Abstract Ternary Ti-30.7wt%Al-xC alloys were prepared with different carbon content (x = 0.2, 0.4, 0.8, 1.2, 1.6, and 2.0 wt%) by vacuum arc melting in order to improve the strength and ductility. Microstructure evolution and mechanical properties of alloys were experimentally and statistically studied, especially the carbide formation mechanism. The results show that Ti2AlC phase appears when carbon content is >0.4%, and its volume fraction increases with increasing carbon content. Lamellar colony size, lamellar space and length-diameter of Ti2AlC phase decrease with increasing carbon. Carbon has the certain solid solubility in matrix. Carbides form when addition of carbon content is over the solid solubility limit. Ti2AlC acts as heterogeneous nucleation particles and carbon decreases the rate of lateral thickening of γ lamellae plates, which are the reasons for refining microstructure. High-melting-point TiC particles act as nucleation particles to form Ti2AlC and refine the Ti2AlC with more TiC content. Tensile strength increases 1.6 times at 750 °C with increasing carbon content. Tensile strength increases 1.5 times from 750 °C to 850 °C with 0.8% carbon and the maximum strain is 3.7%. Precipitation strengthening of Ti2AlC particles and grain boundary strengthening are mainly mechanisms to improve mechanical properties.

中文翻译：

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石墨对电弧熔炼三元TiAl合金组织演变及力学性能的影响

摘要 为了提高强度和延展性，采用真空电弧熔炼方法制备了不同碳含量（x = 0.2、0.4、0.8、1.2、1.6和2.0 wt%）的三元Ti-30.7wt%Al-xC合金。对合金的显微组织演变和力学性能进行了实验和统计研究，特别是碳化物形成机制。结果表明，当碳含量>0.4%时会出现Ti2AlC相，其体积分数随着碳含量的增加而增加。Ti2AlC 相的层状菌落大小、层状空间和长径随着碳的增加而减小。碳在基体中具有一定的固溶度。当添加的碳含量超过固溶度极限时会形成碳化物。Ti2AlC 作为异质成核粒子，碳降低了 γ 片晶的横向增厚率，这就是微观结构细化的原因。高熔点 TiC 颗粒作为成核颗粒形成 Ti2AlC 并细化具有更多 TiC 含量的 Ti2AlC。随着碳含量的增加，抗拉强度在 750 °C 时增加 1.6 倍。抗拉强度从 750 °C 到 850 °C 增加 1.5 倍，碳含量为 0.8%，最大应变为 3.7%。Ti2AlC 颗粒的析出强化和晶界强化是提高力学性能的主要机制。