2007年, 第17卷, 第02期　刊出日期：2007-02-25

  

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  Hole flanging with ironing process of two-ply thick sheet metal

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  中国有色金属学报（英文版）. 2007, 17(02): 221-221.

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   An incremental updated Lagrangian elasto-plastic finite element method(FEM) was employed to analyze the hole-flanging with the ironing of circulate plates using a pre-determined smaller hole at the center of the two-ply sheet metals. An extended r_min technique was employed such that each incremental step size can be determined not only by the yielding of an element Gaussian point, but also by the change under the boundary conditions of penetration, separation, and the alternation of the sliding-sticking state of friction along the tool-sheet interface. Two-ply sheet metals are generally composed of metals that have different mechanical properties. Thus, the forming process of these materials is complicated. A number of experiments and simulations were performed using a conical punch with a cone angle of 45˚. The experimental results were compared with FEM-simulated results. It is found that using the elasto-plastic FEM can effectively predict the generation process of the deformed shape until unloading. The calculated sheet geometries and the relationship between punch load and punch travel are in good agreement with the experimental data.
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  Laser surface alloying fabricated porous coating on
  NiTi shape memory alloy

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  中国有色金属学报（英文版）. 2007, 17(02): 228-228.

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   Laser surface alloying technique was applied to fabricate a metallic porous coating on a solid NiTi shape memory alloy. By laser surface alloying a 40%TiH₂-60%NiTi powder mixture on the surface of NiTi alloy using optimized laser process parameters, a porous but crack-free NiTi layer can be fabricated on the NiTi substrate. The porous coating is metallurgically bonded to the substrate NiTi alloy. The pores are uniformly distributed and are interconnected with each other in the coating. An average pore size of less than 10 μm is achieved. The Ni content of the porous layer is much less than that of the original NiTi surface. The existence of the porous coating on the NiTi alloy causes a 37% reduction of the tensile strength and 55% reduction of the strain as compared with the NiTi alloy. Possible biomedical or other applications for this porous surface with good mechanical strength provided by the substrate are prospective.
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  Thermodynamic investigation of ZrO2-BaO system

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  中国有色金属学报（英文版）. 2007, 17(02): 232-232.

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  Thermodynamic description of ZrO₂-BaO system was developed using the available experimental information. Special attention was paid to the modelling of the perovskite phase BaZrO₃ by a temperature-dependent polynomial to fit the experimental thermodynamic properties. The liquid phases, C_SS (cubic ZrO₂ solid solution) and T_SS (tetragonal ZrO₂ solid solution) were modelled with Redlich-Kister formula. The compounds Ba₂ZrO₄ and Ba₃Zr₂O₇ were treated as stoichiometric phases and the BaO_SS and M_SS (halite BaO and monoclinic ZrO₂ solid solutions) were treated as pure compounds. Comparisons between the calculated and the measured phase diagram as well as the thermodynamic quantities indicate that the most reliable experimental information is satisfactorily accounted for by the present thermodynamic calculation.
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  Hot rolling characteristics of spray-formed AZ91 magnesium alloy

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  中国有色金属学报（英文版）. 2007, 17(02): 238-238.

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   AZ91 magnesium alloy was prepared by spray forming. The spray-deposited alloy was subsequently hot-rolled with a 80% reduction at 350 ℃. The microstructural features of the as-spray-deposited and hot-rolled alloy were examined by optical microscopy, scanning electron microscopy and X-ray diffractometry. The results show that the spray-formed AZ91 magnesium alloy has, compared with the as-cast ingot, a finer microstructure with less intermetallic phase Mg₁₇Al₁₂ dispersed in the matrix due to fast cooling and solidification rates of spray forming process, and, therefore showing excellent workability. It can be hot-rolled with nearly 20% reduction for one pass at lower temperatures (330−360℃), and the total reduction can reach 50% prior to annealing. After proper thermo-mechanical treatment, the spray-formed AZ91 magnesium alloy exhibits outstanding mechanical properties.
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  Effects of sodium tungstate on characteristics
  of microarc oxidation coatings formed on magnesium
  alloy in silicate-KOH electrolyte

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  中国有色金属学报（英文版）. 2007, 17(02): 244-244.

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  Oxide coatings on AM60B magnesium alloy were prepared using the microarc oxidation(MAO) technique in silicate-KOH electrolyte with addition of 0−6.0 g/L Na₂WO₄. The MAO processes in base electrolyte with different concentrations of Na₂WO₄ were studied. The microstructure, compositions and mechanical tribological characteristics of the oxide coatings were also investigated by SEM, XRD, XPS, microhardness analysis and ball-on-disc friction testing, respectively. It is found that the addition of Na₂WO₄ into the base electrolyte has direct effect on the characteristics of voltage—time curves and breakdown voltage in MAO process. The number of micropores at top of the coating surface is increased by the addition of Na₂WO₄. The fraction of forsterite Mg₂SiO₄ in the oxide coating increases with increasing concentration of Na₂WO₄ in base electrolytes. Furthermore, the microhardness and wear resistance of oxide coatings are enhanced as well.
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  Structural stability of intermetallic compounds of Mg-Al-Ca alloy

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  中国有色金属学报（英文版）. 2007, 17(02): 250-250.

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  A first-principles plane-wave pseudopotential method based on the density functional theory was used to investigate the energetic and electronic structures of intermetallic compounds of Mg-Al-Ca alloy, such as Al₂Ca, Al₄Ca and Mg₂Ca. The negative formation heat, the cohesive energies and Gibbs energies of these compounds were estimated from the electronic structure calculations, and their structural stability was also analyzed. The results show that Al₂Ca phase has the strongest alloying ability as well as the highest structural stability, next Al₄Ca, finally Mg₂Ca. After comparing the density of states of Al₂Ca, Al₄Ca and Mg₂Ca phases, it is found that the highest structural stability of Al₂Ca is attributed to an increase in the bonding electron numbers in lower energy range below Fermi level, which mainly originates from the contribution of valence electron numbers of Ca(s) and Ca(p) orbits, while the lowest structural stability of Mg₂Ca is resulted from the least bonding electron numbers near Fermi level.
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  Structure and antibacterial activity of new
  layered perovskite compounds

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  中国有色金属学报（英文版）. 2007, 17(02): 257-257.

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  New layered perovskite compounds, Ag_xNa_2−xLa₂Ti₃O₁₀ (x=0.2, 0.3 and 0.5) were synthesized by an ion-exchange reaction of Na₂La₂Ti₃O₁₀ with AgNO₃ solution and characterized by energy dispersive X-ray analysis(EDX), X-ray diffractometry(XRD), scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS). The ion-exchange processes were optimized, and the antibacterial activity, light permanency and water-resistance were evaluated. Surprisedly, no significant changes in crystal structure of Na₂La₂Ti₃O₁₀ are found by the exchange of silver ions. The Ag_0.3Na_1.7La₂Ti₃O₁₀ particles conglomerate obviously with irregular shape and size. Ag_0.3Na_1.7La₂Ti₃O₁₀, possessing the minimum inhibitory concentrations(MICs) against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) of 180 mg/L and 240 mg/L, has high antibacterial activity, good light permanency and water-resistance. The ionic state silver in Ag_xNa_2−xLa₂Ti₃O₁₀ is the antibacterial active component.
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  Internal oxidation thermodynamics and microstructures of Ag-Y alloy

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  中国有色金属学报（英文版）. 2007, 17(02): 262-262.

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  The thermodynamic data of pure Ag and Y were calculated. The phase constitution, composition of micro-region and microstructures of Ag-Y alloy after internal oxidation were investigated by X-ray diffractometry(XRD), energy dispersion spectrometry(EDS) and scanning electron microscopy(SEM). The results show that the internal oxidation behavior of Ag-Y alloy is feasible from the view of thermodynamics. The upper limit of oxygen partial pressure of Ag-Y alloy oxidation is a function of temperature. Two phases (Ag and Y₂O₃) appear in Ag-Y alloy after the internal oxidation. The surface of Ag-Y alloy is convex because of the volume expansion of oxide in the alloy and the composition of the convex part is Ag. In Ag-Y₂O₃ sintered bulk Y₂O₃ particles are distributed inhomogeneously and conglomerated seriously, but they are dispersed uniformly in the Ag matrix after severe plastic deformation.
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  Forming process of cross-connected finned
  micro-grooves in copper strips

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  中国有色金属学报（英文版）. 2007, 17(02): 267-267.

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  Using ploughing-extrusion method, a cross-connected finned micro-grooves structure was formed on the surface of copper strips with thickness of 0.4 mm. The structure was fabricated by making ‘V’-grooves in copper strips and perpendicular ‘V’-grooves on the opposite side that intersect the first set of grooves. Micro pores appear at the intersection of these cross-connected grooves, and micro fins appear on the groove fringes. So it can be defined as ‘pore-groove-fin’ structure. The preferable ‘pore-groove-fin’ structure can be obtained under the condition that the tool edge inclination angle (χ_γ) is 45˚, both the major extrusion angle (γ_o) and the minor extrusion angle (γ′₀)  are 30˚, both the major formation angle (β) and the minor formation angle (β′) are 10˚, the ploughing-extrusion depth (f_d) is 0.32 mm and the groove pitch is 0.4 mm on surfaces A and B. The formed included angle of groove A is 70˚, and the groove depth is 0.3 mm, while the included angle of opposite perpendicular groove B is 20˚ with the groove depth of 0.35 mm. The obtained fin height is 0.15 mm, the elliptical pore length is 0.2 mm and the width is 0.05 mm. Experiments show that f_d has the greatest influence on the formation of micro pores. Bulges appear on the opposite surface B when the ploughing-extrusion depth on surface A (f_dA) reaches a critical value. The ploughing-extrusion depth on surface B (f_dB) has great influence on the re-growth of fin structure.
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  Effect of Ca on crystallization of Mg-based master
  alloy containing spherical quasicrystal

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  中国有色金属学报（英文版）. 2007, 17(02): 273-273.

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  Spherical icosahedral quasicrystalline phase (I-phase) was obtained by introducing Ca into Mg-Zn-Y alloy under conventional casting conditions. Due to the addition of Ca, Mg₄₅Zn₅₀Y_4.5Ca_0.5 primary I-phase, which is thermodynamically stable and homogeneously distributed, was generated instead of decahedral quasicrystalline phase during the solidification process; the morphology of primary I-phase in the solidification microstructure changed from petal-like one (60−80 μm) to spherical one (≤15 μm). When the mass fraction of Ca reaches 0.05%, spherical I-phase with the largest quantity, highest spheroidization rate and highest circular degree can be obtained. Meanwhile, due to the changed morphology and the decreased size of primary I-phase, the hardness of Mg-Zn-Y-Ca master alloy is reduced. The application of spherical I-phase as particulate reinforced phase provides great opportunities for the improvement of strength and toughness of magnesium alloys.
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  Effect of extrusion wheel angular velocity
  on continuous extrusion forming process
  of copper concave bus bar

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  中国有色金属学报（英文版）. 2007, 17(02): 280-280.

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   The continuous extrusion forming process for producing large section copper concave bus bar under different extrusion wheel angular velocities was studied by three-dimensional finite element technology based on software DEFORM-3D. The rigid-viscoplastic constitutive equation was employed in the model. The numerical simulation results show that the deformation body flow velocity in the die orifice increases gradually with the increase of the extrusion wheel angular velocity. But slippage between the rod and extrusion wheel occurs when the extrusion wheel angular velocity is high. The effective stress near the die orifice enhances gradually with increasing extrusion wheel angular velocity. High stress is concentrated in adjacent regions of the flash gap. The effective strain gradient is greater near the abutment than that near the die orifice. The effective strain of the product increases gradually with increasing extrusion wheel angular velocity. In the deformation process, the deformation body temperature increases remarkably due to friction and deformation. So the cooling is necessary in the region of the die and tools.
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  Effect of annealing treatment on electrochemical
  property of LiNi0.5Mn1.5O4 spinel

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  中国有色金属学报（英文版）. 2007, 17(02): 287-287.

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  LiNi_0.5Mn_1.5O₄ was prepared under different cooling conditions. The electrochemical properties of LiNi_0.5Mn_1.5O₄ prepared under different cooling conditions were investigated. The results show that LiNi_0.5Mn_1.5O₄ synthesized with or without annealing treatment has similar X-ray diffraction patterns that can be indexed to cubic spinel structure. The mass loss occurring above 650 ℃ during the heating process can be mostly gained during the cooling process. LiNi_0.5Mn_1.5O₄ synthesized with an annealing treatment exhibits almost one voltage plateau at around 4.7 V and higher capacity with a quick fading upon cycling, whereas LiNi_0.5Mn_1.5O₄ synthesized without annealing treatment shows two voltage plateaus at around 4.1 and 4.7 V and superior capacity retention upon cycling both at rates of 1/7C and 1C, though the capacity is not high.
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  Synthesis and characterization of layered
  Li(Ni1/3Mn1/3Co1/3)O2 cathode materials
  by spray-drying method

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  中国有色金属学报（英文版）. 2007, 17(02): 291-291.

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  Spherical Li(Ni_1/3Mn_1/3Co_1/3)O₂ was prepared via the homogenous precursors produced by solution spray-drying method. The precursors were sintered at different temperatures between 600 and 1 000 ℃ for 10 h. The impacts of different sintering temperatures on the structure and electrochemical performances of Li(Ni_1/3Mn_1/3Co_1/3)O₂ were compared by means of X-ray diffractometry(XRD), scanning electron microscopy(SEM), and charge/discharge test as cathode materials for lithium ion batteries. The experimental results show that the spherical morphology of the spray-dried powers maintains during the subsequent heat treatment and the specific capacity increases with rising sintering temperature. When the sintering temperature rises up to 900 ℃, Li(Ni_1/3Mn_1/3Co_1/3)O₂ attains a reversible capacity of 153 mA∙h/g between 3.00 and 4.35 V at 0.2C rate with excellent cyclability.
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  Influence of Ti4+ doping on electrochemical
  properties of LiFePO4/C cathode material for
  lithium-ion batteries

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  中国有色金属学报（英文版）. 2007, 17(02): 296-296.

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   To improve the performance of LiFePO₄, single phase Li_1−4xTi_xFePO₄/C (x=0, 0.005, 0.010, 0.015) cathodes were synthesized by solid-state method. A certain content of glucose was used as carbon precursor and content of carbon in every final product was about 3.5%. The samples were characterized by X-ray diffraction(XRD), scanning electron microscopy observations(SEM), charge/discharge test, carbon analysis and electrochemical impedance spectroscopy(EIS). The results indicate that the prepared samples have ordered olivine structure and doping of the low concentration Ti⁴⁺ does not affect the structure of the samples. The electrochemical capabilities evaluated by charge-discharge test show that the sample with 1% Ti⁴⁺ (molar fraction) has good electrochemical performance delivering about an initial specific capacity of 146.7 mA∙h/g at 0.3C rate. Electrochemical impedance spectroscopy measurement results show that the charge transfer resistance of the sample could be decreased greatly by doping an appropriate amount Ti⁴⁺.
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  Influences of complex modification of P and RE
  on microstructure and mechanical properties
  of hypereutectic Al-20Si alloy

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  中国有色金属学报（英文版）. 2007, 17(02): 301-301.

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   P and RE complex modification of hypereutectic Al-Si alloys was conducted. The influences of P, RE content on the microstructure and mechanical properties of alloys were investigated. The complex modifications of P and RE make the coarse block primary silicon obviously refined and the large needle eutectic silicon modified to the fine fibrous or lamella ones. P mainly refines the primary silicon, but excess P is unfavorable to the refinement of primary silicon. RE can well refine the primary and eutectic silicon, but its modification effect on the eutectic silicon is more obvious. P can repress the modification of RE on the eutectic silicon. The alloys with the additions of 0.08% P and 0.60% RE have the optimal microstructure and the highest mechanical properties. Compared with the unmodified alloy, the primary silicon of alloys can be refined from 66.4 μm to 23.3 μm and the eutectic silicon can be refined from 8.3 μm to 5.2 μm. The tensile strength is improved from 256 MPa to 306 MPa and the elongation is improved from 0.35% to 0.48%.
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  Micro-yield behaviors of Al2O3-SiO2(sf)/Al-Si metal matrix composites

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  中国有色金属学报（英文版）. 2007, 17(02): 307-307.

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   Effects of the volume fraction and the size of crystallized alumina silicate short fibers as well as heat treatment processes on micro-yield strength(MYS) of Al₂O₃-SiO_2(sf)/Al-Si metal matrix composite(MMC) that was fabricated by squeezing cast, were investigated by using continuous loading method on an Instron 5569 tester with a special extensometer with an accuracy of 10⁻⁷. The results show that MYS of MMC decreases with the increase of volume fraction and length of the alumina silicate short fibers in the metal matrix composite, respectively. MYS of quenched Al₂O₃-SiO_2(sf)/Al-Si MMC is the lowest, MYS of the MMC through peak-aging treatment is higher than that through other heat treatment methods. And before the peak-aging, MYS of MMC aging treated gradually increases with the increase of the aging time. Aging treatment after solution treatment is a preferred way that enhances micro and macro-yield strength of Al₂O₃-SiO_2(sf)/Al-Si MMC.
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  In-situ weld-alloying plasma arc welding of SiCp/Al MMC

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  中国有色金属学报（英文版）. 2007, 17(02): 313-313.

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  Plasma arc welding was used to join SiC_p/Al composite with titanium as alloying filler material. Microstructure of the weld was characterized by an optical microscope. The results show that the harmful needle-like phase Al₄C₃ is completely eliminated in the weld of SiC_p/Al metal matrix composite(MMC) by in-situ weld-alloying/plasma arc welding with titanium as the alloying element. The wetting property between reinforced phase and Al matrix is improved, a stable weld puddle is gotten and a novel composite-material welded joint reinforced by TiN, AlN and TiC is produced. And the tensile-strength and malleability of the welded joints are improved effectively because of the use of titanium.
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  Corrosion behavior of aluminum alloy 2024-T3
  by 8-hydroxy-quinoline and its derivative
  in 3.5% chloride solution

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  中国有色金属学报（英文版）. 2007, 17(02): 318-318.

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  The corrosion behavior of aluminum alloy 2024-T3 was studied in 3.5% NaCl solution with two fluorescence quinoline compounds named 8-hydroxy-quinoline(8HQ) and 8-hydroxy-quinoline-5-sulfonic acid(HQS). The open circuit potential(OCP) test result indicates that both compounds change the alloy corrosion potential by adsorbing on the electrode surface. Polarization measurements show that 8HQ is a mixed type inhibitor by blocking the active sites of the metal surface, while HQS is a corrosion accelerator by activating the cathodic reaction. Changes of the impedance parameters in the electrochemical impedance spectroscopy(EIS) are related to the adsorption of 8HQ on the metal surface, which leads to the formation of a protective layer. The impedance diagram in the solution with HQS is similar to the one without additional organic compounds. The morphology and composition of the protective layer were studied by using SEM/EDS. The result confirms the function of the additions that the effect of 8HQ is due to the insoluble aluminum chelate, Al(HQ)₃, to prevent adsorption of chloride ion, while the effect of HQS is to break down the oxide film.
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  Corrosion behavior on aluminum alloy LY12
  in simulated atmospheric corrosion process

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  中国有色金属学报（英文版）. 2007, 17(02): 326-326.

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   The corrosion behavior of typical high-strength aluminum alloy LY12 was studied by accelerated corrosion tests of cyclic wet-dry-immersion containing media of NaHSO₃ and NaCl to simulate the corrosion process in different atmosphere environment, and the corrosion mechanism was also discussed. The main experimental techniques include mass loss, morphological check, analysis of corrosion products and electrochemical measurement. The result shows that the mass loss of LY12, with or without cladding, has linear relationship with test time in the three kinds of chemical media, 0.02 mol/L NaHSO₃, 0.006 mol/L NaCl and 0.02 mol/L NaHSO₃+0.006 mol/L NaCl, respectively. A layer of cladding on high-strength aluminum alloy can raise evidently the resistance of atmospheric corrosion. Cl⁻ can promote pitting generation on the oxide film of LY12 when HOS⁻₃  exists, LY12 can react much intensely with HOS⁻₃  derived from anions.
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  Effect of homogenization treatment on microstructure
  and hot workability of high strength
  7B04 aluminium alloy

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  中国有色金属学报（英文版）. 2007, 17(02): 335-335.

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  The effects of homogenization treatment on microstructure, overburnt temperature and hot rolling plasticity of high strength 7B04 aluminium alloy were investigated. Under the condition of homogenization at 470 ℃, the starting melting temperature of the primary eutectics in ingot of non-equilibium solidified 7B04 alloy is 478 ℃. Using two-step homogenization processing at ultra-high temperature which comprises heating the ingots to 470 ℃ at 10 ℃/h and holding for 64 h, and then heating to 500 ℃ at  1 ℃/h and holding for 10 h, the ingots of 7B04 aluminium alloy could safely pass the sensitive overburnt zone between 480 ℃ and 495 ℃, and the ordinary burnt phenomena of the ingots between 480 ℃ and 495 ℃ does not occur because the excess low-melting point eutectic phases in the as-cast alloy dissolve into the matrix during the two-step homogenization processing. Consequently, the hot rolling plasticity of ingot of 7B04 aluminium alloy is greatly improved.
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  Effect of minor Sc and Zr addition on microstructures
  and mechanical properties of
  Al-Zn-Mg-Cu alloys

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  中国有色金属学报（英文版）. 2007, 17(02): 340-340.

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  Three kinds of Al-Zn-Mg-Cu based alloys with 0.22%, 0.36%(Sc+Zr) (mass fraction, %), and without Sc, Zr addition were prepared by ingot metallurgy. By using optical microscopy, transmission electronic microscopy and scanning electron microscopy, the effects of microalloying elements of Sc, Zr on the microstructure of super-high-strength Al-Zn-Mg-Cu alloys related to mechanical properties were investigated. The tensile properties and microstructures of the studied alloys under different heat treatment conditions were studied. The addition of minor Sc, Zr results in the formation of Al₃(Sc,Zr) particles. These particles are highly effective in refining the microstructures, retarding recrystallization, pinning dislocations and subboundaries. The strength of Al-Zn-Mg-Cu alloys was greatly improved by simultaneously adding minor Sc, Zr, meanwhile the ductility of the studied alloys remains at a higher level. The 0.36%(Sc+Zr) alloys gain the optimal properties after 465 ℃/h solution and 120 ℃/24 h aging. The increment of strength is mainly due to strengthening of fine grain and substructure and precipitation of Al₃(Sc, Zr) particles.
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  Magnetic anisotropy in Fe-25Cr-12Co-1Si alloy
  induced by external magnetic field

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  中国有色金属学报（英文版）. 2007, 17(02): 346-346.

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  Structural and magnetic properties of Fe-25Cr-12Co-1Si alloy thermo-magnetically treated under different external magnetic field conditions were investigated. Orientation and morphology of the ferromagnetic α₁ phase embedded in α₂ phase matrix before and after step ageing are characterized by transmission electron microscope(TEM). The results show that the ellipsoidal particles of ferromagnetic α₁ phase are aligned along the direction of external magnetic field during isothermal magnetic ageing. Approximately 28% of the total coercivity can be attributed to the shape anisotropy of α₁ phase particles induced by external magnetic field for Fe-25Cr-12Co-1Si alloy thermo-magnetically treated with a parallel magnetic field.
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  Crystallographic research of spangle on hot dip galvanized steel sheets

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  中国有色金属学报（英文版）. 2007, 17(02): 351-351.

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   The spangles on hot dip galvanized steel sheet were investigated on an X-ray diffraction(XRD) meter by the rotating crystal method. The correlations between the crystallographic orientations of spangles and their morphologies were analyzed. The results show that the correlation can be classified into three types: β=0˚, 0˚＜β＜90˚ and β=90˚ by β. Crystallographic model of single spangle under the ideal condition was established based on the experimental results. The correlation between α and β can be deduced by their geometric relation as an equation.
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  Preparation of helicopter rotor counterbalance
  component by means of permanent-mold casting

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  中国有色金属学报（英文版）. 2007, 17(02): 357-357.

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  Copper alloy was adopted to prepare helicopter rotor counterbalance component by means of permanent-mold casting. Process parameters were determined on the basis of theory calculation and computer numerical simulation. Through controlling mould temperature, pouring temperature and speed, the defects, such as gas cavity, shrinkage porosity, cold shut, can be effectively avoided. The results show that the best process parameters for smelting are as follows: pouring temperature is 1 100 ℃, pouring time is 14 s and opened mould time is 6 min. Mixture of 90% charcoal powder and 10% fluorite were selected as covering agent and 0.01% phosphorus copper acts as oxidizer. The density of rotor counterbalance component after casting in permanent-mold is 99.91% of its theory density. Mechanical properties are as follows: σ_b=315 MPa, σ_0.2=143 MPa, δ=25%, HB=950. The mass deviation is between −5 g and +5 g, the curved surface distortion is less than 0.20 mm, and the largest tolerance of sectional thickness can be controlled between −0.10 mm and +0.10 mm.
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  Properties and structure of RE-Ni-W-P-SiC composite
  coating prepared by impulse electrodeposition

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  中国有色金属学报（英文版）. 2007, 17(02): 363-363.

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  The properties and structure of electrodeposited RE (CeO₂)-Ni-W-P-SiC composite coating were investigated. The results show that the hardness and electrodepositing speed of composite coatings obtained at an impulse current are higher than those at a direct current. The hardness and wear resistance of the coating are obviously increased by adding RE and SiC. The hardness of the coating increases with the increase of treatment temperature and current density, and reaches the optimum value at 400 ℃ and at 10 A/dm², respectively. The optimum operation parameters of electrodeposition of the composite coating are as follows: pH value is 4.5, bath temperature is 65 ℃, and current density is 10 A/dm².
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  Property measurements on spray formed Si-Al alloys

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  中国有色金属学报（英文版）. 2007, 17(02): 368-368.

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  A novel Si-Al alloy was prepared by spray forming process for electronic packaging. Property measurements on spray-formed Si-Al alloys after hot pressing were carried out. The results indicate that the alloys (Si-(30%−40%)Al) have advantageous physical and mechanical characteristics, including low coefficient of thermal expansion (6.9×10⁻⁶−8.7×10⁻⁶/K), high thermal conductivity (118−127 W/(m·K)), low density (2.421×10³−2.465×10³ kg/m³), high ultimate flexural strength (180−220 MPa) and Brinell hardness (162−261). The alloys are easy to machine to tight tolerances using standard machine tools and they can be electroplated with gold finishes and soldered with Sn-Pb alloy without any difficulty.
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  Structure and electronic properties of SiC thin-films
  deposited by RF magnetron sputtering

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  中国有色金属学报（英文版）. 2007, 17(02): 373-373.

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  SiC thin-films were prepared by RF-magnetron sputtering technique(RMS) with the target of single crystalline SiC and then annealed. The surface morphology of thin-films was characterized by AFM. The result shows that the surface of the thin-films is smooth and compact; XRD analysis reveals that the thin-films are amorphous. The thickness, square-resistance and curves of resistance—temperature were measured. The results show that the curves of lnR versus 1/kT both before and after annealing satisfy the expression of lnR∝∆W/kT, where ∆W is electron excitation energy in the range of 0.014 2−0.018 5 eV, and it has a trend of increasing when the temperature is increased. After synthetical analysis we get the conclusion that the electronic mechanism of the thin-films is short distance transition between the localized states in the temperature range of 25−250 ℃. The resistivity is in the range of 2.4×10⁻³−4.4×10⁻³ Ω∙cm and it has the same trend as electron excitation energy when annealing temperature is increased, which further confirms the electronic mechanism of thin-films and the trend of electron excitation energy versus annealing temperature.
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  Electrical conductivity of Cu-Ag in situ filamentary composites

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  中国有色金属学报（英文版）. 2007, 17(02): 378-378.

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  The electrical conductivity of Cu-10Ag in situ filamentary composite was studied during the deformation and annealing processes. The dependence of electrical resistivity of the deformed composites on the true strain presents a two-stage change with increase of the true strain. The intermediate heat treatment and the stabilized annealing treatment to the deformed composite promote the separation of Ag precipitate, and increase the electrical conductivity. The maximum conductivity of the composite experienced the stabilizing heat treatment can reach about 97% IACS with σ_b≥400 MPa at 550 ℃ annealing, and reach about 70% IACS with  σ_b≥1 250 MPa at 300 ℃ annealing. The corresponded strength of the composite was reported. The microstructure reason for the changes of the conductivity was discussed.
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  Effects of deformation on microstructures and properties
  of submicron crystalline Cu-5%Cr alloy

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  中国有色金属学报（英文版）. 2007, 17(02): 384-384.

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  Warm extrusion of submicron crystalline Cu-5%Cr from 100 ℃ to 600 ℃ was investigated. The effects of different extrusion ratios and different extrusion temperatures on microstructures and properties of submicron crystalline Cu-5%Cr were studied. The microstructures of the extruded Cu-5%Cr were characterized by backscattered electron images(BSE) and transmission electron microscopy(TEM). The mechanical properties of the extruded Cu-5%Cr were measured by means of microhardness and tension test. The results show that, the deformation, dynamic recovery and dynamic recrystallization of the extruded Cu-5%Cr are mainly produced in Cu matrix. The higher extrusion ratio leads to more uniform microstructure and finer Cu grains. When being extruded in the range of 100−600 ℃, dynamic recovery of Cu is the dominant process, and dynamic recrystallization of Cu occurred above 300 ℃ is far from end. The most part of microstructure of as-extruded Cu-5%Cr is subcrystallines produced by dynamic recovery, only a few recrystallines exist, and the average size of these grains is not larger than 400 nm. With extrusion temperature rising, the tensile strength and microhardness of Cu-5%Cr decrease, and elongation increases gradually.
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  Nanostructured yttria stabilized zirconia coatings deposited
  by air plasma spraying

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  中国有色金属学报（英文版）. 2007, 17(02): 389-389.

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  Nanostructured yttria partially stabilized zirconia coatings were deposited by air plasma spraying with reconstituted nanosized powder. The microstructures and phase compositions of the powder and the as-sprayed nanostructured coatings were characterized by transmission electron microscopy(TEM), scanning electron microscopy(SEM) and X-ray diffraction(XRD). The results demonstrate that the microstructure of as-sprayed nanostructured zirconia coating exhibits a unique tri-modal distribution including the initial nanostructure of the powder, equiaxed grains and columnar grains. Air plasma sprayed nanostructured zirconia coatings consist of only the nontransformable tetragonal phase, though the reconstituted nanostructured powder shows the presence of the monoclinic, the tetragonal and the cubic phases. The mean grain size of the coating is about 42 nm.
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  Bioactivity of bioresorbable composite based on
  bioactive glass and poly-L-lactide

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  中国有色金属学报（英文版）. 2007, 17(02): 394-394.

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   Bioactive and bioresorbable composite was fabricated by a solvent evaporation technique using poly-L-lactide(PLLA) and bioactive glass (average particle size: 6.8 μm). Bioactive glass granules are homogeneously distributed in the composite with microcrack structure. The formation of hydroxyapatite(HA) on the composite in simulated body fluid(SBF) was analyzed by scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), X-ray diffraction(XRD), and Raman spectra. Rod-like HA crystals deposit on the surface of PLLA/bioactive glass composite after soaking for 3 d. Both rod-like crystals and HA layer form on the surface for 14 d in SBF. The high bioactivity of PLLA/bioactive glass composite indicates the potential of materials for integration with bone.
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  Industrial flow of lead in China

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  中国有色金属学报（英文版）. 2007, 17(02): 400-400.

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  The rules on industrial flow of lead were studied for theoretical foundation of nonrenewable resource conservation and environmental improvement. A model of lead flow in lead product life cycle was developed through lead flow analysis and was used to analyze the relationship between lead product system and its environment, thus the rules on industrial flow of lead were obtained. The results show that increasing eco-efficiency will favor both resource conservation and environmental improvement. Several indices were proposed to evaluate the lead flow. As for application, the lead-flow for China in 1999 was analyzed and the reasons for low eco-efficiency were identified. In the end, some countermeasures were proposed to improve eco-efficiency, and the future lead ore consumption and environment quality were forecasted.
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  Mutagenic breeding of silver-resistant Acidithiobacillus
  ferrooxidans and exploration of resistant mechanism

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  中国有色金属学报（英文版）. 2007, 17(02): 412-412.

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  The silver-resistant Acidithiobacillus ferrooxidans were isolated from 22 acid mine drainage (AMD) samples collected from Dexing Copper Mine and Chengmen Mountain Mine, Jiangxi Province, China. Isolate DX16 is obtained from the sample taken from Dexing Copper Mine and still carries out ferrous ion oxidation when incubated in 9K medium containing silver nitrate (240 mg/L). While isolate H1, a less resistant strain taken from Yin Mountain Mine, has a tolerate level of only 60 mg/L. Based on 16S ribosomal DNA sequencing, both bacterial 16SrDNA sequences are 100% similar to Acidithiobacillus ferrooxidans ATCC 23270. Through ultraviolet irradiation induced mutations, isolate mDX16 that is obtained from DX16 carries out ferrous ion oxidation when incubated in 9K medium containing higher concentration of silver nitrate (250 mg/L). When silver-resistant gene (SilC) analysis is carried out on the two isolates, it is seen that this gene was absent in both.
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  Kinetic process of oxidative leaching of chalcopyrite
  under low oxygen pressure and low temperature

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  中国有色金属学报（英文版）. 2007, 17(02): 418-418.

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   Kinetic process of oxidative leaching of chalcopyrite in chloride acid hydroxide medium under oxygen pressure and low temperature was investigated. The effect on leaching rate of chalcopyrite caused by these factors such as ore granularity, vitriol concentration, sodium chloride concentration, oxygen pressure and temperature was discussed. The results show that the leaching rate of chalcopyrite increases with decreasing the ore granularity. At the early stage of oxidative reaction, the copper leaching rate increases with increasing the oxygen pressure and dosage of vitriol concentration, while oxygen pressure affects leaching less at the later stage. At low temperature, the earlier oxidative leaching process of chalcopyrite is controlled by chemical reactions while the later one by diffusion. The chalcopyrite oxidative leaching rate has close relation with ion concentration in the leaching solution. The higher ion concentration is propitious for chalcopyrite leaching.
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  Leaching of complex sulphide concentrate in acidic
  cupric chloride solutions

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  中国有色金属学报（英文版）. 2007, 17(02): 423-423.

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  The chemical analysis of a complex sulphide concentrate by emission spectrometry and X-ray diffraction shows that it contains essentially copper, lead, zinc and iron in the form of chalcopyrite, sphalerite and galena. A small amount of pyrite is also present in the ore but does not be detected with X-ray diffraction. The cupric chloride leaching of the sulphide concentrate at various durations and solid/liquid ratios at 100 ℃ shows that the rate of dissolution of the ore is the fastest in the first several hours, and after 12 h it does not evolve significantly. If oxygen is excluded from the aqueous cupric chloride solution during the leaching experiment at 100 ℃, the pyrite in the ore will not be leached. The determination of principal dissolved metals in the leaching liquor by flame atomic absorption spectrometry, and the chemical analysis of solid residues by emission spectrometry and X-ray diffraction allow to conclude that the rate of dissolution of the minerals contained in the complex sulphide concentrate are in the order of galena＞sphalerite＞chalcopyrite.
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  Electrochemical process of titanium extraction

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  中国有色金属学报（英文版）. 2007, 17(02): 429-429.

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   A wide variety of processes are being pursued by researchers for cost effective extraction of titanium metal. Electrochemical processes are promising due to simplicity and being less capital intensive. Some of the promising electrochemical processes of titanium extraction were reviewed and the results of laboratory scale experiments on electrochemical reduction of TiO₂ granules were brought out. Some of the kinetic parameters of the reduction process were discussed while presenting the quality improvements achieved in the experimentation.
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  Preparation of flake AgSnO2 composite powders by hydrothermal method

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  中国有色金属学报（英文版）. 2007, 17(02): 434-434.

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   Silver-tin oxide composite powders and silver powders were synthesized by hydrothermal method using NH₃ to complex Ag⁺, SO²⁻₃ to reduce Ag(NH₃)⁺₂ and Na₂SnO₃ as the source of tin. The powders were characterized by XRD, SEM and EDX. The results show that there are macroscopic and microscopic differences between two kinds of powders. Spherical silver powders are   3 μm in diameter, and silver-tin oxide composite powders are mainly flake of about 0.3 μm in thickness. Silver crystal in silver-tin oxide composite powders is preferentially oriented in the (111) crystallographic direction and its oriented index is 2.581. Crystal lattice parameter of silver crystal of silver tin-oxide composite powders is 0.409 34 nm, larger than 0.408 68 nm of silver powders. The XPS analysis shows that silver in silver-tin oxide composite powders is metallic silver and tin oxide in silver tin-oxide composite powders has the red shift for Sn⁴⁺(3d_5/2) and O²⁻(1s).
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  Thermodynamic properties of vapor complex Na2ZrCl6

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  中国有色金属学报（英文版）. 2007, 17(02): 439-439.

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  Thermodynamic studies were carried out for the vapor complex of sodium chloride with zirconium tetrachloride at 718−778 K and 0.5−2.5 kPa by using high temperature phase equilibrium-quenching experiments, taking closed Pyrex glass ampoules as the reaction containers. The results show that the sole predominant vapor complex is Na₂ZrCl₆ for the ZrCl₄-NaCl system under the experimental conditions. The thermodynamic equilibrium constants and other thermodynamic functions of the reaction 2NaCl(s)+ZrCl₄(g)=Na₂ZrCl₆(g) have been derived from the measurements. The results for the changes in enthalpy and entropy are ∆H⁰=(−70.1±1.5) kJ/mol and ∆S⁰=(−105.9±2.0) J/(mol∙K) in the temperature range.