Effects of Mo addition on the mechanical properties and microstructures of Ti-Mn alloys fabricated by metal injection molding for biomedical applications

Pedro Fernandes Santos, Mitsuo Niinomi, Ken Cho, Huihong Liu, Masaaki Nakai, Takayuki Narushima, Kyosuke Ueda, Yoshinori Itoh

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

Ti-Mn alloys fabricated by metal injection molding (MIM) show promising performance for biomedical applications, but their low ductility (caused by high O content and the presence of pores and carbides) requires improvement. Previously, the addition of Mo to cold crucible levitation melted (CCLM) Ti-Mn alloys efficiently improved the ductility of those alloys by promoting mechanical twinning. In the present study, Mo was added to Ti-Mn alloys fabricated by MIM. Unlike fabrication by CCLM, fabrication by MIM can produce alloys with a smaller grain size, and also introduce microstructures such as pores and Ti carbides. Thus, in order to investigate how Mo addition interacts with these typical MIM features, four alloys for biomedical applications were fabricated by MIM: Ti-5Mn-3Mo (TMM-53), Ti-5Mn-4Mo (TMM-54), Ti-6Mn-3Mo (TMM-63), and Ti-6Mn-4Mo (TMM-64). Their microstructures, mechanical properties, and tensile deformation mechanisms were evaluated. Their hardness values range from 312-359 HV, and their Young's modulus values range from 84-88 GPa; both the Vickers hardness and Young's modulus show little variation among the alloys. Although the alloys show fracture features associated with a predominantly ductile fracture mode and Mo addition successfully promotes mechanical twinning in TMM-54, the elongation of these alloys is still critically low. Compared to the TMM alloys fabricated by CCLM, the TMM alloys fabricated by MIM show slightly lower hardness and Young's modulus, and comparable tensile strength, with their low elongation remaining inadequate for such applications. In particular, TMM-63 shows the best combination of mechanical properties among the present alloys, with an elongation of 4% and an ultimate tensile strength of 1145 MPa.

Original languageEnglish
Pages (from-to)271-279
Number of pages9
JournalMaterials Transactions
Volume58
Issue number2
DOIs
Publication statusPublished - 2017

Keywords

  • Deformation mechanisms
  • Mechanical properties
  • Metal injection molding
  • Titanium-manganese-molybdenum alloys
  • β-phase

ASJC Scopus subject areas

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

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