Compositional regions of single phases at 1800°C in Mo-rich Mo-Si-B ternary system

Seong Ho Ha, Kyosuke Yoshimi, Kouichi Maruyama, Rong Tu, Takashi Goto

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)

Abstract

Single-phase regions in Mo-rich Mo-Si-B alloys at 1800°C were experimentally determined using a field-emission (FE) gun-type electron probe micro-analyzer (EPMA) in this study. A quantitative analysis by FE-EPMA was conducted with the calibration method we applied in our previous study to improve the accuracy in the B measurements. The compositional ranges of the determined Mo solid solution, silicide and boride phases were in good agreement with those of Mo-Si and Mo-B binary phase diagrams. On the other hand, the determined solubility of B in Mo solid solution, Mo 3Si and T 1 (Mo 5Si 3) were quite different from that indicated in previously reported ternary phase diagrams. The compositional region of the T 2 (Mo 5SiB 2) single-phase ranges from 9.7 to 13.3at% for Si and from 23.5 to 26.8at% for B. The following two points were made clear by the ternary phase diagram as determined in this study. One is that no stoichiometric T 2 composition is in the T 2 single-phase region, confirming no T 2 single-phase material can be obtained at the stoichiometric composition at 1800°C. The another is that the T 2 region of this study expands to a Si-rich area from the stoichiometric composition.

Original languageEnglish
Pages (from-to)179-188
Number of pages10
JournalMaterials Science and Engineering A
Volume552
DOIs
Publication statusPublished - 2012 Aug 30

Keywords

  • Annealing
  • Electron probe microanalysis (EPMA)
  • Intermetallic compounds
  • Point defects
  • Refractory metals

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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