| 1. |
- Wang, Hao, et al.
(author)
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Preparation and Properties of Microporous Nickel with High Porosity
- 2023
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In: Rare Metal Materials and Engineering. - : Northwest Institute for Nonferrous Metal Research. - 1002-185X. ; 52:3, s. 876-882
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Journal article (peer-reviewed)abstract
- The strategy of sintered closed-hole followed by reopening was proposed to prepare the microporous nickel material with high porosity through the powder metallurgy and subsequential treatments. The carbonyl nickel powder with particle size of 1 mu m was used as raw material, and the effects of sintering process parameters on the pore properties and mechanical properties of microporous nickel were studied. Results show that the porosity measured by mercury injection method of microporous nickel is 53.7%, and the average pore diameter is 612.25 nm at the sintering temperature of 400 degrees C. After machining, the porosity measured by mercury injection method is 54.0%, and the average pore diameter is 511.37 nm, which still satisfies the requirements of engineering application. The strategy provides providing a new approach for the preparation of microporous nickel and other porous metal materials.
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| 2. |
- He, S. W., et al.
(author)
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Cooling Rate Calculation of Non-Equilibrium Aluminum Alloy Powders Prepared by Gas Atomization
- 2009
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In: Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering. - 1002-185X. ; 38, s. 353-356
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Journal article (peer-reviewed)abstract
- The cooling rate of aluminum alloy powders prepared by ultrasonic gas atomization process was calculated through the convection heat transfer principle. A simple and theoretical model is established, which can be expressed as vertical bar dT(d)/dt vertical bar =12/rho.C(p) . (T(d) - T(f)) . k(g)/d(2). The average cooling rates of Al-Ni-Ce-Fe-Cu alloy powders prepared by argon gas atomization and by helium gas atomization are about 10(4)similar to 10(7) K/s and 10(5)similar to 10(8) K/s, respectively. The critical cooling rate is calculated to be 3.74 x 10(5) K/s for Al-Ni-Ce-Fe-Cu alloy amorphous powders prepared by argon gas atomization. The cooling rates of gas-atomized powder particles estimated from secondary dendrite arm spacing are in consistence to those predicted from the theoretical model.
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| 3. |
- Huaizi, He, et al.
(author)
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Effect of Process Parameter Settings and Thickness on Microstructures of EBM Produced TI-6Al-4V Alloy : [工艺参数设置和厚度对电子束熔融加工Ti-6Al-4V合金微观结构的影响]
- 2021
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In: Xiyou jinshu cailiao yu gongcheng. - : Science Press. - 1002-185X. ; 50:2, s. 408-415
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Journal article (peer-reviewed)abstract
- The effect of sample dimensions and process parameters (beam current, scan speed, offset focus and scan length) of electron beam melting (EBM) system on microstructure of the EBM built Ti-6Al-4V alloy was investigated. The microstructure of EBM built Ti-6Al-4V alloy consists of columnar grains of prior β phase. Inside the columnar grain, typical (α+β) structures, namely Widmanstätten α platelets and rod-like β phase formed on the interfaces of the fine α grains, are observed. Grain boundary α layer forms along grain boundary of prior β columnar grain. With the increase of thickness of the test slab, beam energy density and scanning length, the prior β columnar grain grows along the build direction and diameter of which increases. The columnar grain diameter also decreases with the increase in height of the test slab. With increasing the thickness of the test slab and beam energy density, α platelets get coarser.
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| 4. |
- Imran, S., et al.
(author)
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FeGaB(25 nm)/Al 2 O 3 /FeGaB(25 nm) Multilayer Structures : Effects of Variation of Al 2 O 3 Thickness on Static and Dynamic Magnetic Properties
- 2018
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In: Xiyou jinshu cailiao yu gongcheng. - : Rare Metals Materials and Engineering Press. - 1002-185X. ; 47:7, s. 1951-1957
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Journal article (peer-reviewed)abstract
- Iron-gallium (FeGa) thin film has the unique advantages in designing integrated magnetic sensors or chips due to its relatively large magnetostrictive constant compared with other soft magnetic materials. In this work, non-magnetic doping and laminating methods have been employed to control the magnetic and electric properties of this alloy film. By doping a certain amount of boron (B), the coercivities are largely decreased for samples of thickness less than ~30 nm. For thicker films, we find that inserting an ultrathin Al 2 O 3 middle layer is very helpful to control the coercivities with negligible influence on saturation magnetization (M s ). The smallest easy-axis coercivity of 0.98×79.6 A/m is obtained in the multilayer film FeGaB(25 nm)/Al 2 O 3 (0.5 nm)/FeGaB(25 nm). In this case, the resistivity is enhanced by 1.5 times compared with the 50 nm single layer film. Structural characterizations indicate the reductions of crystalline quality and physical dimension of the magnetic grains playing important roles in softening the magnetic properties. Besides, the influences of magnetostatic interaction and morphology characteristics are also considered in facilitating domain reversal. High permeability spectra with gigahertz response are obtained for our multilayer films. The methodology applied here, i. e., enhancing magnetic and electric performance by introducing ultrathin non-magnetic layers, could be translated to other species of soft magnetic materials as well.
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| 5. |
- Man, Shahid, et al.
(author)
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FeGaB(25 nm)/Al2O3/FeGaB(25 nm) Multilayer Structures : Effects of Variation of Al(2)O(3)Thickness on Static and Dynamic Magnetic Properties
- 2018
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In: Xiyou jinshu cailiao yu gongcheng. - : NORTHWEST INST NONFERROUS METAL RESEARCH. - 1002-185X. ; 47:7, s. 1951-1957
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Journal article (peer-reviewed)abstract
- Iron-gallium (FeGa) thin film has the unique advantages in designing integrated magnetic sensors or chips due to its relatively large magnetostrictive constant compared with other soft magnetic materials. In this work, non-magnetic doping and laminating methods have been employed to control the magnetic and electric properties of this alloy film. By doping a certain amount of boron (B), the coercivities are largely decreased for samples of thickness less than similar to 30 nm. For thicker films, we find that inserting an ultrathin Al2O3 middle layer is very helpful to control the coercivities with negligible influence on saturation magnetization (M-s). The smallest easy-axis coercivity of 0.98x79.6 A/m is obtained in the multilayer film FeGaB(25 nm)/Al2O3(0.5 nm)/FeGaB(25 nm). In this case, the resistivity is enhanced by 1.5 times compared with the 50 nm single layer film. Structural characterizations indicate the reductions of crystalline quality and physical dimension of the magnetic grains playing important roles in softening the magnetic properties. Besides, the influences of magnetostatic interaction and morphology characteristics are also considered in facilitating domain reversal. High permeability spectra with gigahertz response are obtained for our multilayer films. The methodology applied here, i.e., enhancing magnetic and electric performance by introducing ultrathin non-magnetic layers, could be translated to other species of soft magnetic materials as well.
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| 6. |
- Niu, L., et al.
(author)
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Fluidized-bed chlorination rates of Kenya rutile ore
- 2014
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In: Xiyou jinshu cailiao yu gongcheng. - 1002-185X. ; 43:6, s. 1377-1380
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Journal article (peer-reviewed)abstract
- The thermodynamics and kinetics of natural rutile carbochlorination have been investigated in a fluidized-bed. Thermodynamic analysis of this system reveals that when C is excess in the solid phase, TiCl4 and CO are the only two stable products in the chemical equilibrium compositions system, and the increase of the ratio of C to TiO2 has little effect on the product composition. At high temperature, the reaction with CO as the product is the dominant reaction. This paper proposed a reaction rate model, and got a rutile chlorination rate formula, which is more consistent with experimental data. For the TiO2-C-Cl2 system, the reaction rate is dependent on both size and density of natural rutile. From 900 to 1000°C, the apparent activation energy is 10.569 kJ/mol. In this temperature range, mass diffusion is the main reaction controlling step. The expression of the chlorine reaction rate in the C-Cl2 system was obtained, and it depends on the degree of reaction, Cl2 concentration and the size of coke.
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| 7. |
- Shiwei, Tian, et al.
(author)
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Effect of Mo Element on Microstructure and Mechanical Properties of TiAl Alloys
- 2022
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In: Xiyou jinshu cailiao yu gongcheng. - : NORTHWEST INST NONFERROUS METAL RESEARCH. - 1002-185X. ; 51:7, s. 2336-2343
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Journal article (peer-reviewed)abstract
- Four TiAl alloys with different Mo contents were designed, and the microstructure and mechanical properties of these MoTiAl alloys were studied by scanning electron microscope, nanoindentation, and hot compression simulation methods. Results show that with increasing the Mo content, the content of. phase is gradually decreased, while that of beta phase is gradually increased. The Mo element mainly exists in the form of beta phase in the TiAl alloy. During the hot isostatic pressing process, the Mo element is diffused from the. and a 2 phases to the beta phase. The nanoindentation hardness of Mo-TiAl alloy reaches the maximum when the Mo content is 1.59at%, and it is negatively correlated with the interlamellar space. As the content of Mo element increases, the flow stress of Mo-TiAl alloys decreases, and the TiAl alloys with 2.11at% and 3.94at% Mo addtion have poor plasticity due to the Al element segregation.
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| 8. |
- Wei, Xiuyu, 1979, et al.
(author)
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Corrosion Behavior of WC-Co-(Ni)-(Cr) Cemented Carbide in Neutral Solution
- 2020
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In: Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering. - 1002-185X. ; 49:1, s. 313-319
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Journal article (peer-reviewed)abstract
- Three groups of WC-Co-(Ni)-(Cr) cemented carbides with different binder phase compositions were prepared by powder metallurgy using WC, Co, Ni and Cr3C2 powders as raw materials. The corrosion behavior of the three alloys in neutral solution was studied by polarization curve test and immersion experiment. The corrosion mechanism was discussed by means of scanning electron microscopy, energy spectrum analysis, X-ray photoelectron spectroscopy (XPS) and EBSD. The results show that in neutral solution the corrosion of WC-Co and WC-Co-Cr cemented carbides is mainly caused by the selective dissolution of Co and the corrosion products after immersion are mainly composed of Co(OH)2. The corrosion resistance of WC-Co cemented carbide in neutral solution can be improved by the addition of Cr, which may be related to the decrease in the content of hcp-Co in the binder phase by adding Cr. Adding Ni and Cr together can further improve the corrosion resistance of WC-Co cemented carbide in neutral solution. After immersion for 480 h in Na2SO4 solution, the WC-Co-Ni-Cr alloy sample is just corroded slightly.
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| 9. |
- Xihe, Liu, et al.
(author)
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Influence of Carbon Nanotubes on Defects in AlSi10Mg Alloy Fabricated by Selective Laser Melting
- 2019
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In: Xiyou jinshu cailiao yu gongcheng. - 1002-185X. ; 48:5, s. 1637-1644
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Journal article (peer-reviewed)abstract
- Pure AlSi10Mg alloy and carbon nanotubes (CNTs)-AlSi10Mg composite with different CNTs additions were fabricated by selective laser melting (SLM). The CNTs-AlSi10Mg composite is strengthened when the CNTs content is lower than 0.05 wt%. With the increasing CNTs content, however, the strength is decreased significantly because of the poor density. In order to understand the influence of CNTs on the defects in SLMed AlSi10Mg alloy, nano-CT technology was used to get the 3D information of the defects. The results indicate that the volume fraction of large defects (with diameter larger than 50 mu m) in the total volume of defects is increased from 12% to 46% in CNTs(0.5wt%)-AlSi10Mg composite. The number of gas pores in CNTs(0.5wt%)-AlSi10Mg composite are significantly increased. The diameter of gas pores in CNTs(0.5wt%)-AlSi10Mg composite are larger than that in pure AlSi10Mg alloy. The agglomeration of CNTs in the powder and gas adsorption are the fundamental reasons for the increase of the two types of defects.
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