Surface hardening of biomedical Ti-29Nb-13Ta-4.6Zr and Ti-6Al-4V ELI by gas nitriding

Masaaki Nakai, Mitsuo Niinomi, Toshikazu Akahori, Naofumi Ohtsu, Hideki Nishimura, Hiroyuki Toda, Hisao Fukui, Michiharu Ogawa

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64 Citations (Scopus)


The microstructure and hardness near the surface of a biomedical titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ), subjected to gas nitriding at 1023-1223 K was investigated in comparison with the conventional biomedical Ti-6Al-4V ELI (Ti64). After gas nitriding, the microstructure near the specimen surface was observed by optical microscopy, X-ray diffraction (XRD), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS). In both alloys, two types of titanium nitrides (TiN and Ti2N) are formed and the α phase is precipitated by gas nitriding. Furthermore, the oxygen impurity in the gas nitriding atmosphere reacts with the titanium nitrides; thus, TiO2 is formed at the outermost titanium nitride layer. The surface hardening was also evaluated by Vickers hardness measurement. The Vickers hardness near the surface of TNTZ and Ti64 increases significantly by gas nitriding.

Original languageEnglish
Pages (from-to)193-201
Number of pages9
JournalMaterials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
Issue number1-2
Publication statusPublished - Jul 15 2008
Externally publishedYes

All Science Journal Classification (ASJC) codes

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


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