The role of C on microstructure and local chemical composition of an as-cast Ti42Al5Mn alloy was systematically characterised. Results show that C is enriched in α2, less dissolved in γ but depleted in β o phase. Crossing the C-solubility limit, approximately 0.3 at. %, leads to the precipitation of h-type carbides (Ti2AlC). Furthermore, a correlation between the lattice site preference and the C-solubility is rationalised by neutron powder diffraction technique, suggesting that Mn tends to substitute the position of Al site within the γ-phase (L10-lattice) with an occupancy rate of 4.31%. Consequently, fewer Ti6-type sites are formed where C is preferentially located. Finally, the interlamellar spacing and phase evolution as well as the preferential distribution of alloying elements are also evaluated.

中文翻译：

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碳对Ti42Al5Mn合金组织和元素分布的影响

系统地表征了 C 对铸态 Ti42Al5Mn 合金的微观结构和局部化学成分的作用。结果表明，C富含α2，在γ中溶解较少，但在βo相中贫化。超过 C 溶解度极限，大约 0.3 at。%，导致 h 型碳化物 (Ti2AlC) 的析出。此外，通过中子粉末衍射技术合理化了晶格位点偏好和 C 溶解度之间的相关性，表明 Mn 倾向于以 4.31% 的占有率取代 γ 相（L10 晶格）内的 Al 位点位置. 因此，在 C 优先位于的地方形成较少的 Ti6 型位点。最后，还评估了层间间距和相演变以及合金元素的优先分布。