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 language | English |
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Pages (from-to) | 1504-1511 |
Number of pages | 8 |
Journal | Acta Materialia |
Volume | 57 |
Issue number | 5 |
DOIs | |
State | Published - Mar 2009 |
Externally published | Yes |
Keywords
- Carbon
- Interstitials
- Mechanical properties
- Three-dimensional atom probe (3DAP)
- Titanium aluminides