High carbon solubility in a γ-TiAl-based Ti–45Al–5Nb–0.5C alloy and its effect on hardening
High carbon solubility in a γ-TiAl-based Ti–45Al–5Nb–0.5C alloy and its effect on hardening
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DOI：
10.1016/j.actamat.2008.11.037
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发表时间：
2009-03
期刊：
影响因子：
9.4
通讯作者：
C. Scheu;E. Stergar;M. Schober;L. Cha;H. Clemens;A. Bartels;F. Schimansky;A. Cerezo
中科院分区：
文献类型：
--
作者：
C. Scheu;E. Stergar;M. Schober;L. Cha;H. Clemens;A. Bartels;F. Schimansky;A. Cerezo
用原子探针层析技术研究了近γ组织Ti-45 Al-5 Nb-0.5C合金中γ-TiAl相中C的分布。在大多数地区，碳原子均匀分布，只有少数富碳的功能被检测到，这可能是科特雷尔气氛周围的位错核心。γ相内的C浓度测得为≤ 0.25at.%，这比其它TiAl合金所报道的溶解度极限高10倍。这种异常高的C溶解度的原因是由现有的模型，它涉及的八面体网站的数量组成的六个Ti原子的溶解度极限的钛。固溶体中大量的C可以解释最近的研究结果，该研究表明，与含有相同Ti、Al和Nb浓度的无C片材相比，含C合金的屈服强度增加了约30%。
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 ∼0.25at.%, 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.