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A Crystallography Study of Bainitic Transformation in a cu-zn-al alloy

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Journal of Materials Science & Technology 1989年第1期5卷 44-50页

作者：安江英朱敏杨大智 Department of Materials Engineering Dalian Institute of Technology China.

The crystallographic nature of initial isothermal phase transformation in cu-26zn-4al (wt-％) was investigated. The kinetic transforma- tion curve, morphology, crystal structure, substructure, orientation relationship and twin relationship of bainite plates have been studied by means of optical and transmission electron microscopy. The experimental results showed that the characteristics of initial 8→bainite transformation are not exactly consistent with that found in martensite transformation, for example, orientation relationship between matrix and bainite does not exist in martensite transformation.

关键词： bainite transformation cu-zn-al alloy orientation relationship

EFFECT OF MARTENSITE ORDERING ON SME IN A cu-zn-al alloy

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Acta Metallurgica Sinica(English Letters) 1989年第1期2卷 7-15页

作者： QI Xuan JIANG Bohong XU Zuyao(T.Y.HSU) Shanghai Jiaotong University,Shanghai.China Qi Xuan,Dept.Marter.Sci.and Eng.,Shanghai Jiaotong University,Shanghai,China

The correlation between the shape memory effect(SME)and the ordering degree in martensite formed through various heat-treatment processes,*** water quenching, step-quenching and aging etc.,has been studied in a cu-26zn-4al *** martensite or- dering degree is estimated by △d,the spacing difference of some pairs of diffracting planes with indices satisfying a relation of(h_1~2-h_2~2)/3=(k_2~2-k_1~2)/n(n=1 for 9R martensite,n=4 for 18R martensite).M 18R martensite is obtained from step-quenching,in which the value of △d increases with the holding duration of step-quenching,and the shape recovery rate η increases synchronouslly.9R martensite is obtained from direct water-quenching,the value of △d is quite large and SME is also good at just quenching *** both △d and η decrease continuously with aging time at room *** stabilization phe- nomenon of martensite is explained by the observation of TEM lattice fringe image,and it may be attributed to the clustering of quenched-in supersaturated vacancies at (001)_M close-packed plane in martensite and decreasing the ordering degree.A reduction in △d and η occuring in the specimens on step-quenching or aging at higher temperature, which may be related to the precipitation of the α-phase and the enrichment of solute atoms, decreases the ordering degree.

关键词： cu-zn-al alloy martensite ordering shape memory effect stabilization

A QUENCHING INDUCED PLANAR DEFECT OF MARTENSITE IN cu-zn-al alloy

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Acta Metallurgica Sinica(English Letters) 1989年第5期2卷 377-379页

作者： ZHU Min YANG Dazhi Dalian University of Technology,Dalian,China Lecturer,Dept.of Matedais Engineering,Dalian University of Technology,Dalian,China

A new kind of planar defect named non-basal plane stacking faults has been studied by using trace analysis and lattice image *** has been found that they are located in (125)_M plane of martensite *** lattice image observation,the non-basal plane stack- ing faults are argued to be induced by two incomplete basal plane stacking faults and may be the results of rapid *** defects are regarded as anomalous structures of martensite.

关键词： martensite cu-zn-al alloy crystal defecis

ON THE STABILIZATION OF THERMOELASTIC MARTENSITE IN A cu-zn-al alloy

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Acta Metallurgica Sinica(English Letters) 1990年第6期3卷 439-441页

作者： WANG Mingpu, LIU Jinwen Central South University of Technology,Changsha,China Lecturer,Dept.of Materials Science and Engineering,Central South University of Technology,Changsha 410083,China

The stabilization of thermoelastic martensite in a rapidly solidified cu-zn-A1 alloy is be- lieved to be the process of disordering in atomic configuration during which the structure of martensite gradually transforms... 详细信息

关键词： cu-zn-al alloy shape memory alloy thermoelastic martensite stabilization

MORPHOLOGY AND STRUCTURE OF TRANSFORMATION PRODUCTS FORMED AT INTERMEDIATE TEMPERATURE IN A cu-zn-al alloy

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Transactions of Nonferrous Metals Society of China 1992年第2期2卷 51-55页

作者： Lu Wei Jiang Bohong Xu Zuyao Shanghai Jiao Tong University Shanghai 200030China

A TTT diagram for th ie precipitation formed at some intermediate temperatures through cooling from high lemperalure parenl phase in a cu-27 27zn-3.73al allay is established by means of dilatormetric *** morphology and structure of transformation products formed at some intermediate tem peratures isothermally through cooling from high temperature parent phase and up-quenching from DO_(3) parent phase are studied by metallographic.X-ray and electron microscopy *** regions in the two separate C curves are obtained according to different morphology of precipitate:rod-like a,plate-like bainite and a rods,and bainite *** aging makes bainite plate change gradually into a whose lattice parameters are no different from that of a formed equilibriumly from parent *** structure is almost orthorhombic long period structure for bainites formed from B_(2) and DO_(3) parent phase,but monoclinic for martensite from DO_(3).They correspond to the overlapping and separating of(1210)and(2010)diffraction peaks respectively,showing the lower degree of ordering in bainite.

关键词： cu-zn-al alloy transformation at intermediate temperature morphology and structure

Microstructure and Shape Memory Effect of cu-26.1zn-4.8al alloy

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Journal of Wuhan University of Technology(Materials Science) 2008年第5期23卷 717-719页

作者：程晓敏 School of Materials Science and Engineering Wuhan University of Technology

The influence of processing parameters on the microstructure and shape memory effect of cu-26.1zn-4.8al alloy was investigated. The treated specimens were characterized by metallography, X-ray diffraction （XRD） and transmission electron microscopy （TEM） to explain the mechanism of shape memory effect in cu-26.1zn-4.8al alloy. The results reveal that the shape memory effect is markedly increased by appropriate quenching and ageing process. XRD shows that γ phase precipitates from martensite when aged at higher temperature and γ precipitates impair the shape memory effect. TEM analysis indicate that the substructure of plate-like martensite consists of twins and stacking faults.

关键词： cu-zn-al alloy shape memory effect microstructure martensite

STABILITIY OF MARTENSITE IN cu-zn-al SHAPE MEMORY alloy AFTER DIRECT OR STEPPED QUENCHING

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Acta Metallurgica Sinica(English Letters) 1990年第6期3卷 410-414页

作者： LU Xiaoye Central south University of Technology,Changsha,China Lecturer,Dept.of Materials Science and Engineering,Central South University of Technology,Changsha 410083,China

The stability of thermoelastic martensite in a cu-14.84 wt-％zn-7.75 wt-％al shape mem- ory alloy with M_s=106°C after direct quenching or stepped quenching has been investigated by using TEM,X-ray diffroctometer and double electric bridge *** martensite aged for about 3 h at room temperature after either direct quenching or stepped quenching (150°C,2 rain)is the M18R *** martensite just directly quenched is not so stable, both its certain diffraction peaks and specific electric resistivity,change with aging at room temperature;whereas it is stable after stepped quenching(150°C.2 min),and its diffraction peaks and specific electric resistivity change no more with aging at room *** above mentioned results seem to be explained by the martensite reordering.

关键词： cu-zn-al alloy shape memory alloy martensite stabilization

KINETICS CHARACTERISTICS OF BAINITE FORMATION IN cu-zn-al alloyS

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Transactions of Nonferrous Metals Society of China 1991年第1期1卷 57-60页

作者： Jiang Lixin Lu Wei Jiang Bohong Xu Zuyao Shanghai Jiao Tong University Shanghai 200030China

TTT diagrams and kinetics curves of bainite formation through up quenching from martensitic slate and of dilatometry and cooling from high temperature parent phase in cu-zn-al alloys are established by ments of dilatometry and metallographic *** results show that the kinetics characteristics of bainite formation obey the Austin-Rickett Equation with n=2.25 for up-quenched specimens and n=1.80 for specimens cooled from high temperature,and the activation energy of bainite formation is about.110 kJ/mol,corresponding to that ofthe diffusion of solute atoms.

关键词： cu-zn-al alloy bainitic transformation kinetics

EFFECT OF Zr ON PHASE TRANSFORMATION IN cu-zn-al SHAPE MEMORY alloyS

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Acta Metallurgica Sinica(English Letters) 1990年第2期3卷 93-98页

作者： XIAO Jichuang FANG Jianneng South China University of Technology,Guangzhou,China XIAO Jichuang Associate Professor,Dept.of Mechanical Engineering No.2,South China University of Technology,Guangzhou 510641,China

An investigation was made of the influence of Zr additive on the high temperature phase trans- formations,martensitic forward/reverse transformations,and shape memory effect of cu-zn-al base alloys by means of differential scanning calorimetry(DSC),X-ray diffraction and *** was found that an addition of 0.35 wt-% zn could effectively inhibit the precipitation of α and γ phases and hence promote the order-martensitic transformations β_2→DO_3→18RM,thus resulting in a minimum activation energy of the martensitic trans- formation and narrow temperature ranges(M_s-M_f)and(A_s-A_f);the alloy so obtained pos- sessed smooth and mobile martensite intervariant interfaces,therefore showing the best shape memory effect.

关键词： cu-zn-al alloy Zr differential scanning calorimetry phase transformation