在单晶Ni基超合金的热疲劳测试中研究内部变形场和相关的微观结构演变
Cui Zong1, Sujie Liu2, Guangcai Ma2
1National Key Laboratory of Advanced High Temperature Structural Materials, Beijing Institute of Aeronautical Materials, Beijing 100095, China.
Materials (Basel, Switzerland)
|June 27, 2024
概括
基超合金中的循环加热和冷却会导致应力和塑性变形. 在碳化物中观察到再结晶,这表明在轮机叶片设计中需要微观结构控制.
科学领域:
- 材料科学 材料科学 材料科学
- 金工业是金工业的一个方面.
- 机械工程 机械工程
背景情况:
- 基超合金对于轮机叶片等高温应用至关重要.
- 恶劣的使用条件,包括循环加热和冷却,会引起显著的应力和变形.
- 了解这些微观结构变化对于组件的寿命至关重要.
研究的目的:
- 研究基超合金在循环热负荷下内部应力场的演变和失位密度分布.
- 分析微结构特征 (碳化物,树突,裂) 对应力度和可塑性的影响.
- 探索在高温下重新结晶现象的潜力.
主要方法:
- 使用高角度分辨率电子反射散射衍射 (HA-EBSD) 来绘制应力和位移密度的地图.
- 微结构分析的重点是碳化物,树突和口/裂纹尖端.
- 样品接受了受控的循环热处理.
主要成果:
- 口附近的应力度呈指数级下降,但因裂生长和脱位排放而改变.
- 裂纹启动是以结晶学方式控制的,与碳化物和树突具有较弱的相关性.
- 在微观结构特征和裂周围诱导了局部可塑性,导致高储能.
- 在50个和80个循环后在碳化物中观察到重新结晶的颗粒,尽管没有大规模的再结晶.
结论:
- 基超合金中的循环热负荷导致局部可塑性和应力再分配.
- 在碳化物中观察到的再结晶突出显示了一种微观结构依赖的现象.
- 建议对热辅助再结晶进行进一步的研究,以优化轮机叶片的微观结构和冷却通道设计.
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