Abstract The hot deformation behaviour and microstructure evolution of TiAl-based alloy with nominal composition Ti-43Al-8Nb-3.6C-0.7Mo (at.%) reinforced with carbide particles were studied. The compression tests were carried out in the temperature range from 900 to 1000 °C and strain rates from 0.0001 to 0.01 s−1 up to a true strain of 0.5. The microstructure of the compression specimens was characterised using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron backscatter diffraction (EBSD). The work hardening stage of the flow curves results from an increment of the dislocation density and deformation twins. The work softening of the composite results from the dynamic recovery (DRV), dynamic recrystallization (DRX) and fragmentation of some coarse Ti2AlC particles. The size of recrystallised grains increases with decreasing Zener-Hollomon parameter. The non-uniform distribution of local strains in the deformed specimens and deformation temperature affect the orientation and fragmentation of coarse Ti2AlC particles. A constitutive model predicting hot deformation behaviour of the studied alloy is proposed and its validity is evaluated and discussed.

中文翻译：

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碳化物颗粒增强TiAl基合金的热变形行为及组织演变

摘要 研究了标称成分为Ti-43Al-8Nb-3.6C-0.7Mo (at.%)的碳化物颗粒增强TiAl基合金的热变形行为和组织演变。压缩试验在 900 至 1000 °C 的温度范围和 0.0001 至 0.01 s-1 的应变速率下进行，真实应变为 0.5。压缩试样的微观结构使用扫描电子显微镜 (SEM)、透射电子显微镜 (TEM) 和电子背散射衍射 (EBSD) 进行表征。流动曲线的加工硬化阶段是由位错密度和变形孪晶的增加引起的。复合材料的加工软化是由动态恢复 (DRV)、动态再结晶 (DRX) 和一些粗 Ti2AlC 颗粒的碎裂造成的。再结晶晶粒的尺寸随着 Zener-Hollomon 参数的减小而增加。变形试样中局部应变的不均匀分布和变形温度影响粗Ti2AlC颗粒的取向和破碎。提出了一种预测所研究合金热变形行为的本构模型，并对其有效性进行了评估和讨论。