Abstract The metadynamic recrystallization (MDRX) of β-solidified TiAl alloy and its effects on microstructural homogeneity were investigated in the present work. Based on the comprehensive microstructure characterizations in terms of scanning electron microscope in back-scattered electron (BSE) mode and electron back scattered diffraction (EBSD) technique, it is found that the occurrence of MDRX during the post-annealing process after hot compression leads to the decomposition of lamellar colonies, grain equalization and reduction of geometrically necessary dislocation. The MDRX in present alloy during interpass annealing process has a hardening effect on the subsequent flow behavior, while it is restricted due to the phase transformation γ to α when annealing at 1200 °C. Moreover, the occurrence of MDRX can reduce the microstructure heterogeneity among various areas induced by the different strains and stain rates, thus, to result in the microstructural homogenization. Through investigating the MDRX behavior, the present work supports important information for optimizing forged microstructure of TiAl alloys.

中文翻译：

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β凝固TiAl合金热变形后退火的超动力再结晶行为

摘要 本文研究了β-凝固TiAl 合金的超动力再结晶(MDRX) 及其对显微组织均匀性的影响。基于背散射电子（BSE）模式和电子背散射衍射（EBSD）技术的扫描电子显微镜综合微观结构表征，发现在热压缩后的后退火过程中MDRX的发生导致层状菌落的分解、晶粒均衡和几何必要位错的减少。现有合金在层间退火过程中的 MDRX 对后续的流动行为有硬化作用，而在 1200 ℃退火时，由于相变 γ 到 α，它受到限制。而且，MDRX 的发生可以减少不同应变和染色率引起的各个区域之间的微观结构不均匀性，从而导致微观结构均质化。通过研究 MDRX 行为，目前的工作为优化 TiAl 合金的锻造微观结构提供了重要信息。