新型第三代粉末高温合金FGH100L的显微组织与力学性能

Microstructure and Properties of a New Third Generation Powder Metallurgy Superalloy FGH100L

采用喷射成形(SF)+热等静压(HIP)+等温锻造(IF)+热处理(HT)工艺制备第三代粉末高温合金FGH100L。研究固溶热处理温度和制备工艺对FGH100L合金的显微组织与力学性能的影响。结果表明,SF+HIP+IF态FGH100L合金显微组织对固溶温度的变化非常敏感,随固溶温度的升高(1110~1170℃),合金的晶粒尺寸长大,γ’强化相的尺寸先增加后减小,其硬度、室温/高温拉伸强度和塑性均呈先增大后减小的趋势。在固溶温度为1130℃时,FGH100L合金中3种尺寸的γ’相的数量平衡匹配较为合理,合金的显微组织特征最佳,合金的硬度和室温/高温拉伸性能均最高。且该温度下,FGH100L合金经SF、SF+HIP+HT和SF+HIP+IF+HT不同工艺处理后,晶粒尺寸先增大后减小;晶粒形貌发生了近球形-多边形-近球形的转变;SF+HIP+HT态合金晶粒尺寸增大,晶界弯曲程度较低。由于SF+HIP+IF+HT工艺使FGH100L合金发生再结晶,细化了晶粒,出现链状组织,形成弯曲晶界,合金具有更高的屈服强度;在SF+HIP+HT和SF+HIP+IF+HT工艺下合金的室温拉伸断口从沿晶脆性断裂转变为穿晶-沿晶混合断裂,高温拉伸断口为沿晶断裂。

Spray forming(SF) is a novel rapid solidification technique. Compared with traditional cast & wrought and powder metallurgy technique, it has the advantages of less segregation and shorter process. In this work, a new third generation powder metallurgy(PM) superalloy FGH100 L was prepared by SF+hot isostatic pressing(HIP)+isothermal forging(IF)+heat treatment(HT) process. The effects of solution heat treatment temperatures and preparation process on the microstructure and mechanical properties of FGH100 L alloy were studied. The results show that the microstructure of SF+HIP+IF stateFGH100 L alloy is very sensitive to changes of solution temperature. With the increase of the solution temperature(1110~1170 ℃), the grain size of the alloy grew, and the size of the γ’ strengthened phase first increased and then decreased. Its hardness, tensile strength and plasticity at room temperature/high temperature all show a trend of increasing followed by decreasing. The quantitative equilibrium of three sizes of γ’ phase in the alloy is more reasonable, the microstructure of the alloy is the best, and the hardness and room temperature/high temperature tensile properties of alloy have the highest parameter values at1130 ℃. At the same temperature, the grain size of FGH100 L alloy increased first and then decreased under different processing conditions of SF, SF+HIP+HT and SF+HIP+IF+HT. The morphology of grains changed from subspherical to polygonal to subspherical. Alloy grain size increases, and the grain boundary bending degree decreases in the process of SF+HIP+HT. Due to SF+HIP+IF+HT process, the alloy recrystallizes, refines the grain, and presents chain-like structure, forming curved grain boundary and having higher yield strength. Under SF+HIP+HT and SF+HIP+IF+HT processes, the tensile fracture of the alloy at room temperature changed from intergranular brittle fracture to transgranular and intergranular mixed fracture, and the tensile fracture at high temperature was intergranular fracture.