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Structural evolution of spray-formed Al-70wt.%Si alloys during iso-thermal holding in the semi-solid state

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Rare Metals 2005年第4期24卷 317-324页

作者： zhang Di CUI Hua WEI Yanguang zhang jishan zhang Yongan XIONG Baiqing The State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China General Research Institute for Nonferrous Metals Beijing 100088 China

The grain growth behavior of spray-formed Al-70wt.%Si alloys was studied in the semi-solid state. The specimens were isothermally heat-treated at various temperatures between the solidus and liquidus of Al-Si alloys and then quenched in water. The microstructure of reheated specimens was characterized using optical and scanning electron microscopies. The isothermal holding experiment was carried out to investigate grain growth behavior as a function of holding time and temperature in the semi-solid state. The coarsening mechanism and the effect of porosity on microstructure were also studied.

关键词： materials science grain growth behavior spray forming Al-70wt.%Si alloys semi-solid processing

Current-driving intergranular corrosion performance regeneration below the precipitates solvus temperature in Al–Mg alloy

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Journal of Materials Science & Technology 2020年第18期52卷 132-139页

作者： Di zhang Zhen zhang Yanlin Pan Yanbin Jiang Linzhong Zhuang jishan zhang Xinfang zhang State Key Laboratory of Advanced Metals and Materials University of Science and Technology Beijing.Beijing 100083China School of Materials Science and Engineering.Central South University Changsha 410083China School of Metallurgical and Ecological Engineering.University of Science and Technology Beijing Beijing 100083China

Heat treatment is an effective method to improve the intergranular corrosion resistance of the sensitized Al–Mg alloy due to dissolution of the grain boundary precipitates above the solvus temperature ofβ-*** grain boundary precipitates will grow and coarsening below the solvus *** this study,the in-situ intergranular corrosion performance regeneration of the sensitized Al–Mg alloy can be realized by low-density electro-pulsing treatment below the solvus temperature ofβ-*** findings show that the dissolution of grain boundary precipitates by electro-pulsing treatment is accelerated at relatively low temperature in comparison to traditional heat *** athermal effect produced by the interaction between atoms and electrons on the dissolution of grain boundary precipitates is the main reason for the improved corrosion resistance below the solvus temperature ofβ-phase.

关键词： Aluminium alloys Phase transformation kinetics Electro-pulsing treatment Intergranular corrosion

Mechanical properties,corrosion behavior and microstructure evolution of zinc and scandium co-strengthened 5xxx alloy

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Journal of Rare Earths 2023年第11期41卷 1819-1826,I0006页

作者： Yanlin Pan Yue Xu Di zhang jishan zhang Guxin Zhou Yujing Lang China Academy of Ordnance Science Ningbo Branch Ningbo315103China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing100083China

Nowadays,it is a challenge to improve the strength of 5xxx aluminium alloy while maintaining its distinctive *** address this,the Zn and Sc modified high strength 5xxx aluminium alloys with good intergranular corrosion resistance were prepared through chill casting,and the effects of minor Sc on mechanical properties,corrosion behavior and microstructure evolution of Al-5.0Mg-3.0Zn alloys were systematically *** results show that the Sc containing alloy has high number density and small size of intragranular precipitates,combined with the solid solution strengthening of Sc and the Al_(3)(Sc_(1-x),Zr_(x))second phase strengthening,the strength of Al-5.0Mg-3.0Zn-0.1Sc alloy is obviously ***,the intergranular corrosion resistance of the Sc containing alloy is also improved due to the formation of a large number of low angle grain boundaries and the weakening of the continuity of precipitated phases along the grain boundaries.

关键词： Al-Mg-Zn Scandium Mechanical properties Intergranular corrosion Transmission electron microscopy(TEM) Rare earths

Characterization of microstructure evolution and mechanical properties of the spray-deposited AZ31 magnesium alloy

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Journal of University of Science and Technology Beijing 2008年第6期15卷 740-746页

作者： Yongbing Li Jinfeng Huang Hua Cui kai Tao Kui zhang jishan zhang State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Beijing General Research Institute for Nonferrous Metals Beijing 100088 China

The cylindrical billets of a Mg-3Al-1Zn （AZ31） alloy were synthesized by spray deposition processing. The microstructure evolution and mechanical properties of the alloy were investigated. The results reveal that the microstructure of the AZ31 alloy is refined significantly by spray deposition processing. A homogeneous and equiaxial-grain structure with an average grain size of 17 μm is obtained. Further grain refinement with an average grain size of 5 μm is attributed to dynamic recrystallization during extrusion processing. The great increase in the density of grain boundary nucleation sites by the finer initial grain sizes makes the dislocation pile-ups near subgrain boundaries being absorbed easily by the boundaries, resulting in an accelerated recrystallization process. The average tensile ultimate and yield strengths of the extruded rods are 321 MPa and 237 MPa, respectively, with an elongation of 15.2% at room temperature, which are remarkably higher than those of the conventional as-cast AZ31 alloy.

关键词： magnesium alloy spray deposition dynamic recrystallization mechanical properties

Bulk nanocrystalline Al prepared by cryomilling

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Journal of University of Science and Technology Beijing 2007年第6期14卷 523-528页

作者： Junsheng Cheng Hua Cui Hanbin Chen Bin Yang Jianzhong Fan jishan zhang State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China Materials Science and Engineering School University of Science and Technology Beijing Beijing 100083 China Beijing General Research Institute for Nonferrous Metals Beijing 100088 China

Bulk nanocrystalline Al was fabricated by mechanically milling at cryogenic temperature （cryomilling） and then by hot pressing in vacuum. By using X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM）, the microstructure evolution of the material during cryomilling and consolidation was investigated. With increasing the milling time, the grain size decreased sharply and reduced to 42 nm when cryomilled for 12 h. The grains had grown up, and the columnar grain was formed under the hot pressing and extrusion compared with the cryomilled powders. The grain size of as-extruded specimen was approximately 300-500 nm. The reason of high thermal stability of this bulk was attributed primarily to the Zener pinning from the grain boundary of the AlN arising from cryomilling and the solute drag of the impurity. Tensile tests show that the strength of nanocrystalline Al is enhanced with decreasing grain size. The ultimate tensile strength and tensile elongation were 173 MPa and 17.5%, respectively. It appears that the measured high strength in the cryomilled Al is related to a grain-size effect, dispersion strengthening, and dislocation strengthening.

关键词： nanocrystalline Al cryomilling thermal stability strengthening mechanism

Advanced cold spray technology:Deposition characteristics and potential applications

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Science China(Technological Sciences) 2012年第2期55卷 357-368页

作者： WU XiangKun zhang jishan ZHOU XiangLin CUI Hua LIU JingChun State Key LaboratoryforAdvanced Metals and Materials University of Science and Technology BeijingBeijing 100083China School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China

Cold spray technology,originated from the Institute of Theoretical and Applied Mechanics Siberian branch of the Russian Academy of Sciences,is a rapidly emerging industrial coating *** sprayed particles with high-velocity impact onto a substrate so as to induce severe plastic deformation and then create a *** its low temperature and high velocity compared with thermal spraying,the cold spraying process is increasingly used in the industries for protective *** deposition characteristics of the particles,coating formation and bonding mechanism of the cold spraying process are different from thermal *** theory investigations of the cold spraying process contribute to the development of the high performance coatings,which makes the cold spraying process as a popular research ***,the deposition characteristics,bonding mechanism,process optimization as well as classical applications of the cold spraying technology in the past are reviewed,and the interesting points for the further development,optimization and applications of this technology are also recommended.

关键词： cold spray deposition coating bond mechanism application

Hot deformation behavior of a spray-deposited AZ31 magnesium alloy

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Rare Metals 2009年第1期28卷 91-97页

作者： LI Yongbing CHEN Yunbo CUI Hua DING Jie ZUO Lingli zhang jishan Advanced Manufacture Technology Center China Academy of Machinery Science and Technology Beijing 100083 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China

The flow stress behavior of an as-spray-deposited AZ31 magnesium alloy with fine grains was investigated by means of compression tests with a Gleeble 1500 thermal mechanical simulator at isothermal constant strain rates of 0.01, 0.1, 1.0, and 10 s^-1; the testing temperatures ranged from 623 to 723 K. It is demonstrated that a linear equation can be fitted between the Zemer-Hollomon parameter Z and stress in a double-log scale. The effect of deformation parameters on the behavior of recrystallization was analyzed. Dynamic recrystallization （DRX） generally occurs at a higher temperature and at a lower strain rate. The constitutive equation of the spray-deposited AZ31 magnesium alloy is presented by calculating the deformation activation energy （199.8 kJ·mol^-1）. The as-spray-formed AZ31 alloy is easier for DRX nucleation at elevated temperatures due to the fine grain, which provides a large amount of nucleation sites and a high-diffusivity path for the atom.

关键词： magnesium alloy spray forming flow stress dynamic recrystallization

Relationship among Mechanical Properties Anisotropy,Microstructure and Texture in AA 6111 Alloy Sheets

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Journal of Wuhan University of Technology(Materials Science) 2016年第3期31卷 648-653页

作者：汪小锋郭明星 CAO Lingyong PENG Xiangyang zhang jishan ZHUANG Linzhong State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China Faculty of Mechanical Engineering&Mechanics Ningbo UniversityNingbo 315211China

We comparatively studied the mechanical properties anisotropy, microstructure and texture of the commercial and the new developed AA6111 alloys through tensile test, optical microscopy, and XRD analysis. The results show that the anisotropy of mechanical properties for the developed AA6111 alloy is lower than that of the commercial alloy. The developed alloy possesses higher r value, lower Ar value and more uniform microstructure, compared with the commercial AA6111 alloy, indicating that the deep drawability of the developed alloy has been improved significantly. The recrystallization textures of the two alloy sheets are also different. The recrystallization texture of the commercial alloy sheet mainly includes Cube and { 114}〈311〉 orientations, while the recrystallization texture of developed alloy sheet consists of Cube, Goss and R orientations. The relationships among the deep drawabilities, microstructure and texture were discussed thereafter.

关键词： AA6111 alloy mechanical properties anisotropy microstructure deep drawability texture

Effect of Ti/B Additions on the Formation of Al_3 Ti of in situ TiB_2/Al Composites

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International Journal of Minerals,Metallurgy and Materials 1999年第4期13卷 285-288页

作者： Bin Yang jishan zhang Xianjin Duan Shuangchun Hu(State Key Laboratory for Advanced Metals and Materials, University of Science and ’Techno1ogy Beijing, Beding 100083, China) State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China

A novel technique for fabricating TiB_2/Al composites in molten aluminum was introduced. The formation mechanism of brittleAl,Ti particulates up to 30 m in size produced in the composites was studied and a method of eliminating them was proposed. The resultsshow that (l) the brittle Al,Ti particulates are always present in the composites when the molar ratio of Ti to B 'T,:nB is l:2; and (2) theformation of the brittle Al,Ti phase can be avoided entirely from the final product by using a proper 'T,:nB of l:4 in the Ti-B-Al *** the former case, the tensile elongation of the composite is only 4%, much lower than the value of pure aluminum (20%). In the latercase, the tensile elongation of this composite is 10%, higher than the value of the composite with a lot ofAl,Ti (4%), whereas the ultimatetensile stfength of the former is nearly that of the later.

关键词： In situ reaction TiB2,/Al composites Al3Ti phase