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Effect of Cr Content on the Compression Properties and Abrasive Wear Behavior of the High-Volume Fraction(TiC–TiB_2)/Cu Composites

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Acta Metallurgica Sinica(English Letters) 2014年第5期27卷 951-956页

作者： Feng Qiu Yue Han Ai Cheng Jianbang Lu Qichuan Jiang key laboratory of Automobile materials Ministry of EducationDepartment of Materials Science and EngineeringJilin University

The （TiC-TiB2）/Cu composites with 50 vol% TiC-TiB2 ceramic particles were successfully fabricated by the combustion synthesis and hot press consolidation in a Cu-Ti-B4C-Cr system. The effects of the Cr content on the microstructures, hardness, compression properties, and abrasive wear behaviors of the composites were investigated. The final products consist of only Cu, TiC, and TiB2 phases, and the ceramic particles are distributed uniformly in these composites. The size of the ceramic particles decreases with Cr addition. As the Cr content increases, the yield strength, ultimate compression strength, microhardness, and abrasive wear resistance of the composites increase, and the fracture strain decreases.

关键词： Metal matrix composites Powder metallurgy Combustion synthesis Abrasive wear

Effect of grain size on corrosion behavior of electrodeposited bulk nanocrystalline Ni

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中国有色金属学会会刊：英文版 2010年第1期20卷 82-89页

作者：秦丽元连建设蒋青 key laboratory of Automobile materials of ministry of education College of Materials Science and Engineering Jilin University

Nanocrystalline (NC) and coarse-grained Ni with different grain sizes (from 16 nm to 2 μm) were fabricated by direct current electrodeposition. Effect of grain size on the electrochemical corrosion behavior of these Ni deposits in different corrosion media was characterized by using potentiodynamic polarization test, electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and immersion corrosion test. Results show that in the NaOH or NaCl solution, the NC Ni exhibits improved corrosion resistance with the decrease of grain size. But in H2SO4 solution, the higher grain boundary density accelerates corrosion due to no passive process and the corrosion resistance of NC Ni decreases with refining grain size. The distinct experimental results of NC Ni in corrosion behavior can be reasonably explained by the positive or negative effect of high-density grain boundaries in different corrosion media.

关键词：纳米晶镍晶粒尺寸腐蚀行为 X射线光电子能谱电化学阻抗谱耐腐蚀性能块体氢氧化钠溶液

Microstructure and mechanical properties of Mg-6Al-0.3Mn-xY alloys prepared by casting and hot rolling

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Transactions of Nonferrous Metals Society of China 2010年第3期20卷 383-389页

作者：苏桂花张亮程丽任刘勇兵曹占义 key laboratory of Automobile materials Ministry of EducationDepartment of Materials Science and EngineeringJilin University

Mg-6Al-0.3Mn-xY(x=0,0.3,0.6 and 0.9,mass fraction,%) magnesium alloys were prepared by casting and hot rolling *** influence of yttrium on microstructure and tensile mechanical properties of the AM60 magnesium alloy was *** results reveal that with increasing the yttrium content,Al2Y precipitates form and the grain size is *** ultimate strength,yield strength and elongation at room temperature are 192 MPa,62 MPa and 12.6%,respectively,for the as-cast Mg-6Al-0.3Mn-0.9Y *** these properties are improved obviously by hot rolling,and the values are up to 303 MPa,255 MPa and 17.1%,respectively,for the rolled Mg-6Al-0.3Mn-0.9Y *** improvement of mechanical properties is attributed to continuous dynamic recrystallization and the existence of highly thermal stable Al2Y precipitate which impedes the movement of dislocation effectively.

关键词： magnesium alloy yttrium hot rolling dynamic recrystallization mechanical properties

Microstructural Evolution of a Hypoeutectoid Pearlite Steel under Rolling-sliding Contact Loading

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Journal of Iron and Steel Research International 2016年第10期23卷 1054-1060页

作者： Qiu-han LI Chi ZHANG Hu CHEN Hao CHEN Zhi-gang YANG key laboratory of Advanced materials of ministry of education School of Materials Science and EngineeringTsinghua University

To study the microstructural evolution of pearlite steel subjected to pure rolling and rolling-sliding contact loading,a hypoeutectoid pearlite steel with composition and microstructure similar to BS11 was designed and twindisc tests of this pearlite steel were performed to simulate the wheel/rail *** a series of twin-disc tests,optical microscope（OM）observation,scanning electron microscope（SEM）observation,X-ray diffraction（XRD）,and micro-hardness tests were conducted to characterize the *** the pure rolling contact condition,a large amount of reticular cracks emerged within 60μm below the contact surface of the samples after 120 000 *** largest deformation was approximately 200μm below the contact *** the rolling-sliding contact condition,the nodularization of pearlite within 100μm below the contact surface was *** microstructure and stress-strain distribution of the area within 2mm below the contact surface were *** distribution of micro-hardness under the contact surface varied with contact *** element method（FEM）was used to simulate the stress-strain *** results of SEM,FEM,and micro-hardness tests indicated that under the pure rolling contact condition,the maximum plastic strain was approximately 200-400μm below the contact ***,under the rolling-sliding contact condition,the maximum plastic strain emerged on the contact *** the pure rolling contact condition,the distribution of micro-hardness was almost identical to that of the equivalent plastic *** the rolling-sliding contact condition,the distribution of micro-hardness was affected by the equivalent plastic strain and tangential stress.

关键词： twin-disc test rail micro-hardness plastic strain finite element method hypoeutectoid pearlite steel rolling-sliding contact

Study of NiCuZn ferrite powders and films prepared by sol gel method

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Chinese Physics B 2011年第2期20卷 495-499页

作者：高良秋于国建王颖魏福林 key laboratory for Magnetism and Magnetic materials of the ministry of education Lanzhou University

This paper reports that a series of NiCuZn ferrite powders and films are prepared by using sol-gel method. The effects of raw material composition and the calcinate temperature on magnetic properties of them are investigated. The NiCuZn ferrite powders are prepared by the self-propagating high-temperature synthesis method and subsequently heated at 700 ℃-1000 ℃. The results show that NiCuZn ferrite powders with single spinel phase can be formed after heat-treating at 750 ℃. Powders obtained from Ni0.4Cu0.2Zn0.4Fel.904 gel have better magnetic properties than those from gels with other composition. After heat-treating at 900 ℃for 3 h, coercivity Hc and saturation magnetization Ms are 9.70e （i Oe = 80 A/m） and 72.4 emu/g, respectively. Different from the powders, NiCuZn films produced on Si （100） from the Ni0.4Cuo.2Zno.4Fe204 gel formed at room temperature possess high properties. When heat-treating condition is around 600 ℃for 6 rain, samples with low Hc and high Ms will be obtained. The minimal Hc is 16.70e and Ms is about 300 emu/cm3. In comparison with the films prepared through long-time heat treating, the films prepared through short heat-treating time exhibits better soft magnetic properties.

关键词： sol-gel. NiCuZn ferrite powder film

Microstructure and tensile properties of as-extruded Mg-Sn-Y alloys

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Transactions of Nonferrous Metals Society of China 2010年第B7期20卷 493-497页

作者：赵宏达秦高梧任玉平裴文利陈冬郭运 key laboratory for Anisotropy and Texture of materials Ministry of EducationNortheastern University

The microstructure and tensile properties of the Mg-1.0%Sn-xY(x=1.5%,3.0%,3.5%,atom fraction)alloys extruded indirectly at 350℃ were investigated by means of optical microscopy,scanning electron microscopy and tensile *** mean grain sizes ofα-Mg matrix in the three extruded alloys are 6,8 and 12μm,respectively,slightly increasing with the addition of Y. The relationship between microstructure and strength was discussed in *** results show that the addition of Y has little effect on the grain refinement of the as-extruded Mg-Sn based alloys *** only MgSnY phase is detected in the Mg-Sn-1.5%Y alloy, and the Sn3Y5 phase in the Mg-Sn-3.5%Y alloy,whereas both of them simultaneously exist in the Mg-Sn-3.0%Y *** particle shape of MgSnY and Sn3Y5 phase,inherited from the solidification,has little change before and after hot ***-Sn-3.0%Y alloy has the highest ultimate tensile strength(UTS),305 MPa,by over 50%compared with that of the other two alloys.

关键词： Mg-Sn-Y alloy extrusion microstructure tensile property

Formation and properties of high Fe-content Fe-(B-Si)-Zr bulk amorphous alloys

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International Journal of Minerals,Metallurgy and materials 2013年第4期20卷 371-374页

作者： Yao-xiang Geng Ying-min Wang Jian-bing Qiang Qing Wang Fan-yang Kong Gui-feng Zhang Chuang Dong key laboratory of materials Modification (ministry of education) Dalian University of Technology

The present work is devoted to the development of Fe-（B-Si）-Zr amorphous alloys with high glass-forming ability and good magnetic properties. Using the cluster-plus-glue-atom model proposed for ideal amorphous structures, [FeFe11B3Si]（Fe1-xZrx） was determined as the cluster formula of Fe-（B-Si）-Zr alloys. The glass formation and thermal stability of the serial alloys, namely, [FeFel^B3Si]（Fel_xZrx）（x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.75, and 1.0）, were studied by the combination of copper mold casting, X-ray diffraction, and differential thermal analysis techniques. The maxima of glass-forming ability and thermal stability were found to occur at the compositions of [FeFe11B3Si] （Fe0.6Zr0.4） and [FeFe11B3Si]（Fe0.5Zr0.5）. The alloys can be cast into amorphous rods with 1.5 ram diameter, and upon reheating, the amorphous alloys exhibit a large undercooled liquid span of 37 K. The saturation magnetization of the [FeFe11B3Si]（Fe0.5Zr0.5） amorphous alloy was measured to be 1.4 T.

关键词： amorphous alloys iron zirconium alloys melt spinning glass-forming ability magnetic properties thermal stability

Equivalent conductivity and its activation energy of NaF-AlF_3 melts

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中国有色金属学会会刊：英文版 2009年第3期19卷 719-723页

作者：胡宪伟王兆文高炳亮石忠宁阚洪敏罗旭东陶文举 The key laboratory of ministry of education for Electromagnetic Processing of materials Northeastern University

Electrical conductivity of NaF-AlF3 melts was measured by continuously varying cell constant(CVCC) technique. Relationships between equivalent conductivity at 990-1 030 ℃ and temperature and composition, and relationship between equivalent conductivity activation energy and composition of the melts were then studied on the basis of two-step decomposition mechanism of AlF63-. According to the changes of molar fractions of different anions in NaF-AlF3 melts, courses of dependence of equivalent conductivity and its activation energy on composition were analyzed. The results show that the influence of temperature on equivalent conductivity of the melts is small in the researched temperature range, and equivalent conductivity increases with increasing the molar fraction of AlF3; there is a minimum point in the activation energy—composition curve when molar fraction of AlF3 is 0.29.

关键词：导电活化能 AlF3 电导率氟化钠融化等效摩尔分数温度范围

Effect of yttrium on thermal stability and crystallization behavior of Nd_(60)Fe_(20)Al_(10)Ni_(10) amorphous alloys

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Journal of Rare Earths 2008年第5期26卷 735-740页

作者：张莎莎田学雷孔凡利 key laboratory of Liquid Structure and Heredity of materials Ministry of Education Shandong University

The effect of yttrium on the thermal stability and crystallization behavior of Nd-Fe-Al-Ni amorphous alloys was investigated using X-ray diffraction （XRD）, differential scanning calorimeter （DSC）, and transmission electron microscopy （TEM）.The results indicated that the as-cast Nd60Fe20Al10Ni10-xYx（X=-0, 2） amorphous alloys were fabricated with some quenched-in crystals, which could be restrained by Y. With the effect of yttrium, both the crystallization temperature and exothermic peak shifted to higher temperatures, illustrating that the thermal stability could be improved. The addition of Y changed the crystallization process and final crystallization results. Moreover, the crystallites in the amorphous matrix became more homogeneous and smaller. Meanwhile, Y was useful for the passivation of oxygen in chemistry and restrained the negative effect of oxygen. The activation energies of the start of crystallization and peaking were 1.21 and 1.16 eV, respectively, according to the Kissinger equation.

关键词： Nd-based amorphous alloy quenched-in crystals thermal stability crystallization behavior activation energy rare earths