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Phase evolution in AlSi20/8009 aluminum alloy during high temperature heating near melting point and cooling processes

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Transactions of Nonferrous Metals Society of China 2020年第5期30卷 1157-1168页

作者： Hai-bin LIU Hua-guang SU ding-fa fu fu-lin JIANG Hui ZHANG College of Materials Science and Engineering Hunan UniversityChangsha 410082China Shanghai Electric Cable Research Institute Co. Ltd.Shanghai 200093China

The AlSi20/8009 aluminum alloy was heated to high temperatures near the melting point and cooled to investigate the effect of external Si addition on the phase evolution of Al12(Fe,V)3 Si dispersion. Differential scanning calorimeter, scanning electron microscope, energy dispersive spectrometer and X-ray diffractometer were *** results showed that Al12(Fe,V)3 Si and Si phases evolved into a needle-like Al4.5 Fe Si phase and a nano-sized V-rich phase during holding the alloy at 580-600℃. With increasing holding temperature to 620-640℃, Al4.5 Fe Si and nano-sized V-rich phases evolved reversibly into Al12(Fe,V)3 Si and Si phases, of which Al12(Fe,V)3 Si occupied a coarse and hexagonal morphology. During the alloy(after holding at 640 ℃) furnace cooling to 570 ℃ or lower, Si and Al12(Fe,V)3 Si phases evolved into strip-like Al4.5 Fe Si and the V-rich phases, which is a novel formation route for Al4.5 Fe Si phase different from Al-Fe-Si ternary system.

关键词： SiCp/8009Al composite phase evolution metallurgical joining re-melting cooling

Strain anisotropy models for refined diffraction line profile analysis in cubic metals

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Transactions of Nonferrous Metals Society of China 2020年第8期30卷 2090-2106页

作者： Xiang DAI fu-lin JIANG Jin LIU Luo-yi WU ding-fa fu Jie TENG Hui ZHANG College of Materials Science and Engineering Hunan UniversityChangsha 410082China Research Center for Steel Kyushu University744 Motooka Nishi-kuFukuoka 819-0395Japan

The present work examined the anisotropy magnitudes obtained from different elastic models of cubic metals(Cu,5383 Al alloy,FCC austenite steel and BCC steel)to explore the origin of strain *** results showed that stable intersections were observed from the modeled and experimental plots of the reciprocal elastic modulus(1/Ehkl)and orientation parameter(Γ).The effectiveness of quasi elasto-plastic model based method in correcting strain anisotropy was further verified in cold-worked *** the important input parameters in dislocation model based diffraction line profile analysis methods,the average diffraction contrast factors(■)of dislocations were observed to depend on elastic *** intersections were found from linear dependence of■onΓ.The conventional input■values indicated distinct dependencies on given elastic constants in diffraction line profile ***,a refined approach was proposed by adopting the optimized intersections as input values,by which more reliable results could be obtained in practical applications.

关键词： metallic materials line profile analysis strain anisotropy dislocations

Characterization of dynamic microstructural evolution of AA7150 aluminum alloy at high strain rate during hot deformation

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Transactions of Nonferrous Metals Society of China 2016年第1期26卷 51-62页

作者：蒋福林张辉翁舒楚傅定发湖南大学材料科学与工程学院长沙410082 Department of Materials Science and Engineering McMaster University 湖南大学湖南省喷射沉积技术及应用重点实验室长沙410082

The AA7150 aluminum alloy was compressed to various strains at strain rate of 10 s（-1） and temperatures of 300 °C and 450 °C, respectively. Flow stress behavior, substructure evolution, morphology and spatial distribution of precipitates were studied based on differential scanning calorimetry analysis and transmission electron microscope observation. The results showed that dynamic flow softening occurs during hot deformation. The main softening mechanism could be concluded as dynamic recovery at 300 °C and continuous dynamic recrystallization at 450 °C. The clear heterogeneous spatial distributions of precipitates are found during deformation and enhanced with increased strain. Higher contents of Cu in T phases are found at 450 °C than at 300 °C, which present a transformation process from T phases to S phases as well. The associated evidence of dynamic precipitation on dislocations and particle-stimulated nucleation, as well as the detailed microstructural inherited relationship and morphological texture（particles preferred orientation） were characterized.

关键词： Al-Zn-Mg alloy hot compression dynamic phenomena microstructure

Flow stress behavior and processing map of extruded 7075Al/SiC particle reinforced composite prepared by spray deposition during hot compression

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Transactions of Nonferrous Metals Society of China 2015年第3期25卷 692-698页

作者：吴红丹张辉陈爽傅定发湖南大学材料科学与工程学院长沙410082 湖南大学湖南省喷射沉积技术及应用重点实验室长沙410082

Hot compression tests of the extruded 7075Al/15%SiC (volume fraction) particle reinforced composite prepared by spray deposition were performed on Gleeble?1500 system in the temperature range of 300?450 °C and strain rate range of 0.001?1 s?1. The results indicate that the true stress?true strain curve almost exhibits rapid flow softening phenomenon without an obvious work hardening, and the stress decreases with increasing temperature and decreasing strain rate. Moreover, the stress levels are higher at temperature below 400 °C but lower at 450 °C compared with the spray deposited 7075Al alloy. Superplastic deformation characteristics are found at temperature of 450 °C and strain rate range of 0.001?0.1 s?1 with corresponding strain rate sensitivity of 0.72. The optimum parameters of hot working are determined to be temperature of 430?450 °C and strain rate of 0.001?0.05 s?1 based on processing map and optical microstructural observation.

关键词： 7075 Al SiC particle-reinforced composite hot compression deformation flow stress processing map superplastic deformation

Microstructure and properties of Al-0.70Fe-0.24Cu alloy conductor prepared by horizontal continuous casting and subsequent continuous extrusion forming

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Transactions of Nonferrous Metals Society of China 2015年第6期25卷 1763-1769页

作者：张晓苑张辉孔祥鑫傅定发湖南大学材料科学与工程学院长沙410082 湖南大学湖南省喷射沉积技术及应用重点实验室长沙410082

A novel process for manufacturing A1-0.70Fe-0.24Cu alloy conductor was proposed, which includes horizontal continuous casting and subsequent continuous extrusion forming （Conform）. The mechanical properties, electrical conductivity and the compressed creep behaviour of the alloy were studied. The results indicate that the Conform process induces obvious grain refinement, strain-induced precipitation of AI7CuzFe phase and the transformation of crystal orientation distribution. The processed alloy has good comprehensive mechanical properties and electrical conductivity. Moreover, a better creep resistance under the conditions of 90 ~C and 76 MPa is shown compared with pure A1 and annealed copper, and the relationship between primary creep strain and time may comply with the logarithmic law. The enhanced properties are attributed to the grain refinement as well as the fine and homogeneously distributed thermally stable A1Fe and A17Cu2Fe precipitation phases.

关键词： A1-0.70Fe-0.24Cu alloy horizontal continuous casting continuous extrusion forming microstructure property

Effect of welding sequence on residual stress in thin-walled octagonal pipe-plate structure

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Transactions of Nonferrous Metals Society of China 2014年第3期24卷 657-664页

作者：傅定发周长青李灿王冠李落星湖南大学材料科学与工程学院长沙410082 湖南大学汽车车身先进设计与制造国家重点实验室长沙410082

A three-dimensional finite element approach based on ABAQUS code was developed to investigate the effect of welding sequence on welding residual stress distribution in a thin-walled 6061 aluminum alloy structure. To obtain sound numerical results, the therrno-mechanical behaviour was simulated using a direct-coupled formulation. Nine different simulation sequences were carried out by single-pass TIG welding of an octagonal pipe-plate joint, and the distributions of longitudinal and transverse residual stresses both on the outer and inner surfaces of the pipe were analyzed. The results suggest that the final residual stresses in the weld and its vicinity are not affected by the initial residual stresses of the structure. Selecting a suitable welding sequence can reduce the final residual stress in an octagonal pipe-plate joint.

关键词： residual stress welding sequence pipe-plate joint single-pass welding initial residual stress

Staged dendrite suppression for high safe and stable lithium-sulfur batteries

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Journal of Energy Chemistry 2025年第1期100卷 674-683页

作者： Jun Jiang Zhenjie Lu Yanwen ding Shujun Liu Zhijie Qi Tian Tang Yunfan Zhang Zhiyuan Ma Jingwen Sun Liang Xue Wenyao Zhang Pan Xiong Xin Wang Junwu Zhu Yongsheng fu Key Laboratory for Soft Chemistry and functional Materials of Ministry of Education Nanjing University of Science and Technology Jiangsu Pylon Battery Co.Ltd

The unavoidable dendrite growth and shuttle effect have long been stranglehold challenges limiting the safety and practicality of lithium-sulfur ***,we propose a dual-action strategy to address the lithium dendrite issue in stages by constructing a multifunctional surface-negatively-charged nanodiamond layer with high ductility and robust puncture resistance on polypropylene （PP） *** uniformly loaded compact negative layer can not only significantly enhance electron transmission efficiency and promote uniform lithium deposition,but also reduce the formation of dendrite during early deposition *** importantly,under the strong puncture stress encountered during the deterioration of lithium dendrite growth under limiting current,the high ductility and robust puncture resistance（145.88 MPa） of as-obtained nanodiamond layer can effectively prevent short circuits caused by unavoidable lithium *** Li||Li symmetrical cells assembled with nanodiamond layer modified PP demonstrated a stable cycle of over 1000 h at 2 mA cm-2with a polarization voltage of only 29.3 ***,the negative charged layer serves as a physical barrier blocking lithium polysulfide ions,effectively mitigating capacity *** improved cells achieved a capacity decay of only 0.042%per cycle after 700 cycles at 3 C,demonstrating effective suppression of dendrite growth and capacity attenuation,showing promising prospect.

关键词： Ductility

利用BLUP法对大约克夏种公猪的21日龄窝重进行遗传评估的研究

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畜牧与兽医 2002年第3期34卷 6-7页

作者：刘定发符利飞蒋隽周红丽广东省农科院畜牧所广东广州510640 湖南省湘潭县畜牧局湖南湘潭411100 湖南农业大学动科院湖南长沙410128

从不同猪场收集 1 2头大约克核心群公猪女儿的相关资料 ,利用BLUP法对 2 1日龄窝重进行遗传评估。结果表明 3个世代公猪的 2 1日龄窝重育种值分别为 55 71kg、 56 90kg和 57 65kg,呈上升趋势。对各世代环境效应的估计表明 ,A、B、E 3个... 详细信息

从不同猪场收集 1 2头大约克核心群公猪女儿的相关资料 ,利用BLUP法对 2 1日龄窝重进行遗传评估。结果表明 3个世代公猪的 2 1日龄窝重育种值分别为 55 71kg、 56 90kg和 57 65kg,呈上升趋势。对各世代环境效应的估计表明 ,A、B、E 3个场的环境条件逐步改善 ,而C。

关键词：大约克夏种公猪 BLUP 21日龄窝重遗传评估

Changes in Atmospheric Circulation during the Winter Regional Extreme Cold Events over China since 1960

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Journal of Meteorological Research 2023年第5期37卷 589-603页

作者： Dongxue fu Yihui ding School of Atmospheric Sciences Nanjing University of Information Science&TechnologyNanjing 210044 Chinese Academy of Meteorological Sciences China Meteorological AdministrationBeijing 100081 Jilin Climate Center Changchun 130062 National Climate Centre China Meteorological AdministrationBeijing 100081

The number of days with occurrence of winter regional extreme cold events(RECEs) in China was found more during 1960/1961–1985/1986(period 1), less during 1986/1987–2005/2006(period 2), but more again during2006/2007–2017/2018(period 3). So far, the differences in the atmospheric circulation favoring RECEs among these three periods are unclear. In this paper, changes in atmospheric circulation during the RECEs over China are examined by using composite analysis based on the station observed temperature data and NCEP–NCAR reanalysis data in winters of 1960/1961–2017/2018. The results show:(1) the stratospheric polar vortex was more active and tended to split before the outbreak of RECEs in period 3 than that in other two periods. The shift of the stratospheric polar vortex to Eurasia helped the upper Arctic cold air to affect the lower latitudes.(2) The troposphere was characterized by a typical or significant three-wave pattern before the outbreak of RECEs in period 2, in contrast to a weakened three-wave pattern in period 1. Compared to periods 1 and 2, the Okhotsk blocking high was stronger in period 3, contributing to the inverted omega-shaped circulation pattern in East Asia–North Pacific section and a shift of global pattern from three-wave to two-wave. The weakened three-wave or two-wave circulation pattern was manifested by the stronger Ural/Okhotsk blocking high, conducive to the strengthening of the meridional circulation and the occurrence of RECEs in East Asia.(3) The Siberian high was the strongest in period 3, followed by period 1, and it was the weakest in period 2. Before the outbreak of RECEs, the Siberian high in period 3 began to intensify one week earlier than that in periods 1 and 2. Thus, the accumulation time of cold air mass in period 3 was the longest. In summary, the synergism of atmospheric circulation at high and low levels in periods 1 and 3 was more conducive to more and strong RECEs than that in period 2. Moreover, the split of the stra

关键词： regional extreme cold events interdecadal variation polar vortex blocking high East Asian trough