Diffraction based identification of an elusive FCC phase in carbo-oxidized titanium

Frederik B. Kværndrup*, Flemming B. Grumsen, Shima Kadkhodazadeh, Kristian V. Dahl, Marcel A.J. Somers, Thomas L. Christiansen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

A face-centered cubic (FCC) phase formed during the carbo-oxidation of hexagonal close-packed (HCP) α-Titanium at 600 to 700 °C. The FCC crystal structure was confirmed using transmission electron diffraction, X-ray diffraction and high angle annular dark field scanning transmission electron microscopy. The a lattice parameter for the FCC resulting from the three methods was consistent with FCC sublattice of titanium atoms in δ-TiH2-x. The FCC phase is hypothesized to form partly due to hydrogen pick-up, the stress state in the foil caused by the mismatch between body centered cubic iron-stabilized β-Titanium and HCP α-Titanium and the tensile stress present in front of the oxygen concentration profile. A transformation of α-Titanium into δ-TiH2-x is accomplished by introducing Shockley partial dislocations on every 2nd closest paced plane, resulting in an orientation relation that has previously been observed for thermally induced FCC γ-Ti. The TiH2-x phase was shown to decompose upon vacuum annealing at 500 °C.
Original languageEnglish
Article number111435
JournalMaterials Characterization
Volume180
Number of pages8
ISSN1044-5803
DOIs
Publication statusPublished - 2021

Keywords

  • Titanium
  • XRD
  • TEM
  • HAADF
  • FCC
  • HCP

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