Journal of Phase Equilibria and Diffusion

, Volume 39, Issue 5, pp 510–518 | Cite as

Phase Equilibria of the Co-Mo-Zr Ternary System at 1000 °C

  • Chaoying Lin
  • Cong ZhangEmail author
  • Shimin Wang
  • Peng Zhou
  • Yong DuEmail author


The isothermal section of the Co-Mo-Zr ternary system at 1000 °C was investigated by using 29 alloys. The annealed alloys were examined by means of x-ray diffraction, optical microscopy, and electron probe microanalysis. It was confirmed that three ternary phases, λ1 (Co0.5-1.5Mo1.5-0.5Zr, hP12-MgZn2), ω (CoMoZr4) and κ (CoMo4Zr9, hP28-Hf9Mo4B), exist in the Co-Mo-Zr ternary system at 1000 °C. And the experimental results also indicated that there are sixteen three-phase regions at 1000 °C. Thirteen of them were well determined in the present work: (1) (γCo) + Co11Zr2 + Co23Zr6, (2) (γCo) + Co23Zr6 + ε-Co3Mo, (3) Co23Zr6 + ε-Co3Mo + μ-Co7Mo6, (4) (Mo) + μ-Co7Mo6 + Co2Zr, (5) (Mo) + Co2Zr + λ1, (6) (Mo) + Mo2Zr + λ1, (7) λ1 + Mo2Zr + CoZr, (8) Co2Zr + CoZr + λ1, (9) Mo2Zr + CoZr2 + ω, (10) κ + Mo2Zr + ω, (11) CoZr2 + liquid + ω, (12) (βZr) + liquid + ω and (13) (βZr) + κ + ω. The homogeneity of λ1 spans in the range of 28.66-50.77 at.% Co and 15.71-37.03 at.% Mo, and that for ω is within the range of 18.66-23.64 at.% Co and 8.53-14.68 at.% Mo. The homogeneity range for κ is from 8.09 at.% to 9.94 at.% Co and 23.13 at.% to 25.58 at.% Mo. The maximum solubility of Zr in μ-Co7Mo6 phase, Mo in Co2Zr phase and Co in Mo2Zr phase were determined to be 6.17, 11.27 and 9.14 at.%, respectively. While the solubility of Zr in ε-Co3Mo and (γCo) phases, Mo in Co11Zr2 and CoZr phases were detected to be extremely small. According to this work, the Co23Zr6 phase contained 15.61 at.% Mo and 12.7 at.% Zr. In addition, the maximum solubility of Co and Zr in (Mo) phase and Mo in (γCo) phase were measured to be 3.50, 5.44 and 7.40 at.%, respectively.


Co-Mo-Zr system electron probe microanalysis isothermal section x-ray diffraction 



The financial supports from Ministry of Industry and Information Technology of China (Grant No. 2015ZX04005008) and Project of Innovation-driven Plan in Central South University (Grant No. 2015CX004) are greatly acknowledged.


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© ASM International 2018

Authors and Affiliations

  1. 1.Hunan Province MuseumChangshaPeople’s Republic of China
  2. 2.Collaborative Innovation Center of Steel TechnologyUniversity of Science and Technology BeijingBeijingPeople’s Republic of China
  3. 3.State Key Laboratory of Powder MetallurgyCentral South UniversityChangshaPeople’s Republic of China
  4. 4.School of Mechanical and Electrical EngineeringHunan University of Science and TechnologyXiangtanPeople’s Republic of China

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