCl3) to magnesium chloride (MgCl2) flux, which effectively decreases and maintains the aMgO in the system at a low level, via the formation of yttrium oxychloride (YOCl). Through thermodynamic assessment using a \( p_{{{\text{O}}_{ 2} }} {\text{-}}p_{{{\text{Cl}}_{ 2} }} \) diagram, as well as experiments, the deoxidation of Ti to an oxygen level below 1000 mass ppm O, via the reaction O (in Ti) + Mg + YCl3 → MgCl2 + YOCl, was confirmed. Furthermore, using the E-pO2− diagram of the M-O-Cl system (M = Y, Mg), the possibility of electrochemical deoxidation is discussed. In the MgCl2-YCl3 flux, Mg deposits on the Ti cathode and simultaneously deoxidizes it. The activity of the deoxidation product, MgO, decreases due to the formation of YOCl and/or the electrochemical oxidation of oxide ions on the carbon anode; thus, the deoxidation of Ti becomes feasible. This new deoxidation technique using rare-earth-containing MgCl2 flux can be applied to the recycling of Ti scraps, in the future.



The authors are grateful to Professors Hongmin Zhu and Osamu Takeda at Tohoku University for their valuable comments and helpful suggestions. This work was financially supported by the Japan Society for the Promotion of Science (JSPS), through a Grant-in-Aid for Scientific Research (S) (KAKENHI Grant No. 26220910).


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Copyright information

© The Minerals, Metals & Materials Society and ASM International 2019

Authors and Affiliations

  • Chenyi Zheng
    • 1
    • 2
  • Takanari Ouchi
    • 1
    Email author
  • Akihiro Iizuka
    • 1
    • 2
  • Yu-ki Taninouchi
    • 1
  • Toru H. Okabe
    • 1
  1. 1.Institute of Industrial ScienceThe University of TokyoTokyoJapan
  2. 2.Department of Materials Engineering, Graduate School of EngineeringThe University of TokyoTokyoJapan

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