Microstructure Evolution and High-Temperature Mechanical Properties of Ti6Al4Nb4Zr Fabricated by Selective Laser Melting

Tomoki Kuroda, Haruki Masuyama, Yoshiaki Toda, Tetsuya Matsunaga, Tsutomu Ito, Makoto Watanabe, Ryosuke Ozasa, Takuya Ishimoto, Takayoshi Nakano, Masayuki Shimojo, Yoko Yamabe-Mitarai

Research output: Contribution to journalArticlepeer-review


Ti6Al4Nb4Zr (mass%) was prepared by selective laser melting (SLM) under various conditions, and the microstructure evolution resulting from SLM processing and subsequent heat treatments was investigated. The effects of the unique SLM-induced microstructure on the high-temperature compressive strength and creep properties of the samples were then elucidated. Under rapid cooling conditions, the martensitic structure formed in a scale-like pattern, with a 100 µm in size, consistent with the laser scanning pattern. By contrast, under slow cooling conditions, the ¡/¢ lamellar structure formed in ¢ grains with a 300 µm grain size instead of in a scale-like pattern. The martensitic structure drastically changed to a Widmanstätten structure during heat treatment. The equiaxed ¡ phase also formed at the interface of the scale-like patterns. By contrast, the ¡/¢ lamellar structure did not exhibit a change in response to heat treatment. The compressive strength of the SLM samples was governed by the martensite ¡ size and the grain size, both of which depended on the cooling rate. The dominant creep deformation mechanism at 600°C and under a loading stress of 137 MPa was grain boundary sliding. The creep life depended on the grain size. The HIP treatment improved the creep life because it eliminated pores introduced by the SLM process.

Original languageEnglish
Pages (from-to)95-103
Number of pages9
JournalMaterials Transactions
Issue number1
Publication statusPublished - 2023


  • compression strength
  • creep
  • heat-resistant Ti alloys
  • selective laser melting

ASJC Scopus subject areas

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


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