摘要
通过蠕变曲线测定和组织形貌观察,研究了FGH95合金的蠕变特征与变形机制。结果表明:经高温固溶及"盐浴"冷却后,FGH95合金的组织结构由细小γ′相及粒状碳化物弥散分布于γ基体所组成,由于沿晶界不连续析出的粒状(Ti,Nb)C相可提高合金的晶界强度,并抑制晶界滑移,故使其在650℃、1034MPa条件下有较小的应变速率和较长的蠕变寿命。合金在蠕变期间的变形机制是位错切割γ或γ′相,其中,当(1/2)<110>位错切入γ相,或<110>超位错切入γ′相后,可分解形成(1/6)<112>肖克莱不全位错或(1/3)<112>超肖克莱不全位错+层错的位错组态;蠕变后期,合金的变形特征是晶内发生单取向和双取向滑移,随蠕变进行位错在晶界处塞积,其引起的应力集中致使裂纹在晶界处萌生及扩展是合金的蠕变断裂机制。
By means of the measurement of creep curves and microstructure observation,an investigation has been made into the creep features and deformation mechanism of FGH95 nickel base superalloy.Results show that after solution treatment at high temperature,the microstructure of the alloy consists of the finer γ′phase and particle-like carbides distributed dispersedly in γ matrix.The fact that the particle-like（Ti,Nb）C phase is discontinuously precipitated along the boundaries may improve the bond strength of the boundaries and restrain the slipping of the boundaries,which results in the alloy possessing the lower strain rate and the longer creep lifetime under the applied stress of 1 034MPa at 650℃.The deformation mechanism of the alloy during creep is that the dislocation shears into γ′phase,thereinto,the（1/2）110 dislocation shearing into γ matrix,or the 110 super-dislocation shearing into the γ′phase may be decomposed to form the configuration of（1/6）112 shockleys dislocation or（1/3）112 super-shockleys dislocation ＋ stacking fault.In the later stage of creep,the deformation features of the alloy are one and two way slipping of dislocations activated in the alloy.As creep goes on,some of the dislocations are congregated in the boundary regions to bring the stress concentration which promotes the initiation and propagation of the microcracks,which is thought to be the fracture mechanism of the alloy during creep.
出处
《粉末冶金技术》
CAS
CSCD
北大核心
2010年第6期415-419,429,共6页
Powder Metallurgy Technology
关键词
FGH95镍基合金
组织结构
蠕变
变形机制
断裂特征
FGH95nickel base superalloy
microstructure
creep
deformation mechanism
fracture features
