粉末高温合金FGH4720Li在近服役温度下的组织演变规律  

Microstructure Evolution Behavior of Powder Superalloy FGH4720Li at Near Service Temperature

作　　者：刘超[1] 姚志浩[1] 郭婧 彭子超[3] 江河[1] 董建新[1] LIU Chao;YAO Zhihao;GUO Jing;PENG Zichao;JIANG He;DONG Jianxin(School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China;AECC Hunan Powerplant Research Institute,Zhuzhou 412002,China;Science and Technology on Advanced High Temperature Structural Materials Laboratory,Beijing Institute of Aeronautical Materials,Beijing 100095,China)

机构地区：[1]北京科技大学材料科学与工程学院,北京100083 [2]中国航发湖南动力机械研究所,株洲412002 [3]北京航空材料研究院先进高温结构材料重点实验室,北京100095

出　　处：《金属学报》2021年第12期1549-1558,共10页Acta Metallurgica Sinica

基　　金：国家重大科技专项项目No.2017-VI-0017-0089;国家自然科学基金项目No.51771017。

摘　　要：利用场发射扫描电镜和萃取相分析等方法对FGH4720Li合金在600~730℃下时效3000 h过程中的组织演变进行了观察和分析。结果表明,γ’_(Ⅰ)相最为稳定,而γ’_(Ⅱ)和γ’_(Ⅲ)相则会发生复杂变化。600℃下时效时,合金组织无明显变化;在650℃下时效3000 h后,仅有γ’_(Ⅲ)相发生长大,其他γ’相无明显变化;当时效温度升高到730℃,γ’_(Ⅲ)相的长大速率加快,然后迅速粗化,时效200 h后,γ’_(Ⅱ)相发生粗化,但B-γ’_(Ⅱ)相会先发生Ostwald熟化现象,吸收大量γ’_(Ⅲ)相而粗化,并且在300~500 h之间发生分裂,然后在500 h后通过互相聚合而粗化,而S-γ’_(Ⅱ)相则始终通过互相聚合的方式来粗化。2种γ’_(Ⅱ)相粗化行为的差异与γ’_(Ⅲ)相的分布特征有关。GH4720 Li is used for turbine disks in a large number of civil and military propulsion systems because of its excellent mechanical properties and corrosion resistance.GH4720 Li turbine disk is mainly manufactured through cast and wrought conventionally,but the addition of a high mass fraction of Ti,Al,and Mo can cause severe element segregation and more difficult microstructure control,which can become more severe as the turbine disk gets larger.Owing to this difficulty,the turbine disk quality cannot be guaranteed if the GH4720 Li turbine disk is still in cast and wrought form,and the manufacturing process will be more complex,resulting in increased costs.However,the powder metallurgy method can efficiently eliminate element segregation and produce a more uniform microstructure than the cast and wrought methods.GH4720 Li alloys manufactured using the powder metallurgy method are called FGH4720 Li alloys.As there has been limited research on FGH4720 Li and no report on the microstructure evolution during long-term ageing for FGH4720 Li to date,it is necessary to study the microstructure evolution behavior during long-term ageing for FGH4720 Li to obtain improved microstructure stability.In this study,field emission scanning electron microscopy and extractive phase analysis were used to investigate the microstructure evolution of FGH4720 Li in the temperature range of 600-730℃up to 3000 h.The results showed that primary gamma prime was the most stable;whereas,secondary and tertiary gamma prime microstructure evolutions were comparatively complex.At 600℃,there was no microstructure change.At 650℃,only the tertiary gamma prime grew,but there was no microstructure change for the other gamma primes up to 3000 h.When the ageing temperature increased to 730℃,the tertiary gamma prime grew faster before coarsening rapidly.After 200 h,the secondary gamma prime coarsened noticeably,but the big secondary gamma prime coarsened by Ostwald ripening first,absorbing a large amount of tertiary gamma prime and splitting up

关 键 词：FGH4720Li粉末高温合金 时效处理 γ’相 组织演变 

分 类 号：TG146.1[一般工业技术—材料科学与工程]