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Theoretical study on Fe-Al clusters: geometric structure, bonding law and electronic structures

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Progress in Natural Science:materials International 2004年第8期 27-32页

作者： CHEN Shougang 1, YIN Yansheng 1*, WANG Daoping 2.and LU Yao 1(1. Institute of materials Science and Engineering, Ocean university of{2., Qingdao 2.6003,{2. 2. key laboratory of liquid structure and heredity of materials, ministry of education,{12., jinan 250061,{2.) Institute of materials Science and Engineering，Ocean university of{2.，Qingdao 2.6003，china key laboratory of {2. structure and heredity of materials，ministry of education，shandong university，jinan 250061，{12. Institute of materials Science and Engineering，Ocean university of{2.，Qingdao 2.6003，china key laboratory of {2. structure and heredity of materials，ministry of education，shandong university，jinan 250061，{12.

structures of the small Fe-Al clusters with different atom proportion are calculated using the B3LYP method in density functional theory (DFT). Calculated results show that the Al atoms lose electrons easily while the Fe atoms capture electrons easily. The most stable geometry is the bonding between Fe and Fe atoms and between Fe and Al atoms with the largest possibility, and the cluster stability law with the same atom proportion accords with the change of the highest occupied molecular orbital (HOMO) energy and the entropy of cluster system. Moreover, the electronic structure study of the ground-state Fe 3Al and Fe 2.rAl clusters shows that the substitution of Cr atom for the Fe atom located at the next neighboring site of Al atom reduces localized electrons not only between Al atom and the next neighboring Cr atom, but also between Al atom and the nearest neighboring Fe atom. Although the substitution increases the plasticity and the magnetism of intermetallic compound, the stability of the system slightly decreases. Our theoretical results agree well with the experimental results.

关键词： density functional theory and B3LYP method FeAl intermetallic compound cluster magnetism.

Molecular dynamics simulation of amorphous segregation in Ag-Rh alloys

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Rare Metals 2003年第3期22卷 164-168页

作者： ZHANG Jingxiang and BIAN Xiufangkey laboratory of {2. structure and heredity of materials, ministry of education, shandong university, jinan 250061, china shandong university Key Laboratory of Liquid Structure and Heredity of Materials Ministry of Education Jinan 250061

Molecular dynamics simulation was carried out to investigate the liquid andamorphous microstructures of binary Ag_x-Rh_((100-x)) (x = 2., 50, 75 in atom fraction) *** feature of homogeneous interatomic binding of Ag-Rh liquid was found and probed, whichcan be retained into amorphous solids upon rapid cooling. Homogeneous binding may occur when thedifference in the elemental atomic sizes is less than 10%. The icosahedra in liquid before theformation of amorphous state exist in a stable state and the network formed by 1551-clusters inmolten alloys would inhibit the crystallization and diffusion of atoms. A higher degree of1551-clusters will be favorable to form metallic glasses.

关键词： metallic glass amorphous segregation molecular dynamics liquid structure Ag-Rh alloy

Role of C and Fe in Grain Refinement of an AZ63B Magnesium Alloy by Al-C Master Alloy

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Journal of materials Science & Technology 2005年第6期21卷 822-826页

作者： Yichuan PAN+, Xiangfa LIU and Hua YANG key laboratory of {2. structure and heredity of materials, ministry of education, shandong university,jinan 250061, china key laboratory of {2. structure and heredity of materials Shandong University Jinan 250061 China

In this study, grain refining effect of Al-1.5℃ master alloy was examined on an AZ63B magnesium alloy, and the refining mechanism was studied through investigating the role of C and Fe in this process. The results show that addition of Al-1.5℃ master alloy leads to significant decrease of the mean grain size from about 2.0μm to 50μm at the center of the AZ63 alloy ingot. Grain refinement by carbon addition is mainly due to the heterogeneity nucleation on the Al-, C-, O-, Fe- and Mn-rich particles, but not constitutional undercooling caused by the carbon solute element. Fe plays an important role in the formation of the nucleating particles, but not acts as an inhibiting element.

关键词： Grain refinement AZ63B Magnesium Al-C master alloy Nucleating particle

Microstructure and Tensile Properties of ZK60 Alloy Fabricated by Simplified Rapid Solidification Powder Metallurgy (S-RS P/M) Process

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Journal of materials Science & Technology 2010年第2期26卷 151-155页

作者： Zhenya Zhang, Huashun Yu , Shaoqing Wang, Haitao Wang and Guanghui Min key laboratory of {2. structure and heredity of materials, ministry of education, shandong university, jinan 250061, china key laboratory of {2. structure and heredity of materials Ministry of Education Shandong University Jinan 250061 China

This study investigated the microstructures and mechanical properties of ZK60 alloy prepared by a simplified rapid solidification powder metallurgy （RS P/M） processing system （S-RS P/M）, which consists of warm press in dry air and hot extrusion. Microstructure characterizations showed that S-RS P/M alloy consisted of magnesium matrix and oxide stringers of ~1 #m in width. TEM （transmission electron microscopy） observations illustrated nano-size magnesia particles （10-30 nm） constituted oxide stringer in detail. Due to a relatively higher volume of nano-size magnesia particle produced during S-RS P/M process, 0.2. yield strength of S-RS P/M ZKO0 alloy was found to be as high as 382.MPa, which is 10% higher than that of RS P/M alloy. The improvement in mechanical properties is mainly attributed to the combination effects of Orowan mechanism and coefficient of thermal expansion （CTE） mismatch because of the approximately same average grain size.

关键词： Microstructure Mechanical properties Rapid solidification powder metallurgy Nano-size magnesia

Fabrication of ceramic layer on an Al-Si alloy by MAO process

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Rare Metals 2003年第2期22卷 103-106页

作者： SONG Xigui, BIAN Xiufang, QI Xiaogang, and ZHANG Junyankey laboratory of {2. structure and heredity of materials, ministry of education, shandong university (Southern Campus), jinan 250061, china (Received 2.02.04-11) shandong university (Southern Campus) Key Laboratory of Liquid Structure and Heredity of Materials Ministry of Education Jinan 250061 shandong university (Southern Campus) Key Laboratory of Liquid Structure and Heredity of Materials Ministry of Education Jinan 250061

The MAO (Micro-Arc Oxidation) process is applied to a eutectic Al-Si alloy(Al-12.0 percent Si-l.0 percent Cu-0.9 percent Mg (mass fraction)). The oxide ceramic layer wasfabricated with about 2.0 mum thickness and 3000 Hv micro-hardness. By XRD (X-ray diffractometry)and DSC (differential scanning calorimetry) analyses, the oxide layer consists of amorphous Al_2._3,which is distinct from the results reported by the other researchers. The SEM photographs of suchlayer show that the layer is fixed tightly on the substrate alloy. So this alloy can he used in thehigh temperature and friction environment alter it is treated with such process.

关键词： metal material ceramic layer MAO process Al-Si alloy

Nanocrystal Model for liquid Metals and Amorphous Metals

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Journal of materials Science & Technology 2010年第1期26卷 69-74页

作者： X.L. Tian, C.W. Zhan, J.X. Hou, X.C. Chen and J.J. Sun key laboratory of {2. structure and heredity of materials, ministry of education, shandong university, jinan 250061, china key laboratory of {2. structure and heredity of materials Ministry of Education Shandong University Jinan 250061 China

A nanocrystal model for liquid metals and amorphous metals has been developed. With the nanocrystal model, the broadening peak profiles （BPPs） of Cu, Al, Al65Cu2.Fe15 alloy, Cu7oNi30 alloy and Fe50Si50 alloy were gained by broadening the X-ray diffraction （XRD） peaks of a crystal lattice. By comparing the BPPs with the XRD intensity curves measured on the liquid metals, it is found that the BPPs are closely in agreement with the XRD intensity curves, respectively, except the FesoSiso alloy. Therefore, the nanocrystal model can be used to determine if the atomic cluster {2. of the liquid metal is similar to the {2. of its crystal lattice.

关键词： liquid metal Atomic cluster structure Crystal lattice

Formation of superthick Al-based amorphous ribbon

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Chinese Science Bulletin 2003年第19期48卷 2145-2147页

作者： WANG Shenghai, BIAN Xiufang & JIA Yubo key Lab of liquid {2. and heredity of materials, ministry of education of china, South Campus of shandong university, jinan 250061, china key Lab of liquid {2. and heredity of materials Ministry of Education of China South Campus of Shandong University Jinan China

The Al-Ni-La-Ce-Pr-Nd amorphous ribbon with a super-thickness of 140 mm has been produced by the melt spinning technique. The thickness is as twice as that achieved by the melt spinning technique in the corresponding period (the largest thickness of 65 mm). The crystallization was characterized by using a differential scanning calorimetry. The activation energies are calculated based on the Kissinger equation and the effects of the La, Ce, Pr and Nd on the glass forming ability of Al-based alloy are discussed in the paper.

关键词：铝基非晶形合金熔体纺丝玻璃成型性能固相反应

Influence of nickel and copper on liquid structure of CuAlNi shape memory alloys

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Chinese Science Bulletin 2002年第1期47卷 85-88页

作者： PAN Xuemin & BIAN Xiufangkey laboratory of {2. structure and heredity of materials, education ministry, shandong university, Ji’nan 250061, china key laboratory of {2. structure Education Ministry Shandong University Ji'nan 250061 China

liquid structure of molten pure Cu, Cu-12.l, Cu-12.l-4Ni (mass fraction, %) alloys has been investigated using the X-ray diffraction method. It is found that the main peak of the structure factor of pure Cu is symmetrical. In the front of main peak, the curve takes on a shape of parabola, whereas a distinct pre-peak has been found around a scattering vector magnitude of 18.5 nm-1 in the structure factor of the liquid Cu-12.l alloy. This pre-peak increases its inten-sity with the addition of Ni in the liquid Cu-12.l-4Ni alloy. The appearance of a pre-peak is a mark of the mediate-range order. Based on Daken-Gurry theory and according to mu-tual interaction between unlike atoms, the analysis of corre-lation between different composition and liquid structure was done: the strong interaction exists between Cu and Ni, so Cu-Al can form strong chemical bond which causes compound-forming behavior. Therefore, the medium-range size clusters can form in melt. The presence of the pre-peak corresponds to these

关键词： Cu-12.l-4Ni alloy liquid structure shape memory alloy X-ray diffraction.

Gradual solution heat treatment of AlSiCuMg cast alloys

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Rare Metals 2003年第4期22卷 304-308页

作者： WANG Guiqing , BIAN Xiufang ,and ZHANG Junyan1) The key laboratory of {2. structure and heredity of materials, ministry of education, shandong university, jinan 250061, china2. Department of Material Science and Technology, shandong Architectural Engineering Institute, {12. 2.0014, china shandong university The Key Laboratory of Liquid Structure and Heredity of MaterialsMinistry of Education Jinan 250061

The microstructure characteristics of AlSiCuMg cast alloys were studied withdifferent Cu content and the gradual solution treatment by DSC, SEM, TEM and mechanical method. Themelting point of alpha (Al) + Si decreases and polynary eutectic phases with low melting point formwith increase of Cu content. Gradual solution treatment includes two steps: solution treating nearthe melting point of polynary eutectic phase to take it dissolve first, and then increasing solutiontemperature to take the remainder copper intermetallics dissolved into alpha (Al). Grain boundariesmelting can be avoided by gradual solution treatment, even the maximum solution temperature isabove final solidification point, and the age hardening response increases correspondingly

关键词： aluminum alloy gradual solution heat treatment differential scanningcalorimetry (DSC) polynary eutectic phase