摘要
开展了不同Re和Ta含量抗热腐蚀单晶高温合金900℃长期时效的实验研究,定量分析了0~7500 h时效过程中γ′形貌、尺寸的演化和拓扑密排(TCP)相析出规律。结果表明,2Ta2Re、5Ta0Re、5Ta2Re、8Ta0Re和8Ta2Re 5种合金中,随Ta和Re含量增加,γ′相尺寸变小,且γ′相粗化速率变慢,粗化速率分别为:1.445×10^-5、1.569×10^-5、1.390×10^-5、1.465×10^-5和1.384×10^-5μm^3/h。提高Ta和Re的含量可以降低合金的有效扩散系数并增加扩散激活能,从而降低粗化速率,其中Re的作用更显著。时效2000 h后,含Re合金依次析出了TCP相,高Ta含Re合金析出较严重。Ta和Re交互作用影响了γ和γ′两相元素的分配行为,其中8Ta2Re合金Ta进入γ′相使其晶格常数变大的同时,也促进了Re、W、Cr等元素在γ基体中的分配,促进TCP相析出。
The development of gas turbines urgently requires the development of new single crystal superalloys with capacity to service for long time at higher temperature and under hot corrosion environment.In order to take into account both the strength and structural stability of the alloy,it is an effective way to increase the content of key strengthening elements Re and Ta reasonably,and control the mismatch ofγ/γ’to delay the growth kinetics ofγ’.In this work,the long-term thermal exposure(LTTE)experiments of single crystal superalloys with different Re and Ta contents at 900℃were carried out.The evo-lution of morphology and size ofγ’,and the precipitation of topological close-packed(TCP)phase during 0~7500 h ageing process were quantitatively analyzed.The results show that the size and the coarsening rate ofγ’phase decreases with the increase of Ta and Re content in 2 Ta2 Re,5 Ta0 Re,5 Ta2 Re,8 Ta0 Re and 8 Ta2 Re alloys.The coarsening rates are 1.445×10^-5,1.569×10^-5,1.390×10^-5,1.465×10^-5 and 1.384×10^-5μm^3/h respectively.With the increase of Ta and Re content,the effective diffusion coefficient decreases and the diffusion activation energy increases,thus of the coarsening rate of precipitated phase decreases.After ageing for 2000 h,TCP phase was precipitated in turn in alloys containing Re,and the precipitation of TCP phase was more serious in alloys containing higher content of Ta.The interaction between Ta and Re affects the atomic distribution behavior of elements inγandγ’,in which 8 Ta2 Re alloy Ta enters theγ’phase to increase its lattice constant,and at the same time promotes the distribution of elements such as Re,W and Cr in theγmatrix,which results in more negativeγ/γ’mismatch and promotes the precipitation of TCP phase.
作者
黄太文
卢晶
许瑶
王栋
张健
张家晨
张军
刘林
HUANG Taiwen;LU Jing;XU Yao;WANG Dong;ZHANG Jian;ZHANG Jiachen;ZHANG Jun;LIU Lin(State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi'an 710072,China;Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China)
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2019年第11期1427-1436,共10页
Acta Metallurgica Sinica
基金
国家重点研发计划项目No.2016YFB0701400
国家自然科学基金项目Nos.51331005和51631008~~
关键词
抗热腐蚀单晶高温合金
长期时效
组织稳定性
hot-corrosion resistant single crystal superalloy
long-term thermal exposure
microstructural stability
