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GRAIN　STRUCTURE　CONTROL　OF　NICKEL－BASE　SUPERalloys　IN　CASTING　PROCESS：　EFFECT　OF　MELT　ADDITIONS

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Chinese Journal of Aeronautics 1996年第2期9卷 126-129页

作者： Liu Lin Zhang Rong Zheng Jiangbang (Dept. of Applied Physics, Northwestern Polytechnical University, Xi’an, China, 710072)zhen Baolin (Dept. Of Superalloys, Central Iron & Steel Research Institute, Beijing, China, 100081) Dept. of Applied Physics NW Polytechnical University Xi'an 710072 China Dept. of Superalloys Ctrl. Iron and Stl. Res. Institute Beijing 100081 China

Grain structure, dendrite morphologies and shape of MC type carbides ina nickel-base superalloy IN 738 LC are investigated with the addition of carbides,boride, nitride and intermetallic compounds. The results show that the grain size of theingots can be refined extensively to the order of ASTM M11～12 by combination of anintermetallic compound NixAly, addition together with lowering melt homogeneoustreatment temperature during the melting and casting process. In addition, the processcould restrain the formation of script-type carbides. The new process does not changethe phase constitution, freezing characteristics and sub-structure stability. Therefore, itis considered as an effective and practical method of grain refinement for superalloys.

关键词： nickel alloys heat resistant alloys crystallites additives intermetallics

GRAIN STRUCTURE CONTROL OF NICKEL－BASE SUPERalloys IN CASTING PROCESS：EFFECT OF FOUNDRY VARIABLES

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Chinese Journal of Aeronautics 1995年第2期8卷 145-150页

作者： Liu Lin(Dep. of Applied Physics,Northwestern Polytechnical University,Xivan,China,710072)

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关键词： nickel heat resistant alloys castings grain size

EFFECT OF heat TREATMENT ON INTERMEDIATE TEMPERATURE STRESS RUPTURE PROPERTIES OF ALLOY K403

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Chinese Journal of Aeronautics 1997年第4期10卷 64-69页

作者： Zheng Yunrong, Li Shuyuan, Ma Shuwei (Beijing Institute of Aeronautical Materials, Beijing, 100095, China)

The standard heat treatment of cast nickel base superalloy K403 is the solid solution treatment of 1210℃/4h, air cooling. It is very difficult to meet the requirements of Aviation Standard HB5155, in which the stress rupture life at 750℃ and 645MPa is longer than 50h. The results showed that the intermediate temperature stress rupture properties impaired by treatment of 1210℃/4h were due to precipitation of too small γ′ phase(<0.2μm) in grains and absence of the secondary carbides at grain boundaries. Microstructure containing the intergranular M6C carbides with envelope of γ′ and the residual coarse γ′ was obtained by means of 1180℃/4h treatment, therefore the stress rupture life was obviously increased to meet the demand of HB5155. The effect of γ′ size was also discussed from the view point of deformation mechanism in this paper.

关键词： cast alloys heat resistant alloys heat treatment microstructure intermediate temperature stress rupture properties deformation mechanism

Precipitate Contribution to the Acoustic Nonlinearity in Nickel-Based Superalloy

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Chinese Physics Letters 2009年第8期26卷 219-222页

作者： Chung-Seok KIM Cliff J. LISSENDEN Engineering Science and Mechanics The Pennsylvania State University 212 EES Bldg. University Park PA 16802 USA

The influence of γ′ precipitate on the acoustic nonlinearity is investigated for a nickel-based superalloy, which is subjected to creep deformation. During creep deformation, the cuboidal γ′ precipitate is preferentially coarsened in a direction perpendicular to the applied stress axis. The length and shape factor of the γ′ precipitate increase with creep time. The increase of relative acoustic nonlinearity with increasing fraction of creep life is discussed in relation to the rafting of γ′ precipitate, which is closely related to the scattering and distortion of the acoustic wave

关键词： PRECIPITATION (Chemistry) NONLINEAR acoustics NICKEL alloys heat resistant alloys CREEP (Materials) DEFORMATIONS (Mechanics) SOUND wave scattering

EFFECT OF SOLIDIFICATION RATE ON MICRO－STRUCTURES OF DIRECTIONALLYSOLIDIFIED SUPERALLOY DZ22

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Chinese Journal of Aeronautics 1995年第4期8卷 282-286页

作者： Liu Zhongyuan Li Jianguo Shi Zhengxing Fu Heiizhi,(Northwestern Polytechnical University, Xi’an, China, 710072)She Li Chen Rongzbang Wang Luohao(Beijing institute of Aeronautical Materials, Beijing, China, 100095)

The effect of solidification rate on the microstructures of directionallysolidified superalloy DZ22 was studied with the help of a ZMLMC directionalsolidification apparatus which has a superhigh temperature gradient. The results showthat the size and shapes of Y', (Y+Y') and MC change seriously with the increase in cool-ing rate. When the cooling rate is equal to 54.2K . s-1, Y' particles distnbute evenly;eutectic (Y+Y') in group block and MC in block are distributed in the interdendriticzone.

关键词： heat resistant alloys microstructure solidification. rates