热模锻造+直接时效粉末高温合金的强化机制

来源期刊：金属学报2010年第3期

论文作者：宁永权 谢兴华 姚泽坤 郭鸿镇 谭立军 陶宇

文章页码：324 - 328

关键词：镍基高温合金； 粉末高温合金； 热模锻造+直接时效； 强化机理

Key words：Ni base superalloy； powder metallurgy superalloy； hot-die forging + direct aging； strengthening mechanism

摘    要：对涡轮盘用镍基粉末高温合金FGH 4096进行了热模锻造+直接时效处理,探索细化粉末高温合金毛坯组织的工艺及相关增强机制.结果表明:在不降低延伸率的前提下,直接时效处理对于热模锻造后的合金具有明显的强化作用,并且以多方向变形配合直接时效的强化效果最为显著.按多方向热模锻造+直接时效工艺,可使FGH 4096合金的组织显著细化,平均晶粒尺寸达6μm,γ′相析出尺寸达80 nm.OM,SEM和TEM观察表明,除多方向大变形可直接破碎晶粒、细化晶粒外,反复再结晶也是细化晶粒的有效途径;同时,洁净的再结晶晶界完全取代了原始粉末颗粒边界.直接时效处理后保留了多方向变形产生的位错缠结,并且获得更为细小的γ′相.热模锻造+直接时效处理后合金所表现出来的超高强度主要源自于细晶强化、晶界强化、形变强化和γ′相强化的综合作用.

Abstract: Hot-die forging+direct aging processing was used to improve the microstructure and mechanical property of P/M superalloy FGH 4096,a kind of materials used in turbine disk,which includes a solution treatment at 1130℃ for 0.5 h,multiaxially forging (total deformation about 100%) and direct aging at 760℃ for 16 h.in addition,drawing (70%) and upseting (40%)+direct aging treatment has also been invesigated.OM,SEM and TEM were employed to study the microstructure evolution and strengthen mechanism.It was found that the direct aging treatment has obvious effect on strengthening,especially,for the multiaxially forged alloy,in which dynamic recrystallization appeared, and the previous particle boundary is replaced by clean recrystallized boundary and the grain is refined to about 6μm.After direct aging the average size of γ’ phase is 80 nm,and the tangled dislocation is still reserved.The strengthening mechanisms include grain refinement,clean boundary,thermomechanical deformation and γ’ phase precipitation.