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PSEUDO-DENDRITE GROWTH CHARACTERISTICS OF γ′PRECIPITATES IN SINGLE CRYSTAL NICKEL BASE SUPERALLOY |
ZHANG Jinghua; YAO Xiangdong;ZHANG Zhiya; LI Yingao;GUAN Hengrong;HU Zhuangqi(Institute of Metal Research; Chinese Academy of Sciences; Shenyang)(Manuscript received 17 March; 1994) |
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Cite this article:
ZHANG Jinghua; YAO Xiangdong;ZHANG Zhiya; LI Yingao;GUAN Hengrong;HU Zhuangqi(Institute of Metal Research; Chinese Academy of Sciences; Shenyang)(Manuscript received 17 March; 1994). PSEUDO-DENDRITE GROWTH CHARACTERISTICS OF γ′PRECIPITATES IN SINGLE CRYSTAL NICKEL BASE SUPERALLOY. Acta Metall Sin, 1994, 30(10): 453-462.
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Abstract An investigation has been made of the nucleation and growth characteristics of the pseudo-dendritic γ′precipitates in a single crystal nickel base superalloy which is directly aged after homogenizing and solutioning at high temperature. The results show that the temperature for the pseudo-dendritic γ′ precipitation is sensitive to the alloy composition in local area and that the relationship between the nucleation density (Ⅰ) and undercooling (△Tγ′) for the pseudo-dendritic γ′ precipitates is given by logarithmic expression: I(μm~2) = 2.5×10~(-3) exp(0. 11△T_(γ′)). The size of the pseudo-dendritic γ′precipitates is proportional to the direct aging time under small undercooling. The preferential growth direction of the pseudo-dendrite γ′precipiatates is <110> which is completely coherent with matrix. The formation mechanism for pseudo-dendrite γ′prencipitates involves both the diffusion and non- diffusion controlled. It intends to form nucleus symmetrically.Correspondent: ZHANG Jinghua, assoiate professor, Institute of Metal Research, Chinese Academy of Sci ences. Shenyang 110015
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Received: 18 October 1994
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