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

TY - JOUR

T1 - High carbon solubility in a γ-TiAl-based Ti-45Al-5Nb-0.5C alloy and its effect on hardening

AU - Scheu, C.

AU - Stergar, E.

AU - Schober, M.

AU - Cha, L.

AU - Clemens, H.

AU - Bartels, A.

AU - Schimansky, F. P.

AU - Cerezo, A.

N1 - Funding Information: Fruitful discussion with R. Gerling and G. Dehm are kindly acknowledged. Many thanks to A. Stark for the lattice parameters. The UK facility for atomic-scale analysis at Oxford (opal) has been established with funding from the Engineering and Physical Sciences Research Council (EPSRC) under Grant No. EP/077664/1. Access to opal was funded under the ESTEEM project.

PY - 2009/3

Y1 - 2009/3

N2 - 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.

AB - 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.

KW - Carbon

KW - Interstitials

KW - Mechanical properties

KW - Three-dimensional atom probe (3DAP)

KW - Titanium aluminides

UR - http://www.scopus.com/inward/record.url?scp=60249100326&partnerID=8YFLogxK

U2 - 10.1016/j.actamat.2008.11.037

DO - 10.1016/j.actamat.2008.11.037

M3 - 文章

AN - SCOPUS:60249100326

SN - 1359-6454

VL - 57

SP - 1504

EP - 1511

JO - Acta Materialia

JF - Acta Materialia

IS - 5

ER -