High carbon solubility in a γ-TiAl-based Ti-45Al-5Nb-0.5C alloy and its effect on hardening

C. Scheu*, E. Stergar, M. Schober, L. Cha, H. Clemens, A. Bartels, F. P. Schimansky, A. Cerezo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

63 Scopus citations

Abstract

The C distribution within the γ-TiAl-phase of a Ti-45Al-5Nb-0.5C alloy with near-γ microstructure was studied by atom probe tomography. In most areas, the C atoms were homogeneously distributed, and only a few C-enriched features were detected, which were presumably Cottrell atmospheres surrounding dislocation cores. The C concentration within the γ-phase was measured to be ∼0.25 at.%, which is a factor of 10 higher than the solubility limit reported for other TiAl alloys. The reason for this unusually high C solubility is explained by an existing model, which relates the number of octahedral sites consisting of six Ti atoms to the solubility limit of interstitials. The large amount of C in solid solution can explain the results of a recent study which showed that the C-containing alloy had a ∼30% increase in yield strength compared with a C-free sheet containing the same Ti, Al and Nb concentrations.

Original languageEnglish
Pages (from-to)1504-1511
Number of pages8
JournalActa Materialia
Volume57
Issue number5
DOIs
StatePublished - Mar 2009

Keywords

  • Carbon
  • Interstitials
  • Mechanical properties
  • Three-dimensional atom probe (3DAP)
  • Titanium aluminides

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