定向凝固DZ125合金热暴露后显微组织演变及其相应持久性能的研究  

Microstructural Evolution and Corresponding Stress Rupture Property in DZ125 Alloy after Thermal Exposure

作　　者：陈亚东[1,2] 郑为为 郑运荣[1] 冯强[1] Chen Yadong;Zheng Weiwei;Zheng Yunrong;Feng Qiang(State Key Laboratory for Advanced Metals and Materials,University of Science and Technology Beijing,Beijing 100083,China;General Technical Department,China North Vehicle Research Institute,Beijing 100072,China)

机构地区：[1]北京科技大学新金属材料国家重点实验室,北京100083 [2]中国北方车辆研究所总体技术部,北京100072

出　　处：《稀有金属》2018年第10期1009-1017,共9页Chinese Journal of Rare Metals

基　　金：高等学校博士学科点专项科研基金项目(20120006110026);国家科技部高技术研究发展计划项目(2012AA03A513);教育部技术支撑重点项目(625010337)资助

摘　　要：定向凝固DZ125合金由于其优异的中高温综合性能而被广泛用于制备先进航空发动机涡轮叶片。目前，对于DZ125合金在高温作用下的组织演变与持久性能退化的研究较少，其不同退化组织对性能的影响机制尚不明确。本研究对DZ125合金在900～1100℃下进行了100—900h的热暴露实验，对热暴露后的组织进行观察及定量表征，随后进行980℃／220MPa下的持久性能测试。结果表明：热暴露后合金γ′相显著溶解，少量枝晶间MC型碳化物向M23c6及M6c型碳化物转变。热暴露后DZ125合金在980℃／220MPa下的持久寿命显著下降，大部分裂纹起始于合金倾斜晶界的碳化物处。γ′相的大量溶解降低了合金基体强度，是其持久性能下降的主要原因，而碳化物的转变对其性能的影响较小。本研究有利于理解DZ125合金各类组织演变与性能退化的关系，对基于显微组织演变的DZ125合金涡轮叶片的服役损伤评价具有重要指导意义。Directionally-solidified DZ125 alloy was widely used in manufactures of turbine blades in aero-engine due to its excellent combination property at high temperature. The researches about mierostructure and property degradation of DZ125 alloy after high temperature thermal exposure were still limited, and the influence of different microstructural degradation on property was still unclear. In this study, DZ125 alloy was thermally exposed in the temperature range of 900 - 1100 ℃ for 100 -900 h, then the mierostructures were characterized. Stress rupture properties were conducted under the condition of 980 ℃/220 MPa after thermal exposure. Significant dissolution of γ′ precipitates was observed after thermal exposure, some MC carbides in the interdendritic region transformed to M23C6 and MrC carbides. The creep rupture life decreased significantly after thermal exposure, and most of the cracks initiated near the carbides along few tilt grain boundaries. The significant dissolution of γ′ precipitates reduced the strength of matrix, which was the main reason for the degradation of stress rupture properties. However, the evolution of carbides showed little effect on the properties. This study was helpful for understanding the relationship between microstructural evolution and property degradation of DZ125 alloy, and provided reference for the approach to evaluate the service-induced damage in turbine blades made of DZ125 alloy.

关 键 词：DZ125合金 热暴露 显微组织 持久性能 断裂行为 

分 类 号：TG132.32[一般工业技术—材料科学与工程] TG156.1[金属学及工艺—合金]