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Hot workability of Mg-9Y-1MM-0.6Zr alloy

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Journal of Rare Earths 2011年第5期29卷 460-465页

作者：马鸣龙何兰强李兴刚李永军张奎 State Key Lab of non-ferrous metals and Processes General Research Institute for Non-Ferrous Metals

The behavior evolvement of Mg-9Y-1MM-0.6Zr （WE91） alloy during hot deformation process was discussed. The flow stress behavior of magnesium alloy over the strain rate range of 0.001 to 1 s–1 and the temperature range of 653 to 773 K was studied on a Gleeble-1500D hot simulator under the maximum deformation degree of 60%. The experimental results showed that the relationship between stress and strain was obviously affected by the strain rate and deformation temperature and the flow curves observed were typical of the occurrence of dynamic recrystallization. The flow stress of WE91 magnesium alloy during high temperature deformation could be represented by the Zener-Hollomon parameter in the hyperbolic Arrhenius-type equation. The average deformation activation energy Q and strain coefficient n were 224.11 kJ/mol and 3.08 by calculation,respectively. The processing maps were calculated and analyzed according to the dynamic materials model. The map at strain of 0.916 exhibited three domains with peak efficiency of 49%,44% and 42%,respectively. It was found that the alloy could be extruded at 693 K with mechanical properties of σ0.2=240 MPa,σb=315 MPa and δ=15.5%.

关键词： rare-earth magnesium alloy plastic behavior processing map microstructures

Microstructure evolution of 7050 aluminum alloy during hot deformation

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Transactions of nonferrous metals Society of China 2010年第2期20卷 189-194页

作者：李俊鹏沈健闫晓东毛柏平闫亮明 General research institute for non-ferrous metals

Hot compression of 7050 aluminum alloy was performed on Gleeble 1500D thermo-mechanical simulator at 350 ℃ and 450 ℃ with a constant strain rate of 0.1 s-1 to different nominal strains of 0.1, 0.3 and 0.7. Microstructures of 7050 alloy under various compression conditions were observed by TEM to investigate the microstructure evolution process of the alloy deformed at various temperatures. The microstructure evolves from dislocation tangles to cell structure and subgrain structure when being deformed at 350 ℃, of which dynamic recovery is the softening mechanism. However, continuous dynamic recrystallization (DRX) occurs during hot deformation at 450 ℃, in which the main nucleation mechanisms of DRX are subgrain growth and subgrain coalescence rather than particle-simulated nucleation (PSN).

关键词： microstructure evolution dynamic recovery dynamic recrystallization hot deformation 7050 alloy

Annulus electromagnetic stirring for preparing semisolid A357 aluminum alloy slurry

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中国有色金属学会会刊：英文版 2009年第5期19卷 1104-1109页

作者：白月龙徐骏张志峰石力开 General research institute for non-ferrous metals

The effects of pouring temperature and annulus gap width on the microstructure of the semi-solid A357 aluminum alloy slurry prepared by annulus electromagnetic stirring(AEMS)technology were *** results show that low pouring temperature and narrow annulus gap are advantageous to obtaining the small spherical primaryα(Al)*** lower the pouring temperature is and the smaller the annulus gap width is,the more uniform,the smaller and the more spherical the microstructure is. The microstructures obtained by the ordinary electromagnetic stirring and AEMS were *** results indicate that the primaryα(Al)particles are globular,small and distribute homogeneously in the slurry obtained by *** in the slurry obtained by the ordinary electromagnetic stirring,the primaryα(Al)particles are small dendrites in the edge of the slurry and they are large and rosette-like or dendritic in the inner of the slurry.

关键词：电磁搅拌制备温度金浆料半固态铝环形浇注温度水泥浆

Preparation of semi-solid slurry at power frequency by annulus electromagnetic stirring method

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中国有色金属学会会刊：英文版 2009年第S3期19卷 531-536页

作者：白月龙徐骏张志峰石力开 General research institute for non ferrous metals

The effect of stirring frequency on the semi-solid A357 aluminum alloy microstructure was investigated by annulus electromagnetic stirring(AEMS) method. The microstructures obtained by AEMS method and ordinary electromagnetic stirring(EMS)method were compared and analyzed. The results show that the primary α(Al) particles become more spherical and fine, and disperse uniformly in a liquid matrix with increasing stirring frequency, and higher stirring frequency is advantageous to obtain the fine spherical semi-solid microstructure by AEMS. Compared with the microstructures obtained at stirring frequency of 50 Hz in EMS, the fine spherical and uniformly distributed semi-solid microstructures can be still obtained at stirring frequency of 50 Hz in AEMS, so stirring frequency of 50 Hz is recommended in AEMS to save investment cost on frequency-conversion facilities.

关键词： A357 aluminum alloy semi-solid electromagnetic stirring slurry preparation

Effects of isothermal homogenization on microstructure evolution of Mg-7Gd-5Y-1MM-0.5Zr alloy

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Journal of Rare Earths 2015年第4期33卷 439-444页

作者：李蒙李兴刚张奎李永军马鸣龙石国梁袁家伟刘靖宝 State Key Laboratory for Fabrication and Processing of non-ferrous metals General Research Institute for Non-Ferrous Metals

Optical microscopy （OM）, scanning electronic microscopy （SEM） and X-ray diffraction （XRD） were performed to inves- tigate the influence of homogenization on the microstructures of the Mg-7Gd-5Y-1MM （Ce-rich RE）-0.5Zr magnesium alloy. The results indicated that α-Mg, Mg24（GdY）5 phase, Mg5（GdY） phase and Mg12MM phase coexisted together in as-cast alloy; the micro- structures were largely characterized by α-Mg matrix and gray globular or elliptic ball Mg12MM phase, in addition to those with cubic block Mg24（GdY）5 phase after homogenization; the reasonable homogenization regime was maintained at 530 ℃ for 32 h.

关键词： homogenization treatment magnesium microstructure evolution rare earths

Microstructural evolution of aluminum alloy 7B04 thick plate by various thermal treatments

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中国有色金属学会会刊：英文版 2008年第1期18卷 40-45页

作者：李志辉熊柏青张永安朱宝宏王锋刘红伟 State Key Laboratory for Fabrication and Processing of non-ferrous metals General Research Institute for Non-ferrous Metals

The microstructure of an AA 7B04 alloy in the form of plate was investigated using differential scanning calorimetry(DSC)and TEM analysis *** properties and electrical conductivity of AA 7B04 under various heat treatment conditions were also *** results reveal that peak-aged microstructure contains GP zones and η' precipitates *** retrogressing and reaging(RRA),the η' and η precipitates disperse in the alloy matrix,and the η precipitates distribute coarsely and sparsely,decorating the grain boundaries,together with precipitate free zones(PFZs)around *** is also shown that selecting of suitable heat treatments can provide optimal precipitates in matrix and at grain boundaries,which gives rise to a combination of high strength and stress corrosion cracking(SCC)resistance in such materials.

关键词：铝合金显微结构热处理金属学

Effect of homogenization on microstructure and properties of WE91 alloys

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Journal of Rare Earths 2013年第8期31卷 830-836页

作者：马鸣龙张奎李永军李兴刚石国梁 State Key Laboratory for non-ferrous metals and Processes Beijing General Research Institute for Non-Ferrous Metals

The microstructure and properties of the Mg-9Y-1MM-0.6Zr alloy were studied by scanning electron microscopy, optical microscopy, transmission electron microscopy, hardness and tensile testing. Homogenization was confirmed, and the solidification model was established. The as-cast alloy was mainly composed of ct-Mg and eutectic structures. The suitable homogenization pa- rameters were 535℃ for 18 h. Most of the eutectic structure dissolved in this process. Only the Mg4.26Y95.74 and Mg12 （MM） phases were remained in, and only a few microstructure occurred for prolonged time. The ultimate tensile strength of the alloy increased up to 232 MPa after homogenization, but the yield strength and the elongation were almost as same as the as-cast state. In the as-cast al- loys the cracks started in the eutectic structure, and then intergranular fracture occurred, but in the homogenate alloys residual phases became the source of the cracks and then tmnscrystalline fracture took place. The most important roles of homogenization were the decomposition of the eutectic structure, furthermore the intergranular fracture turned into a transcrystalline fracture, which was one of the main reasons to increase the strength of the alloys.

关键词： rare earth magnesium alloy homogenization microstructure mechanical property

Influence of Procedure Parameters on Rheological Property of Semi-Solid AZ91D Magnesium Alloy

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Journal of Rare Earths 2004年第z2期22卷 47-49页

作者： Jiang Yunxi Xie Shuisheng Li Xinggang Li Lei General research institute for non-ferrous metals Beijing 100088China General Research Institute for Non-Ferrous MetalsBeijing 100088China General Research Institute for Non-Ferrous MetalsBeijing 100088China General Research Institute for Non-Ferrous MetalsBeijing 100088China

Semi-solid AZ91D magnesium alloy was investigated in isothermal steady-state condition. The influence of stirring technological parameters such as stirring temperature and shear rate to apparent viscosity of semi-solid alloy slurry was discussed. Apparent viscosity increases with stirring temperature decreases at the same shear rate. At the same stirring temperature, apparent viscosity decreases rapidly at first with shear rate increases, and then apparent viscosity decreases slowly with shear rate increases, when shear rate reaches a certain value, apparent viscosity appears tiny increase. According to the experimental data, the relation between solid volume fraction and apparent viscosity of semi-solid AZ9l D alloy at shear rate 238 s- 1 is fitted by regression method, it supplies useful data to the numerical simulation of semi-solid AZ91D alloy die casting process.

关键词： AZ91D alloy semi-solid rheological property procedure parameter

Corrosion behavior of extrusion, under-aged, peaked-aged and over-aged WE93 alloys in Na HSO_3 solutions

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Journal of Rare Earths 2014年第12期32卷 1170-1174页

作者：蒋全通马鸣龙张奎李兴刚李永军石国梁袁家伟 State Key Lab for non-ferrous metals and Process General Research Institute for Non-ferrous Metals

The corrosion behaviors of extrusion, under-aged, peaked-aged and over-aged WE93 alloys in Na HSO3 solutions were investigated by optical microscopy（OM）, scanning electron microscopy（SEM） and X-ray diffraction（XRD）.The weight loss rates, corrosion morphologies and polarization curves were *** peak-aged specimen in Na HSO3 salt spray had the highest corrosion rate of 0.9787 mg/cm2/d, while extrusion specimen led to the lowest of 0.2184 mg/cm2/*** specimens could be arranged in decreasing order of corrosion rates： extrusion 〈under-aged〈over-aged〈peak-aged. Polarization curves also gave effective evaluation of corrosion rates in agreement. The NaHSO3 played a great role in the corrosion behaviors of WE93 alloys. The main reasons were that HSO3- developed a reaction： O2＋2HSO3 ＋2e→2HSO42→2H＋＋2SO42- to generate H＋, accelerating the process of corrosion reaction. SO4 2- stimulated corrosion and led to an autocatalytic type of reaction： MgZ＋＋SO4^2-＋7H2O→MgSO4-7H2O. XRD characterized that Mg（OH）2 and MgSO4·7H2O were the main corrosion products.

关键词： corrosion behaviors WE93 alloy Na HSO3 rare earths