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Bi Z.,Control Iron and Steel Research Institute, China | Bi Z.,Beijing Key Laboratory of Advanced High Temperature Materials | Qu J.,Control Iron and Steel Research Institute, China | Du J.,Control Iron and Steel Research Institute, China | Zhang J.,Control Iron and Steel Research Institute, China
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2013

The cast microstructure of a new difficult-to-deform superalloy zk151, was observed by high resolution field emission scanning electron microscope. The effects of elements on the thermodynamic equilibrium phases were studied by Thermo-Calc software. The results show that there is serious segregation of Mo, Nb and Ti during the solidification, which promotes γ'+γ eutectic. The main precipitates of zk151 alloy are a large fraction of cubic γ', some carbides, borides and μ phase. Higher Cr, Mo, Nb and Ti contents can improve the primary and final melting points. The contents of Al, Ti and Nb can influence the precipitation temperature and mass fraction of γ' phase. Contents of Cr and Mo promote precipitation of M23C6 and M6C respectively. Furthermore, the increment of Cr, Mo and W content leads to more precipitation of μ phase. Source


Wang J.-T.,Control Iron and Steel Research Institute, China | Wang J.-T.,Beijing Key Laboratory of Advanced High Temperature Materials | Han W.,Control Iron and Steel Research Institute, China | Luo H.-L.,Control Iron and Steel Research Institute, China | Li S.-P.,Control Iron and Steel Research Institute, China
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2014

Two-step homogenization treatment was conducted for MX246A alloy and the homogenized microstructure was observed by scanning electron microscope (SEM). The tensile properties of as-cast and homogenized MX246A alloy were tested at 850°C and 1100°C. The results show that comparing with as-cast alloy, the ductility of homogenized MX246A alloy at 1100°C is improved, but at 850°C the ductility is reduced. A large amount of M6C carbides surrounded by γ' envelope precipitate is around interdendritic and grain boundary for homogenized MX246A alloy. During the tensile process, cracks can originate around the carbides and propagate along the carbide/-γ' envelope interface. The poor toughness of γ' envelope and poor ductility of homogenized MX246A alloy at 850°C are due to the stress concentration caused by the carbides can not be released. Source


Xia T.,Control Iron and Steel Research Institute, China | Xia T.,Beijing Key Laboratory of Advanced High Temperature Materials | Zhang Y.,Control Iron and Steel Research Institute, China | Chi Y.,Control Iron and Steel Research Institute, China
Fenmo Yejin Jishu/Powder Metallurgy Technology | Year: 2013

FGH96 superalloy produced by PERP+HIP with various Hf and Zr contents was studied in this paper. The Hf, Zr amount was designed as 0.0+0.04%, 0.3%+0.04%, 0.6%+0.04% and 0.3%+0.06%. Optical microscope(OM) and second electricon microscope(SEM) were employed to investigate microstructures and fracture surfaces. The tested mechanical properties were listed as follows: room temperature(RT) and 800°C impact, RT, 650°C and 750°C tensile, and 650°C/970MPa unnotched/notched(R=0.15 mm) stress rupture. The results show that precipitations at PPB of FGH96 alloy can not form continuous films and hardly has destructive effects to the alloy. PPB are eliminated, elevated temperature properties are improved as well as stress rupture life and plasticity are especially enhanced with appropriate amount of Hf. While the alloy includes Hf, excess Zr lead to a continuous oxdie precipitations along the PPB, which severely degrade its endurance property. The optimum content of Hf, Zr in FGH96 alloy is 0.6%, 0.04%. Source


Yan J.,China Aviation Powerplant Research Institute | Tang C.,Control Iron and Steel Research Institute, China | Tang C.,Beijing Key Laboratory of Advanced High Temperature Materials | Bi Z.,Control Iron and Steel Research Institute, China | And 5 more authors.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2016

The effect of cooling mediums (AC, OQ, WQ) on microstructure (grain size and γ' phase) and mechanical properties in GH720Li alloy was studied by using optical microscope (OM) and field emission scanning electron microscope (FESEM), respectively. The results show that the cooling mediums have no effect on the grain size and primary γ' phase, but have obvious influence on cooled γ' phase (secondary γ' and thirdly γ'). With the increase of cooling rate of mediums (AC Source


Zhang Y.-W.,Control Iron and Steel Research Institute, China | Zhang Y.-W.,Beijing Key Laboratory of Advanced High Temperature Materials | Han S.-B.,Control Iron and Steel Research Institute, China | Han S.-B.,Beijing Key Laboratory of Advanced High Temperature Materials | And 3 more authors.
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2016

The partition behavior of hafnium (Hf) among different phases in FGH4097 powder metallurgy (PM) superalloy with different Hf additions and its effects on the precipitation behavior of γ′ phase, MC carbide and γ phase were studied by means of 3DAP, FEG-SEM, TEM and physiochemical phase analysis. The results show, that with increasing Hf addition, the contents of Hf in different phases increase, the mass fraction of Hf in γ′ phase almost keeps unchanged, the mass fraction of Hf in MC carbide increases and that in γ matrix decreases, which means that the partition ratio of Hf between γ′ phase and MC carbide decreases while the ratio between γ′ phase and γ matrix increases. Mass content of Hf partitioned to γ′ phase is much more than that partitioned to MC carbide, while the mass concentration of Hf in carbide is as much as 20 times of that in γ′ phase. © 2016, Central South University of Technology. All right reserved. Source

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