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不同温度热暴露对 Ti-22Al-25Nb 合金氧化、微观组织及性能的影响
Influence of Different Heat Exposure Temperatures on the Oxidation,Microstructure, and Room-temperature Tensile Properties ofTi-22Al-25Nb Alloy
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- DOI:
- 作者:
- 赵晓彬 1，贾润晨 1，谭海兵 2，曾卫东 1
ZHAO Xiaobin1, JIA Runchen1, TAN Haibing2, ZENG Weidong1
- 作者单位:
- 1. 西北工业大学 凝固技术全国重点实验室，陕西 西安 710072；2. 中国航发四川燃气涡轮研究院，四川 成都 610400
1. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China; 2. SichuanGas Turbine Research Institute of AECC, Chengdu 610400, China
- 关键词:
- Ti2AlNb 合金; 高温热暴露; 微观组织；力学性能
Ti2AlNb alloy; high-temperature exposure; microstructure; mechanical properties
- 摘要:
- Ti-22Al-25Nb 合金作为新一代高温轻质结构材料，兼具高比强度与优异蠕变性能，在航空航天领域具有广阔应用前景。但当温度超过 750 ℃时抗氧化性能的下降，制约了其应用发展。为揭示高温热暴露对合金结构稳定性与力学性能的耦合效应，本文对 Ti-22Al-25Nb 环件进行了 700、750 与 800 ℃热暴露处理，结合室温拉伸、显微硬度实验及多尺度显微表征，分析了表层氧化层与富氧层演化、细片层 O 相形貌转变及其对室温强度与塑性的影响机制。 结果表明，随热暴露温度升高，氧化层与富氧层逐步增厚并形成连续表面脆性层，且致密性降低；同时细片层 O 相厚度增加、长宽比降低，致使其阻碍作用下降，屈服强度下降。 而表面脆性层的形成则导致裂纹在早期即达到临界尺寸，致使室温强度与塑性同步劣化。
Ti-22Al-25Nb alloys are recognized as pioneering high-temperature lightweight structural materials characterizedby their exceptional combination of high specific strength and excellent creep resistance, thereby presenting broadapplication prospects in the aerospace field. However, the decline in oxidation resistance at temperatures exceeding 750 ℃limits its development and application. To elucidate the coupling effects of high-temperature thermal exposure on thestructural stability and mechanical properties of the alloy, Ti-22Al-25Nb annular components were subjected to thermalexposure at 700, 750 and 800 ℃ . By integrating room-temperature tensile tests and microhardness experiments withmultiscale microscopic characterization (SEM, TEM), the evolution of the surface oxide layer and oxygen-rich layer, themorphological transformation of the fine plate-like O phase, and their impact mechanisms on the room-temperature strengthand plasticity were analysed. The results indicate that with increasing thermal exposure temperature, the oxide layer andoxygen-rich layer progressively thicken, forming a continuous brittle surface layer with reduced compactness. Concurrently,the thickness of the fine plate-like O phase increases as the aspect ratio decreases, leading to a diminished hindrance effectand a reduction in yield strength. The formation of the brittle surface layer causes cracks to reach critical sizes at an earlystage, resulting in simultaneous degradation of the room-temperature strength and plasticity