Effects of Nb and Zr addition on introduction of misfit dislocations onto α2/γ lamellar boundaries and change of lattice misfit in fully lamellar TiAl alloy

Yasunari Toriyama, Kyosuke Yoshimi, Kouichi Maruyama

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

Changes in microstructures of α2/γ lamellar boundaries was studied on fully lamellar Ti-38Al-xM (at%, x = 0, 3, M = Zr, Nb) alloys over a wide range of average lamellar thickness from 290 to 20 nm. The lamellar structure was formed by isothermal aging and lamellar thickness was controlled by changing aging temperature. The addition of Nb or Zr alters the lattice mismatch between α2 and γ phases. At lamellar boundaries the mismatch is accommodated by elastic deformation and/or by introducing misfit dislocations. The elastic deformation totally accommodates the lattice mismatch (coherent boundary) when γ lamellae are thin enough. Misfit dislocations are introduced to accommodate partly the mismatch when γ lamellar thickness exceeds a critical value λc. Density of the misfit dislocations saturates to an upper limit ds in thick lamellar structures. The critical value of λc decreases and the saturation level ds increases with increasing lattice mismatch. Zr increases and Nb decreases the lattice mismatch.

Original languageEnglish
Pages (from-to)96-102
Number of pages7
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume71
Issue number1
DOIs
Publication statusPublished - 2007 Jan

Keywords

  • Interface
  • Lamellar structure
  • Lattice misfit
  • Misfit dislocation
  • Titanium aluminides

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

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