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Flow field design and process stability in electrochemical machining of diamond holes

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Chinese Journal of Aeronautics 2016年第6期29卷 1830-1839页

作者： Zhao Jianshe Wang Feng Liu Zhuang Zhang Xiangli gan weimin Tian Zongjun College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Digital ECM Building Laboratory of Jiangsu Province Changzhou Institute of Technology

The metal grille, commonly composed of an amount of diamond holes, has been growingly used as a key structure on stealth aircraft. Electrochemical machining(ECM) promises to be increasingly applied in aircraft manufacturing on the condition that process stability is *** this work, a flow field model was designed to improve the process stability. This model is endowed with a variety of flow channel features, together with vibrating feeding modes. The flow field distribution on the bottom surface of the diamond hole was discussed and evaluated as *** numerical results show that a short arc flow channel could significantly enhance the uniformity of electrolyte velocity distribution and a vibrating feeding of the cathode enables to reduce both fluctuations of the electrolyte velocity and pressure on the bottom surface of the diamond ***, the flow field mutations were eliminated. It is verified from the experimental results that a short arc flow channel, when combined with vibrating feeding, is capable of improving machining localization and process stability markedly. What is more, the side gap on the bottom surface of the diamond hole could also be reduced by the abovementioned approach.

关键词： Diamond hole Electrochemical machining Flow fields Stability Vibrating

Improving the Young’s modulus of Mg via alloying and compositing–A short review

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Journal of Magnesium and Alloys 2022年第8期10卷 2009-2024页

作者： Hailong Shi Chao Xu Xiaoshi Hu weimin gan Kun Wu Xiaojun Wang National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of TechnologyHarbin 150001PR China Center for Analysis and Measurement Harbin Institute of TechnologyHarbin 150001PR China GEMS at MLZ Helmholtz-Zentrum Hereon Lichtenbergstrsasse 1Garching D-85748Germany School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001PR China

Lightweight,high-modulus structural materials are highly desired in many applications like aerospace,automobile and biomedical *** the lightest metallic structural material,magnesium(Mg)has great potential but is limited by its low intrinsic Young’s *** paper reviews the investigations on high-modulus Mg-based materials during the last *** nature of elastic modulus is introduced,and typical high-modulus Mg alloys and Mg matrix composites are ***,Mg alloys enhance Young’s modulus of pure Mg mainly by introducing suitable alloying elements to promote the precipitation of high-modulus second phases in the alloy ***,Mg matrix composites improve Young’s modulus by incorporating high-modulus particles,whiskers and fibers into the Mg *** modulus strengthening effectiveness brought by the two approaches is compared,and Mg matrix composites stand out as a more promising *** addition,two well-accepted modulus prediction models(Halpin-Tsai and Rule of mixtures(ROM))for different Mg matrix composites are *** effects of reinforcement type,size,volume fraction and interfacial bonding condition on the modulus of Mg matrix composites are ***,the existing challenges and development trends of high-modulus Mg-based materials are proposed and prospected.

关键词： Elastic modulus Mg alloy Mg matrix composite Modulus prediction model Mechanical properties

Studies on reaction mechanisms and distinct chemiluminescence from cyanoimino neonicotinoids triggered by peroxymonosulfate in advanced oxidation processes

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Chinese Chemical Letters 2023年第3期34卷 206-208页

作者： Mengdie Cai weimin gan Zhiqin Ding Hongping Cai Lijun Wei Xianglei Cheng Jiangxi Province Key Laboratory of Preventive Medicine School of Public HealthNanchang UniversityNanchang 330006China

In this study, we proposed a novel method to investigate the advanced oxidation process of neonicotinoids(NNIs) from the perspective of concomitant chemiluminescence(CL) reaction. It was found that in the presence of cobalt ions with cyanoimino NNIs, acetamiprid(ACE) and thiacloprid(THI), could promote peroxymonosulfate and Ru(bpy)_(3)^(2+) to produce strong CL, but no CL occurred with nitro-involved NNIs as alternatives. Experimental dada from UV absorption spectra and chemiluminescence spectra suggested that new cyclic compounds might be formed during the reaction. Based on the results of free radical scavenging experiment and mass spectra, a new degradation and reaction mechanism of cyanoiminocontaining NNIs was proposed. ACE or THI were first attacked by SO_(4)^(·-) to form benzyl radicals, which in turn reacted with the carbon atoms of cyano group through electrophilic addition reaction in the formation of intramolecular ring. Then a redox reaction between Ru(bpy)_(3)^(3+) and imino group immediately took place with CL emission(610 nm). The new mechanistic knowledge would be meaningful for other contaminants for their interactions with PMS.

关键词： Advanced oxidation processes Chemiluminescence mechanisms Annulation reaction Peroxymonosulfate Acetamiprid Thiacloprid

New insight into deformation induced α variant selection in a metastable β titanium alloy during isothermal compression at 600℃

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Progress in Natural Science:Materials International 2021年第3期31卷 471-476页

作者： Ke Hua Fan Zhang Hongchao Kou Qiong Wan Yongliang Zhang weimin gan Jinshan Li State Key Laboratory of Solidification Processing Northwestern Polytechnical University Center of Advanced Lubrication and Seal Materials Northwestern Polytechnical University German Engineering Materials Science Center at MLZ Helmholtz-Center Geesthacht

Variant selection during phase transformation creates a specific transformation texture and finally affects the mechanical properties of the *** transformation lattice deformation associated selection mechanism has not been well *** the present work,the a variant selection in a Ti-7 Mo-3 Nb-3 Cr-3 Al alloy under isothermal compression at low temperature was *** results show that the selection of the a variants is strongly affected by the imposed strain and the load with the dependence on the effective strain distribution induced by macroscopic shape *** the center region of the compressed sample,4 Burgers orientation relationship(BOR) variants orienting in four different directions and forming two sets of ’cross-shaped’ clusters were *** variants consumed the maximum strain contribution to the macroscopic *** the edge region of the compressed sample,only 2 BOR variants with 90°/ or 10°/ disorientation relationship were *** selection criterion was still obeyed by the variants but with restriction from the local effective strain distribution induced by macroscopic shape *** present work provides the clear information on the interweaving of the imposed compression with the internal lattice deformation and its impact on the β to α transformation variant selection.

关键词： Variant selection Phase transformation Titanium alloy Strain accommodation

Enhanced tensile plasticity of a CuZr-based bulk metallic glass composite induced by ion irradiation

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Journal of Materials Science & Technology 2019年第10期35卷 2221-2226页

作者： Peng Xue Simon Pauly weimin gan Songshan Jiang Hongbo Fan Zhiliang Ning Yongjiang Huang Jianfei Sun State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China IFW Dresden Institute for Complex MaterialsHelmholtzstraβe 20D-01069 DresdenGermany German Engineering Materials Science Centre(GEMS)at Heinz Maier-Leibnitz Zentrum(MLZ) Helmholtz-Zentrum Geesthacht GmbHGarchingGermany Key Laboratory of Micro-systems and Microstructures Manufacturing(Harbin Institute of Technology) Ministry of EducationHarbinChina

N^+ ion irradiation is utilized to tune the structure and mechanical properties of a Cu48Zr47.2Al4Nb0.8 bulk metallic glass composite(BMGC). Ion irradiation increases the disorder near the surface, as probed by neutron diffraction, and, moreover, causes the phase transformation from B2Cu Zr to B19’ CuZr martensitic phase in the studied BMGC. The tensile plasticity of the BMGC is dramatically improved after ion irradiation, which results from multiple shear banding on the surface and the martensitic transformation of the B2 to B19’ Cu Zr martensitic phase. The experimental results are strongly corroborated by complementary molecular dynamic simulations.

关键词： Bulk metallic glass composite Ion irradiation Neutron diffraction Molecular dynamics simulation Mechanical properties

Comparison on crack propagation under tension at 150℃ of Mg-2Zn-1.5Mn alloy sheets with and without crack notch

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Journal of Magnesium and Alloys 2023年第5期11卷 1536-1548页

作者： Qiang Liu Jiangfeng Song Qiuyan Shen Liangyin Wu Bin Jiang weimin gan Kaihong Zheng Fusheng Pan National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 400044China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China GEMS at MLZ Helmholtz-Zentrum HereonGarching D-85748Germany Institute of New Materials Guangdong Academy of SciencesGuangzhou 510650China

Generally,edge crack of rolled magnesium alloy sheets initiates in the RD(rolling direction)-ND(normal direction)plane and then propagate in the RD-TD(transverse direction)***,the Mg-2Zn-1.5Mn(ZM21)alloy sheets with and without crack notch were designed to carry out in-situ tensile experiments under 150℃(the same temperature of rolling),with the aim to understand their crack propagation *** scanning electron microscopy(SEM)and electron backscattered diffraction(EBSD)techniques were utilized to reveal microstructural evolution in real time at designated *** results show that the prismatic slip,basal slip,and extension twining play synergistic role in coordinating strain during the tensile process in ZM21 alloy sheet at 150℃.In both tensile samples with and without crack notch,localized strain is mainly concentrated at relatively fine grain area and the grain boundaries or triple junctions of the grains with large basal Schmid factor(SF)difference,which eventually leads to severe surface roughening and subsequent crack *** with the sample without crack notch,the pre-cracked sample exhibits severer deformation at the crack tip due to strain *** gradient distribution is observed at the crack tip region in the pre-cracked *** crack propagation path of the sample with pre-crack is identified and the underlying mechanism is also discussed.

关键词： ZM21 alloy In-situ tensile test Crack propagation path Crack notch

Impact of asymmetry deformation on microstructure and mechanical properties of AZ31B alloy sheets deformed by on-line heating rolling

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Progress in Natural Science:Materials International 2022年第1期32卷 96-103页

作者： Biquan Xiao Jiangfeng Song Hua Zhao Qiang Liu weimin gan Fei Guo Bin Jiang Fusheng Pan State Key Laboratory of Mechanical Transmission College of Materials Science and Engineering Chongqing University GEMS at MLZ Helmholtz-Zentrum Geesthacht College of Materials Science and Engineering Chongqing University of Technology National Engineering Research Center for Magnesium Alloy Chongqing University

The effect of asymmetry deformation on microstructure and mechanical properties of AZ31 sheet was investigated in the present paper. Two AZ31 sheets were rolled together with an on-line heating rolling mill and separated from each other afterwards. For each sheet, the strain on both surface during rolling was asymmetry and this rolling method is called asymmetry rolling(AR) in present work. For comparison, symmetry rolling(SR) was also carried out on the same rolling mill that only one sheet was rolled in one pass. The sheets deformed by AR showed more homogeneous microstructure with higher recrystallization level and symmetry distributional basal ***, SR sheets showed many narrow shear bands which distributed as “V” shape along rolling direction,while less shear bands with wider size are observed in AR sheet. The shear bands in AR sheet distributed as a line and across the entire thickness of the sheet, resulting in layered bimodal structure. Based on the unique microstructure and texture characteristics, AR sheet has lowest mechanical property anisotropy and a good balance of strength and elongation.

关键词： Magnesium Asymmetry rolling Microstructure Mechanical properties

Unexpected formation of hydrides in heavy rare earth containing magnesium alloys

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Journal of Magnesium and Alloys 2016年第3期4卷 173-180页

作者： Yuanding Huang Lei Yang Sihang You weimin gan Karl Ulrich Kainer Norbert Hort Institute of Materials Research Helmholtz-Zentrum GeesthachtZentrum für Material-und KüstenforschungMax-Planck-Str.121502 GeesthachtGermany Key Laboratory for Anisotropy and Texture of Materials Education Ministry of ChinaSchool of Materials Science and EngineeringNortheastern UniversityShenyang 110819China

Mg–RE(Dy,Gd,Y)alloys show promising for being developed as biodegradable medical *** is found that the hydride REH_(2) could be formed on the surface of samples during their preparations with water *** amount of formed hydrides in Mg–RE alloys is affected by the content of RE and heat *** increases with the increment of RE *** the surface of the alloy with T4 treatment the amount of formed hydride REH_(2) is *** contrast,the amount of REH2 is lower on the surfaces of as-cast and T6-treated *** formation mechanism is attributed to the surface reaction of Mg–RE alloys with *** part of RE in solid solution in Mg matrix plays an important role in influencing the formation of hydrides.

关键词： Magnesium alloy Microstructure Hydride Heat treatment Rare earths

Role of multi-microalloying by rare earth elements in ductilization of magnesium alloys

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Journal of Magnesium and Alloys 2014年第1期2卷 1-7页

作者： Yuanding Huang weimin gan Karl Ulrich Kainer Norbert Hort Institute of Materials Research Helmhlotz-Zentrum GeesthachtMax-Planck-Str.1D-21502 GeesthachtGermany

The present work investigates the influences of microalloying with rare earths on the mechanical properties of magnesium *** amount of each rare earth element is controlled below 0.4 wt.%in order not to increase the cost of alloy *** synergic effects from the multi-microalloying with rare earths on the mechanical properties are *** obtained results show that the as-cast magnesium alloys multi-microalloying with rare earths possesses a quite high ductility with a tensile strain up to 25-30%at room ***,these alloys exhibit much better corrosion resistance than AZ31 *** preliminary in situ neutron diffractions on the deformation of these alloys indicate that the multi-microalloying with rare earths seems to be beneficial for the activation of more slip *** deformation becomes more homogeneous and the resultant textures after deformation are weakened.

关键词： Microalloying Magnesium alloy Ductility Rare earth element