Abstract TiAl alloys with nominal compositions of Ti–47Al–2Nb–2Cr-(0.2, 0.5)C were prepared via electromagnetic cold crucible directional solidification. Effects of alloying element carbon on the solidification behavior, microstructure and mechanical properties of the TiAl alloy were investigated. Experimental results revealed that alloying with carbon reduced the B2 phase content and refined the lamellar structure. Also, additions of 0.5 at.% carbon changed the primary phase from single β to the mixture of β and α, and promoted the formation of Ti2AlC particles. The yield strength of the alloy enhanced as the carbon content increased, while the ultimate strength of the alloy containing 0.2 at.% and 0.5 at.% C decreased consequently. Dislocation glide governed the plastic deformation of the two directionally solidified C-containing TiAl alloys. The strain rate sensitivity value and activation volume of the both experimental alloys decreased with the increase of strain. The hindrance of Ti2AlC particles to dislocations movements caused stress concentration and premature cracking.

中文翻译：

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电磁冷坩埚定向凝固含碳γ-TiAl合金的组织和力学性能

摘要 通过电磁冷坩埚定向凝固制备了名义成分为 Ti-47Al-2Nb-2Cr-(0.2, 0.5)C 的 TiAl 合金。研究了合金元素碳对TiAl合金凝固行为、组织和力学性能的影响。实验结果表明，与碳合金化降低了 B2 相含量并细化了层状结构。此外，添加 0.5 at.% 的碳将主相从单一的 β 变为 β 和 α 的混合物，并促进了 Ti2AlC 颗粒的形成。合金的屈服强度随着碳含量的增加而提高，而含 0.2 at.% 和 0.5 at.% C 的合金的极限强度随之降低。位错滑移控制了两种定向凝固的含碳 TiAl 合金的塑性变形。两种实验合金的应变率灵敏度值和活化体积都随着应变的增加而减小。Ti2AlC 颗粒对位错运动的阻碍导致应力集中和过早开裂。