bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Glass Components Ratio on Structure and Properties of Baiyunebo Tailing Glass-Ceramics
Authors: Du Yong Sheng , Li Bao Wei , Zhang Xue Feng
Published: March 2013

Glass-ceramic in the CaO-MgO-Al2O3-SiO2 quaternary system was prepared using Baiyunebo tailing and fly ash as main raw materials by the method of melting. The processes of producing glass-ceramic included mixture, melting, molding, annealing, heat treatment, etc. The processing schedule for glass melting temperature, nucleation and crystallization temperature were chosen as 1450°C, 720°C and 850°C. The influences of glass components ratio on the structure were investigated by X-ray diffraction (XRD). It can be found that the main crystalline phase of augite, anorthite, magnesioferrite or magnetite mainly depended on glass components ratio. The results of mechanical measurements indicated that the bending strengths, density and chemical durability of glass-ceramics were concerned with the main crystal phase. The glass ceramics with augite phase had higher performance compared with others.
The Catalysts Performance of [Bmim]6PMO9V3O40/ACF on Flue Gas Desulfurization
Authors: Wang Tao , Xiao Gao , Zhao Ling , Hua Jian
Published: March 2013

The supported [Bmim]6PMo9V3O40 was synthesised by using the ion liquid [Bmim]Cl and heteropoly acid H6PMo9V3O40, and was supported on the active carbon fibre.The results of FT-IR showed that the structure of Ionic liquid cation and anion heteropoly acid on the active carbon fibre did not changed during the synthesising and supporting of the [Bmim]6PMo9V3O40. The catalysts performance of [Bmim]6PMo9V3O40/ACF on Flue Gas Desulfurization was investigated. The investigation was focused on the influence of the capacity of [Bmim]6PMo9V3O40, the oxygen centent, and reaction temperature on [Bmim]6PMo9V3O40/ACF for flue gas desulfurization. The experimental results showed that the desulfurization rate was up to 100%, lasting for 100 minutes,the sulfur capacity was as high as 400 mg/g in 4h, as desulfurization codition for the oxygen centent of 8% and the temperature of 60°C.
Preparation and Characterization of Electrodeposited Bi2Te3-YSey Thermoelectric Films
Authors: Zou Zhi Gang , Chen Song , Cai Ke Feng
Published: March 2013

The nucleation and growth model of Bi2Te3-ySey film on indium tin oxide-coated glass substrates from an aqueous acidic electrolyte at room temperature were studied using cyclic voltammetry, chronopotentiometry and field emission scanning electron microscope. The electrodeposition process was irreversible and controlled by diffusion, with a limiting current density of 1.78 mA/cm2. When the deposition current density was lower than the value or above the value but with agitation, the formation and growth of the film were controlled by instantaneous nucleation and gradually growth process, and homogeneous film was formed. While when the current density was larger than the value without agitation, flocculent film was obtained. Bi2Te3-ySey film deposited at 4 mA/cm2 with agitation showed smoother morphology compared with the film deposited at 1 mA/cm2. The electrical conductivity and Seebeck coefcient of the two Bi2Te3-ySey films were measured after being transferred onto a non-conductive rubberized fabric support. Both the films showed n-type conduction, and the former showed higher electrical conductivity and power factor.
Uptake of Heavy Metals by Trees: Prospects for Phytoremediation
Authors: Liu Wei Tao , Ni Jun Cheng , Zhou Qi Xing
Published: March 2013

It is known that heavy metals are taken up and translocated by plants to different degrees. Phytoremediation, the use of plants to decontaminate soil by taking up heavy metals, shows considerable promise as a low-cost technique and has received much attention in recent years. However, its application is still very limited due to low biomass of hyperaccumulators, unavailability of the suitable plant species and long growing seasons required. Therefore, to maximize phytoextraction efficiency, it is important to select a fast-growing and high-biomass plant with high uptake of heavy metals, which is also compatible with mechanized cultivation techniques and local weather conditions. Trees in particular have a number of attributes (e.g. high biomass, economic value), which make them attractive plants for such a use. This paper reviews the potential for the phytoremediation of heavy metal-contaminated land by trees. In summary, we present the research progress of phytoremediation by trees and suggest ways in which this concept can be applied and improved.
Hydrothermal Synthesis and Photocatalytic Activity of TiO2@CNTs Nanocomposite
Authors: Zhang Xuan Hui , Zheng Xiang , Cheng Yuan , Li Guo Hua , Hu Xian Chao
Published: March 2013

TiO2@CNTs nanocomposite was synthetized by a hydrothermal method at 453 K, using titanium tetrachloride as a precursor and nitrified CNTs as a support. The crystal phase, morphology, microstructure and element distribution of the sample were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscope (TEM), and scanning transmission electron microscopy (STEM-Mapping). The photocatalytic activity of the sample was measured by degrading methyl orange under UV illumination. The results showed that the titania particles in the shape of regular polygon decorate on the outer surface of CNTs evenly, and their sizes were about 7-20 nm. Moreover, photocatalytic activity of the nanocomposite was better than that of P25 Degussa and nitrated CNTs followed the apparent pseudo-first-order rate law. These results point out that synergistic effect exists between the titania and the carbon nanotubes in the nanocomposite.
Properties of Infrared High Reflectance Mo Film for Solar Selective Coatings by MF Sputtering
Authors: Zheng Li Qing , Zhou Fu Yun , Diao Xun Gang
Published: March 2013

Mo thin films were prepared by Mid-Frequency twin target magnetron sputtering as the high reflectivity coating in high temperature solar selective coating. The structure and optical properties of the coatings were studied by X-ray diffraction, scanning electron microscopy and Fourier Transform Infrared Spectrometer and spectrophotometer, the optical constants were inversely calculated by Handley equation. The highest infrared reflectivity of 94% reached at the bias voltage of-150 V and sputtering current 12A of the Mo cathode source, which satisfy the requirement for low thermal emittance solar selective coating applications. The thin films with body centered cubic structure grew along the (110) surface as column crystal, optical constants of Mo thin film were similar with bulk Mo. The thermal emittance of the infrared high reflectance Mo based selective absorber coating can control in 0.15 (400).
Purification of Multicrystalline Silicon by Cold Crucible Directional Solidification and Impurity Distribution
Authors: Liu Tong , Zhao You Wen , Don Zhi Yuan , Chen Teng , Wang Jun , Xie Hui
Published: March 2013

In order to get solar grade silicon, large cold crucible has been used in an induction heat furnace. By controlling the relative location of the crucible and coils, directional solidification was realized. More than 200 kg multi-crystalline silicon ingot was produced in a batch with short work time. The removal rate of most metal impurities was high, typically higher than 99% for transition metals like iron. Non-metallic elements such as boron and phosphorus could not be removed efficiently because of larger equilibrium segregation coefficient. The concentration of phosphorus was one third of the feedstock due to the vaporization in the melting process. The distribution of impurities agreed with the solidification principle. Quartzes and carbon was not used, which ensured silicon prevent from the contamination. Cooperated with other methods, large scale of solar grade silicon was produced.
Ion-Beam Sputtering Deposited Cu-Doped CdS Thin Film
Authors: Liang Guang Xing , Fan Ping , Cao Peng Ju , Zheng Zhuang Hao
Published: March 2013

Cu-doped CdS thin film has been successfully deposited by ion-beam sputtering deposition. The structural, morphology, optical and electrical properties of as-deposited and annealed Cu-doped CdS thin films were investigated. The heavily Cu-doped CdS films annealed at 400 °C was demonstrated to be improved in structural, morphology, electrical and optical properties. X-ray diffraction (XRD) analysis indicated the formation of polycrystalline CdS film with the structure of hexagonal wurtzite phase. No distinct impurity of Cu and Cu-S phase was detected in Cu-doped CdS thin films. Atomic force microscopy (AFM) revealed that the grain size was increased after annealed. Optical transmission and absorption spectroscopy measurement revealed a high absorption and energy band gap was of about 2.40 eV. The CdS thin film was of p-type conductivity and the resistivity was found to be 1.28×10-1Ωcm.
Responses of Thin Film Photovoltaic Cell to Irradiation under Double Laser Beams of Different Wavelength
Authors: Yuan Yu Chen , Wu Chen Wu , Chen Guang Nan
Published: March 2013

During the process of Laser beam long-range energy transmission based on the photovoltaic principle, the temperature elevation of the photovoltaic cell under Laser irradiation would greatly affect its photoelectric conversion efficiency. In this work, the heat generation mechanism of thin-film photovoltaic cell under Laser irradiation was analyzed based on the energy conversion relationship between light, electricity and heat. The output voltage characteristic of a thin film GaInP/GaAs/Ge triple-junction photovoltaic cell under irradiation of dual-wavelength Laser beam was investigated, and the results show the dependence of the conversion efficiency on the temperature and the valve effect, which was caused by the long wavelength Laser and would sharply reduce the photovoltaic conversion efficiency of short wavelength Laser. The temperature field of the multi-layer structure subjected to Laser irradiation was analyzed by finite element method, and the results indicate that the temperature elevation pattern depends on the spatial distribution of the light absorption and can be adjusted via optimizing the photovoltaic cell structure.
Performance of Composite Cements in the Repair of Porcine Thoracolumbar Burst Fracture In Vitro
Authors: Mao Ke Zheng , Mao Ke Ya , Cheng Zi Shen , Li Peng , Chen Zong Gang , Wang Xu Mei , Cui Fu Zai
Published: March 2013

An ideal injectable bone cement should be able to fill fully the fractures gap and provide good mechanical support. In the present work, the mineralized collagen and calcium sulphate dehydrate (CSD) was incorporated into α-calcium sulphate hemihydrates (α-CSH) to explore an injectable composite cement. The injectability, the setting time and the biomechanics properties were investigated. A porcine thoracolumbar burst fracture model was used to evaluate the biomechanical performance of composite cements. The porcine thoracolumbar burst fracture models in vitro were prepared. A half of models was made by the vertebroplasty of the composite cements, the other half of models was used as control. Imaging analysis showed the composite cements distributed uniformly and solidified well. Biomechanical test showed the ability of the composite cements to repair spinal burst fractures was significant.
A Hybrid High-Tc Superconducting Magnetic Levitation Sculpture Model
Authors: Zheng Jun , Jing Hai Lian , Liao Xing Lin , He Da Bo , Chen Ji Fu , Wang Su Yu
Published: March 2013

Different from other applications, this paper explores how to use the stable high-Tc superconducting (HTS) magnetic levitation (maglev) to lift the sculpture art to a high levitation position for satisfying the artists requirement for the light artistic concept. With a combination of the permanent magnet (PM) levitation and HTS maglev technologies, a sculpture model was built to sustain a stable levitation with a levitation height of over 80 mm. In this hybrid HTS maglev sculpture model, three PM rings are arranged as upper, middle, and bottom as a double-layer axial levitation structure; six rectangular YBaCuO bulks are fixed along the side of the PM rings upper-layer as a stabilizer component along the radial direction. When the bottom PM ring was driven up by the lifting bolt, the upper PM ring, which was fixed with the art, can be lifted much higher. Then the required artistic effect will be enhanced. After the model was designed and optimized by finite element method, it was experimentally validated by the HTS maglev measurement system. This levitation design is helpful to the realization of a real-scale levitation sculpture art, and can also provide references to superconducting radial magnetic bearing systems.
Template-Directed Electrodeposition of SnO2 Nanotubes and 1D Zn/SnO2 Core-Shell Nanostructures
Authors: Lai Min , Jian Yi , Ma Yan , Zheng Gai Ge , Zhong Kun , Li Xiang
Published: March 2013

Template-directed electrosynthesis has been employed widely to prepare solids of defined dimension. It offers controllable routes to create nanostructures. In this study, one electrochemical method to fabricate one-dimensional metal oxide nanostructures was developed. The electrochemistry strategy was employed to manipulate the pH value within the pores of a template and the growth of continuous one-dimensional metal oxide nanostructures was controlled. The strategy was exemplified by the growth of tin oxide nanotubes. At room temperature, the reduction of nitrate within pores was employed to electrogenerate hydroxide ions and drive local precipitation of stannic oxide nanotubes. The nanotube walls displayed nearly uniform thickness along their entire length which were obtained within commercial track-etched polycarbonate membranes. One-dimensional Zn/SnO2 core-shell nanostructures were achieved by the further electrodeposition of Zn within SnO2 nanotubes.
Adsorption for Au3+ by Persimmon Tannins Immobilized on Collagen Fiber
Authors: Liu Feng Lei , Wang Zhong Min , Cui Jian , Zhou Zhi De , Li Gui Yin , Zhou Huai Ying
Published: March 2013

A novel adsorbent which is effective to adsorb Au3+ was prepared using immobilized persimmon tannin (PT) on collagen fiber by glutaraldehyde crosslinking. The adsorption behaviour of this new adsorbent to Au3+ in aqueous solution was investigated. The effects of various factors such as initial solution pH, temperature, ionic strength and initial concentration of Au3+ on the influence of the adsorption process were studied. The equilibrium adsorption capacity reached 2347 mg/g at 323 K and pH value 2.0 when the initial concentration of Au3+ in aqueous solution was 500 mg/L. The immobilized PT was characterized by FT-IR, XRD and SEM. The results indicated that Au3+ changed to gold by oxidation adjacent phenol hydroxyl groups of persimmon tannin. Experiments also showed that adsorption isotherms of immobilized tannin for Au3+ could be described by Langmuir models. Immobilized PT adsorption provided a new way for the separation of the precious metal ions
Biotemplate Synthesis of Porous Ceria Fiber and Study on its Catalytic Performance
Authors: Chen Feng , Liu Cheng Bao , Chen Zhi Gang
Published: March 2013

Hierarchical porous ceria with nanocrystalline was successfully synthesized using filter paper as biotemplate. Unique biomorphic microstructures were characterized by Field Emission Scanning Electron Microscope (FESEM), transmission electron microscopy (TEM) and nitrogen absorption-desorption technique. The obtained ceria material showed the repetitious biomimetic structure consisting of fibre with diameter of ca. 1-3 μm and nanopores which had 2-4 nm apertures. The small crystallite diameter (6-8 nm) and the high specific surface area (71.3 m2·g-1) of porous CeO2 were measured by wide-angle X-ray Diffraction (XRD), high resolution TEM (HRTEM) and the BET method. While the concentration of acid fuchsine was 20 mg/L, the porous sample had a higher decoloring rate in a shorter time than others. The decoloring rate can reach 100% after 200 min.
Influences of Excess PbO on Optical Properties and Microstructures of La Modified 0.75Pb (Mg1/3Nb2/3)O3-0.25PbTiO3 Electro-Optic Transparent Ceramics
Authors: Ji Wen Long , He Xi Yun , Cheng Wen Xiu , Qiu Ping Sun , Zheng Xin Sen
Published: March 2013

La-modified 0.75Pb (Mg1/3Nb2/3)O3-0.25PbTiO3(PLMNT) electro-optic (EO) transparent ceramics were synthesized through a columbite precursor method. Excess PbO (10, 15 and 20 mol %) was added to study the effect on the transparency, electro-optic effect, and microstructures of PLMNT transparent ceramics. The phase structure of different samples can be identified as single perovskite structure with no second phase detected. The average grain size increased as the concentration of excess PbO increased from 10 mol% to 20 mol%. On the contrary, the transparency decreased with the increase of the concentration of excess PbO. When the concentration of excess PbO was 10 mol%, the transmittance was about 62% at 632.8nm. The EO coefficient was calculated through measuring the birefringence as a function of electric field. The EO coefficient increased with the increase of the concentration of excess PbO and the maximum EO coefficient reached 40.6×10-16(m/V)2 when the excess PbO was 20 mol%.
Joining of High Strength Graphite with Silicon Resin and SiO2 Addition
Authors: Liu Hong Li , Yang Jiu Jun , Hu Shi You , Qv Lie , Zhao Xue Lian , Li Guo Zun
Published: March 2013

Joining of the high strength graphite to itself has been realized using silicon resin YR3370 with SiO2 powders as joining materials. The joining strength of the joints is strongly affected by adding SiO2 powders and joining temperature. Adding SiO2 filler can effectively reduce holes and cracks in the joining interlayer. Therefore it can enhance the joining strength. The maximum shearing strength of the joints is 21.1MPa, which is equal to 52.8% of the strength of the graphite substrate. This value is obtained at the joining temperature of 1200°C. The thickness of interlayer is about 25μm. The joining interlayer is uniform and dense, and the contact at the interfaces is good.
Fabrication of Silicon Carbide Reticulated Porous Ceramics through Organic Foam Infiltration Process
Authors: Jiang Guo Jian , Wang Min Hui , Liu Yun Ying , Ding Liu Liu , Deng Ling , Xu Jia Yue , Shen Hui , Jin Min
Published: March 2013

Reticulated silicon carbide porous ceramics was fabricated through organic foam infiltration process by using silicon carbide slurry prepared from silicon carbide, alumina and clay and other raw materials. The effect of solid content on the viscosity and Zeta potential of the slurry were investigated. The results showed that the viscosity of slurry increased with the increase of the solid content. The absolute value of Zeta potential increased with the increase of pH value of the slurry from acid to alkaline aptitudes, and it became smaller with the further increase of the pH value. The maximum was reached at the pH around 10. The viscosity of slurry in the range of 4000mPas ~ 5000mPas was appropriate to prepare reticulated silicon carbide porous ceramics. The sintered body collapsed or cracked apparently, when the viscosity was too low. On the other hand, the viscosity could not be too high because its hard for slurry to impregnate foam. The performance of the samples coated once and recoated was compared. The porosity of the sample with one layer was higher than that of the samples with two layers. However, the recoating process improved the compressive strength and flexural strength of the reticulated silicon carbide porous ceramic.
Porous TiN Ceramics Fabricated by Carbothermal Reduction Method
Authors: Lu Yuan , Yang Jian Feng , Chen Zhi Liang , Han Jian Jun , Li Jing Jing , Yun Ke
Published: March 2013

Porous TiN ceramics with high porosity and uniform pore structure was prepared following the carbothermal reduction reaction between TiO2 and carbon. Influences of sintering additives and particle size of TiO2 on the microstructure and mechanical properties of porous TiN ceramics were investigated. Microstructure and mechanical properties of porous TiN ceramics were studied by XRD, SEM and three-point bending measurement. XRD analysis proved that the TiN phase has completely formed after reaction. In addition, SEM analysis showed that the resultant porous TiN ceramics were composed of fine grains with uniform pore structure. The addition of La2O3 not only accelerated the densification of porous TiN ceramics, but also decreased the porosity and increased the flexural strength. With a decrease in TiO2 particle size, the linear shrinkage increased and the porosity decreased accordingly.
Tailoring Microstructures and Mechanical Properties of AlCoCrFeNiTi0.3 High-Entropy Alloys by Heat Treatment
Authors: Qiao Jun Wei , Wang Y.F. , Wang R.Q. , Shi J.Y. , Sang S.B. , Yang H.J.
Published: March 2013

The microstructures and mechanical properties of AlCoCrFeNi0.3 high-entropy alloys (HEAs) are tailored through heat treatment. During heat treatment, the dendrite phase with a body-centered-cubic (bcc) structure transformed into the interdendrite phase with a bcc structure. Due to the element accumulation with higher hardness in the interdendrites and the increase of volume fraction of interdendrites, the average hardness of AlCoCrFeNi0.3 HEAs increased with the heat-treatment temperature, and the highest hardness was 625 HV. After 500 heat treatment, the optimized mechanical properties under quasi-static compression were achieved, and the yielding strength and fracture plasticity were 2.30 GPa and 9 %, respectively. Upon dynamic loading, the mechanical properties of HEAs were greatly enhanced.
Cu-Zr-Nb Crystalline-Amorphous Composites Investigated by Thermodynamic Calculation and Ion Beam Mixing Experiments
Authors: Liang S.H. , Wang T.L. , Bai X. , Li J.H.
Published: March 2013

The formation of Cu-Zr-Nb metallic glass was predicted by thermodynamic calculation and then five Cu-Zr-Nb ternary metallic multilayered films were designed and prepared by electron depositing. The metastable supersaturated solid solutions, amorphous phase as well as their composites were able to be obtained in these Cu-Zr-Nb metallic multilayered films upon ion beam mixing. The observations provided a clew to improve the ductibility of the metallic glasses. Some possible interpretations were presented concerning the formation of the crystalline-amorphous composite.
Fabrication of Platinum Nanoparticles through Ionic Liquid Method and its Catalytic Properties in Hydrogenation Reaction
Authors: Ding Liu Liu , Jiang Guo Jian , Li Wen Jun , Liu Yun Ying , Xu Jia Yue
Published: March 2013

Room temperature ionic liquid [1-butyl-3-methylimidazoliuBF4 was prepared under microwave irradiation. Platinum (Pt) nanoparticles were synthesized in the ionic liquid with ethanol as reductant. The structure and morphology of the Pt nanoparticles were characterized by SEM, FTIR and TG-DTA. The results show that the mean diameter of the nanoparticles was about 10nm and the surface was modified with the room temperature ionic liquid. The catalytic property was evaluated by hydrogenation of benzaldehyde in ethanol and the conversion reached up to 80% under hydrogen pressure.
Preparation of Multilayered Ti-Al Alloys by Solid Reaction
Authors: Sun Yan Bo , Liu Mao Wen , Ge Su Jing , Ma Feng Mei , Ma Chao Li
Published: March 2013

The multilayered materials with different combinations of Ti, Al and Ti-Al intermetallics were prepared by heat treatment and hot pressing (HP) with elemental foils. The microstructures and phase formation of the obtained samples were detected by scanning electron microscopy (SEM), electron probe microanalysis (EPMA), energy dispersive spectroscopy (EDS) and X-ray diffractometer (XRD). When the HP is applied under the melt point of aluminum, aluminum is the only diffusive element across the oxide films on the surface of the initial foils; however, some unusual TiAl3 particles are found in the multilayered structure due to the broken of oxide films; after hot pressing for 4 hours, all the aluminum was consumed; many voids exist at the centerline of TiAl3 layers, which are mainly caused by Kirkendall effect and the difference of molar volumes between reactants and products; before the aluminum is completely consumed, TiAl3 is the only product in the solid reaction under the melting temperature of aluminum; however, other Ti-Al intermetallics like Ti3Al and TiAl are formed in the updated temperature diffusion after aluminum is consumed.
The Microstructure and Compression Behavior of Multi-Step Forging Ti-45Al-8Nb Alloy after Annealing at 1100 °C
Authors: Song Lin , Xu Xiang Jun , Lin Jun Pin , Zhang Lai Qi
Published: March 2013

Effects of annealing treatment on microstructure and the compressive properties of hot-worked Ti-45Al-8Nb-(W, B, Y) alloy were investigated. Microstructure of the extrusion plus multi-step forging pancake before and after heat treatment was analyzed by SEM and TEM, respectively. The annealing was conducted by holding samples at 1100°C for 2hrs, and followed by air cooling and furnace cooling. The mechanical properties were measured by Instron test machine. The microstructure evolution during compressive deformation was analyzed by TEM. The results showed that after the annealing the microstructure change could not be observed under SEM but can be observed under TEM. Many dislocation clusters were removed by heat treatment. The heat treated samples had similar compression behaviors with the pancake. TEM investigation showed that the numerous twin intersections occured in γ matrix during compression. The twin spaces tended to decrease as the deformation and the intersection increasing.
Residual Stresses in Spray Quenched EW75 Magnesium Alloy
Authors: Liao Hong Bin , Ma Ming Long , Li Xing Gang , Zhang Kui , Li Yong Jun , Shi Guo Liang
Published: March 2013

Cooling curves and residual deflection during spray quench process are measured by using thermometric instrument and spiral micrometer, separately, in extruded EW75 magnesium alloy. By using Numerical analysis, temperature and stress with the change of time during quenching were also investigated. The results showed that: when the spray speed was 6L/min, the steam film stage was obvious, as the speed reached to 9L/min, steam stage disappeared. The residual deflection increased with the spray speed increased. When the spray speed was 6L/min, the residual deflection was 3.38mm and increased to 3.88mm as the spray speed increased to 9L/min. But with the increase of spray speed, the growth rate of deflection induced. The results of the numerical simulation indicated that during the quench process, the surface cools faster than body and shrink more severely at first, leading stress distribution is compress at surface while tensile in body. Plastic deformation happens at this time. And then along with the surface cooling speed reduced, the body cool speed is greater than surface; the shrink in body is also greater, thus the compress stress turn to be tensile and contrary change take place at surface. With the increasing distance from the cross section, the tensile stress is reduced gradually, in 5.3mm, there exists a zero stress layer, then turns to compressive stress.
Dynamic Precipitation Behaviors and Mechanical Properties of Mg-12Gd-3Y-0.5Zr Alloy Processed by Secondary Extrusion
Authors: Li De Jiang , Zhou Yin Peng , Zeng Xiao Qin , Ding Wen Jiang , Chen Bin , Liu Ying Zheng
Published: March 2013

Secondary extrusion at 350 °C with the extrusion ratio of 12.25, 25 and 44 was carried out on the Mg-12Gd-3Y-0.5Zr (GW123K) alloy, and the cooling method of the secondary extruded alloys was air cooling and water quenching. Quantitative metallographic analysis method was also employed to study the distribution and volume fraction of dynamic precipitates during the extrusion process. The results showed that secondary extrusion could result in significant grain refinement and the grain size increased with extrusion ratio, which the minimum average grain size was about 5.4μm in the alloy under λ=12.25. The volume fraction of dynamic precipitates decreased with increasing extrusion ratio and the maximum volume fraction was measured to be about 49.2% in the alloy under λ =12.25. Water quenching after extrusion can effectively inhibit dynamic precipitation and the volume fraction of the precipitates ratio decreased from 41.1% after air cooling to 19.6% after water quenching in the same extrusion condition. Tensile properties results showed that the age hardening response of the alloys was decreased by dynamic precipitation and water quenching was an efficient method which is able to avoid this behavior in some extent.
Experimental and Numerical Investigation of the Grain Size Evolvement of AZ31 Mg Alloy during High Ratio Extrusion
Authors: Lin Jin Bao , Ma Li Feng , Chen Yan Xia , Wang Chao , Liang Qing Xiang , Cui Xiao Chao
Published: March 2013

The grain size evolvement of AZ31 magnesium alloy during high ratio extrusion (HRE) was investigated by experiment and numerical simulation. A Yada model was established according to the results of experimental study and trial calculation. Effects of the deformation temperature, extrusion ratio and extrusion velocity on the grain size were analyzed. The results showed that the microstructure of the AZ31 alloy was dramatically refined by high ratio extrusion. The deformation conditions exhibited obvious effects on the grain size, and the deformation conditions were interplaying and interacting with each other during the HRE process. Compared to the deformation temperature and extrusion velocity, the severe plastic deformation induced by the high ratio extrusion is a major cause of grain refinement. With the increasing of the extrusion velocity, the grains could be refined due to a shorter recrystallized grain growth time. At the same time, the deformation temperature increased with the increasing of the plastic strain rate, which results in faster recrystallized grain growth. Finally, recommended method is advised to further refine the grain size.
Effect of Rolling Reduction on Microstructure and Mechanical Properties of Mg-9Gd-3Y-0.5Zr Alloys
Authors: Li S.Q. , Tang Wei Neng , Chen Rongshi , Han En-Hou , Ke Wei
Published: March 2013

Rolling processing has been carried out on samples cut from the extruded Mg-9Gd-3Y-0.5Zr seamless tubes. Effects of rolling reduction, 5%, 20% and 70% per pass, on its microstructure and mechanical properties were investigated. The results showed that the strength and ductility varied with increasing rolling passes at different rolling reduction. The strength of the alloy rolled by 5% reduction per pass gradually improved with increasing rolling passes, and its ductility remained basically constant. However, when 20% reduction per pass was applied, the strength and ductility of the alloy after rolling increased at first and then decreased a little after the accumulative strain higher than 52%. Moreover, as reduction reached 70% per pass, macro-cracks were induced when rolling at 420°C, while the samples were rolled at a high temperature of 500°C and a larger reduction of 70% per pass exhibited the mechanical properties comparable to those fabricated by 5% and 20% reduction. This indicated that a relatively higher productivity via rolling as well adequate mechanical properties can reach for the large scale of industrial products.
Effect of Sm on the Microstructure and Mechanical Property of Mg-xSm-0.4Zn-0.3Zr Alloys
Authors: Su Xin , Li De Jiang , Xie Yan Cai , Zeng Xiao Qin , Ding Wen Jiang
Published: March 2013

The effect of Sm content (2, 4, 6, 8wt.%) on the microstructures and mechanic properties of gravity casting Mg-xSm-0.4Zn-0.3Zr alloys were investigated. The results showed that the cast alloy mainly consists of α-Mg matrix and Mg41Sm5 phase distributed at the grain boundaries, and the amount of the second phase increased with the rise of Sm content. After the solution treatment (T4), the second phase disappeared, however small amount of cuboid-like phase were found inside the grain, and its volume fraction also increases with the rise of Sm content. It is found in the age hardening curves of the alloys at 175, 200, and 225 °C that the alloys with various components almost showed the same trend of age hardening. While the higher the Sm content, the harder the alloy. With the Sm content increases, the yield strength (TYS) of cast alloys (F state) were obviously improved, however the tensile strength (UTS) became lower because of the quick drop of the elongation. The elongations of solid solution (T4) and aging (T6) alloy became lower, while the yield strength and tensile strength increased at first and then decreased. The optimized component is Mg-4Sm-0.4Zn-0.3Zr, which the mechanic properties at T6 state are: TYS=131MPa; UTS=261MPa; δ=6.8%.
Fabrication and Properties of Rapidly Quenched Fe-6.5wt.%Si Alloy Ribbons
Authors: He Rui Qi , He Jian Ping , Fang Xian Shi , Jin Xiao Ou , Liang Yong Feng , Ye Feng , Lin Jun Pin
Published: March 2013

Fe-6.5wt.%Si alloy is one excellent soft magnetic material. In the present study, rapid quenching was applied to fabricate ultra-thin ribbons of Fe-6.5wt.%Si alloy by melt spinning. Continuous ribbons of 20 mm wide, 35-45 μm thick were fabricated with optimized experimental parameters. The ribbons exhibited metallic luster appearance, and can be wound without cracks. Microstructure, texture and mechanical properties of the ribbons were investigated. It was found that the rapidly quenched ribbons had intense {100} plane texture, and exhibited some extent of bending capability. Finally the ribbons were cold rolled and the surface smoothness was improved for stacking purpose.
Effect of ECAP Pass on Corrosion Behavior of High-Al Content Magnesium Alloys
Authors: Fan Qiang , Liang Wei , Bian Li Ping , Cheng Man Qing
Published: March 2013

In view of low strength and poor corrosion resistance of Mg alloys, a Mg-12Al-0.7Si alloy was designed, fabricated and subjected to equal channel angular pressing (ECAP) in order to refine the microstructure. Microstructure observation and electrochemical performance test were conducted to investigate the influence of the microstructural variation subjected to multi-pass ECAP processing on the corrosion behavior of the alloy. The results showed that both α-Mg matrix and β-Mg17Al12 of the alloy were significantly refined after processing for different passes (2,4,6,8) through route BC, and the 4-pass ECAPed alloy in 3.5% NaCl solution presents the lowest weight loss, lower corrosion current and higher corrosion potential in the polarization curves. The reason for high corrosion resistance of 4-pass ECAPed alloy and the effects of grain size of the matrix and the particle size, distribution of second phase and dynamic precipitates on corrosion behavior of the alloy were discussed.
Biodegradable Behaviors in Simulated Body Fluid of Mg-Gd-Y-Zr Alloy with Micro-Arc Oxide Coating
Authors: Yin Kai Yang , Lu Tian Feng , Dong Qing , Sun Bing Yi , Chen Bin
Published: March 2013

The effects of micro-arc oxidation (MAO) on corrosion resistance of Mg-Gd-Y-Zr magnesium alloy have been studied. The Mg-Gd-Y-Zr with thicker oxide coating presented higher corrosion resistance in simulated body fluid (SBF). The corrosion rates were measured by several methods including hydrogen evolution volume measurement, weight-loss method and determination of pH as an auxiliary reference. The surfaces of specimens were observed by SEM and white light confocal microscopy before and after the corrosion. Besides the effects of MAO, the pitting resulted from breakage of oxide coating played a notable role as well. This provided a new direction towards the enhancement of corrosion resistance of magnesium alloy.
Hot Deformation Behavior and Microstructural Evolution of Mg-Nd-Zn-Zr Magnesium Alloy
Authors: Wu Wen Xiang , Jin Li , Dong Jie , Zhang Zhen Yan , Ding Wen Jiang
Published: March 2013

The hot deformation behaviors and microstructural evolution of Mg-3.0Nd-0.2Zn-0.4Zr (wt. %, NZ30K) alloy were investigated by means of the isothermal hot compression tests at temperatures of 350-500 °C with strain rates of 0.001, 0.01, 0.1 and 1s-1. The results showed that the flow stress increased to a peak and then decreased which showed a dynamic flow softening. The flow stress behavior was described by the hyperbolic sine constitutive equation with an average activation energy of 193.8 kJ/mol. The average size of dynamically recrystallized grains of hot deformed NZ30K alloy was reduced by increasing the strain rate and/or decreasing the deformation temperature. A large amount of fine particles precipitated in the grains interior and at the grain boundaries when heated to the compression temperatures and soaked for 5min below 450 °C. However, the volume fraction of particles decreased significantly when soaked for 5 min at 500 °C, and the coarse particles precipitated mainly at the grain boundaries. Hot deformation at the temperature of 500 °C around and at the strain rate range of 0.1s-1 was desirable for NZ30K alloy.
Microstructure and Mechanical Properties of Extruded Mg-Zn-Y Alloy
Authors: Wang Feng , Li Ji Bao , Mao Ping Li , Liu Zheng
Published: March 2013

A high strength and toughness extruded Mg-Zn-Y alloy based on quasicrystal-strengthening has been studied. The effect of extrusion and heat treatment on the microstructures and mechanical properties of Mg-Zn-Y alloy were studied by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrum (EDS), X-ray diffraction (XRD) and tensile testing. The experimental results indicated that the coarse dendrite crystals were broken through the hot extrusion, and dynamic recrystallization appeared during the hot extrusion, which obviously refined the hot-extruded microstructure to the average grain size about 20μm. A large amount of strengthening phases such as Mg3Zn6Y(I-Phase), Mg12ZnY(X-Phase) and MgZn2, which were massive, grainy and clavate, dispersedly precipitated from the matrix along grain boundary during ageing treatment at 225 after extrusion, and made the sliding of grain boundaries restrained, which resulted in an enhancement for mechanical properties to a great extent. At the same time, the tensile strength and yield strength increased after ageing treatment. After ageing treatment of 225×24h, the highest tensile strength and yield strength of the extruded Mg-Zn-Y alloy were obtained: σb=506.7MPa, σ0.2=373.5MPa, which were increased by 104.8% and 120.4%, respectively, compared with the extruded Mg-Zn-Y alloy, however the elongation decreased to 16.52%.
Influences of Al, Ce on the Microstructure and Mechanical Properties of As-Cast Mg-6Zn Alloy
Authors: Liu Rui Dong , Dong Xu Guang , Wei Fu Jun , Yang Yuan Sheng
Published: March 2013

The effects of minor Al and Ce on the microstructures, room-temperature and high-temperature mechanical properties of as-cast Mg-6Zn magnesium alloys were investigated. With the Al addition into Mg-6Zn alloy, the coarse eutectic Mg51Zn20 phases were refined and distributed discontinuously. After adding 0.5wt.% Ce into Mg-6Zn-1Al alloy, a new needle-like Al2CeZn2 phase was observed. Meanwhile, the volume fraction of Mg51Zn20 phase decreased and the semi-continuous Mg51Zn20 phase became discontinuous globular morphology. It has been observed that the addition of Ce element coarsens the grains, and 1wt.% Al addition enhanced the yield strength and ultimate strength from 86.35MPa, 229MPa to 90.7MPa, 238MPa, respectively. Moreover, the Ce addition can significantly increase the high-temperature mechanical properties of cast Mg-6Zn-1Al alloy.
Evaluation of Inclusions in P/M Superalloy
Authors: Yuan Hua , Li Zhou , Zhang Guo Qing , Xu Wen Yong , Liu Na
Published: March 2013

The non-metallic inclusions in master alloy, P/M superalloy and HIP powder billet were studied in this paper. The results show that the amount of inclusions in master alloy is higher than that of the superalloy powers. The EB-button analysis shows that the main non-metallic inclusions in both the master alloy and the HIP powder billet is Al2O3.The amount of the inclusion in master alloy is about 0.166cm2/kg and the size of most inclusions is in the range of 100μm to 200μm, while the maximum inclusion size reaches 400μm.In the P/M superalloy billet, the content of inclusion is only 0.01cm2/kg and the size of most inclusions is less than 50 μm.
Effects of Long-Term Aging Treatment on Stress Rupture Properties of FGH95 Ni-Base Superalloy
Authors: Tian Su Gui , Xie Guang Liang , Xie Jun , Zhou Xiao Ming
Published: March 2013

The effect of long-term aging on stress rupture properties was investigated by means of microstructure observation and properties measurement. The results show that, after long-term aging for 500 h at 723 K, the coarser particle-like γ phase is precipitated along the grain boundaries of alloy, significant amount of γ particles are regularly distributed within the grain. Moreover, some carbide particles precipitated depressively along the boundaries and within the grain. As the aged time and temperature increase, the size of fine γ particles in the alloy increases slightly, and the stress rupture property of the alloy decreases under the condition of 923K and 1034MPa. The deformation features of the alloy during creep are that the dislocations slip in the matrix or shear into the γ phase, the dislocations shearing into the γ phase may be decomposed to form the configuration of the two partial-dislocations plus stacking fault. As the creep goes on, the slipping traces with different orientations appear in the surface of the specimen, and some slipping steps are formed in the region near the boundaries, which may cause the stress concentration to promote the initiation and propagation of the cracks along the boundaries up to creep fracture.
Isothermal Corrosion Behaviors of TiAl–Nb Alloys in Liquid Zn-55Al-1.6Si (wt.%)
Authors: Sun Peng Fei , Jin Xiao Ou , Hu Yi Fan , Lin Jun Pin
Published: March 2013

The isothermal static corrosion of Ti-45Al-8Nb and Ti-53Al-20Nb (at.%) in liquid Zn-55Al-1.6Si (wt.%) at 630°C was studied. Incubation periods without any corrosion occurred are exhibited in both alloys. After the incubation time, the corrosion rate increases noticeably which is controlled by the reaction-diffusion and dissolution mechanism. Thick transition layers were formed. The EDS results show that Si and Al diffused into the TiAl-Nb alloys preferentially, while Zn was hindered from diffusing and segregated in spots. All the transition layers are porous and composed mainly of Al3Ti (Nb), SiTi and AlNbZn2. The fracture of the transition layers of Ti-45Al-8Nb should be attributed to the defects of the lamellar colony boundaries. nanoIndenter was used to check the mechanical properties of the materials. The results show that the transition layers have higher micro-hardness and elastic modulus than the matrix.
The Influence of the Re-Melting Times on Microstructure and Mechanical Properties for Revert Alloy K452
Authors: Yuan Chao , Guo Jian Ting , Liu Chang Jiang , Hou Jie Shan , Li Gu Song
Published: March 2013

The influence of the re-melting times on chemical composition, microstructure, and mechanical properties of revert alloy K452 were systemically investigated. It was shown that the key factor in the engineering application was the control of gas content and porosities level in revert alloy. By an advancing technology in combination with the superheat treatment, adding a small amount of alloying elements such as C, Al, Ti, and using ceramic foam filters during vacuum induction melting, the composition and mechanical properties of the revert alloy in addition of 50% scrap were similar to that in the virgin alloy, which has successfully been used in applications for nozzle vanes of some new gas turbines.
Atomic Interchange Potentials Calculation of Ni-Al-Cr Alloy Based on Microscopic Phase Field Method
Authors: Dong Wei Ping , Jing Zhang , Chen Zheng
Published: March 2013

The effects of increasing atomic interchange potentials to the precipitation process and microstructure of Ni-Al-Cr alloy have been simulated based on the microscopic phase field theory. The first nearest neighbour atomic interchange potentials of Ni-Al-Cr alloys for L12 and D022 phase was calculated out according to the formula which were referenced on the relation equation between atomic interchange potentials and long range order parameters by Khachaturyan. The results indicated that Ni-Al (WNi-Al) and Ni-Cr (WNi-Cr) s first nearest neighbor atomic interaction potentials will increase linearly while the temperatures rose. Moreover WNi-Al increased but WNi-Cr decreased roughly linearly if Al atoms concentration rose, and conversely inversed. In addition, these atomic interchange potentials changing with temperature and concentration were in good agreement with earlier study.
Laser Remelting Effect on the Joint Property of Diffusion Bonding of TiAl Intermetallics and TC4 Alloy
Authors: Xue Zi Gong , Huang Yuan Xun , Wang Yong Tian , Hai Xiao Jing
Published: March 2013

The influence of laser remelting on the mechanical property and fracture behavior of the superplastic diffusion bonding between TiAl intermetallics and TC4 alloy was investigated. The joint bonded by the pre-remelted samples displayed well diffusion, but the mechanical properties of the joint should be further enhanced. The mechanical properties of the joint pre-remelted under the diffusion bonding conditions of 915/80MPa/1h are lower than that of the joint without remelting. After the heat treatment on pre-remelted joint sample at 860, the mechanical properties have been enhanced greatly.
Research on Gradient Heat Treatment of Dual-Property Disk for Alloy FGH96
Authors: Wang Yu , Zou Jin Wen , Zhang Guo Qing , Wang Wu Xiang
Published: March 2013

The transient temperature field in the dual-property disk of alloy FGH96 was investigated during the solution heating process of the gradient heat treatment by numerical simulation. The temperature curves for the different locations of the disk were attained. Then, the gradient heat treatment experiment was carried out, and the heat profiles were obtained. The numerical and the experimental results were almost consistent. The method of heat transfer for the bore of the disk was changed evidently through effective fixture design during the gradient heat treatment. The gradient of temperature (ΔT) can reach 121 or more, which lead to a supersolvus heat treated rim and subsolvus heat treated bore for the disk.
Grain Competition Mechanism of a Ni3Al-Based Single Crystal Superalloy IC6SX
Authors: Jiang Li Wu , Li Shu Suo , Wu Mei Ling , Han Ya Fang
Published: March 2013

The grain competitive growth and elimination during the directional solidification of a Ni3Al-base single crystal superalloy IC6SX prepared by spiral grain selection method was studied systematically. The experimental results revealed that there were 5 kinds of mechanism during the grain competitive growth and elimination. The grains with preferred growth direction and smaller deviation angle to growth direction have stronger competitiveness, and the mutual thwarting of dendrites played an important role in the processing of grains competitive growth. The results can explain the competitive growth mechanism during the directional solidification and can be used to optimize processing parameters to lay an important foundation for improving preparation processes of single crystal superalloys.