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Microstructure and properties of joint for stirring brazing of dissimilar Al/Mg alloy during heating processes

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Rare Metals 2015年第4期34卷 245-250页

作者： hui-bin xu hui-bin Sun hui Yang Lu-Xin Chi Jun Chen School of Materials Science and Engineering Chongqing University of Technology

In this paper, 2024 Al alloy and AZ31B Mg alloy were brazed with aid of stirring without flux in air. The effects of the brazing temperature on microstructure and shear strength of the joint were investigated. The diffusion zone is found at joint interface near Al base metal, which consists of Al-Zn-Sn solid solution. At the same time, continuous intermetallic compounds （IMCs） phase and broken ones are found at joint interface near Mg base metal, which mainly consists of the Mg2Sn phase. With the increase of the brazing temperature, the shear strength at the joint interface near A1 base metal rises gradually. On the contrary, that of the joint interface near Mg base metal obviously decreases.

关键词： Stirring brazing 2024 Al alloy AZ31B Mg alloy Temperature

Corrosion Resistance of Friction Stir Welded Al–Cu–Li Alloy AA2099-T8

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Acta Metallurgica Sinica(English Letters) 2020年第1期33卷 127-134页

作者： Yan-Long Ma hui-bin xu Zhao-Yuan Liang Lei Liu College of Materials Science and Engineering Chongqing University of TechnologyChongqing 400054China Chongqing Municipal Engineering Research Center of Institutions of Higher Education for Special Welding Materials and Technology Chongqing University of TechnologyChongqing 400054China

In order to study the eff ect of friction stir welding(FSW)on corrosion resistance of Al–Cu–Li alloy AA2099-T8,the microstructure and microhardness of FSW joints were characterized,and then,the corrosion behavior of the FSW joints was investigated by the immersion and potentiodynamic polarization tests in a 3.5%NaCl solution at room *** is indicated that the alloy was softened by FSW,with the lowest hardness appearing at the boundary between the nugget zone and the thermo-mechanically aff ected *** exposed to the NaCl solution,the FSW joint was characterized by shallow pits and was free of severe localized corrosion,probably due to dissolution of T 1(A 2 CuLi)phase in the FSW *** is suggested that further work should be carried out to evaluate the galvanic coupling eff ect between the FSW joint and the base metal,as well as the stress corrosion cracking resistance of the FSW joint.

关键词： Frictions stir welding(FSW) Al–Cu–Li alloy AA2099 Localized corrosion

Microstructure, mechanical and corrosion properties of electron-beam-melted and plasma-transferred arc-welded WC_P/NiBSi metal matrix composites

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Rare Metals 2019年第9期38卷 814-823页

作者： Chang Liu hui Peng Yue Zhao Yuan Yuan Hong-Bo Guo hui-bin xu School of Materials Science and Engineering Beihang UniversityBeijing 100191China Beijing Key Laboratory for Advanced Functional Material and Thin Film Technology Beihang UniversityBeijng 100191China Key Laboratory of Aerospace Materials&Performance(Ministry of Education) Beihang UniversityBeijng 100191China School of Mechanical Materials and Mechatronic Engineering Faculty of Engineering and Information SciencesUniversity of WollongongWollongongNSW 2522Australia Zhuzhou Seed Cemented Carbide Technology Co.Ltd Zhuzhou 412000China

As one of the new additive manufacturing processes,electron beam melting(EBM)has seen its promising potential in the fabrication of metal matrix composites(MMCs)components with complex *** this work,WC_P/NiBSi MMCs were fabricated by EBM and plasma-transferred arc welding(PTAW)for a comparative *** microstructures of both samples were examined using a scanning electron microscope(SEM)equipped with an electron backscattered diffraction(EBSD)*** macrohardness was tested using a Rockwell hardness method(Type C),while the microhardness was measured using different loadings(0.5-1.0 N)based on different *** anti-abrasion performance was tested as per the ASTM G105 *** corrosion behavior of the MMCs was also assessed by potentiodynamic *** results indicate that the EBM bulk and the PTAW cladding MMCs exhibit different microstructures due to the different local solidification *** is believed to lead to the varied mechanical properties and corrosion resistance of the MMCs,and the possible mechanisms were also discussed.

关键词： Electron beam melting Metal matrix composites Microstructure Carbides Additive manufacturing

Existence patterns of Dy in β-NiAl from first-principles calculations

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Rare Metals 2016年第4期35卷 356-360页

作者： Tian Zhang Hong-Bo Guo Sheng-Kai Gong hui-bin xu School of Materials Science and Engineering Beihang University

Intermetallic compound β-NiA1 is a promising material in high temperature applications due to its high melting temperature, high strength, low density, and good oxidation resistance. However, its application remains limited because of its relatively poor cyclic oxidation resistance. Addition of reactive element （RE） Dy can improve the cyclic oxidation of NiA1 alloys significantly. However, the mechanism of Dy addition is not clear. Even the existence pattern of Dy in NiA1 is unspecified. Therefore, in the present study, the impurity formation energies of Dy in stoichiometric NiA1, Ni-rich, and Al-rich NiA1 for the substitution cases were studied by first-principles density functional theory. The results show that Dy could hardly substitute for either Ni or A1 atoms in NiA1. However, calculations for dissolution energies show that Dy could be easily dissolved in AI vacancies in all three types of NiA1, which provides a new existence pattern of Dy in NiA1 beyond experimental detection.

关键词： Existence pattern Dy A1 vacancies First-principles

Phase transition and mechanical properties of Ni_(30)Cu_(20)Mn_(37+x)Ga_(13-x)(x=0–4.5) alloys

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Rare Metals 2014年第5期33卷 547-551页

作者： Huan-Fang Wang Jing-Min Wang Cheng-Bao Jiang hui-bin xu School of Materials Science and Engineering Beijing University of Aeronautics and Astronautics

Ni30Cu20Mn37＋xGa13-x（x = 0–4.5） alloys were studied with the phase transformation and mechanical properties. With the increase of Mn content, the martensitic transformation temperatures increase and the Curie temperature decreases. Simultaneously, the room temperature microstructure evolves from single phase of austenite to dual phases containing martensite and precipitation. Both the ductility and the strength of the polycrystalline alloys are significantly improved by the precipitation. Coupled magnetostructural transition from weak magnetic martensite to ferromagnetic austenite is obtained in both single-phase and ductile dual-phase alloys.

关键词： Ferromagnetic shape memory alloys(FSMAs) Martensitic transformation Magnetostructural transition Mechanical properties

High-temperature oxidation resistance of Si-coated C/SiC composites

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Rare Metals 2024年第9期43卷 4566-4572页

作者： Jie Xiao Hua-Yue Zhang Sheng-Kai Gong hui-bin xu Hong-Bo Guo School of Materials Science and Engineering Beihang UniversityBeijing 100191China Key Laboratory of High-Temperature Structure Materials and Protective Coatings(Ministry of Industry and Information Technology) Beihang UniversityBeijing 100191China

In this paper,Si coatings were sprayed onto C/SiC composite substrates by atmospheric plasma spraying(APS).The high-temperature oxidation behavior of the substrate and coating at temperatures of 1100 and 1300℃was also *** C/SiC ceramic matrix composite will be damaged seriously and even failed due to the oxidation of carbon fibers in *** Si coating effectively improved the oxidation resistance of the C/SiC substrate in the high-temperature oxidation *** effect of the thickness of the Si coatings on the oxidation resistance was *** 150-μm coating is proved to enable the substrate to have the lowest oxidation weight loss and the best oxidation resistance after static oxidation for 5 h.

关键词： Ceramic matrix composites(CMCs) Carbon fiber Si coating Oxidation Plasma spray

Internal friction behavior of Ni_(50.5)Mni_(25)Ga_(24.5)alloy with cellular microstructure

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Rare Metals 2023年第5期42卷 1706-1711页

作者： Jun-Yi Liu Jing-Min Wang Cheng-Bao Jiang hui-bin xu Zhi-Song Xiao School of Materials Science and Engineering Beihang UniversityBeijing100191China School of Physics and Nuclear Energy Engineering Beihang UniversityBeijing100191China

Ni_(50.5)Mn_(25)Ga_(24.5)alloy with cellular microstructure was *** effect of the cellular microstructure on the internal friction(IF)behavior associated with martensitic transformation(MT),premartensitic transformation(PMT)and twin boundary motion(TBM)was *** with conventional NiMn-Ga alloys,the temperature span of the IF_(MT)peak is significantly expanded,the IF_(PMT)is weakened,and no IF_(TBM)is *** IF_(MT)and IF_(PMT)in the cellular microstructure exhibit unique frequency dispersion feature which has never been observed in conventional Ni-Mn-Ga *** effect of point defects associated with the cellular microstructure is considered to understand the observed results.

关键词： Martensitic transformations Internal friction Microstructure Point defects

Joint interface during arc milling brazing of aluminum alloy to low carbon steel with cutter milling at various rotation speeds

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Rare Metals 2017年第11期36卷 872-877页

作者： hui-bin xu Song Tang Hai-Feng Xi Peng-Yu Gao Mo-Yang Li School of Materials Science and Engineering Chongqing University of Technology State Key Laboratory of Advance Welding and Joining Harbin Institute of Technology

In this study, 5052 steel were joined by a new way aluminum alloy and Q235 of arc milling brazing, with the Zn15%A1 filler metal and no use of flux. Effect of rotation speed on mechanical properties and microstructure of joint interface was investigated. The results show that increasing rotation speed is in favor of formation of weld and spread of filler metal on substrate. The fine grain with homogeneous composition in brazed seam can be realized by the stronger stirring in pool induced by milling at more higher rotation speed. And, a composite joint reinforced with needle-like or block-like Fe-A1-Zn intermetallic compounds （IMCs） particle can be obtained by arc milling brazing, which comes from the reaction between steel scrape and Zn-A1 filler alloy. The test on strength of joint interface shows that with the increase in rotation speed, there is a peak value in variation ranges of strength of joint interface. This is to say, when rotation speed is 2720 ***-~, the strength of joint has maximum value （182.01 MPa）. Moreover, a thin and discontinuous IMCs layer at joint interface can be obtained by increasing rotation speed. But at a low or high rotation speed, there also is a crack at joint interface, which weakens the strength of joint interface. Only at 2720 ***-1, a good joint interface without an obvious crack can be realized.

关键词： Dissimilar materials Intermetallic compounds Rotation speed Arc brazing Milling

Directional solidification behavior of turbine blades in DZ125 alloy:design of blade numbers on assembly

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Rare Metals 2021年第5期40卷 1134-1144页

作者： Yong Shang Yan-Ling Pei Sheng-Kai Gong Yi Ru Yuan-Chao Yu Ru-Hao Zhou Shu-Suo Li hui-bin xu School of Materials Science and Engineering Beihang UniversityBeijing 100191China

The influence of blades assembly,i.e.,the blade number on the solidification process,heat exchange and grain structure on a directionally solidified Ni-based superalloy DZ125 was investigated by combining the experimental and simulation *** casting process was simulated thermodynamically by ProCAST software,where the interface heat transfer coefficient was precisely determined by a measurement with *** is a good agreement between experimental and simulation *** was interestingly found that with the number of blades increasing from 6 to 10,due to the decrease in radiation absorption efficiency,the maximum temperature and the heating rate decrease in the mold,during the preheat *** the withdrawal procedure,increased assembly numbers reduce the radiation exchange from mold to the enclosure,resulting in the decrease in cooling rate and temperature gradient of the *** the end of withdrawal,the slower cooling rate of the outside balances the temperature distribution of internal and external surfaces on the rabbet of blade.

关键词： Directional solidification Superalloy ProCAST Interfacial heat transfer coefficient