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Effects of electric pulse modification on liquid structure of Al-5%Cu alloy

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Transactions of Nonferrous Metals Society of China 2013年第9期23卷 2792-2796页

作者：王建中齐锦刚赵作福郭洪生赵涛辽宁工业大学材料科学与工程学院锦州121001 北京科技大学冶金与生态工程学院北京100083

The electric pulse modification （EP, EPM） of liquid metal is a novel method for grain refinement. The structure of EP-modified Al-5%Cu melt was characterized by high-temperature X-ray diffractometry. The results show that the Cu-containing Al clusters remarkably increase in the EP-modified melt, furthermore, these clusters in that case tend to contract due to the decrease of relevant atomic radius and the co-ordination number. This kind of liquid-phase structure leads to a more homogeneous Cu-rich phase distribution in the final solidification structure. Differential scanning calorimetry （DSC） tests indicate that the solidification super-cooling degree of the EP-modified liquid phase is 2.36 times that of the unmodified. These facts suggest that the atom cluster changes in EP-modified Al-5%Cu melt would disagree with that by EPM model previously proposed in liquid pure metal.

关键词： electric pulse modification Al-Cu melt atomic cluster liquid structure

Influence of liquid structure on Solid Transformation of CuAINi Shape Memory Alloy

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Journal of Materials Science & Technology 2003年第2期19卷 147-149页

作者： Xuemin PAN, Xiufang BIAN Weimin WANG and Jingyu QIN1) State Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Dalian 116023, China2) Key Laboratory of liquid structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061, China

Molten Cu-13AI and Cu-13AI-4Ni (mass fraction) alloys have been investigated using X-ray diffraction method. A distinct pre-peak has been found in the structure factors. The pre-peak increases its intensity with decreasing temperature and addition of Ni. The structural unit size corresponding to the pre-peak equals to magnitude of (111) planar distance of phase. The appearance of a pre-peak is due to existence of clusters with -phase-like structure in melt. Quantity and size of clusters increase with decreasing temperature but their structural unit size remains constant. Cu-13AI-4Ni shape memory alloy ribbons can be fabricated by rapid solidification technique. Order degree of martensite and temperature of the reverse martensitic transformation increase with decreasing liquid quenching temperature. phase particles develop from incorporating and growing of the clusters during solidification, thus result in the correlation between liquid structure and solid transformation.

关键词： CuAINi alloy liquid structure Shape memory alloy X-ray diffraction

liquid structure of High Purity Steel

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Liquid Structure of High Purity Steel

structure of liquid Aluminum and Hydrogen Absorption

第二届先进钢铁结构材料国际会议

作者： ZHAI Qijie~1, LUO Jun~3, ZHAO Pei~2, HU Hanqi~3(1.Shanghai University, Shanghai 200072, China 2.Central Iron & Steel Research Institute, Beijing 100081, China 3.University of Science and Technology Beijing, Beijing 100083, China)

＜正＞The liquid structure of high purity steel near the melting point has been studied with a liquid metal diffractometer. It is shown that the cluster size, coordination number, distance of the nearest neighbor atoms, and number of atoms in a cluster all decrease with increasing temperature. Small prepeaks before first main peak were found in the structure factors, and the prepeaks became slightly obscure as the temperature increases, which indicates that there exists a medium-range order structure in liquid steel and the medium-range order disappears as the temperature increases.

关键词： liquid structure High Purity Steel X-ray Diffraction

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Journal of Wuhan University of Technology(Materials Science) 2011年第1期26卷 93-97页

作者：柳洋孙宝德 State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong University

The hydrogen content in aluminum melts at different temperature was detected. The structure in aluminum melts was investigated by molecular dynamics simulation. The first peak position of pair correlation function, atomic coordination number and viscosity of aluminum melts were calculated and they changed abnormally in the same temperature range. The mechanism of hydrogen absorption has been discussed. From molecular dynamics calculations, the interdependence between melt structural properties and hydrogen absorption were obtained.

关键词： hydrogen absorption aluminum melts liquid structure viscosity molecular dynamics simulation

Origin of the pre-peak in the structure factor of liquid Fe-4.30C-0.21Ce alloy

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Journal of University of Science and Technology Beijing 2003年第2期10卷 56-59页

作者： HaoweiWang XinyingTeng YifuYe HuanrongWang GuanghuiMin StateKeyLaboratoryofMetalMatrixComposites ShanghaiJiaotongUniversityShanghai200030China CollegeofResourceandEnvironmentEngineering EastChinaUniversityofScienceandTechnologyShanghai200237China KeyLab.ofliquidstructureandHeredityofMaterials MinistryofEducationSouthCampusofShandongUniversityJinan250061China

The liquid structure of Fe-4.30C and Fe-4.30C-0.21Ce alloys was studied by high temperature X-ray diffractometer. The results show that for Fe-C alloy the nearest neighbor distance of the eutectic alloy is 0.259-0.260 nm at the temperature range of 1200-1400℃, which increases to 0.269-0.271 nm with the addition of 0.21% (mass fraction) Ce in the Fe-C alloy at the same temperature range. There is a pre-peak at Q = 15.5 nm-1 on the original intensity curve and structure factor S(Q) of the liquid Fe-4.30C-0.21Ce alloy, which was caused by the Ce atoms in the C-Ce clusters. Combined with the shared face, the tetragonal structure can meet the requirement for the distance of Ce-Ce atoms. It also shows that the cluster size in the liquid Fe-4.30C-0.21Ce alloy increases with the decreasing temperature.

关键词： pre-peak liquid structure cerium eutectic Fe-C alloy

Detailing the structure of liquid THF Based on an EPSR Study

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Computational Chemistry 2015年第1期3卷 1-7页

作者： Alexandre Borges Joao M.M.Cordeiro Department of Physics and Chemistry Sao Paulo State UniversityIlha SolteiraBrazil

The structure of pure liquid tetrahydrofuran (THF) has been investigated via Monte Carlo simulations in the wake of a previous Empirical Potential structure Refinement (EPSR) study on that liquid (Bowron, D.T.;Finney, J.L.;Soper, A.K. (2006) J. Am. Chem. Soc., 128, 5119). The molecules are allatoms rigid structures and the intermolecular potential used is described for the classical 6-12 Lennard-Jones plus Coulomb in the NPT ensemble at 1 atm and 25°C. THF is a poorly structured liquid. Typical preferred orientation of molecules has been explored and calculations shown different types of molecular pairs exist concurrently in the liquid. The geometry of those pairs was deeply investigated and its influence in the liquid structure discussed. The lack of molecular organization in the liquid is closely related to the existence of that diversity of molecular pairs. Its geometry changes from antiparallel up to T-like depending on the distance between the molecules in the pairs.

关键词： Monte Carlo Simulations Tetrahydrofuran liquid structure

Short-Range and Medium-Range Order in liquid Cu-Ni Alloy

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Chinese Physics Letters 2002年第2期19卷 233-235页

作者： Tian Xue-Lei Ye Yi-Fu Teng Xin-Ying Shi Zhi-Qiang Wang Huan-Rong Min Guang-Hui QIN Jing-Yu Key Laboratory of liquid structure and Heredity of Materials Ministry of Education Shandong University and Ji'nan 250061

The liquid structure of the Cu70Ni30alloy has been investigated using a-high-temperature x-ray diffractometer. At all temperatures above its liquidus, a distinctpre-peak has been found around a scattering vector magnitude of 13.5nm-1. The height of the pre-peak decreases gradually with increasing temperature but it clearly exists up to a temperature of1400°C. This behaviour indicates that stable medium-range order atomic clusters exist in the melt. It is concluded that theshort-range order atomic clusters of the liquid Cu70Ni30alloy mainly consist of Cu atoms with centred Ni atoms. The appearance of the pre-peak in the structure factor of the liquidCu70Ni30alloy is caused by the interaction between centred Ni atoms locating in the neighbouring atomic clusters

关键词： atomic clusters Temperature nickel alloys Atoms liquid structure liquids structure FACTORS

Metastable liquid properties and rapid crystal growth of Ti-Ni-Al alloy investigated by electrostatic levitation and molecular dynamics simulation

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Science China(Technological Sciences) 2021年第10期64卷 2200-2210页

作者： XIAO RuiLin RUAN Ying LIN MaoJie QIN JingYu LI Hui HU Liang WEI BingBo MOE Key Laboratory of Materials Physics and Chemistry under Extraordinary Conditions School of Physical Science and TechnologyNorthwestern Polytechnical UniversityXi’an 710072China Key Laboratory for liquid-Solid Structural Evolution and Processing of Materials Ministry of EducationShandong UniversityJinan 250061China

Electrostatic levitation technique and molecular dynamics simulation were performed to investigate the thermophysical properties,liquid structure and crystal growth dependence on undercooling of Ti_(85)Ni_(10)Al_(5) *** liquid Ti_(85)Ni_(10)Al_(5) alloy was substantially undercooled up to 335 K(0.18T_(L)).As undercooling increased,the potential energy of the liquid alloy decreased and the alloy entered into a high metastable *** this state,the atoms tended to bond with each other and the clusters were inclined to convert into high-coordinated clusters,as confirmed by the fraction of the high-coordinated clusters *** enlarged clusters and enhanced local structure stability contributed to the increase of the thermophysical parameters and crystal growth velocity,and eventually dendrite *** density,the specific heat and the surface tension of liquid alloy exhibited a linear relation with temperature and the shear viscosity of liquid alloy showed exponential variation which showed good agreement with the calculation results by molecular dynamics *** growth velocity first increased slowly and then dramatically once the undercooling exceeded the *** achieved maximum crystal growth velocity was 12.4 m s^(−1) and it was up to 326 times of the value at 94 K undercooling.

关键词： electrostatic levitation thermophysical properties liquid structure crystal growth molecular dynamics

Effect of copper addition on the thermal contraction of indium melt clusters

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Rare Metals 2003年第3期22卷 215-220页

作者： CHENGSujuan WANGZhonghua QINXubo BIANXiufang KeyLaboratoryofliquidstructureandHeredityofMaterials MinistlyofEducationShandongUniversityJinan250061China ShandongDacahengPesticideCo.Ltd. Zibo255000.China

The structure of In-1 %Cu and In-5%Cu (mass fraction) alloy melts werestudied at different temperatures above liquidus by using a high-temperature X-ray diffractometerand were compared with that of pure In melt. Experimental results show that with the addition of 1%Cu or 5% Cu, the thermal contraction phenomenon of atom clusters occurs in melts with thetemperature increasing like pure In melt. With the addition of 1% Cu, the thermal contraction ofatom clusters increases and the contraction is not homogeneous in the whole measurement temperaturerange. The sudden change and noticeable contraction can be found in the range of 280-390 ℃. Thetemperature range of the sudden change is lower than that of pure In melt. With the addition of 5%Cu, the thermal contraction of atom clusters decreases and the contraction is not consistent in thewhole measurement temperature range. The anomalous change can be measured at about 600 ℃. At thesame superheating temperature, the nearest interatomic distance r_1 of the melts containing copperis smaller than that of pure In melt, implying that the cluster structure of melts containing copperis more compact.

关键词： liquid structure thermal contraction X-ray diffraction cluster copperaddition in melt