一种镍基单晶高温合金870℃高周疲劳变形微观结构研究（英文）  

Dislocation Structure in a Single Crystal Nickel Base Superalloy During High Cycle Fatigue at 870 ℃

作　　者：水丽[1] 徐运超 胡壮麒[2] Shui Li;Xu Yunchao;Hu Zhuangqi(Shenyang Ligong University, Shenyang 110159, China;Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China)

机构地区：[1]沈阳理工大学,辽宁沈阳110159 [2]中国科学院金属研究所,辽宁沈阳110016

出　　处：《稀有金属材料与工程》2018年第4期1054-1058,共5页Rare Metal Materials and Engineering

基　　金：National Natural Science Foundation of China(50171045)

摘　　要：研究了一种镍基单晶高温合金在870℃时的高周疲劳性能及其变形组织结构。结果表明:该合金的疲劳寿命随着应力水平的升高而减小,870℃时光滑试样的疲劳强度为443 MPa;利用透射电镜(TEM)观察疲劳循环试样的位错组态,发现在疲劳变形的初始和中期阶段,位错组态主要为界面位错,位错在基体通道中{111}面运动,并交互反应形成三维位错网络结构。当应力水平提高到550 MPa以上时,在变形的末期,观察到高密度位错集中于位错滑移带及位错切入γ'相现象。在循环应力和高温叠加作用下,基体通道中诱发析出大量圆形细小二次γ'相。二次γ'相的析出有益于阻止基体位错的滑动,抑制位错切入γ'相,有利于提高合金的疲劳强度。Dislocation structure and its impact on the mechanical behavior of a γ＇strengthened nickel base single crystal alloy under high cycle fatigue（HCF） at 870 ℃ was studied. The results indicate that HCF lifetime declines with increase of applied stress amplitude. In the early stages, the fatigue deformation occurs by forced bowing of dislocations through the narrow γmatrix channels on {111} planes. During mid-term fatigue stages, most of the dislocations formed in the matrix are located in the γ/γ＇ interfaces, whose intersection and reaction produce new dislocation segments and three-dimensional dislocation networks. The Burgers vectors of the dislocations in the network are 1/2〈110〉. The interaction of cyclic stress with high temperature induces the precipitation of homogeneous globular γ＇ particles, which is beneficial to fatigue strength. At the end of fatigue test, the cyclic stress leads to the formation of persistent slip bands moving through the γ matrix channels and γ＇ particles. Dislocation shearing through the γ＇ phase is found occasionally. The extrinsic stacking faults is also observed.

关 键 词：镍基单晶高温合金 高周疲劳 位错 

分 类 号：TG132.3[一般工业技术—材料科学与工程]