预压缩对镍基单晶高温合金DD98持久性能的影响及其作用机理  

EFFECTS OF PRE-COMPRESSION ON THE STRESS RUPTURE PROPERTIES OF Ni BASE SINGLE CRYSTAL SUPERALLOY DD98 AND ITS MECHANISM

作　　者：刘金来[1] 金涛[1] 孙晓峰[1] 张静华[1] 管恒荣[1] 胡壮麒[1] 

机构地区：[1]中国科学院金属研究所,沈阳110016

出　　处：《金属学报》2006年第8期843-849,共7页Acta Metallurgica Sinica

摘　　要：研究了单轴预压缩对镍基单晶高温合金DD98的微观组织和持久性能的影响及其原因．在热处理态的基础上,于真空中1050℃下分别实施了180 MPa/6h和220 MPa/6h两种预压缩．观察到预压缩后的试样中形成了与应力轴平行的P型γ′筏．同时,在竖直通道内的γ/γ′界面上形成了位错网．单轴预压缩对持久寿命的影响因测试条件不同而变化,但预压缩试样的延伸率均得到提高．在高温低应力持久时,预压缩形成的P型筏转化为宽度不同的波浪状N型筏,导致位错越过γ′方式有所差异．在低温高应力时,P型筏仅表现出微弱的向N型筏转化的趋势．此时,两种预压态试样中均形成位错缠结．在中等温度及应力时,两种预压态中的P型筏则转化为较混乱的N型筏,其位错特征是不规则位错网．The effects of uniaxial pre-compressions in vacuum at 1050 ℃ by 180 MPa/6 h and 220 MPa/6 h on the microstructure and stress rupture properties of single crystal superalloy DD98 were investigated. It is shown that P-type γ＇ raft parallel to stress formed during pre-compression. Moreover, dislocation networks appeared on γ/γ＇ interface in vertical channels. The effect on stress rupture lifetime varied with the test conditions, but the pre-compression increased the elongations under all test conditions. Under high-temperature and low-stress, the pre-compression made P-type raft transform into wave-like N-type raft with different widths in two samples, and dislocations overpass γ＇ particles by different means. Under low-temperature and high-stress the P-type raft showed only a slight tendency to transform into N-type one, and the entangled dislocations appeared in two pre-compressed samples after stress rupture. Under intermediate temperature and stress, the P-type raft can still transform into N-type one but very irregular, and the dislocations formed irregular networks.

关 键 词：镍基单晶高温合金 预压缩 持久 形筏 位错 

分 类 号：TG146.1[一般工业技术—材料科学与工程]