高性能镍基粉末高温合金中γ′相形态致锯齿晶界形成机理研究  

Formation Mechanism of Serrated Grain Boundary Caused by Different Morphologies of γ′ Phases in a High-performance Nickel-based Powder Metallurgy Superalloy

作　　者：杨万鹏[1] 胡本芙[1] 刘国权[1,2] 吴凯[1] 

机构地区：[1]北京科技大学材料科学与工程学院,北京100083 [2]北京科技大学新金属材料国家重点实验室,北京100083

出　　处：《材料工程》2015年第6期7-13,共7页Journal of Materials Engineering

基　　金：国家高技术研究发展计划(2013AA031601);国家预研基金项目(9140A12070507QT0202)

摘　　要：采用光学显微镜、场发射扫描电子显微镜和透射电子显微镜,系统研究了低错配度的第三代高性能粉末高温合金(FGH98I)在热处理条件下由合金晶界上γ′相不同析出行为造成的锯齿晶界。结果表明:在晶界上析出γ′相形态不同是锯齿晶界形成的主导因素。热处理时固溶冷却速率不同,晶界上析出的γ′相数量、尺寸和形态不同,对晶界锯齿形状有强烈影响。当冷却速率由0.1℃/s增大至10.8℃/s时,晶界锯齿振幅由4.02μm变为0.63μm,锯齿的波长则随冷却速率增大而变大。γ′相形态失稳的不同形状和尺寸是造成晶界锯齿振幅大小的主要因素。晶界两侧分布着不同密度的γ′相颗粒,也可使晶界发生位移形成波浪式小振幅锯齿晶界。根据实验结果,提出了有关锯齿晶界的形成模式。The formation of serrated grain boundaries as a result of different precipitation behaviors of γ＇ phases at the grain boundaries in the third generation high-performance nickel-based powder metallurgy superalloy （FGH98I） of very small lattice misfit between the precipitate phases and the matrix was systematically studied under varying heat treatment conditions,using optical microscope,field emission scanning electronic microscope and transmission electronic microscope.The results show that the dominant factor of formation of serrated grain boundaries is that the morphologies of γ＇ phases precipitate at the grain boundaries are different.The quantity,size and morphology of the γ＇ phases precipitate at the grain boundaries vary with different solution cooling rates of the heat treatment process,which has a strong influence on the formation of serrated grain boundaries.Amplitudes of the grain boundary serrations are found to decrease from 4.02μm to 0.63μm as cooling rates increase from 0.1 ℃/s to 10.8 ℃/s,however,the wavelength of the grain boundary serrations increases as cooling rates increase.Different morphologies and size of γ＇ phases which grow into morphology of unstable protrusion result in different amplitudes of the grain boundary serrations.Different densities of γ＇ particles distributing along the grain boundaries by both sides can drive the grain boundaries to move to produce the grain boundaries with small wavy serrations.Different formation modes of serrated grain boundaries are put forward based on our experiment results.

关 键 词：粉末高温合金 γ'相 锯齿晶界 

分 类 号：TG113.2[金属学及工艺—物理冶金]