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Transactions of Nonferrous Metals Society of China 2011年第1期21卷 65-71页

作者：胡小武李双明高思峰刘林傅恒志西北工业大学凝固技术国家重点实验室西安710072

primary dendrite arm spacing（PDAS） of α phase in directionally solidified Pb-26%Bi（mass fraction） hypo-peritectic alloys was measured by considering the effect of melt convection in cylindrical samples with different *** experimental results show the measured PDAS increases with increasing diameter of the *** the growth velocity of 5 μm/s,its value changes from 161.5 μm for the sample with 1.8 mm in diameter to 240.4 μm for the sample with 7 mm in *** strong melt convection in large diameter samples causes a high bulk alloy composition and a high concentration gradient in peritectic β phase,resulting in a larger ***,the high concentration gradient could effectively promote the peritectic transformation,enhancing the dissolution of the thin α dendrite.

关键词： Pb-26%Bi hypo-peritectic alloy primary dendrite arm spacing melt convection directional solidification

Influence of directional solidification variables on primary dendrite arm spacing of Ni-based superalloy DZ125

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China Foundry 2009年第4期6卷 300-304页

作者： Zhang Weiguo Liu Lin Huang Taiwen Zhao Xinbao Qu Min Yu Zhuhuan Fu Hengzhi State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi＇an 710072 China

The primary dendrite morphology and spacing of DZ125 superalloy have been observed during directional solidification under high thermal gradient about 500 K/cm. The results reveal that the primary dendrite arm spacing decreases from 94 μm to 35.8 μm with the increase of directional solidification cooling rate from 2.525 K/s to 36.4 K/s. The regression equation of the primary dendrite arm spacings A, versus cooling rate is λ1=0.013（GV）-0.32. The predictions of Kurz/Fisher model and Hunt/Lu model accord reasonably well with the experimental data. The influence of directional solidification rate under variable thermal gradient on the primary dendrite arm spacing has also been investigated.

关键词： directional solidification thermal gradient cooling rate primary dendrite arm spacing superalloy

Microstructure and Stress-Rupture Property of Large-Scale Complex Nickel-Based Single Crystal Casting

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Acta Metallurgica Sinica(English Letters) 2018年第8期31卷 887-896页

作者： Min Huang Gong Zhang Dong Wang Jia-Sheng Dong Li Wang Lang-Hong Lou Institute of Metal Research Chinese Academy of SciencesShenyang 110016China University of Chinese Academy of Sciences Beijing 100049China

The microstructure and stress-rupture property of the large-scale complex single crystal（SX） casting DD10 were investigated in high-rate solidification process. It is found that the primary dendrite arm spacing（PDAS） does not increase monotonically with the height increase. When across the platform, the temperature gradient increases due to the effect of platform, and the corresponding PDAS decreases. The distribution of eutectic volume fraction in large-scale complex SX casting is affected by PDAS, solid back diffusion, and the development of high order dendrites. The eutectic volume fraction contained in the sample taken below the platform decreases with the height increase. While the eutectic volume fraction contained in the sample taken upper the platform increases gradually with the height increase. After heat treatment,most of the γ/γ＇ eutectics are eliminated and the components are distributed uniformly. The similar stress rupture properties of the samples at different heights in the same direction are obtained.

关键词： Large-scale single crystal Platform primary dendrite arm spacing Eutectic volume fraction Stress-rupture property

Effect of abruptly changing withdrawal rate on solidification microstructure in directionally solidified Al-4.5wt%Cu alloy

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China Foundry 2014年第1期11卷 8-13页

作者： Yang Luyan Li Shuangming Zhong Hong Ren Ruohua Fu Hengzhi State Key Laboratory of Solidif ication Processing Northwestern Polytechnical University

Al-4.5wt.%Cu alloy has been directionally solidified at constant and abruptly changing withdrawal rates, respectively. The effects of the withdrawal rate on solidification microstructure, primary dendrite arm spacing(PDAS) and liquid solute distribution in front of the solid-liquid interface were investigated. The experimental results for the PDAS at a constant withdrawal rate agree well with the values calculated by the Hunt, Trivedi and Hunt-Lu models. At an abrupt change in the withdrawal rate, the maximum to minimum ratio of the PDAS at a given solidification parameter, i.e. λ1max/λ1min, is more than 2, and the PDAS values are remarkably history-dependent. Further, the liquid-solute distribution curve based on theoretical calculation shows that the larger the initial withdrawal rate is, the smaller the minimum of liquid solute concentration in front of the solid-liquid interface is after the abrupt change in withdrawal rate.

关键词： directional solidification abrupt change of withdrawal rate primary dendrite arm spacing liquid-solute distribution Al-4.5wt.%Cu alloy