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Rare Metals 2009年第4期28卷 401-404页

作者： ZHU Man YANG Gencang WAN Diqing WANG Zhijun zhou yaohe State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi＇an 710072 China

In the present investigation, the microstructures and growth morphology of Mg32（Al,Zn）49 Frank-Kasper phase in rapidly solidified Mg32Al17Zn32 temary alloys were studied in detail. The samples were characterised by X-ray diffraction analysis （XRD）, scanning electron microscopy （SEM）, field-emission scanning electron microscopy （FE-SEM） and energy dispersive spectrum （EDS）. The results show that the microstructures mainly consist of Mg3e（Al,Zn）49 Frank-Kasper phase and interdendritic Mg-rich O-phase. Under rapid solidification condition, Mg32（Al,Zn）49 Frank-Kasper phase reveals a perfect faceted dendritic characteristic in the shape of a three-fold symmetric microstructure with doublet tips in the axes direction. Observations for fracture surfaces show that the growth morphology of Mg32（Al,Zn）49 grains was truncated cubic, and its growth mechanism was also discussed.

关键词： Frank-Kasper phase rapid solidification faceted dendrite growth morphology

Free-volume evolution of glassy Zr_(65)Al_(7.5)Ni_(10)Cu_(17.5) during inhomogeneous deformation

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Chinese Science Bulletin 2007年第24期52卷 3443-3447页

作者： LIU HuiBin LI JinFut CAO QingPing zhou yaohe zhou yaohe State Key Laboratory of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200030 China

Free-volume evolutions of the as-cast and pre-annealed Zr65Al7.5Ni10Cu17.5 metallic glasses during cold-rolling were investigated using differential scanning calorimetry. As deformation degree increases, free volume in the glasses always increases first and then saturates above a critical strain, while the structure remains completely amorphous. The glass with less initial free volume possesses a higher increase rate of free-volume content during deformation, and as a result the free-volume contents of all the glasses approach each other at higher strains. Coalescence of free volume in shear bands into nanovoids is proposed to be responsible for the saturation of free-volume content at high strains.

关键词：金属眼镜退火塑胶变形自由体积

Influence of RE Content on Damping Capacity of Alloy ZA27

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Journal of Rare Earths 1999年第2期17卷 43-46页

作者： Zhang, Zhongming Wang, Jincheng Xu, Donghui Lu, Yili Yang, Gencang zhou, yaohe Northwestern Polytechnical Univ Xi'an China

The modification mechanism and damping capacity(Q-1) of conventional ascast ZA27 alloy modified by Al10%RE were investigated. Cantilever beam technique was used to measure the damping capacity. The experimental results show that the addition of RE to the ZA27 alloy can refine microstructure and improve the damping capacity, the best modification effect and the highest damping capacity can be obtained at 03%RE content. It is believed that the damping mechanism of ZA27 alloy is associated with the viscous sliding or slipping of grain boundaries and interfaces, and the more the grain boundaries and interfaces, the higher the damping capacity of ZA27 alloy can be obtained.

关键词： Rare Earths ZnAl alloy Modification Damping capacity Damping mechanism

Solidification Structure Formation of Undercooled Single Phase Alloys

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Journal of Materials Science & Technology 2002年第4期18卷 295-298页

作者： Jinfu LI yaohe zhou Wanqi JIE Gencang YANG School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200030China State Key Laboratory of Solidifcation Processing Northwestern Polytechnical UniversityXi'an 710072China

Solidification structure variation of single phase alloy with undercooling prior to nucleation has been widely studied. The progress, especially during the last decade, is reviewed so as to give a comprehensive knowledge for it, in which the emphases are laid on the structure evolution mechanism and the potential application. Lastly, the future interesting subjects are presented.

关键词： Single phase alloy Undercooling Solidification Microstructure

DENUCLEATION AND HIGH UNDERCOOLING OF Ni-32.5%Sn EUTECTIC ALLOY

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Acta Metallurgica Sinica(English Letters) 1991年第8期4卷 115-120页

作者： WEI Bingbo YANG Gencang zhou yaohe Northwestern Polytechnical University,Xi’an,China Northwestern Polytechnical Univ Xi'an China

Undercoolings up to 397 K(0.283 T_E)have been obtained for Ni-32.5% Sn eutectic alloy melted by superheating-cooling cycles and denucleating with inorganic *** predomi- nant dissipation of heat for highly undercooled alloy melt is through *** approxi- mate method is consequently derived to calculate its mean specific heat from measured cooling *** the aid of high speed cinematography,it is revealed that the surface or interface heterogeneous nucleation takes place in preference to homogeneous nucleation even though the undercooling has exceeded 0.2 T_E.

关键词： undercooling rapid solidification nucleation eutectic alloy specific

δ/γtransformation in non-equilibrium solidified peritectic Fe-Ni alloy

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Science China(Physics,Mechanics & Astronomy) 2007年第4期50卷 421-431页

作者： CHEN YuZeng LIU Feng YANG GenCang LIU Ning zhou yaohe State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China

Through phase transformation kinetic analysis and experimental observation,the δ/γtransformation occurring in the non-equilibrium peritectic Fe-4.33at.%Ni alloys was systematically *** to JMA solid-state transformation ki-netic theory,the Time-Temperature-Transformation(TTT)curves of the δ/γtrans-formation in peritectic Fe-Ni alloy were *** this basis,the physical cor-relation between the δ/γtransformation and the initial undercooling of melt(T)was *** results indicate that the change of T can alter not only the overall δ/γtransformation pathways but also the transformation fraction with re-spect to each transformation mechanism.

关键词： δ/γ transformation undercooling non-equilibrium solidification peritectic reaction Fe-Ni alloy

INFLUENCE OF MOULD ROTATION ON MACROSEGREGATION IN INGOT

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Acta Metallurgica Sinica(English Letters) 1989年第8期2卷 81-86页

作者： YU Qiuping zhou yaohe

The macrosegregation formation in an ingot and the influence of rotating mould upon it were analysed on the basis of interdendritic *** the ingot mould rotates unidirectionally,the centrifugal volume force acts on all inner parts,and when the ingot mould rotates alternately, the tangential alternate force is also formed,and both have various influences on the different modes of interdendritic *** is shown that as the ingot mould rotates unidirectionally or alternately with a moderate angular speed,the interdendritic unstable flow may be controlled effectively and the formation of segregation may be ***,it seems to be significant for reducing the segregation such as A-type etc.,in the steel ingot.

关键词： ingot macrosegregation interdendritic flow

Rolling-induced microstructure change in Zr_(65)Al_(7.5)Ni_(10)Cu_(12.5)Ag_5 bulk metallic glass

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Chinese Science Bulletin 2011年第36期56卷 3948-3951页

作者： zhou Wei LU BinFeng KONG LingTi LI JinFu zhou yaohe State Key Laboratory of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai200240 China

The microstructures and free-volume evolutions of as-cast and pre-annealed Zr65Al7.5Ni10Cu12.5Ag5 bulk metallic glasses during rolling deformation have been investigated. No phase transformation is detected in the as-cast/rolled specimen. However,the structural stability of the glass against plastic deformation is worse after pre-annealing,indicated by nanocrystallization in preannealed/rolled specimens with large deformation degrees. Moreover,with increasing deformation degree,the free-volume content in a pre-annealed/rolled specimen increases at a lower average rate than that in an as-cast/rolled specimen.

关键词：大块金属玻璃微观结构诱导滚动自由体积塑性变形平均增长率轧制过程

Liquid-phase Separation in Rapid Solidification of Undercooled Fe-Co-Cu Melts

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Journal of Materials Science & Technology 2012年第7期28卷 622-625页

作者： Ning Liu Feng Liu Zheng Chen Gencang Yang Changlin Yang yaohe zhou School of Metallurgy and Materials Engineering Jiangsu University of Science and Technology Zhangjiagang 215600 China State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xilan 710072 China School of Materials Science and Engineering China University of Mining and Technology Xuzhou 221008 China

The homogeneous liquid was separated into two phases, （Fe, Co）-rich LI and Cu-rich L2, once the melt was undercooled below a liquid-phase separation temperature Tsep. If the duration from Tsep to Tsl （solidification temperature of LI phase）, termed the liquid-phase separation interval Δt, exceeded a critical value, an eggtype structure was observed. By utilizing differential thermal analyses （DTA）, the solidification process of the undercooled Fe-Co-Cu alloys was studied. Additionally, an immiscible boundary was obtained, which was a convex parabola with a symmetrical axis of XCu=0.52. Depending on the relative amounts of LI and L2, the minor phase was nucleated firstly to form liquid droplets and separated from the original liquids at the beginning of liquid-phase separation.

关键词： Undercooled Fe-Co-Cu alloys Egg-type structure Liquid-phase separation

Entropy as a selection rule for crystal growth in undercooled binary eutectic melts

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Chinese Science Bulletin 2009年第6期54卷 1012-1018页

作者： LU YiPing XI ZengZhe YANG GenCang LIN Xin zhou yaohe State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi'an 710072 China School of Materials and Chemical Engineering Xi'an Technological University Xi'an 710032 China

A solution entropy model was developed for the undercooled binary eutectic alloy systems. As an ex-tension of Taylor and Fidler et al.'s model, the present model considered the change of phase compo-sition with the increase of undercooling. Furthermore, the sub-regular solution model and the interac-tion parameter (IAB) were also introduced. In this paper, the extended model is used to calculate the solution entropy for binary eutectic phases under the undercooled condition, and the application scope of the model is also extended. Not only the growth manner of eutectic phases, but also the transition of morphologies may be predicted and explained by calculating the solution entropy of eutectic phases under the non-equilibrium condition with the developed model. Experimental results show that the developed model is valid for the undercooled Ni-Si and Ni-Sn eutectic alloy systems.

关键词：熵模型共晶相二元晶体生长选择规则熔体相互作用参数正规溶液模型