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International Journal of Minerals,Metallurgy and Materials 2022年第1期29卷 108-118页

作者： Ruiqing Lu Long Zhang Shuwei Zheng Dingfa Fu Jie Teng Jianchun Chen Guodong Zhao Fulin Jiang Hui Zhang College of Materials Science and Engineering Hunan UniversityChangsha 410082China Hunan Province Engineering Research Center for High Performance Super Long Scale Light alloy Materials Yueyang 414005China Hunan Jinlianxing Special Materials Co. Ltd.Yueyang 414005China

al-mg alloys are an important class of non-heat treatable alloys in which mg solute and grain size play essential role in their mechanical properties and plastic deformation behaviors.In this work,a cyclical continuous expanded extrusion and drawing(CCEED)process was proposed and implemented on an al-3mg alloy to introduce large plastic deformation.The results showed that the continuous expanded extrusion mainly improved the ductility,while the cold drawing enhanced the strength of the alloy.With the increased processing CCEED passes,the multi-pass cross shear deformation mechanism progressively improved the homogeneity of the hardness distributions and refined grain size.Continuous dynamic recrystallization played an important role in the grain refinement of the processed al-3mg alloy rods.Besides,the microstructural evolution was basically influenced by the special thermomechanical deformation conditions during the CCEED process.

关键词： al-mg alloy plastic processing microstructure mechanical properties dynamic recrystallization

Strengths and Fracture Mechanisms of al_2O_3 Short Fiber Reinforced al-mg alloy Matrix Composite at Elevated Temperatures

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Journal of Materials Science & Technology 2002年第3期18卷 257-260页

作者： Guozheng KANGDepartment of Applied Mechanics and Engineering, Southwest Jiaotong University, Chengdu 610031, ChinaChuan YANG and Jixi ZHANGDepartment of Materials Engineering, Southwest Jiaotong University, Chengdu 610031, China [ Manuscript received Janu Dept. of Appl. Mech. and Eng. Southwest Jiaotong Univ. Chengdu 610031 China

Using the experimental and theoretical methods, the tensile strengths and fracture mechanisms of AI2O3 short fiber reinforced AI-mg alloy matrix composite at elevated temperatures were researched. The interfacial microstructural characteristics and the fracture surfaces of the composite at different temperatures were observed by transmission electron microscope (TEM) and by scanning electron microscope (SEM), respectively. Then, from the results of microscopic observation, the fracture mechanisms of the composite at different temperatures are discussed. Finally, the tensile strengths of the composite at elevated temperatures were predicted by statistical integration average (SIA) method with the consideration of various fracture mechanisms. It was shown that the strengths and fracture mechanisms of the composite at elevated temperature (300℃) were significantly different from those at room temperature due to the variations of interfacial bonding states. The tensile strengths predicted by the SIA method at elevated temperatures agreed well with the experimental results.

关键词： Fracture A12O3 al-mg alloy Composite

Microstructure and mechanical properties of friction-stir-welded high-mg-alloyed al-mg alloy plates at different rotating rates

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Rare Metals 2021年第8期40卷 2167-2178页

作者： Ying-Li Li Wei-Jun Xia Hong-Ge Yan Ji-Hua Chen Tian Ding You-Ping Sun Xin-Yu Li School of Materials Science and Engineering Hunan UniversityChangsha410082China Hunan Provincial Key Laboratory of Spray Deposition Technology and Application Hunan UniversityChangsha410082China School of Mechanical and Transportation Engineering Guangxi University of Science and TechnologyLiuzhou545006China

Hot-rolled high-mg-alloyed al-mg alloy(al-9.2 mg-0.8 Mn-0.2 Zr-0.15 Ti,labeled as 5 A12)plates were successfully friction stir welded at rotating rates ranging from 750 to 1500 r·min^(-1) at a constant welding speed of50 mm·min^(-1).The joints were characterized by optical microscopy(OM),electron backscatter diffraction(EBSD),transmission electron microscopy(TEM),scanning electron microscopy(SEM),electron-dispersive spectroscopy(EDS),and tensile testing.all the joints are volume defectfree and exhibit fine,equiaxed dynamic recrystallization(DRX)grains with high-angle grain boundaries(HAGBs)fractions of 88.6%-93.3%in the nugget zones(NZs).The DRX grain size and the second-phase particle size in the NZs have a parabolic relation with the rotating rate.Furthermore,among the joints tested,the joint prepared at1000 r·min^(-1),which has the highest ultimate tensile strength((478±3)MPa)and the largest elongation to rupture(22.5%±1.4%)—approximately 87.5%and145.2%those of the base metal,respectively,exhibits the smallest grain size of 2.93μm,as well as the smallest particle size in the NZs.These excellent mechanical properties can be ascribed to the combined effects of the fine DRX grains with high fraction of HAGBs and the fine second-phase particles with a uniform distribution.

关键词： al-mg alloy Friction stir welding Dynamic recrystallization High ductility

Effect of the addition of al-Ti-C master alloy on the microstructure and microhardness of a cast al-10mg alloy

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Journal of University of Science and Technology Beijing 2006年第2期13卷 149-153页

作者： Kuibo Yin Xiufang Bian Na Han Xiujun Yao Yan Zhao Jiankun Zhou Key Lab of Liquid Structures and Heredity of Materials Ministry of Education Shandong University South Campus Jinan 250061 China National Laboratory of Solid State Microstructures Nanjing University Nanjing 210093 China

The microstructure and microhardness of a cast al-10wt%mg （henceforth al-10mg） alloy with 0.2wt% addition of al- 5Ti-0.25C master alloy were compared with those of a refiner-free alloy of similar chemical composition. It was found that this level of the master alloy addition not only caused an effective grain refinement, but also caused a significant increase in the microhardness of the al-10mg alloy. Microchemical analysis revealed that TiC particles existed in the grain center. The relationship between the holding time and grain size was also studied. It shows that the grain refining efficiency is faded observably with the holding time. This is explained in terms of the instability of TiC particles.

关键词： al-mg alloy al-Ti-C alloy microhardness grain refinement

Microstructure and crystal growth direction of al-mg alloy

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China Foundry 2015年第2期12卷 129-135页

作者： Ti-jun Chen Hai-yang Guo Xiang-wei Li Yuan Hao Key Laboratory of Gansu Advanced Nonferrous Metal Materials Lanzhou University of Technology

The microstructures and crystal growth directions of permanent mould casting and directionally solidified al-mg alloys with different mg contents have been investigated. The results indicate that the effect of mg content on microstructure is basically same for the alloys prepared by these two methods. The primary grains change from cellular crystals to developed columnar dendrites, and then to equiaxed dendrites as the mg content is increased. Simultaneously, both the cellular or columnar grain region and the primary trunk spacing decrease. all of these changes are mainly attributed to the constitutional supercooling resulting from mg element. Comparatively, the cellular or columnar crystals of the directionally solidified alloys are straighter and more parallel than those of the permanent mould casting alloys. These have straight or wavy grain boundaries, one of the most important microstructure characteristics of feathery grains. However, the transverse microstructure and growth direction reveal that they do not belong to feathery grains. The mg seemingly can affect the crystal growth direction, but does not result in the formation of feathery grains under the conditions employed in the study.

关键词： al-mg alloy microstructure crystal growth direction feathery grains permanent mould casting directional solidifi cation

Microstructural evolution and strengthening mechanism of al–mg alloys with fine grains processed by accumulative continuous extrusion forming

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Journal of Materials Science & Technology 2022年第33期128卷 195-204页

作者： Bowei Yang Yu Wang Minqiang Gao Changfeng Wang Renguo Guan School of Materials Science and Engineering Northeastern UniversityShenyang 110819China Key Laboratory of Near-Net Forming of Light Metals of Liaoning Province Dalian Jiaotong UniversityDalian 116028China Engineering Research Center of Continuous Extrusion Ministry of EducationDalian Jiaotong UniversityDalian 116028China

In this work,the mechanical properties and strengthening mechanisms induced by microstructural evolution in a rheo-extruded 5087 alloy processed via accumulative continuous extrusion forming(ACEF)were investigated.Electron back-scattered diffraction(EBSD)and transmission electron microscopy(TEM)were utilized to characterize the microstructure of the alloy subjected to ACEF with various passes.The grain refinement caused by continuous dynamic recrystallization(CDRX)was discussed.The results demonstrated that after 3 passes of ACEF,there was a significant grain refinement effect on the alloy,and the average grain size decreased from 45.6μm to 2.5μm;the ultimate tensile strength(UTS)and yield strength(YS)of the alloy increased to 362.8 MPa and 234.6 MPa,respectively.Dislocation cells/walls generated during deformation promoted the formation of low angle grain boundaries(LAGBs).The accumulative strain accelerated the transformation of LAGBs to high angle grain boundaries(HAGBs).Dislocation pile-up enhanced the driving force of CDRX,and nano-sized al_6(Mn,Fe)phases at the grain boundaries inhibited the growth of grains due to the pinning effect.Based on the quantitative estimation,dislocation strengthening and grain boundary strengthening dominated the enhancement in YS of the ACEFed alloy.

关键词： al-mg alloy Grain refinement Mechanical property Dynamic recrystallization Strengthening mechanism

Toughening Effects through Optimizing Cell Structure and Deformation Behaviors of al–mg Foams

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Acta Metallurgica Sinica(English Letters) 2022年第12期35卷 2014-2026页

作者： Hao Yu Xudong Yang Weiting Li Xudong Rong Siyuan Guo Lishi Ma Lizhuang Yang Junwei Sha Naiqin Zhao Tianjin Key Laboratory of Composite and Functional Materials School of Materials Science and EngineeringTianjin UniversityTianjin 300350China Sino-European Institute of Aviation Engineering Civil Aviation University of ChinaTianjin 300300China School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Key Laboratory of Advanced Ceramics and Machining Technology Ministry of EducationTianjin 300350China

As widely used protective materials,the application of al foams is still limited by their low intrinsic mechanical properties caused by the brittleness of struts.The introduction of mg is recently demonstrated effective to improve the mechanical performance of al foams;however,the mechanism of mg modification is still not clear.In this work,al-mg foams are developed through a powder metallurgy process with excellent compression performance and high energy absorption capacity.The effects of mg modification on the cell structure,toughness,and deformation behavior are investigated systematically.As a result,the small cell size of~1.8 mm and the high sphericity of 0.92 are achieved with 5% of mg addition,delivering high compression stress of 8.5±0.43 MPa and energy absorption capacity of 6.9±0.36 MJ/m^(3),simultaneously.The synergistic mechanism for the improved mechanical performance is also demonstrated to be the combination of stress transfer and plastic deformation behavior of cells.The results provide a new strategy to develop high-performance foam materials by improving toughness and further promote the practical application.

关键词： Powder metallurgy aluminum foam al-mg alloy Plastic deformation Cell structure

Temperature and Stress Dependence of Occurrence of Strain Burst in Cyclic Creep of AI-mg alloy

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Journal of Materials Science & Technology 1992年第3期8卷 177-180页

作者：朱世杰阳志安王中光 State Key Laboratory for Fatigue and Fracture of Materials Institute of Metal ResearchShenyang110015China To whom correspondence should be addressed State Key Laboratory for Fatigue and Fracture of Materials Institute of Metal ResearchShenyang110015China

Cyclic creep tests of al-mg alloy have been conducted at a wide range of stress and temperature.When mg content is beyond 0.45%, the strain bursts can be observed in the cyclic creep curves.There exists a critical stress for the occur- rence of the strain burst,which increases with an in- crease of mg content and is almost 60% of the ul- timate tensile stress.The occurrence of strain burst is proposed to be controlled by the easiness of the cross-slip of dislocations.For al-mg alloy,the dynamic strain aging plays an important role in the strain bursts.

关键词： cyclic creep al-mg alloy strain burst cross-slip

Effects of Sc, Zr and Tion the microstructure and properties of al alloys with high mg content

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Rare Metals 2010年第1期29卷 66-71页

作者： WANG Xu CHEN Guoqin LI Bing WU Lianmei JIANG Darning School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China

The effects of trace Sc, Zr, and Ti on the microstructure and hardness of A1 alloys with high mg content （al-6mg, al-8mg, and al-10mg） were studied by optical microscope, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and Brinell hardness. The grain size of the as-cast alloys was refined by the addition of Sc and Zr, and it was further refined by the addition of Ti. With the same contents of Sc, Zr, and Ti, an increase in mg content was beneficial to the refinement due to the solution of mg into α-al. The refined microstructures of the as-cast alloys were favorable for Brinell hardness. Addition of Sc, Zr, and Ti to the al-10mg alloy results in the improvement of peak hardness and it is about 45% higher than that of the al-10mg alloy, which is due to fine precipitations of al3（SC1-xZrx）, al3（Sc1-xTix）, and al3（Sc1-x-yZrxTiy）.

关键词： al-mg alloy homogenization microstructure Brinell hardness element addition

Synergistic Balance of Strength and Corrosion Resistance in al-mg-Er alloys

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Acta Metallurgica Sinica(English Letters) 2020年第5期33卷 659-670页

作者： Haifei Zhou Zhouhai Qian Mengcheng Zhou Xuebing Liu Yong Li Xinfang Zhang Zhejing Electric Power Corporation Research Institute Hangzhou 310014China State Key Laboratory of Advanced Metallurgy School of Metallurgical and Ecological EngineeringUniversity of Science and Technology BeijingBeijing 100083China

High-strength,corrosion-resistant,and lightweight al-mg alloys perform an important function in harsh coastal service environments.Corrosion resistance is generally inversely correlated with strength;hence,it is difficult to simultaneously optimize both.In this study,a low-magnesium Er-containing al-based alloy that is stronger and more corrosion resistant than al-based alloys have been reported.The alloy contains Er,and the precipitation of al3 Er within a face-centered cubic matrix is obtained by a series of smelting-casting,heat treatment,and rolling processes.It is presumed that the strengthening phase of al3 Er pinning dislocations improves alloy strength.It also increases the recrystallization temperature of cold-rolled matrix and induces the distribution of small-angle grain boundaries,thus allowing the alloy to achieve excellent environmental corrosion resistance.As a result,strength and corrosion resistance are simultaneously improved.

关键词： al-mg alloy al3Er Strength Corrosion resistance Er