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Surface Nanocrystallization of Magnesium Alloy AZ91D by High-Energy Shot Peening

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Journal of Wuhan university of Technology(materials {2.) 2009年第4期24卷 515-519页

作者：张津 school of materials {2. & engineering University of Science and Technology Beijing College of materials science & {2. Chongqing University of Technology

High-energy shot peening （HESP）, a method to produce severe plastic deformation by high velocity flying balls, was applied on die cast magnesium alloy AZ91D. Effects of surface nanocrystallization by HESP and heat treatment at different temperatures were investigated. The mi- crostructure evolution was conducted using X-ray diffraction （XRD） and field emission scanning electronic microscopy （FESEM）. The hardness was measured by microhardness tester. The experimental results show that surface nanocrystrallization of AZ91D obtained by HESP would lead to the increase of microhardness. Low temperature heated at 100℃ for 1 h do not change the property obviously. However, both the microstructure and microhardness vary greatly after heat treatment at 400℃ for 1 h.

关键词： AZ91 D surface nanocrystallization HESP microhardnss corrosion resistance

Characterization of tensile fracture in heavily alloyed Al-Si piston alloy

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Progress in Natural science:materials International 2011年第5期21卷 380-385页

作者： Guo-hua ZHANG~(1,2.,Jian-xin ZHANG~3,Bing-chao LI~3,Wei CAI~1 1.school of materials {2. and engineering,Harbin Institute of Technology,Harbin 150001,china 2.shandong Binzhou Bohai Piston Co.,Ltd,Binzhou 2.6602.china 3.school of materials {2. and engineering,shandong {12.,Ji'nan 2.0061,china [a] school of materials {2. and engineering Harbin Institute of Technology Harbin 150001 China [b] shandong Binzhou Bohai Piston Co. Ltd Binzhou 256602 China [c] school of materials {2. and engineering Shandong University Ji'nan 250061 China

This paper focuses on a typical automotive piston material to characterize its fractographic appearance after tensile rupture. The fracture of this heavily alloyed Al—Si alloy takes place in a brittle *** consecutive eutectic zone is found to break by debonding of Si platelets from the Al matrix or by fracturing of Si *** various intermetallic particles break up complicatedly under the stress field of the propagating *** fracture tends to pass through or approach to the boundary between the eutectic Al matrix and Si platelets and there is a strong interaction between the propagating crack and the obstructing intermetallic compound.A tensile fracture mechanism in the heavily alloyed Al-Si alloy is elucidated.

关键词： tension test aluminum alloys facets fracture

Phase transition in the Zr_(60)Al_(15)Ni_(2.) bulk metallic glass subjected to rolling at room temperature

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science china(Technological sciences) 2006年第6期49卷 655-662页

作者： YAN Zhijie1, 2. LI Jinfu1, ZHOU Yaohe1 & WU Yanqing3 1. State Key Laboratory of Metal Matrix Composites, school of materials {2. and engineering, Shanghai Jiao Tong university, Shanghai 2.0030, china 2. school of materials {2. and engineering, Taiyuan university of {2. and Technology, Taiyuan 03002., china 3. school of Environmental {2. and engineering, Shanghai Jiao Tong university, Shanghai 2.0030, china State Key Laboratory of Metal Matrix Composites School of Materials Science engineering Shanghai Jiao Tong University Shanghai 200030 China school of materials {2. engineering Taiyuan University of Science Technology Taiyuan 030024 China school of Environmental science engineering Shanghai Jiao Tong University Shanghai 200030 China

The microstructure evolution of the Zr60Al15Ni2. metallic glass during rolling at room temperature is investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC); high-resolution transmission electron microscopy (HREM). The results show that the values of full width at half maximum (FWHM) of the XRD patterns; exothermic enthalpy ΔH of DSC plots do not monotonically change with the variation of deformation degrees . As is not large than 2.%, the values of FWHM; ΔH are lower than that of the as-cast state. When reaches 30%, the values of FWHM; ΔH become larger than that of the as-cast state, while their values begin to decrease again as reaches about 85%. These results indicate that the reversible transitions between ordered; disordered atomic configurations occur during rolling, which is further verified by the HREM images. The reversible phase transition can be explained by the competition between the diffusion controlled reordering; shear-induced disordering during rolling.

关键词： metallic glasses, plastic deformation, phase transformations, shear bands.

Spinning Deformation Criteria of Thin-walled Tubular Part with Longitudinal Inner Ribs

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Journal of Wuhan university of Technology(materials {2.) 2006年第4期21卷 169-172页

作者：江树勇 engineering Training Center Harbin Engineering University Harbin 150001China

As a successive and local plastic deformation process, backward ball spinning was applied for the purpose of prodacing thin-walled tubular parts with longitudinal inner ribs. According to the local plastic deformation theoo,, the application of yield criterion to the spinning process and the influence of the radial spinning force component on the formability of inner ribs were analyzed. Based on yield criterion and plastic mechanics, the stable flow rule of metal material and forming criteria of the inner ribs were obtained aad conformed to the experimental results so as to contribute greatly to improving the ball spinning process and optimizing the process variables, such as the diameter of ball, the reduction in a pass and the wall thickness of tubular blank, which have a significant influenee on the formability of the inner ribs. The knowledge of the influence of the process variables such as the diameter of ball, the reduction in a pass and the wall thickness of tubular blank on the spinning process is essential to preventing the quality defects of the spun parts and obtaining the desired spun parts.

关键词： ball spinning power spinning spinning force criterion

Effect of Nd_2.e_(14)B/α-Fe Nanocomposite Permanent Magnets with a Combined Co and Nb Additions

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Journal of Wuhan university of Technology(materials {2.) 2009年第5期24卷 725-727页

作者：马瑞 school of materials {2. and Metallurgy engineering Guizhou University

Influence of Co＋Nb on the Nd8Fe82.o3Nb1B6 nanocomposite magnets was investigated by adding Co element combined with Nb element. Results show that the high temperature stability of two phases is increased. Adding Co＋Nb could improve the glass forming ability of the alloy, reduce the size of grains, increase the exchange coupling ability of two phases, and obviously increase the magnetic properties of the alloy. The optimal magnetic properties are Br=1.14 T, Hcj=32. kA/m, （BH）max=109.3 kJ/m^3

关键词： nanocomposite permanent magnets glass forming ability exchange coupling ability magnetic properties

Theoretical analysis of alloy multiplying factor by the empirical electron theory of solids and molecules

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science china(Technological sciences) 2007年第6期50卷 807-814页

作者： SONG YuePeng1,2. LIU GuoQuan2. LI ZhiLin3, FENG ChengMing1 1 Mechanical and Electronic engineering College, shandong Agricultural {2., Tai’an 2.1018, china 2.College of materials science and engineering, {2. of science and Technology, Beijing 100083, china 3 College of Material science and engineering, Beijing {2. of Chemical Technology, Beijing 10002., china Mechanical Electronic engineering College Shandong Agricultural University Tai’an 271018 China College of materials science engineering University of Science Technology Beijing 100083 China College of Material science engineering Beijing University of Chemical Technology Beijing 100029 China

By introducing the distribution probability of structural units in austenite contain- ing alloying elements and considering its effects on phase transformation, this paper establishes a calculation model of distribution probability of structural units. A new valence electron structure (VES) parameter-transformation effect coefficient of alloying elements (HL), is defined and then studied both theoretically and ex- perimentally. The relationship between the parameter HL and the multiplying factor (the quenching capability factor) of alloying elements is studied. The results indi- cate that the two parameters (HL and the quenching capability factor) have the same variation characteristic and substance feature. Therefore, the multiplying factor virtually expresses the relative quantity of structural units in the alloying elements-containing austenite.

关键词： multiplying factor (the quenching capability factor), empirical electron theory of solids and molecules, transformation effect coefficient of alloying elements, structural units in austenite containing alloying elements

Chemical Extraction Preparation of Delithiated Cathode materials of Li-ion Battery

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Journal of Wuhan university of Technology(materials {2.) 2009年第6期24卷 863-866页

作者：闫时建 school of materials {2. and engineering Taiyuan University of Science and Technology

A method of conventional chemical reaction to prepare delithiated cathode materials of Li-ion battery was introduced. The cathode material of Li-ion battery was mixed with oxidizing agent Na2.2.8 in water solution, and the solution was stirred continuously to make the chemical reaction proceed sufficiently, then the reaction product was filtered and finally the insoluble delithiated cathode material was obtained. A series of tests were conducted to verify the composition, crystal structure and electrochemical property of the delithiated cathode materials were all desirable. This method overcomes the shortcomings of battery charging preparation and chemical extraction preparation employing other oxidizing agents.

关键词： chemical extraction delithiated cathode material Li-ion battery

Dominant point detecting based non-uniform B-spline approximation for grain contour

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science china(Technological sciences) 2007年第1期50卷 90-96页

作者： ZHAO XiuYang1, YIN YanSheng1,2.& YANG Bo3 1 shandong Key Laboratory of engineering Ceramics, shandong university, Jinan 2.0061, china 2.school of materials, Ocean university of china, Qingdao 2.6003, china 3 State Key Laboratory of Advanced Technology for materials Synthesis and Processing, Wuhan university of {12. and Technology, Wuhan 430070, china 1. shandong Key Laboratory of engineering Ceramics Shandong University Jinan 250061 China 2. school of materials Ocean University of China Qingdao 266003 China 3. State Key Laboratory of Advanced Technology for materials Synthesis and Processing Wuhan University of Science and Technology Wuhan 430070 China

Three-dimension reconstruction from serial sections has been used in the last decade to obtain information concerning three-dimensional microstructural ge-ometry. One of the crucial steps of three-dimension reconstruction is getting compact and fairing grain contours. Based on the achievement of closed raw con-tours of ceramic composite grains by using wavelet and level set, an adaptive method is adopted for the polygonal approximation of the digitized raw contours. Instead of setting a fixed length of support region in advance, the novel method computes the suitable length of support region for each point to find the best es-timated curvature. The dominant points are identified as the points with local maximum estimated curvatures. Periodic closed B-spline approximation is used to find the most compact B-spline grain boundary contours within the given tolerance. A flexible distance selection approach is adopted to obtain the common knot vector of serial contours consisting of less knots that contain enough degrees of freedom to guarantee the existence of a B-spline curve interpolating each contour. Finally, a B-spline surface interpolating the serial contours is generated via B-spline surface skinning.

关键词： composite B-spline dominant points control points grain contour

Thermochemical Evaluation of Combustion Synthesis of Al_2._3/B_4C Composite

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International Journal of Minerals,Metallurgy and materials 1998年第2期12卷 90-92页

作者： Yonghe Liu~(1,2.) Sheng Yin~(1)) Weijing Zhang~(1)) Hoyi Lai~(1)) 1) materials science and {2. school, UST Beijing, Beijing 100083, china 2. school of materials science and {2., shandong university of Technology, Jinan 2.0014 materials science and {2. school UST Beijing Beijing 100083 China school of materials {2. and engineering Shandong University of Technology Jinan 250014 China

The equilibrium phase and adiabatic temperature for combustion synthesis of Al_2._3/B_4C employing Al, B_2._3 and C as starting materials is analyzed by both conventional and CALPHAD method. The adiabatic temperature calculed by CALPHAD method is significantly lower than that obtained by conventional method. The CALPHAD calculation also reveals that the equilibrium phases presented at the adiabatic temperature are different to the desired composites. The adiabatic temperature in this system can be lowered by introducing Al_2._3 as diluents. The maximum amount of Al_2._3 that can be added to the system while maintain a self-sustaining combusion mode is 1.3 mol.

关键词： thermochemical evaluation SHS Al_2._3/B_4C composite