New chemical layered structure in Ti-Cr alloys

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The new chemical layered structure, referred to as a chemical stripe structure, was found as a metastable state in the (bcc → hcp + C15) metastable phase separation in the Ti-Cr alloys. Note that a metastable separation is here defined as a separation characterized by a positive value of the second derivative of Gibbs free energy with respect to chemical composition. The experimental data showed that the layered structure had periodicity of 4 × d002, about 0.72 nm, and chemical ordering of Ti: Cr = 3 : 1, and that a lot of antiphase boundaries with phase shifts of π/2 and π were involved in the structure. The coherent length of the layered structure was estimated to be about 15 nm along the modulated direction. In addition to these features, it was found that the layered structure was formed from the local bct state as another metastable state, not directly from the zone structure consisting of one Cr layer. On the basis of these data, the physical origin of the formation of the chemical layered structure is also discussed.

Original languageEnglish
Pages (from-to)1689-1695
Number of pages7
JournalMaterials Transactions
Volume43
Issue number7
Publication statusPublished - 2002 Jul

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metastable state
antiphase boundaries
Metastable phases
Gibbs free energy
Phase shift
Phase separation
periodic variations
chemical composition
phase shift
Derivatives
Chemical analysis
Direction compound

Keywords

  • Layered structure
  • Metastable phase separation
  • Titanium chromium alloy
  • Transmission electron microscopy

ASJC Scopus subject areas

  • Materials Science(all)
  • Metals and Alloys

Cite this

New chemical layered structure in Ti-Cr alloys. / Hirata, Akihiko; Tanimura, Makoto; Koyama, Yasumasa.

In: Materials Transactions, Vol. 43, No. 7, 07.2002, p. 1689-1695.

Research output: Contribution to journalArticle

Hirata, Akihiko ; Tanimura, Makoto ; Koyama, Yasumasa. / New chemical layered structure in Ti-Cr alloys. In: Materials Transactions. 2002 ; Vol. 43, No. 7. pp. 1689-1695.
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