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Journal of Magnesium and Alloys 2020年第1期8卷 91-102页

作者： mengran zhou Yoshiaki Morisada Hidetoshi Fujii Joining and Welding Research Institute(JWRI) Osaka UniversityJapan

The effects of 2%Ca addition on the microstructure and the mechanical properties of the asymmetric double-sided friction stir welded magnesium alloy AZ61 were *** to the Ca-free AZ61magnesium alloy,the addition of 2%Ca significantly refines the grains in the stir zone after *** to the existence of thermally stable Al2Ca particles,there is no noticeable change in the grain size in the stir zone regardless of the welding heat *** electron backscattered diffraction analysis at the center of the stir zone confirmed the significant deterioration of the(0001)texture strength from the addition of 2%*** tensile test of the joint suggested that the addition of 2%Ca provides stable tensile properties to the joint regardless of the welding *** critical(0001)texture strength that determines the ultimate tensile strength decreased from 20 to 15 by the Ca *** addition of Ca enhanced the deterioration of the plastic elongation when the(0001)texture strength increased.

关键词： Mg alloy Friction stir welding Microstructure Mechanical properties Texture

Simultaneous enhancement of mechanical properties and corrosion resistance of as-cast Mg-5Zn via microstructural modification by friction stir processing

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Journal of Magnesium and Alloys 2023年第6期11卷 1931-1943页

作者： Fei Long Gaoqiang Chen mengran zhou Qingyu Shi Qu Liu State Key Laboratory of Tribology Tsinghua UniversityBejjing 100084China Department of Mechanical Engineering Tsinghua UniversityBejjing 100084China

Magnesium alloys are ideal lightweight materials;however,their applications are extremely limited due to their low strength,poor ductility,and weak corrosion *** the present study,a friction stir processing(FSP)treatment was employed to optimize the mechanical properties and corrosion resistance of an as-cast Mg-5Zn *** average grain size of the Mg-5Zn alloy was refined from 133.8μm to1.3μm as a result of *** different directions,FSP exhibited the enhancement effects on different mechanical ***,according to the potentiodynamic polarization results,the corrosion current density at the free-corrosion potential of the FSPed sample,was 4.1×10^(-6)A/cm^(2)in 3.5 wt.%Na Cl aqueous solution,which was significantly lower than that of the as-cast *** impedance spectroscopy revealed that the polarization impedance,Rp,of the FSPed sample was 1534Ω/cm^(2)in 3.5 wt.%NaCl aqueous solution,which was 71.4%greater than that of the as-cast *** corrosion morphology of the FSPed sample in 3.5 wt.%NaCl aqueous solution exhibited largely uniform corrosion,rather than severe localized corrosion characteristics,which further reduced the corrosion depth on the basis of reducing the corrosion current *** results presented herein indicate that FSP is a viable technique for simultaneously improving the mechanical properties and corrosion resistance of the as-cast Mg-5Zn alloy.

关键词： Friction stir processing Magnesium alloy Corrosionmode Texture softening Anisotropy in mechanical properties

Quasi-in-situ investigation into the microstructure and texture evolution of pure magnesium during friction stir welding

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Journal of Magnesium and Alloys 2020年第4期8卷 1071-1083页

作者： zhou mengran Sun Yufeng Morisada Yoshiaki Ushioda Kohsaku Fujii Hidetoshi Joining and Welding Research Institute Osaka UniversityOsaka 567-0047Japan The State Key Laboratory of Tribology Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China School of materials science and engineering Zhengzhou UniversityZhengzhou 450001China

The quasi-in-situ microstructure and texture evolution along the real flow path of pure magnesium during friction stir welding were *** representative stages were involved from the base metal to the formation of the final stir *** material experienced compression,preheating,acceleration,deceleration,and subsequent annealing over the course of the welding process.A highly concentrated(0001)texture,denoted as''orientation convergence^,was initiated at the beginning of the acceleration stage(shearing deformation zone)in front of the *** continuous and discontinuous dynamic recrystallization occurred simultaneously in the stir zone,and continuous dynamic recrystallization was determined to be the primary recrystallization *** marker material morphology and EBSD data were used to elucidate the in-situ evolution of the shear direction and shear plane along with the real flow path.

关键词： Magnesium Friction stir welding Texture evolution Material flow EBSD

Effect of the processing route on the microstructure and mechanical behavior of superlight Mg-9Li-1Zn alloy via friction stir processing

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Journal of Magnesium and Alloys 2022年第11期10卷 3064-3081页

作者： mengran zhou Zhuoran Zeng Chun Cheng Yoshiaki Morisada Qingyu Shi Jian-Yih Wang Hidetoshi Fujii Joining and Welding Research Institute(JWRI) Osaka UniversityOsakaJapan Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China State Key Laboratory of Tribology Tsinghua UniversityBeijingChina Key Laboratory for Advanced Materials Processing Technology Ministry of Education of China Tsinghua UniversityBeijing 100084China College of Engineering and Computer Science Australian National UniversityACT 2601Australia Department of Materials Science and Engineering National Dong-Hwa UniversityHwa-LianTaiwanChina

In this study, the effect of the processing route using a friction stir processing(FSP) method on the microstructure and mechanical behavior of a Mg-9Li-1Zn alloy was systematically investigated. In the FSP method, the odd-numbered(1st and 3rd) process directions and even-numbered(2nd and 4th) passes were alternated to distribute the strain throughout the whole processed zone uniformly. Consequently, the processed zone had a much more uniform microstructure and hardness distribution than the processed zone obtained using the conventional FSP method. Using this method, the grain size of a Mg-9Li-1Zn sheet alloy was refined from ~31 μm to ~0.21 μm with uniformly distributedα and β phases. The processed alloy exhibited a high strength-ductility synergy with an ultimate tensile strength(UTS) of 220.1 MPa and total elongation of 70.0% at a strain rate of 10^(-3)s^(-1), overwhelmingly higher than those of the base metal, 155.6 MPa in UTS and 36.0%in elongation. The in-situ SEM-DIC analysis and TEM observation demonstrated that such an outstanding ductility with moderate strength is caused by grain boundary sliding, the dominant deformation mechanism of the ultra-fine-grained sample after FSP. The processing route with reverse processing direction was proven to be efficient in producing the ultrafine grain size microstructure and improving the mechanical properties of superlight Mg-9Li-1Zn alloy.

关键词： Mg-Li-Zn alloy Friction stir processing Microstructure In-situ SEM-DIC Mechanical properties

Microstructural evolution and its influence on mechanical and corrosion behaviors in a high-Al/Zn containing duplex Mg-Li alloy after friction stir processing

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Journal of Materials Science & Technology 2024年第17期184卷 245-255页

作者： Yixing Zhu mengran zhou Yingxin Geng Shun Zhang Tongzheng Xin Gaoqiang Chen Yifan zhou Xiaoyu zhou Ruizhi Wu Qingyu Shi State Key Laboratory of Clean and Efficient Turbomachinery Power Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology Ministry of EducationBeijing 100084China Key Laboratory of Superlight Materials&Surface Technology(Ministry of Education) Harbin Engineering UniversityHarbin 150001China Key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian 116024China Beijing North Vehicle Group Corporation Beijing 100072China

Ultralight Mg-Li alloys offer promising applications across various ***-Li alloys enriched with Al and Zn hold theoretical potential for achieving excellent mechanical strength and corrosion ***,the structural and performance characteristics of such Mg-Li alloys,particularly after thermo-mechanical processing,remain inadequately explored and *** study investigated the mi-crostructural evolution of a Mg-9Li-5Al-4Zn alloy after friction stir processing and its consequent effects on the mechanical and corrosion *** grain size of the alloy was effectively refined and sta-bilized during friction stir processing at various heat *** yield strength of the alloy increased by 86.4%after friction stir processing under the highest heat input condition,which was attributed to fine grain strengthening,solid solution strengthening and dispersion ***,the alloy ex-perienced a slight decrease in elongation after the friction stir *** alloy subjected to friction stir processing with the highest heat input exhibited a minimal corrosion current density of 6.10×10^(−6) A/cm^(2),which was only 25%of the base *** enhanced anti-corrosion properties can be attributed to the dispersion and distribution of precipitated particles induced by friction stir processing,which hin-dered the micro-galvanic corrosion and promoted the generation of a compact surface film,leading to minimal and uniform *** investigation can be significant for understanding the metallurgical mechanisms and performance evolution of Mg-Li alloys during thermomechanical processes.

关键词： Mg-Li-Al-Zn alloy Friction stir processing Microstructure evolution Thermal-mechanical stability Corrosion behavior

Influence of high temperature oxidation on mechanical properties and in vitro biocompatibility of WE43 magnesium alloy fabricated by laser powder bed fusion

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Journal of Materials Science & Technology 2024年第12期179卷 26-39页

作者： Jinge Liu Shuyuan Min Zijun Mao mengran zhou Bingchuan Liu Dazhi Liu Fei Song Peng Wen Yun Tian Yufeng Zheng The State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China Department of Orthopaedics Peking University Third HospitalBeijing 100191China Institute for Precision Medicine Tsinghua University Beijing Tsinghua Changgung HospitalBeijing 102218China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Engineering Research Center of Bone and Joint Precision Medicine Ministry of EducationBeijing 100191China School of Materials Science and Engineering Peking UniversityBeijing 100871China Tangshan Weihao Magnesium Powder Co. Ltd.Qian'an 064406China

Laser powder bed fusion(L-PBF)has been used to fabricate biodegradable Mg implants of WE43 alloy,but the degradation is too fast compared with the term bone *** studies show that high temperature oxidation(HTO)can successfully inhibit the degradation of WE43 *** this work,the influence of HTO on L-PBF samples of WE43 alloy was investigated regarding tensile,compressive,and abrasive resistance,as well as in vitro cytotoxicity,cell proliferation,hemolysis,and *** with the as-built L-PBF samples,HTO increased grain size and grain texture,stabilized and coarsened precipitates,and caused discontinuous static recrystallization in the *** oxide layer at the surface of the HTO samples improved surface roughness,hydrophilia,hardness,and abrasive *** tensile strength decreased slightly from 292 to 265 MPa,while the elongation substantially increased from 10.97%to 16.58%after *** in vitro cell viability,cell proliferation,hemolysis,and osteogenic effect were considerably enhanced due to the improvement of surface quality and the initial inhibition of excessive Mg^(2+)***,HTO is of great benefit to the surface performance,ductility,and biocompatibility of WE43 alloy fabricated by L-PBF for biodegradable applications.

关键词： Additive manufacturing Biodegradable metal Magnesium alloy WE43 High temperature oxidation

Influence of layer thickness on formation quality,microstructure,mechanical properties,and corrosion resistance of WE43 magnesium alloy fabricated by laser powder bed fusion

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Journal of Magnesium and Alloys 2024年第4期12卷 1367-1385页

作者： Bangzhao Yin Jinge Liu Bo Peng mengran zhou Bingchuan Liu Xiaolin Ma Caimei Wang Peng Wen Yun Tian Yufeng Zheng State Key Laboratory of Tribology in Advanced Equipment Beijing100084China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Institute for Precision Medicine Tsinghua UniversityBeijing102218China Department of Orthopaedics Peking University Third HospitalBeijing 100191China Beijing AKEC Medical Co. Ltd.Beijing 102200China School of Materials Science and Engineering Peking UniversityBeijing 100871China Engineering Research Center of Bone and Joint Precision Medicine Ministry of EducationBeijing 100191China

Laser powder bed fusion(L-PBF)of Mg alloys has provided tremendous opportunities for customized production of aeronautical and medical *** thickness(LT)is of great significance to the L-PBF process but has not been studied for Mg *** this study,WE43 Mg alloy bulk cubes,porous scaffolds,and thin walls with layer thicknesses of 10,20,30,and 40μm were *** required laser energy input increased with increasing layer thickness and was different for the bulk cubes and porous *** tended to occur at the connection joints in porous scaffolds for LT40 and could be eliminated by reducing the laser energy *** thin wall parts,a large overhang angle or a small wall thickness resulted in porosity when a large layer thicknesses was used,and the porosity disappeared by reducing the layer thickness or laser energy input.A deeper keyhole penetration was found in all occasions with porosity,explaining the influence of layer thickness,geometrical structure,and laser energy input on the *** the samples achieved a high fusion quality with a relative density of over 99.5%using the optimized laser energy *** increased layer thickness resulted to more precipitation phases,finer grain sizes and decreased grain *** the similar high fusion quality,the tensile strength and elongation of bulk samples were significantly improved from 257 MPa and 1.41%with the 10μm layer to 287 MPa and 15.12%with the 40μm layer,in accordance with the microstructural *** effect of layer thickness on the compressive properties of porous scaffolds was ***,the corrosion rate of bulk samples accelerated with increasing the layer thickness,mainly attributed to the increased number of precipitation phases.

关键词： Magnesium alloy WE43 Laser powder bed fusion Layer thickness Process optimization

Insight the long-term biodegradable Mg-RE-Sr alloy for orthopaedics implant via friction stir processing

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Bioactive Materials 2024年第11期41卷 293-311页

作者： Yixing Zhu mengran zhou Weikang Zhao Yingxin Geng Yujie Chen Han Tian Yifan zhou Gaoqiang Chen Ruizhi Wu Yufeng Zheng Qingyu Shi State Key Laboratory of Clean and Efficient Turbomachinery Power Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing100084PR China Key Laboratory for Advanced Materials Processing Technology Ministry of EducationBeijing100084PR China Department of Orthopedics The First Affiliated Hospital of Chongqing Medical UniversityChongqing400016PR China Key Laboratory of Superlight Materials&Surface Technology(Ministry of Education) Harbin Engineering UniversityHarbin150001PR China School of Materials Science and Engineering Peking UniversityBeijing100871PR China

Magnesium alloys,noted for their substantial mechanical strength and exceptional biocompatibility,are increasingly being considered for use in biodegradable ***,their rapid degradation and significant hydrogen release have limited their applications in *** this study,a novel Mg-RE-Sr alloy was created by friction stir processing to modify its microstructure and enhance its degradation *** microstructural characterization,the friction stir processing effectively refined the grains,accelerated the re-dissolution of precipitates,and ensured a uniform distribution of these *** processed alloy demonstrated improved comprehensive properties,with an in vitro corrosion rate of approximately 0.4 mm/y and increases in ultimate tensile strength and elongation by 37%and 166%,***,in vivo experiments involving a rat subcutaneous implantation model revealed a slower degradation rate of 0.09 mm/y and a uniform degradation process,basically achieving the requirements for ideal performance in orthopaedic *** superior degradation characteristics were attributed to the synergistic effect of attenuated galvanic corrosion and the formation of a dense Y(OH)3/Y2O3 film induced by an exceptional microstructure with a highly solid-soluted matrix and uniformly refined ***,the alloys exhibited excellent biocompatibility and did not cause undesirable inflammation or produce toxic degradation *** improvements in biocompatibility and degradation characteristics indicate great promise for the use of this friction stir processed alloy in osteosynthesis systems in the clinical setting.

关键词： Magnesium alloy Friction stir processing Microstructural evolution Biodegradable Biocompatibility

A novel aluminum-carbon nanotubes nanocomposite with doubled strength and preserved electrical conductivity

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Nano Research 2021年第8期14卷 2776-2782页

作者： Shuai Zhang Gaoqiang Chen Timing Qu Jinquan Wei Yufan Yan Qu Liu mengran zhou Gong Zhang Zhaoxia zhou Huan Gao Dawei Yao Yuanwang Zhang Qingyu Shi Hua Zhang State Key Laboratory of Tribology Key Laboratory for Advanced Materials Processing Technology Ministry of Education of ChinaDepartment of Mechanical Engineering Tsinghua UniversityBeijing 100084China Key Lab for Advanced Materials Processing Technology of Education Ministry School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Loughborough materials characterization center Department of materialsLoughborough UniversityLoughboroughLEU 3TUUK State Key Laboratory of Special Cable Technology Shanghai Electric Cable Research Institute Co.Ltd.Shanghai 200093China School of Mechanical Engineering Beijing Institute of Petrochemical Technology Beijing 102617China

Enhancing the mechanical strength of highly conductive pure metals usually causes significant reduction in their electrical *** example,introducing phase/matrix interfaces or more grain boundaries,are common and effective methods to strengthen *** it simultaneously increases the electron scattering at the interface,thus reducing the electrical *** this study,we demonstrate that pure aluminum(Al)/carbon nanotubes(CNTs)nanocomposites prepared by friction stir processing have successfully broken through these *** yield strength and tensile strength of Al/CNTs nanocomposites have improved by 104.7%and 51.8%compared to pure Al,while the electrical conductivity remained comparable to that of pure *** explore the potential mechanisms,the interface between CNTs and Al was examined and characterized by transmission electron microscopy(TEM)and Raman *** interfacial reaction compounds were present and no visible physical gaps were observed at CNTs and Al *** defined it as a clean and tightly bonded *** the quantity of phase interface has increased,the electrical conductivity of the nanocomposite remains approximately *** attribute the preserved electrical conductivity to the clean and tightly bonded CNTs/Al interface in the nanocomposite.

关键词： carbon nanotubes/aluminum nanocomposites mechanical properties electrical conductivity friction stir processing interface

Application of the Spectrum Peak Positioning Technology Based on BP Neural Network in Demodulation of Cavity Length of EFPI Fiber Optical Sensor

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Journal of Computer and Communications 2013年第7期1卷 67-71页

作者： mengran zhou Mengya Nie Anhui University of Science and Technology Huainan Anhui China.

An Extrinsic Fabry-Perot Interferometric (EFPI) fiber optical sensor system is an online testing system for the gas density. The system achieves the measurement of gas density information mainly by demodulating the cavity length of EF- PI fiber optical sensor. There are many ways to achieve the demodulation of the cavity length. For shortcomings of the big intensity demodulation error and complex structure of phase demodulation, this paper proposes that BP neural net-work is used to locate the special peak points in normalized interference spectrum and combining the advantages of the unimodal and bimodal measurement achieves the demodulation of the cavity length. Through online simulation and actual measurement, the results show that the peak positioning technology based on BP neural network can not only achieve high-precision demodulation of the cavity length, but also achieve an absolute measurement of cavity length in large dynamic range.

关键词： EFPI Fiber Optical Sensor The Demodulation of Cavity Length BP Neural Network The Peak Positioning Technology