固溶工艺对镍基单晶高温合金初熔温度的影响

孙铭,王恒喆,龙海波,毛圣成,张泽,韩晓东

固溶工艺对镍基单晶高温合金初熔温度的影响

孙铭,王恒喆,龙海波,毛圣成,张泽,韩晓东

(1.北京工业大学材料与制造学部,北京100124;2. 浙江大学材料科学与工程学院,杭州310027)

     固溶处理是消除镍基单晶高温合金凝固偏析的重要手段,而进行固溶处理的前提是具备合适的固溶窗口。随合金的发展,固溶窗口逐渐变窄,从而加大了固溶处理的难度。由于固溶窗口为动态窗口,其上限的初熔温度会随合金内部γʹ相及共晶的溶解而提高,因此开展固溶工艺对合金初熔温度影响机制的研究具有重要意义。然而,目前缺乏不同固溶工艺对合金初熔温度影响机制及作用机理的相关研究。本文采用电子显微学为研究手段,对比研究了阶段式和连续式固溶处理对初熔温度的影响规律。研究发现,固溶处理会促进合金的均匀化行为,而均匀化程度随固溶工艺中高温下保温时间的延长而增加;均匀化效果越好的样品,其初熔温度提升更大,但是均匀化效果越好的合金内部也存在较多由“柯肯达尔效应”所诱发形成的固溶微孔。

关键词  镍基单晶高温合金;固溶处理;初熔温度;微观组织

中图分类号:TG132.3+2;TG115.21+5.3;TB31  文献标识码A                doi:10.3969/j.issn.1000-6281.2024.02.003

 

Effect of solid solution process on the solid solution window of Ni-base single crystal superalloy

SUN Ming1, WANG Hengzhe1, LONG Haibo1, MAO Shengcheng1, ZHANG Ze1, 2, HAN Xiaodong1

(1. Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124;2. School of Materials Science and Engineering, Zhejiang University, Hangzhou Zhejiang 310008, China)

Abstract  Solution heat treatment is an essential method to eliminate the solidification segregation of Ni-based single-crystal superalloys. The premise for the solution heat treatment is that there should exist a suitable solution window. With the development of the alloy, the solid solution window gradually narrows, increasing the difficulty of solution heat treatment. Since the solid solution window is dynamic, the upper limit of the initial melting temperature increases with the dissolution of the γʹphase and eutectic in the alloy. Therefore, it is of great significance to study the influence of the solution heat treatment process on the initial melting temperature. However, there is a lack of relevant research. In this paper, the effects of step and ramp solution heat treatment on microstructure and initial melting temperature was studied by transmission electron microscope (TEM). It was found that solution heat treatment promoted the homogenization behavior. The degree of homogenization increased with the prolongation of the holding time at high temperatures in the solution heat treatment process. The better homogenization effect increased the initial melting temperature, but it also promoted the Kirkendall effect and induced more solid solution micropores.

Keywords    Ni-based single crystal superalloys; solution window; solution process; initial melting temperature

 

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