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Microstructure of az91d magnesium alloy semi-solid billets prepared by SIMA method from chips

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中国有色金属学会会刊：英文版 2010年第S3期20卷 749-753页

作者：许红雨吉泽升胡茂良王振宇 School of Materials Science and Engineering Harbin Univ ersity of Science and Technology

az91d magnesium alloy chips were adopted to prepare semi-solid *** chips were subjected to a series ofisothermal treatments for various holding times at 783?843 K after being compressed into billet at 523 *** semi-solid microstructure of az91d magnesium alloy containing spherical solid particles was *** effects of reheating temperature and holding time on microstructures were *** the semi-solid forming mechanism was *** result shows that semi-solid billets with highly spheroidal and homogeneous grains can be prepared from chips by strain induced melt activation(SIMA) ***,it is found that increasing the heating temperature can accelerate the spheroidizing process and reduce the solid volume *** the increase of the holding time,the solid particles become more globular,the grains grow slowly and the solid volume fraction slightly *** the same time,owing to the decrease ofinterfacial energy,the intragranular liquid phases form by the diffusion of solute atoms,the grain boundaries melt and grains separate from each other during the isothermal *** grains gradually spheroidize and begin to merge with a further increase of the holding *** is considered that the semi-solid forming process includes three stages:the recrystallization and the growth of grain stage,the semi-solid microstructure forming stage controlled by the diffusion of solute,and the spheroidization of solid particle stage controlled by the liquid-solid interface tension.

关键词： az91d magnesium alloy chip strain induced melt activation(SIMA) semi-solid microstructure evolution mechanism

Effects of Ce and Sb on the microstructure and properties of az91d magnesium alloy prepared by the EPC process

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Rare Metals 2008年第1期27卷 41-45页

作者： LI Jiqiang dONG Xuanpu FAN Zitian WANG Yuanqing State Key Laboratory of Material Processing and die ＆ Mould Technology Huazhong University of Science and Technology Wuhan 430074 China

The effects of small amounts of cerium and antimony additions on the microstructure and the mechanical properties of az91d（Mg-9Al-Zn） based alloy were researched via the expendable pattern casting（EPC） *** results show that the microstructure is obviously refined and the tensile strength of the az91d based alloy at ambient temperature is significantly *** compared to az91d,the az91d-1.0%Ce-0.4%Sb alloy has higher ultimate tensile strength and *** ultimate tensile strength and elongation are enhanced by 39% and 47%,*** morphology of the tensile fracture of the az91d-1.0%Ce-0.4%Sb alloy has more characteristics of *** indicates that it has had a larger plastic deformation before *** tensile strength and elongation decrease with the increase of Ce and Sb contents because of the coarsening and volume increase of CeSb and Al11Ce3 phases.

关键词： az91d Ce Sb microstructure mechanical properties

Numerical simulation of temperature field of az91d magnesium alloy during equal channel angular extrusion

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Acta Metallurgica Sinica(English Letters) 2010年第1期23卷 35-40页

作者： Xiaohua ZHANG Yuansheng CHENG Shouting LUO School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China

The temperature field of az91d magnesium alloy extruded by equal channel angular extrusion （ECAE） has been simulated using finite element method （FEM）. A series of tests were designed to obtain the simulation parameters： flow stress of azgld, friction factor and heat transfer coefficient. The simulated temperature agrees well with the measured one. The evolution of temperature and influencing factor was discussed in details. Furthermore. the extrusion pressure of ECAE was analyzed.

关键词： Simulation Temperature field ECAE az91d Magnesium alloy

Microstructure and mechanical properties of rheo-diecasting az91d Mg alloy

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中国有色金属学会会刊：英文版 2010年第S3期20卷 862-867页

作者：杨柳青康永林张帆徐骏 General Research Institute for Nonferrous Metals School of Materials Science and Engineering University of Science and Technology Beijing

Taking az91d magnesium alloy as experimental material,the rheo-diecasting process was implemented by combining the self-developed taper barrel rheomoulding(TBR) machine with high pressure die casting(HPdC) *** characteristics of the rheo-diecasting components were investigated in different processing *** evolution and solidification behavior of the semisolid slurry during the rheo-diecasting process were discussed,and tensile properties of the components were studied as *** results show that,with the rotation speed of the internal taper barrel increasing,the microstructure of the components becomes fine with solid particles nearly spherical and uniformly distributed on the *** the rotation speed is 700 r/min,the primary α-Mg particles have an average size of about 45 μm and a shape factor of about 0.81;the primary α-Mg particles become round and homogeneous with shearing temperature increasing,but the average size is slightly larger The solidification of the alloy melt during the rheo-diecasting process is composed of two distinct stages:the primary solidification and the secondary *** with the conventional die-casting process,the rheo-diecasting process would improve the tensile properties of the components,especially the elongation by 80%.

关键词： az91d magnesium alloy rheo-diecasting microstructural characteristics tensile properties

Interfacial reaction between az91d magnesium alloy melt and mild steel under high temperature

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China Foundry 2024年第2期21卷 159-167页

作者： Jia-hong dai Jian-yue Zhang Bin Jiang Xiang-jun Xu Zhong-tao Jiang Hong-mei Xie Qing-shan Yang Guo-qing Zhang College of Materials Science and Engineering Yangtze Normal UniversityChongqing 408100China National Engineering Research Center for Magnesium Alloys College of Materials Science and EngineeringChongqing UniversityChongqing 400044China Chongqing Jiulongyuan High-tech Industry Group Co. Ltd.Chongqing 400080China Loncin Industry Co. Ltd.Chongqing 400080China department of Materials Science and Engineering The Ohio State UniversityColumbusOH 43210USA Chongqing Key Laboratory of Materials Surface&Interface Science Chongqing University of Arts and SciencesChongqing 402160China School of Metallurgy and Material Engineering Chongqing University of Science and TechnologyChongqing 401331China

The metallurgical quality control of magnesium(Mg)and Mg alloys in melting process is required to ensure a satisfied mechanical and corrosion performance,while the typical used steel crucible introduces impurities and interfacial interaction during melting ***,a systematic study about impurities diffusion and interfacial interaction between molten Mg and steel is *** the present study,the interfacial reaction between molten az91d Mg alloy and mild steel during melting process was investigated with the melting temperatures of 700℃,750℃ and 800℃.The results show that Al(Fe,Mn)intermetallic layer is the intermetallic primarily formed at the interfaces of az91d melt and mild ***,Al_(8)(Mn,Fe)5is indexed between Al(Fe,Mn)and ***_(3)C appears between the mild steel and Al(Fe,Mn)at 700℃ and 750℃,but absent at 800℃ due to the increased solubility of carbon in Mg *** is found that the growth of the intermetallic layer is controlled by diffusion mechanism,and Al and Mn are the dominant diffusing species in the whole interfacial reaction *** measuring the thickness of different layers,the growth constant was *** increases from 1.89(±0.03)×10^(-12)m^(2)·s^(-1)at 700℃ to 3.05(±0.05)×10^(-12)m^(2)·s^(-1)at 750℃,and 5.18(±0.05)×10^(-12)m^(2)·s^(-1)at 800℃.Meanwhile,the content of Fe is linearly increased in az91d with the increase of holding time at 700℃ and 750℃,while it shows a significantly increment after holding for 8 h at 800℃,indicating holding temperature is more crucial to determine the Fe content of az91d than holding time.

关键词： az91d mild steel interface reaction intermetallic growth kinetics

Improvement on the Corrosion Resistance of az91d Magnesium Alloy by Aluminum diffusion Coating

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Journal of Materials Science & Technology 2007年第3期23卷 379-382页

作者： Hongwei HUO Ying LI Fuhui WANG College of Life and Chemistry Science Shenyang Normal University Shenyang 110034 China State Key Laboratory of Corrosion and Protection Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

By combination of magnetron sputtering deposition and vacuum annealing, an aluminum diffusion coating was prepared on the substrate of az91d alloy to improve its corrosion resistance. The microstructure and composition of the diffusion coating was investigated by scanning electron microscopy and X-ray diffraction. The diffusion coating was mainly comprised of β phase-Al12Mg17. The continuous immersion test in 3.5 wt pct neutral NaCl solution indicated that the specimen with diffusion coating had better corrosion resistance compared with the bare az91d alloy specimen. The potentiodynamic polarization measurement indicated that the diffusion coating could function as an effectively protective layer to reduce the corrosion rate of az91d alloy when exposed to 3.5 wt pct NaCl solution.

关键词： az91d Magnesium alloy Corrosion diffusion coating

Effect of high shear rate on solidification microstructure of semisolid az91d alloy

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中国有色金属学会会刊：英文版 2010年第S3期20卷 868-872页

作者：朱光磊徐骏张志峰刘国钧 General Research Institute for Non-ferrous Metals

To investigate the effects of rotation speed and shearing time on morphology of semisolid az91d alloy,experimental work was undertaken using a twin-screw slurry *** results show that increasing the rotation speed and reasonable time can give rise to substantial grain refinement during continuous shearing stage,which can be attributed to the increasing of effective nucleation rate caused by the extremely uniform temperature due to high shear rate and high degree of *** with low rotation speed at the same thermal condition,the analysis indicates that the microstructures obtained at high rotation speed are homogenous spherical and fine grains instead of dendritic or rosette and exhibits uniform distribution in the eutectic matrix.

关键词： semisolid high shear rate solidification az91d rotation speed

direct Electroless Nickel Plating on az91d Magnesium Alloy from a Sulfate Solution and its deposition Mechanism

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材料热处理学报 2004年第05B期25卷 1098-1101页

作者： GUChang-dong LIANJian-she LIGuang-yu NIULi-yuan JIANGZhong-hao TheKeyLabofAutomobileMaterials MinistryofEducationChinaCollegeofMaterialsScienceandEngineeringJilinUniversityNanlingCampusChangchun130025China

A bath of electroless plating Ni on the az91d magnesium alloy, containing sulfate nickel, was given in this paper. The nucleation mechanism of Ni-P deposits on the az91d magnesium alloy was studied by using XRd and SEM. The electroless Ni-P deposits were preferentially nucleated on the (Mg17Al12) phase and extended to the primary and eutectic a phases of the az91d magnesium alloy.

关键词：非电解淀积 az91d 镁合金硫酸盐溶液

Energy-storage Welding Connection Characteristics of Rapid Solidification az91d Mg Alloy Ribbons

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Journal of Materials Science & Technology 2004年第4期20卷 431-434页

作者： JinfengXU QiuyazHAI SenYUAN SchoolofMaterialsScienceandEngineering Xi'anUniversityofTechnologyXi'an710048China SchoolofMaterialsScienceandEngineering Xi'anUniversityofTechnologyXi'an710048China

Energy-storage welding connection characteristics of rapidly solidified az91d Mg alloy ribbons with 40-70 μm thickness are investigated using a microtype energy-storage welding machine. The microstructure and performance of the connection joints are analyzed and studied. The research results indicate that energy-storage welding is able to realize the spot welding connection of az9Id Mg alloy ribbons. The welding nugget consists of developed α-Mg equiaxed grains with the sizes of 1.2-2.7 μm and intergranular distributed β-Mg17Al12 compounds. The thickness of bond zone is about 4 μm and the solidification microstructure is characterized by the fine equiaxed grains with the sizes of 0.8-1.2μm and grain boundary has become coarsening. The columnar crystal in Haz also becomes slightly coarsening and the grain boundary has broadened, however, there is no obvious change in its primitive morphology and crystallographic direction. When welding energy is about 2.0 J, the welding joints with higher shear strength and smaller electrical resistivity are obtained.

关键词： az91d Rapid solidification Energy-storage welding Microstructures Properties