FGH113A (WZ-A3) 粉末高温合金长期组织稳定性研究

Study on Microstructure Long-term Stability of Powder Metallurgy Superalloy FGH113A(WZ-A3)

摘要:

采用光学显微镜、扫描电镜及能谱仪等观察分析了760℃和815℃长期时效下,FGH113A(WZ-A3)合金的晶粒组织、γ′强化相、碳化物等演变规律,通过力学性能测试分析了长期时效对合金拉伸性能的影响。结果表明：760℃和815℃长期时效对合金的晶粒尺寸与形貌均无明显影响。760℃长期时效后合金的γ′强化相尺寸与形貌无明显变化,但815℃长期时效至440h,γ′相开始长大且形貌由近立方状向近球形转化。760℃长期时效2020h后,碳化物由弥散分布的颗粒状,转变为晶界聚集析出连续型碳化物；815℃长期时效440h后,晶内开始析出针状碳化物,2020h后明显可见颗粒状碳化物在晶界富集,晶内针状碳化物持续增多。在704℃和760℃拉伸测试条件下,长期时效760℃/440h和760℃/2020h合金抗拉强度相当,屈服强度在2020h后反而有小幅提升；长期时效815℃下,合金拉伸性能表现出类似规律,拉伸强度较好与晶粒度保持稳定和晶界碳化物的钉扎作用有关。新型镍基粉末高温合金FGH113A在760℃和815℃长期时效下表现出优异的稳定性。

Abstract:

The evolution of grain structures, γ" strengthening phases and carbides of FGH113A (WZ-A3) alloy during long-term aging treatment at 760 ℃ and 815 ℃ were studied by means of Optical Microscope (OM), Scanning Electron Microscope (SEM), and Energy Dispersive Spectrometer (EDS) and the effect of long-term aging on the tensile properties of the alloy was analyzed. The results show that the long-term aging at 760℃ and 815℃ has no significant effect on grain size and grain morphology of the alloy. After long-term aging at 760℃, the size and morphology of the γ" strengthening phases have no obvious effect, but after long-term aging at 815℃ for 440h, the γ" phases begin to grow and the morphology changes from quasi-cubic to quasi-spherical. After long-term aging at 760℃ for 2020h, the carbides have changed from dispersed granular particles to aggregated at grain boundaries. After long-term aging at 815℃ for 440h, needle-like carbides begin to precipitate in the grains. After 2020h, granular carbides are enriched at the grain boundaries and form chains, at the same time, the needle-like carbides precipitated in the grains further increased. Under the tensile tests of 704°C and 760°C, the tensile strengths of the alloy during long-term aging treatment 760°C/440h and 760°C/2020h were equivalent, but the yield strengths increased slightly after 2020h; the tensile properties of the alloy show similar discipline at 815 long-term aging. The key reasons for the better tensile strength stability of the alloy were attributed to the stable grain structures and the pinning effect of grain boundary carbides. The new nickel-based powder superalloy FGH113A exhibits excellent stability under long-term aging at 760°C and 815°C.