Effect of building position on phase distribution in Co-Cr-Mo alloy additive manufactured by electron-beam melting

Taiyo Takashima, Yuichiro Koizumi, Yunping Li, Kenta Yamanaka, Tsuyoshi Saito, Akihiko Chiba

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Cobalt-chromium-molybdenum (Co-Cr-Mo) alloys are used for biomedical implants such as artificial joints because they have excellent wear and corrosion resistance and biocompatibility. Electron-beam melting (EBM) is a type of additive manufacturing technique for metals. We used EBM to fabricate 20 rods of a Co-Cr-Mo alloy with height of 160 mm arranged in a 4× 5 matrix and observed the phase constitution in the middle part (at a height of 80 mm) of the rods by scanning electron microscopy-electron backscatter diffraction. We found that the rods in the center part of the matrix consisted of more of the face-centered cubic (γ) phase and less of the hexagonal close-packed (ϵ) phase than rods in the outer part. This happened because even though each rod was fabricated under the same beam condition, the rods at the center had been exposed to higher temperature than those in the outer part, and less thermal dissipation took place because the neighboring rods were also heated by the electron beam. This difference in the thermal histories should be taken into consideration when many objects are fabricated simultaneously.

Original languageEnglish
Pages (from-to)2041-2047
Number of pages7
JournalMaterials Transactions
Volume57
Issue number12
DOIs
Publication statusPublished - 2016

Keywords

  • Biomedical cobalt-chromium-molybdenum alloy
  • Custom-made artificial joints
  • Electron-beam melting
  • Preheat

ASJC Scopus subject areas

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

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