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Microstructural evolution in Al–Zn–Mg–Cu–Sc–Zr alloys during short-time homogenization

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International Journal of Minerals,Metallurgy and Materials 2015年第5期22卷 516-523页

作者： Tao Liu Chun-nian He Gen Li Xin Meng Chun-sheng Shi nai-qin zhao Department of Materials Science and Engineering Tianjin University Tianjin Key Laboratory of Composite and Functional Materials Collaborative Innovation Center of Chemical Science and Engineering

Abstract： Microstructural evolution in a new kind of aluminum （A1） alloy with the chemical composition of AI-8.82Zn-2.08Mg- 0.80Cu-3.31Sc-0.3Zr was investigated. It is found that the secondary phase MgZn2 is completely dissolved into the matrix during a short homogenization treatment （470℃, 1 h）, while the primary phase A13（Sc,Zr） remains stable. This is due to Sc and Zr additions into the A1 al- loy, high Zn/Mg mass ratio, and low Cu content. The experimental findings fit well with the results calculated by the homogenization diffusion kinetics equation. The alloy shows an excellent mechanical performance after the short homogenization process followed by hot-extrusion and T6 treatment. Consequently, a good combination of low energy consumotion and favorable mechanical properties is obtained.

关键词： aluminum alloys microstructural evolution short-time ,homogcnization grain refinement

Carbon and few-layer MoS2 nanosheets co-modified TiO2 nanosheets with enhanced electrochemical properties for lithium storage

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Rare Metals 2018年第2期37卷 107-117页

作者： Hui-Hui Lu Chun-Sheng Shi nai-qin zhao En-Zuo Liu Chun-Nian He Fang He Tianjin Key Laboratory of Composite and Functional Materials Tianjin UniversityTianjin 300350China Collaborative Innovation Center of Chemical Science and Engineering Tianjin 300072China

Carbon and few-layer MoS2 nanosheets co- modified TiO2 nanocomposites （defined as MoS2-C@TiO2） were prepared through a facile one-step pyrolysis reaction technique. In this unique nanostructure, the TiO2 nanosh- eets with stable structure serve as the backbones, and carbon coating and few-layer MoS2 tightly adhere onto the surface of the TiO2. It needs to be pointed out that the carbon coating improves the overall electronic conductivity and the few-layer MoS2 facilitates the diffusion of lithium ions and offers more active sites for lithium-ion storage. As a result, when evaluated as lithium-ion battery anodes, the MoS2-C@TiO2 nanocomposites exhibit markedly enhanced lithium storage capability compared with pure TiO2. A high specific capacity of 180 mA.h.g-1 has been achieved during the preliminary cycles, and the specific capacity can maintain 160 mA.h.g-1 at a high current density of 1C （1C=167 mA.g-1） even after 300 discharge/ charge cycles, indicating the great potential of the MoS2- C@TiO2 on energy storage.

关键词： Few-layer MoS2 nanosheets Carbon Co-modified TiO2 nanosheets Lithium-ion battery anodes

Microstructural evolution and mechanical behavior of in situ synthesized MgAl_(2)O_(4)whiskers reinforced 6061 Al alloy composite after hot extrusion and annealing

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Rare Metals 2023年第5期42卷 1732-1742页

作者： Geng Hao Chun-Sheng Shi nai-qin zhao En-Zuo Liu Chun-Nian He Fang He Li-Ying Ma School of Materials Science and Engineering Tianjin UniversityTianjin 300350China Tianjin Key Laboratory of Composite and Functional Materials Tianjin UniversityTianjin 300350China Collaborative Innovation Centre of Chemical Science and Engineering Tianjin 300072China

In situ synthesized MgAl2O4whiskers reinforced 6061 Al alloy composites were fabricated by a powder metallurgy ***-sized MgAl2O4spinel whiskers distributed uniformly in 6061 Al alloy matrix without any interfacial product and laid along the extrusion direction after hot ***-extruded composite samples were annealed at 530,580,600 and 630℃for 1 h and examined by electron backscattered diffraction to investigate the recrystallization behavior of obtained *** and texture evolution was investigated,and it is found that the recrystallization process is inhibited by whiskers because of Zener *** fibrous grains remain until 630℃,and deformation textures still exist even in specimen annealed at 630℃.Hardness and tensile tests show that the completely recrystallized sample has an ultimate tensile strength of 218 MPa and a hardness of HV52 compared with 283 MPa and HV 69 of the unannealed *** properties of the annealed samples decline slightly with annealing temperature increasing up to 600℃.

关键词： Composite In situ synthesized whiskers Recrystallization Microstructure Texture

Fabrication of Carbon Nanotube-Reinforced 6061Al Alloy Matrix Composites by an In Situ Synthesis Method Combined with Hot Extrusion Technique

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Acta Metallurgica Sinica(English Letters) 2016年第2期29卷 188-198页

作者： Chun-Nian He Chao Feng Ji-Chuan Lin En-Zuo Liu Chun-Sheng Shi Jia-Jun Li nai-qin zhao School of Materials Science and Engineering Tianjin KeyLaboratory of Composite and Functional MaterialsTianjin University Tianjin 300072 China Collaborative Innovation Center of Chemical Science and Engineering Tianjin 300072 China Chengdu SIWI High-Tech Industry Co. Ltd Chengdu 611731 China

Carbon nanotube （CNT）-reinforced 6061Al alloy matrix composites were prepared by chemical vapor depo- sition （CVD） combined with hot extrusion technique. During the preparation process, the 6061Al flakes obtained by ball milling of the 6061Al spherical powders were subjected to surface modification to introduce a hydrophilic polyvinyl alcohol （PVA） membrane on their surface （6061Al@PVA） to bond strongly with nickel acetate [Ni（II）]. Then the 6061Al@PVA flakes bonded with Ni（II） were calcined and reduced to Ni nanoparticles, which were then heat-treated at 580 ℃ to remove PVA for obtaining even Ni/6061Al catalyst. After that, the as-obtained Ni/6061Al catalyst was employed to synthesize CNTs on the surface of the 6061Al flakes by CVD. After hot extrusion of the CNT/6061Al composite powders, the as-obtained CNT/6061Al bulk composites with 2.26 wt% CNTs exhibited 135% increase in yield strength and 84.5% increase in tensile strength compared to pristine 6061Al matrix.

关键词： Metal matrix composites (MMCs) Microstructure Mechanical properties Carbon

In-situ homogeneous synthesis of carbon nanotubes on aluminum matrix and properties of their composites

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Transactions of Nonferrous Metals Society of China 2014年第7期24卷 2331-2336页

作者：李海鹏范佳薇康建立赵乃勤王雪霞李宝娥天津大学材料科学与工程学院天津300072 河北工业大学材料科学与工程学院天津300130 天津工业大学材料科学与工程学院天津300387

Using nickel catalyst supported on aluminum powders, carbon nanotubes （CNTs） were successfully synthesized in aluminum powders by in-situ chemical vapor deposition at 650 ℃. Structural characterization revealed that the as-grown CNTs possessed higher graphitization degree and straight graphite shell. By this approach, more homogeneous dispersion of CNTs in aluminum powders was achieved compared with the traditional mechanical mixture methods. Using the in-situ synthesized CNTs/Al composite powders and powder metallurgy process, CNTs/Al bulk composites were prepared. Performance testing showed that the mechanical properties and dimensional stability of the composites were improved obviously, which was attributed to the superior dispersion of CNTs in aluminum matrix and the strong interfacial bonding between CNTs and matrix.

关键词： aluminum matrix composites carbon nanotubes chemical vapor deposition in-situ synthesis

用非晶合金细化变质处理A356铝合金的显微组织和力学性能

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机械工程材料 2017年第1期41卷 65-71页

作者：苏云高崔振铎朱胜利(指导) 赵乃勤丁俭赵维民天津大学材料科学与工程学院天津300072 天津市材料复合与功能化重点实验室天津300072 河北工业大学材料科学与工程学院先进材料加工与装备研究所天津300132

通过添加不同量的Zr_(56)Co_(22)Al_(16)Ag_6非晶合金条带对用Al-5Ti-1B预细化的A356铝合金进行细化变质处理,然后再进行固溶时效热处理,研究了合金的显微组织和力学性能,并探讨了非晶合金的细化强化机制。结果表明:随着非晶合金添加量... 详细信息

通过添加不同量的Zr_(56)Co_(22)Al_(16)Ag_6非晶合金条带对用Al-5Ti-1B预细化的A356铝合金进行细化变质处理,然后再进行固溶时效热处理,研究了合金的显微组织和力学性能,并探讨了非晶合金的细化强化机制。结果表明:随着非晶合金添加量的增加,铝合金的晶粒尺寸和二次枝晶间距均逐渐减小,力学性能得到了提高;铝合金的共晶组织中出现了弥散分布的颗粒状Al_3Zr相,该相作为非均质形核的核心,起到细化晶粒的作用;加入质量分数为0.4%的非晶合金,并设定孕育期为10min,铝合金可获得最佳的细化效果,其经固溶时效处理后的抗拉强度和伸长率比未加入非晶合金的分别提高了7%和64.4%。

关键词： A356铝合金 Zr56Co22Al16Ag6非晶合金条带力学性能

加入Al-5Ti-B细化剂和Al-2Zr-Sc中间合金后铝锌镁合金的组织和拉伸性能

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机械工程材料 2017年第1期41卷 38-42页

作者：丁俭杜喜望靳子惠夏兴川赵乃勤赵维民刘利华河北工业大学材料科学与工程学院天津300130 天津大学材料科学与工程学院天津300072 中信戴卡轮毂制造有限公司秦皇岛066003

在单独或复合添加Al-2Zr-Sc中间合金和Al-5Ti-B细化剂的条件下对铝锌镁合金进行细化处理,研究了不同细化条件下铸态铝镁锌合金的显微组织和力学性能。结果表明:单独加入质量分数为0.4%的Al-2Zr-Sc中间合金或Al-5Ti-B细化剂都可以细化铝... 详细信息

在单独或复合添加Al-2Zr-Sc中间合金和Al-5Ti-B细化剂的条件下对铝锌镁合金进行细化处理,研究了不同细化条件下铸态铝镁锌合金的显微组织和力学性能。结果表明:单独加入质量分数为0.4%的Al-2Zr-Sc中间合金或Al-5Ti-B细化剂都可以细化铝镁锌合金的晶粒,且加入Al-2Zr-Sc中间合金后有Al3(Sc,Zr)相析出,提高了合金的抗拉强度;复合添加质量分数均为0.2%的Al-2Zr-Sc中间合金和Al-5Ti-B细化剂后,晶粒的细化效果最优,相比于基体合金,平均晶粒尺寸减小了20μm,抗拉强度提高了32%,这主要是细晶强化和析出强化共同作用的结果;晶界处长杆状第二相的存在导致复合细化合金的伸长率比单独细化合金的低。

关键词：铝锌镁合金稀土钪细化剂力学性能

Persistent alterations in gray matter in COVID-19 patients experiencing sleep disturbances:a 3-month longitudinal study

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Neural Regeneration Research 2025年第10期20卷 3013-3024页

作者： Kaixuan Zhou Gaoxiong Duan Ying Liu Bei Peng Xiaoyan Zhou Lixia qin Lingyan Liang Yichen Wei qingping Zhang Xiaocheng Li Haixia qin Yinqi Lai Yian Lu Yan Zhang Jiazhu Huang Jinli Huang Yinfei Ouyang Bolin Bin Mingming zhao Jun Liu Jianrong Yang Demao Deng Guangxi Key Laboratory of Special Biomedicine School of MedicineGuangxi UniversityNanningGuangxi Zhuang Autonomous RegionChina Department of Radiology the People’s Hospital of Guangxi Zhuang Autonomous RegionGuangxi Academy of Medical SciencesNanningGuangxi Zhuang Autonomous RegionChina Department of Sleep Medicine the People’s Hospital of Guangxi Zhuang Autonomous RegionNanningGuangxi Zhuang Autonomous RegionChina Department of Radiology The Second Xiangya HospitalCentral South UniversityChangshaHunan ProvinceChina Guangxi Clinical Research Center for Sleep Medicine the People’s Hospital of Guangxi Zhuang Autonomous RegionNanningGuangxi Zhuang Autonomous RegionChina

Sleep disturbances are among the most prevalent neuropsychiatric symptoms in individuals who have recovered from severe acute respiratory syndrome coronavirus 2 *** studies have demonstrated abnormal brain structures in patients with sleep disturbances who have recovered from coronavirus disease 2019(COVID-19).However,neuroimaging studies on sleep disturbances caused by COVID-19 are scarce,and existing studies have primarily focused on the long-term effects of the virus,with minimal acute phase *** a result,little is known about the pathophysiology of sleep disturbances in the acute phase of *** address this issue,we designed a longitudinal study to investigate whether alterations in brain structure occur during the acute phase of infection,and verified the results using 3-month follow-up data.A total of 26 COVID-19 patients with sleep disturbances(aged 51.5±13.57 years,8 women and 18 men),27 COVID-19 patients without sleep disturbances(aged 47.33±15.98 years,9 women and 18 men),and 31 age-and gender-matched healthy controls(aged 49.19±17.51 years,9 women and 22 men)were included in this *** COVID-19 patients with sleep disturbances were included in a longitudinal *** found that COVID-19 patients with sleep disturbances exhibited brain structural changes in almost all brain *** cortical thicknesses of the left pars opercularis and left precuneus were significantly negatively correlated with Pittsburgh Sleep Quality Index ***,we observed changes in the volume of the hippocampus and its subfield regions in COVID-19 patients compared with the healthy *** 3-month follow-up data revealed indices of altered cerebral structure(cortical thickness,cortical grey matter volume,and cortical surface area)in the frontal-parietal cortex compared with the baseline in COVID-19 patients with sleep *** findings indicate that the sleep disturbances patients had altered morphology in the cortical an

关键词： brain structure cortical gray matter volume cortical surface area cortical thickness hippocampus magnetic resonance imaging Pittsburgh Sleep Quality Index severe acute respiratory syndrome coronavirus 2 infections sleep disturbances sub-cortical volume

ANALYSIS OF SEEPAGE FLOW IN A CONFINED AQUIFER WITH A STANDING COLUMN WELL

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Journal of Hydrodynamics 2007年第1期19卷 84-91页

作者： LI Min DIAO nai-ren FANG zhao-hong Engineering college Guangdong Ocean University Zhanjiang 524088 China The Ground Source Heat Pump Research Center Shandong Jianzhu University Jinan 250101 China

The standing column well for ground source heat pump systems is a promising technology with high efficiency and environmental benefit, where groundwater is drawn from the bottom of a well and then re-injected to its top after transferring heat with heat pumps. Heat transfer analysis of great significance and aquifer involves complex problems. Determining the groundwater seepage flow is a precondition to solve the energy equation describing the heat transfer of the system. Only when piezometric head is obtained, the seepage velocity can be determined according to Darcy＇s law. In this article the groundwater seepage flow in an axial symmetrical geometry was studied under the assumption that gross groundwater flow is neglected. An analytical solution of the groundwater seepage flow for a confined aquifer was acquired by using the integral transform method, which may provide a foundation for heat transfer analysis of the standing column well system.

关键词： ground source heat pump standing columnwell seepage flow heat transfer