材料期刊网

采用喷射成形制备FGH4095高温合金坯,观察其组织及强化相γ＇相形貌、尺寸和分布,研究了喷射成形沉积坯组织均匀性对力学性能的影响,分析了材料的拉伸断裂行为.结果表明：喷射成形FGH4095高温合金组织均匀细小,无宏观偏析,体密度为8.21 g/cm3,致密度达99.03%,具有较好的组织均匀性;基体中除了晶界上分布着块状γ＇相颗粒外,在晶粒内部还存在大、小2种尺寸的γ＇颗粒,其中大的γ＇颗粒呈团簇状,小γ＇颗粒呈圆形;经过热处理,大γ＇颗粒逐渐熔解,晶粒内部新的细小γ＇相析出,并且伴随着原有小γ＇颗粒长大;拉伸过程中材料表现为韧性断裂,局部组织缺陷对拉伸强度有明显影响,而γ＇相和碳化物阻碍位错运动,使得位错在γ＇和碳化物区域堆积,并形成位错缠结.

The microstructure of spray formed FGH4095 superalloy and the feature of precipitates γ′ were observed by optical microscope(OM),scanning electronmicroscope(SEM) and transmission electron microscope(TEM),the influence of high isotropy in microstructure on the tensile properties of FGH4095 nickel-base superalloy has been studied,and the fracture mechanism was analyzed during the tensile experiment.The results showed that the high-quality billet of FGH4095 superalloy exhibited high-isotropy,much fine grains and segregation-free macrostructure.The average density of billet before heat treatment(HT) is 8.21 g/cm3,and the relative density is 99.05%.There are square particles of γ′ phase distributing in the grain boundaries,meanwhile,there are two different sizes of γ′ particles within the grains.Among them,the bigger γ′ particles exhibit arrays of every 8 square particles during spray forming cooling procedure.The cube γ′ particles disappear with the growth of finer γ′ precipitates after heat treatment.Some of pores and defects located in the local region of microstructure may bring out the stress concentration to promote the budding and expanding of the micro-cracks,which is thought to be the fracture mechanism of the alloy during the tensile process.The γ′ precipitates and particles carbide which are discontinuously precipitated along the boundary can effectively hinder the dislocation motion that results in better properties.