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Hot deformation characterization of as-homogenized Al-Cu-Li X2A66 alloy through processing maps and microstructural evolution

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Journal of Materials Science & Technology 2019年第10期35卷 2409-2421页

作者： Liwei Zhong wenli gao Zhaohui Feng Zheng Lu Congcong Zhu College of Materials Science and Engineering Hunan UniversityChangsha 410082China Institute of Aluminum Alloy Beijing Institute of Aeronautical MaterialsBeijing 100095China Beijing Engineering Research Center of Advanced Aluminum Alloys and Applications Beijing Institute of Aeronautical MaterialsBeijing 100095China

Uniaxial compression tests were carried out on an Al-Cu-Li alloy at a temperature range of 300–500℃ and a strain rate range of 0.001–10 s^-1. Four representative instability maps based on Gegel, AlexanderMalas(A-M), Kumar-Prasad(K-P) and Murty-Rao(M-R) criteria were constructed. Through formula deduction and microstructural observation, it can be concluded that M-R criterion is more accurate than K-P criterion, and the first two criteria are better than Gegel and A-M criteria. From a power dissipation map and a M-R instability map, the optimized processing parameters are 480–500℃/0.001–0.1 s^-1 and 420–480℃/0.1-1 s^-1. The corresponding microstructural analysis shows that dynamic recovery and partial dynamic recrystallization are main dynamic softening mechanisms. Transmission electron microscopy observation indicated that a large number of primary coarse T1(Al2 Cu Li) particles precipitated in the homogenized specimen. After deformation at 500℃, most of the primary T1 particles dissolved back into the matrix, and secondary fine T1 particles precipitated at deformation-induced dislocations, high angle grain boundaries and other dispersed particles.

关键词： Al-Cu-Li alloy Hot deformation Processing map Dynamic recrystallization Precipitate

Microstructure characteristics and mechanical properties of Al/Mg joints manufactured by magnetic pulse welding

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Journal of Magnesium and Alloys 2023年第7期11卷 2366-2375页

作者： Congcong Zhu Shiwei Xu wenli gao Yifan Meng Sen Lin Lu Dai College of Materials Science and Engineering Hunan UniversityChangsha 410082China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China Beijing Spacecrafts Beijing 100094China

The effective connection of 1050 Al and AZ31 Mg was realized by magnetic pulse *** maximum tensile-shear force of the dissimilar Al/Mg metal lap joint reached 97%of that of the 1050 Al alloy base material by optimizing the process *** microstructure of dissimilar Al/Mg welded joints was analysed by Scanning Electron Microscope(SEM),Energy Dispersive Spectrometer(EDS)and Electron Backscattered Diffraction(EBSD).The results show that the key to obtaining high shear strength of Al/Mg dissimilar metal joints is mainly due to the following two *** the one hand,grain refinement and element interdiffusion occur at the *** the other hand,no intermetallic compounds are formed at the interface.

关键词： Al/Mg dissimilarmaterials Magneticpulsewelding Mechanicalproperties Interface EBSD

An Improved Rate Control Method Based on Modification at Scene Change for H.264

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Wuhan University Journal of Natural Sciences 2007年第6期12卷 1047-1050页

作者： RU Guobao gao wenli FU Jianfeng School of Electronic Information Wuhan University Wuhan430072 Hubei China

This paper presents an improved rate control method for H.264. First, the scene changes are detected by the average absolute difference of the brightness histograms between the adjacent frames. Then, the bit allocation and quantization parameters are adjusted, using a certain threshold. In addition, the calculation of the mean absolute difference （MAD） is modified in an alternative way, which makes the rate distortion optimization （RDO） more accurate. Extensive simulation results show that the proposed method, compared with G012, can improve the average peak signal-to-noise ratio （PSNR） and moderate the image quality.

关键词： brightness histogram mean absolute difference (MAD) rate distortion optimization (RDO) rate control scene change

Decoupled Ce-Nd Isotopic Systematics of the Neoproterozoic Huangling Intrusive Complex and Its Geological Significance, Eastern Three Gorges, South China

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Journal of Earth Science 2016年第5期27卷 864-873页

作者： Yongjuan gao wenli Ling Xiaofei Qiu Ziwan Chen Shansong Lu Xiao Bai Xiujuan Bai Junbo Zhang Hongmei Yang Ruichun Duan Chengdu Institute of Geology and Mineral Resource Chengdu 610081 China State Key Laboratory of Geological Progresses and Mineral Resources China University of Geosciences Wuhan 430074 China School of Earth Sciences China University of Geosciences Wuhan 430074 China Wuhan Center of Geological Survey Wuhan 430205 China

Cerium is one of multivalent rear earth elements, which can transfer from trivalence to tretavalence at oxidizing environment. This process may cause variable degrees of fractionation of Ce from other trivalent rear earth elements, and thus may provide specific insight into the geological processes associated with marked redoxomorphism. Multiple geochemical tracing of Sr-Nd-Ce isotopes are performed on the felsic and mafic intrusives of the Neoproterozoic（~800 Ma） Huangling complex located at the eastern Three Gorges, South China. The intrusive rocks exclusively show various extents of negative Ce anomalies. On the εCe-εNd plot, most samples from the mafic intrusions scatter within the second quadrant, whereas those from the felsic intrusions within the fourth Quadrant. Both of the two groups exhibit relatively large range of ？Ce（t） variation but limited ？Nd（t） range, which cause a deviation from the ＂crustal array＂ and reveal a decoupled Nd-Ce isotope correlation. The intermediate-felsic suite have varied Ce/Ce＊ ratios but broadly proximate εCe（t） values, indicating that their negative Ce anomalies were generated during the magmatism; on the contrary, a positive correlation between εCe（t） and Ce/Ce＊ is observed for the intermediate-mafic suite, an indication of an origin of post-magmatic alteration or metamorphism for their Ce anomalies. Calculation of model age, the occurrence age of negative Ce anomalies（TCe） for the intermediate-mafic samples infers that the alteration events took place 〉350 Ma. Data showed that negative Ce anomalies of the felsic intrusions may reflect an increase of oxygen fugacity during magma ascending, rather than an inheritance from their source rocks. This explanation implies that the Neoproterozoic magmatism occurred at the continental nucleus of the Yangtze block were developing at a geodynamic context of rapidly regional uplifting.

关键词： negative Ce anomalies Ce-Nd isotopic decoupling alteration oxidation environment.

Fe对Ni/SBA-16催化CO低温甲烷化促进作用的研究

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化工学报 2022年第1期73卷 241-254页

作者：高文莉辛忠华东理工大学化工学院上海市多相结构材料化学工程重点实验室上海200237 华东理工大学化学工程联合国家重点实验室上海200237

为了提高Ni/SBA-16催化剂在低温下CO甲烷化中的活性,通过引入Fe助剂制备了Ni-Fe/SBA-16双金属催化剂。对催化剂进行XPS、XRD、HRTEM及EDS-mapping表征的结果表明,Fe的加入与Ni形成了Ni_(3)Fe合金,减小了金属颗粒尺寸,使得还原后金属颗... 详细信息

为了提高Ni/SBA-16催化剂在低温下CO甲烷化中的活性,通过引入Fe助剂制备了Ni-Fe/SBA-16双金属催化剂。对催化剂进行XPS、XRD、HRTEM及EDS-mapping表征的结果表明,Fe的加入与Ni形成了Ni_(3)Fe合金,减小了金属颗粒尺寸,使得还原后金属颗粒平均粒径从60 nm降低到30 nm左右。同时H_(2)-TPR的结果表明,Ni_(3)Fe合金的形成增强了金属Ni与载体之间的相互作用,从而能够减弱Ni颗粒在还原过程及反应过程中的团聚。最后,由CO-TPD和H_(2)-TPD的测试结果可知,Ni_(3)Fe合金的形成促进了催化剂对反应气体CO和H_(2)的解离,从而提高了催化剂在低温下的CO甲烷化活性。当空速为150000 h^(-1)、压力为0.1 MPa、V(H_(2))∶V(CO)∶V(N_(2))=3∶1∶1时,CO最低完全转化温度可以从300℃降低到250℃,同时CH_(4)的选择性保持在90%。

关键词：双金属催化剂一氧化碳甲烷介尺度分子筛纳米颗粒

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Structure Identification for Force-Induced Reaction Using Single-Molecule Conductance Measurement

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CCS Chemistry 2023年第8期5卷 1888-1895页

作者： Jueting Zheng wenli gao Taige Lu Lijue Chen Luchun Lin Ruiyun Huang Yongxiang Tang Gang Dong Junyang Liu Yifei Pan Wengui Weng Wenjing Hong State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical Engineering and Institute of Artificial Intelligence and Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(IKKEM)Xiamen UniversityXiamen 361005 Department of Chemistry College of Chemistry and EngineeringXiamen UniversityXiamen 361005

Spiropyran derivatives are prototype mechanophores with a promising application as molecular sensors because of their changeable structure under external force ***,the chemical structure evolution under external stimuli remains unclear due to the uncertainty and difficulty in distinguishing the structures of different ring-opened merocyanine isomers generated in the force-induced *** we identify the structure of isomers produced by the force-induced reaction of spiropyran derivatives using a single-molecule conductance measurement and an unsupervised clustering *** found that the original data from the single-molecule conductance measurement can be divided into four clusters through unsupervised *** introducing a photoinduced reaction and theoretical calculation,we identified and attributed the four clusters of data to the multiple states of the molecular *** work demonstrates that a single-molecule break junction measurement can distinguish the isomers in the force-induced reaction,suggesting the great potential of single-molecule conductance measurement and unsupervised clustering approaches for structural analysis.

关键词： single-molecule conductance measurements force-induced reaction unsupervised clustering structure identification

微合金元素Nb对低碳铸钢强度和冲击韧性的影响

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材料导报 2018年第2期32卷 238-242页

作者：傅定发冷宇高文理湖南大学材料科学与工程学院长沙410082

采用中频炉冶炼制备不同Nb含量的微合金低碳铸钢,用光学显微镜(OM)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、液压万能强度试验机、半自动冲击试验机等手段研究了Nb微合金化对低碳铸钢显微组织、强度和冲击韧性的影响。结果表明,添... 详细信息

采用中频炉冶炼制备不同Nb含量的微合金低碳铸钢,用光学显微镜(OM)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、液压万能强度试验机、半自动冲击试验机等手段研究了Nb微合金化对低碳铸钢显微组织、强度和冲击韧性的影响。结果表明,添加合适的微合金元素Nb可以使低碳铸钢的晶粒尺寸减小20.8%~34.6%,同时促进细小NbC析出相的形成,能有效提高低碳铸钢的强度和冲击韧性,晶粒细化和析出强化为其主要的强韧化机制。其中,含Nb量为0.044%的微合金铸钢屈服强度为350 MPa,抗拉强度为520 MPa,室温冲击功为119.7J。与普通低碳铸钢相比,其塑性基本保持不变,但屈服强度、抗拉强度和室温冲击功分别提高了20.7%、7.2%和25.6%。

关键词：低碳铸钢 Nb合金化微观组织强度冲击韧性

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学位论文参考文献的自动抽取及标注

现代图书情报技术 2008年第11期 72-75页

作者：高文利高元先湖南涉外经济学院文学部长沙410205 湖南涉外经济学院图书馆长沙410205

针对学位论文撰写过程中参考文献管理困难的问题,利用参考文献有严格格式规范的特点,运用信息抽取技术实现学位论文参考文献的自动抽取和标注。

关键词：参考文献信息抽取标注

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7A85铝合金板材双级时效工艺研究

湖南大学学报（自然科学版） 2022年第12期49卷 100-107页

作者：刘艳丽袁航高文理湖南大学材料科学与工程学院湖南长沙410082

双级时效工艺可以在保证Al-Zn-Mg-Cu系铝合金材料高强度的同时,增加合金的耐腐蚀性能.通过室温拉伸、电导率测量、扫描电镜(SEM)、透射电镜(TEM)等检测分析,研究7A85铝合金板材在不同双级时效制度下的力学性能和组织变化.结果表明,材料... 详细信息

双级时效工艺可以在保证Al-Zn-Mg-Cu系铝合金材料高强度的同时,增加合金的耐腐蚀性能.通过室温拉伸、电导率测量、扫描电镜(SEM)、透射电镜(TEM)等检测分析,研究7A85铝合金板材在不同双级时效制度下的力学性能和组织变化.结果表明,材料的断裂方式为穿晶型断裂与沿晶型断裂共存;双级时效参数对7A85铝合金板材强度和电导率的影响因子排序为:终时效时间>终时效温度>初时效温度>初时效时间;对延伸率的影响因子排序为:终时效温度>初时效温度>终时效时间>初时效时间.通过正交试验得出7A85铝合金板材合宜的双级时效制度为110℃/6 h+155℃/8 h,此时合金的抗拉强度达到617.0 MPa,延伸率为12.6%,为7A85铝合金板材在航空航天领域的应用提供参考和借鉴.

关键词： 7A85铝合金正交试验双级时效拉伸性能显微组织