ISSN:1003-8620

CN:42-1243/TF

主管:中信泰富特钢集团股份有限公司

主办:大冶特殊钢有限公司

特殊钢 ›› 2024, Vol. 45 ›› Issue (1): 12-17.DOI: 10.20057/j.1003-8620.2023-00093

所属专题: 高温合金开发

• 产品研发 • 上一篇    下一篇

镍基高温合金U720Li在750 ℃不同氧化阶段的恒温氧化行为

秦墨周, 赵广迪, 武金江, 赵媛媛, 王国安   

  1. 辽宁科技大学材料与冶金学院,鞍山 114051
  • 收稿日期:2023-05-26 出版日期:2024-01-30 发布日期:2024-02-01
  • 通讯作者: 赵广迪
  • 作者简介:秦墨周(2001—),男,本科
  • 基金资助:
     辽宁科技大学创新创业项目(项目号:x202210146025),国家自然科学基金项目(项目号:51904146)

Isothermal Oxidation Behavior of Nickel-based Superalloy U720Li in Different Oxidation Stages at 750 ℃

Qin Mozhou, Zhao Guangdi, Wu Jinjiang, Zhao Yuanyuan, Wang Guoan   

  1. School of Materials and Metallurgy, University of Science and Technology Liaoning, Anshan 114051, China
  • Received:2023-05-26 Published:2024-01-30 Online:2024-02-01

摘要: 航空发动机涡轮盘服役温度的不断升高,对材料的抗氧化性能提出了更严苛的要求。U720Li合金是一种具有较高承温能力的涡轮盘用镍基高温合金,其长期服役温度高达750 ℃。阐明该合金在服役温度下的氧化行为,对延长涡轮盘的服役寿命具有重要意义。本文采用静态增重法测定了锻态U720Li合金在750 ℃的氧化动力学曲线,用XRD、SEM-EDS等手段分析了不同氧化阶段的氧化膜形貌、结构及元素分布。结果表明,U720Li合金在其服役温度下具有优异的抗氧化性能,在750 ℃的恒温氧化动力学曲线大致遵循立方规律,达到了完全抗氧化级别。分析认为,U720Li合金在氧化初期生成了疏松的γ-Cr2O3,随着氧化的进行,γ-Cr2O3层不断剥落,氧化膜变得更加连续致密并形成复杂多层结构,且在氧化膜附近基体内形成γ´贫化层。在稳定氧化阶段,氧化膜更加连续致密并形成规整的双层结构,包括致密的α-Cr2O3外氧化层和α-Al2O3内氧化层。连续致密的α-Cr2O3和α-Al2O3层的形成能够有效阻止氧的内扩散及合金元素的外扩散,保障了U720Li合金的优异抗氧化性能。

关键词: U720Li合金, 氧化行为, 氧化膜, γ′贫化层, 服役温度

Abstract: The increasing service temperature of aero-engine turbine discs makes more stringent requirements for oxidation resistance of the materials. U720Li alloy is a high-strength nickel-based superalloy for turbine discs with a long-term service temperature up to 750 ℃. Clarifying the oxidation behavior at service temperatures of this alloy is of great significance for improving the service life of high-performance turbine discs. In this paper, the oxidation kinetics curve of forged U720Li alloy at 750 ℃ has been determined by the static weight gain method, and the oxide film morphology, structure and element distribution in different oxidation stages were analyzed by XRD and SEM-EDS. The results show that the U720Li alloy has excellent oxidation resistance at its service temperature, and its isothermal oxidation kinetic curve at 750 ℃ basically follows the cubic law, reaching the full anti-oxidant level. It has been analyzed that the loose γ-Cr2O3 is generated at the early oxidation stage of U720Li alloy. The γ-Cr2O3 layer spalls continuously as the oxidation proceeds, and the oxide film becomes more continuous and dense and forms a complex multilayer structure. Meanwhile, a γ´ depleted layer is gradually formed within the matrix nearby the oxide film. In the stable oxidation stage, the oxide film becomes more continuous and dense, forming a regular double-layer structure which includes the dense α-Cr2O3 outer layer and α-Al2O3 inner layer. The formation of continuous dense α-Cr2O3 and α-Al2O3 layers can effectively prevent the internal diffusion of oxygen and external diffusion of alloying elements, which guarantees the excellent oxidation resistance of U720Li alloy.

Key words: U720Li Alloy, Oxidation Behavior, Oxide Film, γ′ Depleted Layer, Service Temperature

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