bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of Aluminum Titanate Powder at Low Temperature via Nonhydrolytic Sol-Gel Method by Using Aluminum Powder
Authors: Jiang Wei Hui , Xu Zhi Fang , Liu Jian Min , Zhu Qing Xia , Zhang Quan
Published: March 2013

Aluminum titanate (Al2TiO5) powder has been synthesized at low temperature via nonhydrolytic sol-gel method by using aluminum powder as aluminum source, titanium tetrachloride as titanium source, anhydrous ethanol as oxygen donor with different catalysts. The phase transformation of aluminum titanate xerogel powder during heat treatment and the influence of the mixing orders of raw materials, catalyst kinds on the synthesis of aluminum titanate were investigated by means of differential-thermal analysis (DTA-TG), X-ray diffraction (XRD), transmission electron microscope (TEM). The results indicated that aluminum titanate powder was easily synthesized at 750 °C by using AlCl3 as catalyst with a mixing order of adding TiCl4 before AlCl3 into aluminum alcohol mixture. The catalytic order of the different catalysts in the preparation process of aluminum titanate is: FeCl3> AlCl3> MgCl2. The catalyst promoted the activation of metal aluminum powder and played a major role in the synthesis of aluminum titanate powder at low temperature via nonhydrolytic sol-gel method.
Fabrication of a SiC-Ti Functionally Graded Bonding Interlayer by Precursor Method
Authors: Liu Hong Li , Hu Shi You , Yang Jiu Jun , Zhao Xue Lian , Qiu Bai Shen
Published: March 2013

SiC-Ti functionally graded material (FGM) was prepared by polymer-derived method in order to resolve connection problem between the ceramic matrix and its composite materials, as well as metal at high-temperature. Gradient materials were fabricated successfully by polymer-derived method combined with hot-press sintering process at 1300. The microstructure of the prepared samples was studied, and the results revealed that this FGM had a compact structure, without obvious interface between different layers. The distribution of elements was gradient according to the SEM and EDX results.
Evolution of Microstructures and Properties of the AlxCrCuFeNi2 High-Entropy Alloys
Authors: Ma Sheng Guo , Chen Zhao Di , Zhang Yong
Published: March 2013

The microstructure and Vickers hardness of the AlxCrCuFeNi2(x=0.5, 1.0, and 2.0 in molar ratio) high-entropy alloys with as-cast and heat-treated states were investigated. X-ray diffraction (XRD) patterns suggested that for the Al0.5 alloy annealed at 900,an incomplete phase transformation from FCC to BCC occurred, while for the Al2.0 alloy as heated at 500 and 700, a converse phase transformation from BCC to FCC was obtained. Compared with the as-cast dendrites, after heat treatment, the microstructure of the alloys was obviously coarsened or spheroidized or homogenized, whereas the resultant hardness has almost not decreased even at high heating temperatures, which indicated the probability of ordering for this alloy system and thus effectively compensating the stress and structural relaxations. The Al2.0 alloy reached the maximum hardness value of 610 HV by annealing at 1100, which might be ascribed to the worm-like nanoprecipitations and the enhanced fraction of B2-ordered precipitations. By cold rolling, the Al0.5 alloy is able to reach the yield strength of 1055 MPa and the fracture strength of 1179 MPa, which was a significant improvement in comparison with the as-cast alloy.
Synthesis of Silver Particles by Replacement Reaction
Authors: Wan Chuan Yun , Zhan Wei
Published: March 2013

Silver particles were synthesized by reducing silver ions with copper metal. The as-synthesized silver particles were characterized by scanning electron microscope (SEM). The effects of synthesis conditions on particle morphology were studied. The results showed that dendritic structures were readily synthesized when the silver nitrate solution kept stationary. The low concentration of silver ion was benefit to get perfect silver dendrite. The use of ammonium made the silver shape transferring from dendritic to spherical. The ultrasonic wave accelerated the diffusion of mass and produced spherical silver particles. These results indicated that dendritic silver particles were easy to obtain in non-equilibrium condition while the shape of silver rod-like or spherical was easy to get in equilibrium condition. The morphology and the size of silver particles depend on the synthesis conditions. The formation mechanism of dendritic silver particles were also deduced.
Effect of Fe on Crystallization Process of Zr-Co-Al-(Fe) Bulk Metallic Glasses
Authors: Tan J. , Pan Fu Sheng , Li C.J. , Wang J.F. , Eckert J.
Published: March 2013

The change in the internal states of Zr56Co28Al16 bulk metallic glass (BMG) upon minor substitution of Co with Fe was investigated for alloys with different compositions of Zr56Co28-xAl16Fex (x = 0, 1 and 2, respectively). Results exhibited that the ductile Zr-Co-Al-Fe BMGs were obtained and showed better glass-forming ability (GFA) via a small amount of Co partial replacement by Fe. In addition, the addition of a small amount of Fe enhanced the crystallization process and reduced the activation energy. The micro-alloying with Fe reduced the heat of mixing, which made the rearrangement of atoms easier during the crystallization process.
Preparation of Fe76Si9B10P5 Nanocrystalline Magnetic Cores by Direct-Nanocrystallizing Method during Spark-Plasma Sintering
Authors: Wang Ming Gang , Liu Tong , Zhao Zhan Kui
Published: March 2013

Bulk nanocrystalline Fe76Si9B10P5magnetic cores were sintered using spark-plasma technique through direct-nanocrystallizing method by Fe76Si9B10P5amorphous alloy gas atomization powder. The saturated magnetic induction of magnetic cores was 1.5 T, and the maximum permeability was 1470. Coercive force was 38 A/m. X-ray analysis showed that the crystallization temperature of Fe76Si9B10P5alloy decreased with the increase of the pulse current and sintering pressure. High resolution electron microscopic analysis results showed that the smaller nanograin size were obtained after spark-plasma sintering with the crystallization temperature decrease. In addition, the crystallization behaviour of the Fe76Si9B10P5during sintering process was analyzed, and the influence of direct crystallization during spark-plasma sintering on the soft magnetic properties was discussed.
The Effect of High Gravity Field on the Hydrothermal Preparation of the Nanostructured Materials
Authors: Li Wen Jun , Zhou Tang , Ding Liu Liu , Fang Lu
Published: March 2013

The nanostructured ZnS, CdS/CdCO3and MnCO3were prepared by the hydrothermal method with gravity field of 1000 /g in the oil/water system at 100-150 for 0.5h. The products were characterized by eld-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and BET method. The results showed that the ZnS samples obtained using ZnCl2and Na2S2O3as precursors at 100-120 for 0.5h were the polycrystalline microspheres self-assembled by the crystallites with the size of 3-25nm. The pore volume of polycrystalline microspheres decreased with the increase of the size of the applied gravity forces. The morphology of CdS/CdCO3samples obtained at 100 for 0.5h was the flower-like structure, while the as-prepared samples at 120 for 0.5h were the nanoceramic microspheres in shape. The gravity force favors the formation of CdS/CdCO3samples. Moreover, the MnCO3polycrystalline flake can be obtained at 100-120 for 0.5h under gravity field of 1000 /g.
Diffusion Bonding of Fe-Based Amorphous Ribbon to Crystalline Cu
Authors: Dong F.T. , Xue Xiang Yi , Kou Hong Chao , Wang Jun , Niu C.X. , Li J.S.
Published: March 2013

A copper rod/FeSiB amorphous ribbon/copper rod sandwich laminated composite material has been successfully fabricated by co-pressing at temperatures within supercooled liquid region. The bonding interface has been characterized by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). Results showed that a good bonding interface could be obtained only when the initial surface were carefully polished. The diffusion zone confirmed by EDS is about 60nm, indicating the bonding is in atomic metallurgical level via limited diffusion. The present results show that even the diffusion length is very small, diffusion bonding in the supercooled liquid region could be an effective way for fabricating Fe-based metallic glass/Cu laminated composites
Effects of Heat Treatments on Corrosion Behavior of Mg AT72 Alloy
Authors: Wang Zhi Qin , Li De Jiang , Zeng Xiao Qin , Wu Xiao Mei , Ding Wen Jiang
Published: March 2013

The effects of heat treatments, including T4, T5, T6 treatments, on corrosion behaviors of Mg-7Al-2Sn (AT72) alloy processed by high vacuum die casting have been investigated. The optical microscope, scanning electron microscope observations were used to analyze the microstructures, especially the distribution of second phase, phase contents and grain size. The hydrogen evolution tests, electrochemical methods including open circuit potential curves and polarization curves were used to describe the corrosion properties as well. The results indicated that different heat treatments had influence on microstructures, especially distribution of second phase, phase contents and grain sizes. The existence of second phase had a relationship with corrosion properties, in which the as-cast samples showed low corrosion rate in hydrogen evolution tests while the heat treatment methods had little impact on improving corrosion resistance. The electrochemical analyses also agreed with this observation. Based on these results, the optimized heat treatment method for corrosion resistant AT72 magnesium alloy has been established.
Formation of Stray Grains in Directionally Solidified Ni-Based Superalloy with Cross-Section Change Regions
Authors: Xuan Wei Dong , Ren Zhong Ming , Liu Huan , Tu Ting Sheng
Published: March 2013

The formation mechanism of stray grains in cross-section change region of casting clusters for single crystal superalloy DD483 were investigated experimentally during the conventional directional solidification. The results showed that the stray grains formation was different on the two sides of the platform. Indeed, stray grains formation in the region of the cross-section change on the shadow side showed a high probability, while the heater side, no stray grains appeared. Additionally, the cooling curves at the cross-section change region also showed that the distribution of temperature was different on the two side of the platform. The formation of stray grain can be attributed to the local undercooling at the cross-section change region is exceed the critical undercooling for nucleation, led to the heterogeneous nucleation, while the asymmetric temperature distribution should be responsible for asymmetrical formation of stray grains on the two sides of the platform.
Influence of Solution Temperature on Compositions Segregation and Creep Behavior of a Single Crystal Nickel-Based Superalloy
Authors: Tian Su Gui , Xue Y.C. , Zeng Z.
Published: March 2013

By means of solution treatment at various temperatures, creep properties measurement and microstructure observation, the effects of heat treatment on composition segregation and creep properties were investigated. Results show that the various segregation extents of the elements are displayed in the alloys solution treated at different temperatures, and the segregation extent of the elements is improved with the solution temperature elevated, which may obvious improve the creep resistance of the alloy. And no rafted structure of the γ phase is detected in the alloy during creep at medium temperature. The deformation features of the alloy during creep at medium temperature are that the slipping of dislocations is activated in the γ matrix channels, and dislocations shearing into the γ phase may be decomposed to form the configuration of partials + stacking faults, which may hinder the cross-slipping of the dislocations to improve the creep resistance of the alloy.
The Effect of Cryogenic Treatment on the Microstructure and Properties of Ti-6Al-4V Titanium Alloy
Authors: Gu Kai Xuan , Li Zhi Qiang , Wang Jun Jie , Zhou Yuan , Zhang Hong , Zhao Bing , Ji Wei
Published: March 2013

The effect of cryogenic treatment on the microstructure and properties of Ti-6Al-4V has been studied in this paper. The program controlled SLX cryogenic box was used to conduct the cryogenic treatment and the subsequent low temperature temper. The scanning electron microscope was used to study the morphology of microstructure and fracture surface. As the results show that the cryogenic treatment increases the elongation of Ti-6Al-4V from 16.5 percent to 24.5 percent, at the same time, the strength increases slightly, this indicates that cryogenic treatment can improve the comprehensive mechanical properties. The microstructure measurement revealed that there is a tendency of reduction in the precipitated particles after cryogenic treatment. The cross section is flat and the size of dimples is more uniform. It is concluded that the change in the precipitation particle had a great influence in the mechanical properties.
Influence of Different Pouring Temperature to Properties and Organization of A356 Aluminum Alloy under Specified Conditions
Authors: Zhao Li Li , Yang Lv Ming , Zhou Tie Tao
Published: March 2013

Due to the excellent casting performance, good corrosion resistance, high strength and casting manufacturing costs, A356 casting aluminum alloy is widely used in automobile wheel industry of China. However, for the restrictions of the production equipment, technology and the production craft level, there are problems that product quality is not satisfied and the production efficiency is low in the mass manufacturing. In this paper, the effect of pouring temperature and mold temperature on the microstructure and mechanical properties were investigated on the basis of cooperation project with Bin Zhou wheel hub manufacturing company. The quantitative relationship between mechanical properties and microstructure was studied by statistical methods. The results indicate that pouring temperature is the main element to affect the mechanical properties of permanent mold casting A356 and the optimum pouring process parameter is about 744 .Mechanical properties have a liner relationship with secondary dendrite arm spacing in a certain extent.
The Intelligent Control Method of the Density of the Metal Injection Molding Billet Based on ANN
Authors: Zheng Zou Shun , Leng Rui Rui
Published: March 2013

According to the metal powder injection molding process, the main influence factors of injection molding billet density distribution (such as: injection velocity, injection temperature, injection pressure, etc) was analyzed and a multiple input & multiple output BP neural network model for injection molding was build up to predict the density distribution of the billet intelligently based on ANN and GA. In addition, in light of the requirements for the density distribution of the metal injection molding billet, the influence factors were controlled intelligently. Applying this model in the metal injecting process, the density distribution of billet was predicted according to the injection parameters and the injection parameters was optimized according to the required density distribution of the billet. As the result, the error was less than 5% between the prediction values and the actual values of the density distribution of billet. With the optimized injection parameters to the injection process, the density distribution of billet closed to the requirements was achieved.
The Dynamic Recrystallization Model of 7050 Al-Alloy during Hot Deformation
Authors: Zhang Zhi Hao , Hou Wen Rong , Pang Qing Hai , Xie Jian Xin
Published: March 2013

In this paper, the compression stress-strain curves of 7050 Al-alloy under various deformation conditions were obtained, and the recrystallization structures were analyzed. The main parameters of dynamic recrystallization model were determined. The rationality of the model parameters were verified by hot compression and extrusion. The results show that the accuracy of the model is high enough for predicting the recrystallization of the 7050 Al-alloy during hot deformation. Comparison of the experiment and calculated results in hot compression shows that the maximum relative error of the recrystallization fraction is 11.4%. Comparison of the experiment and calculated results in hot extrusion shows that the maximum relative error of the recrystallization fraction is 13.0%, and that of the recrystallization grain size is 14.9%.
Preparation of Tungsten-Copper Composite Powder by Electroless Plating
Authors: Wang Ying , Zou Jun Tao , Zhang Qing He
Published: March 2013

In this paper, tungsten-copper composite powder was prepared on the particle size of 6 ~ 10μm tungsten powder surface by electroless copper plating. The orthogonal experimental results show that the primary and secondary order of factors affecting the deposition rate followwing the sequence: copper sulfate solution concentration > pH value> solution temperature> formaldehyde concentration > complexing agent concentration. The process of the electroless copper plating on the tungsten powder surface was investigated, and the best electroless copper plating solution composition and operation conditions were obtained as follows: plating temperature 323 K, stirring speed 30 r/min, PH =13, loadage 8g/L, CuSO4 5H2O 0.032 mol/L, HCHO 0.274 mol/L, TEA 0.1208 mol/L, 2, 2 'league pyridine 12 mg/L.
Effect of Heat Treatment on Microstructure and Properties of Cu-3Ti-1Al Alloy
Authors: Wang Xian Hui , Sun Xiao Chun , Yang Xiao Hong , Liang Shu Hua
Published: March 2013

The effect of heat treatment on the microstructure and properties of Cu-3Ti-1Al alloy was investigated. The microstructure was characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM), and the hardness and electrical conductivity were tested as well. The results showed that the hardness and electrical conductivity of Cu-3Ti-1Al alloy increased significantly after solid solution and ageing treatment. The strengthening effect of Cu-3Ti-1Al alloy was attributed to the formation of intermetallic phase such as Ti3Al and fine precipitates of coherent β-Cu4Ti. With increase of the aging time and the temperature, the precipitates became coarse and incoherent with Cu matrix, and the discontinuous precipitate β started to grow from grain boundaries toward grain interior, which decreased hardness. As the formation of Ti3Al, β-Cu3Ti and β-Cu4Ti phase can efficiently reduce Ti concentration in Cu matrix. The electrical conductivity of Cu-3Ti-1Al alloy increases. In the range of experiments, the optimal heat treatment process for Cu-3Ti-1Al alloy is solid solution at 850°C for 4h and ageing 500°C for 2h, and the hardness and electrical conductivity are 227HV and 12.3%IACS, respectively.
The Precipitation and Strengthening Mechanism of Cu-Ni-Si-Co Alloy
Authors: Wang Qiang Song , Xie Guo Liang , Mi Xu Jun , Xiong Bai Qing , Xiao Xiang Peng
Published: March 2013

The precipitates, mechanical properties and strengthening effect of Cu-Ni-Si,Cu-Ni-Si-Co0.8 and Cu-Ni-Si-Co1.9 alloys are investigated. It is concluded from the TEM and XRD analysis that the strengthening of Cu-Ni-Si-Co alloy is mainly attributed to precipitates of both Ni2Si and Co2Si phases, with the same structures and very close lattice parameters. The addition of 1.9 wt% Co barely affects the precipitation process of Ni2Si or Co2Si, and may not be beneficial for enhancing the strength. The strengthening of Cu-Ni-Si-Co alloy is determined by the Orowan mechanism, and a critical precipitate radii rc about 1.5 nm corresponding to the peak strength is obtained through the theoretical analysis. It can be deduced that the peak strength of aged Cu-Ni-Si-Co alloy is obtained with the microstructures containing metastable phase and Ni2Si (or Co2Si) precipitates.
W-Ti Alloy Prepared by Hydrogen Reduction of Nanometer WO3-TiH2 Powders
Authors: Xiao Peng , Qu Ying Chun , Yang Xiao Hong , Liang Shu Hua
Published: March 2013

In this study, TiH2 and WO3 powders were co-milled together, then the ultrafine powders were reduced at H2 atmosphere, and W-Ti alloys were prepared by the solid phase sintering. The main purpose of WO3 powder instead of the W powder was to use the transition of the lattice type of WO3, and the lattice distortion and defects in the lattice of W would promote Ti atom diffusing into W. It was easy to form a W-rich solid solution and reduce the effect of Ti-rich phase. The results showed that when the milling time of WO3-TiH2 was 24h, the particle size of mixed powder reached nanoscale, and WO3 particles were coated on the surface of TiH2 particles. The particle size changed unobviously with the increase of the milling time. The XRD analysis showed that the milled WO3 and TiH2 were not decomposed in the milling process. When WO3-TiH2 milled powders were decomposed in the H2 atmosphere at 800, WO3 reduction was not sufficient, and the middle phase of WO2 was existed. When the reduction temperature was 850 for 2h, WO3 was reduced to W, and the phase of WO2 was disappeared. A small amount of TiO2 was formed by the decomposed Ti and decomposed O from WO3. W-10Ti alloys were prepared by the solid-phase sintering with the reduced powders at 850. It was found that the amount of W-rich solid solution in W-10Ti alloy was decreased, because the diffusion of Ti to W was inhibited by a small amount of TiO2 in grain boundaries during the sintering process.
Microstructure and Mechanical Properties of AZ81 Magnesium Alloy after Unequal Channel Angular Pressing
Authors: Luo Xiao Ping , Zhang Ming Gang , Zhou Jun Qi
Published: March 2013

The microstructure and mechanical properties of AZ81magnesium alloys after unequal channel angular pressing (UCAP) was investigated using self-made 90° die under different temperature. The results showed that under the same pressing speed, there was a better grain refinement and mechanical property improvement with the decreasing of pressing temperature, however, the tiny cracks on the surface of the processed samples increased. When squeezed at 250 , the average grain was refined from the initial 150um to10um. The tensile strength was changed to 350Mpa, and the elongation was of 10. Tensile fractures presented the increment of dimples structure, which was the result of refined α-Mg matrix and intermetallic compound β-Mg17Al12 phase by severe shear and plastic deformation at high temperature press.
Influences of High-Temperature Short-Time Endurance Performance of Heat Resistant Steel for Ultra Supercritical Units
Authors: Tang Hua , Xiao Feng , Ding Jian Sheng , Li Zhi Hong
Published: March 2013

Heat-resistant steel (12%wt. Cr) used in the ultra supercritical set blade was quenched and tempered by vacuum heat treatment furnace, the mechanical properties and metallographic structures at room temperature can meet the specific requirements. However, there are some problems existed on high-temperature short-time lasting performance. To improve the high temperature endurance performance of materials, the experimental testing and analysis were carried out fro different types of specimen. The research showed that short-time rupture is a kind of creep fracture, and short lasting strength was closely related to test temperatures between laths and grain boundary and carbide coarsening. Energy spectrum analysis revealed that cast in the hole had high B element content (19.98%wt.), which meant grain boundaries of the B at high temperature began to migrate and form in the crystal B in that second phase particles are contained, and grain boundary strength was obviously decreased. The enduring high temperature experiment indicated that the strength were declined rapidly and fractured suddenly at high temperature.
Investigation of Deibinding and Sintering of 3Y-ZrO2 Gear Fabricated by Micro Powder Injection Molding
Authors: Liu Lin , Chen Yu , Ni Xin Lei , Yin Hai Qin , Qu Xuan Hui
Published: March 2013

The rapid development of micro-system and its related products has caused an upsurge of micro components, and the micro powder injection molding is potential for its mass production. In this work, the solvent debinding mechanism of the in-house feedstock was studied. The influence of solvent debinding, thermal debinding and sintering on the micro gears was investigated. The weight loss of 3Y-ZrO2 micro gears ranging from 200 to 900μm were compared by using six types of solvent including ether mixture withanhydrous alcohol, petroleum ether, chloroform and are hexane etc. The thermal debinding scheme was determined based on the DSC and TGA results of the binder system. The effect of the heating rate on the micro gears was investigated. The experimental results showed that the petroleum ether mixture with anhydrous alcohol yielded the best debinding effect for the micro gears, which was controlled by diffusion and dissolution. Using the established debinding and sintering schedule, the defect free micro gears were successfully fabricated.
Effects of Strain Rate on Tensile Deformation Behavior of Quenching and Partitioning Steel
Authors: Liu Chao , Wang Lei , Liu Yang
Published: March 2013

The effects of strain rate on the tensile deformation behavior of quenching and partitioning (Q&P) steel applied to the auto industry were investigated. The results indicated that the strength of Q&P steel raised with increasing strain rate. The variation of elongation which presented the trend of declining (10-4 s-1~101 s-1) followed by rising to the peak (8×101 s-1) then falling again (102 s-1~103 s-1), is mainly caused by the transformation from retained austenite to martensite, namely the TRIP effect.
Properties and Fabrication of Alumina Dispersion Strengthened Copper Alloy with High Softening Temperature
Authors: Han Sheng Li , Qin Xiao Dong , Cai Yi Xiang , Luo Kai , Xie Huan Wen , Li Da Ren
Published: March 2013

Cu-Al2O3 alloy combine both high electronic conductivity and high softening temperature. Cu-Al2O3 alloy was fabricated by internal oxidation and hot extrusion methods in the present investigation. Microstructure and properties of Cu-Al2O3 alloy was studied. The influence of preparation parameters, hot extrusion parameters and heat treatment on the properties of the alloy was investigated. The results indicated that the grain of the alloy was very small with a size between 2-10μm. Softening temperature of the Cu-0.6% Al2O3 alloy and Cu-1.0% Al2O3 alloy was 900. Cu-0.6%Al2O3 alloy and Cu-1.0% Al2O3 alloy meeting the requirements for electrode in resistance welding is the ideal substitution of the traditional electrode materials for resistance welding.
Magnetic Properties for Magnetic Quantum Dot Arrays: Fast Fourier Transformation and Micromagnetism Study
Authors: Ye Qing Ying , Chen Shui Yuan , Zhong Ke Hua , Chen Xiu Lai , Huang Zhi Gao
Published: March 2013

Based on the Monte-Carlo simulation and fast Fourier transformation-micro-magnetism (FFTM) method, magnetic properties with different parameters for the 4×4 Magnetic Quantum Dot Arrays (QDA) were studied. The calculating processes show that the same calculated results can be obtained by both methods above. But the FFTM method can save much time in obtaining results, which suggest that the method be employed to study more complex systems. The calculated results indicate that there exists obvious difference in the magnetic hysteresis loops with different temperatures, which can be well explained by considering the relationship between the easy-magnetization axis and the organization anisotropy of the QDA system. Furthermore, saturation field (Hs) increases with the dipolar interaction increasing, which is attributed to the competition between dipolar energy (ED) and Zeeman energy (EZ). The calculated results can fit the experimental results very well. Besides, it is found that the dipolar interaction constant D has a great influence on magnetic properties.
Analysis and Simulation of the UOE Pipe Production Processing by Finite Element Method
Authors: Zhao Yang , Ren Qiang , Zou Tian Xia , Li Da Yong , Peng Ying Hong
Published: March 2013

Large-diameter pipes used in offshore applications are commonly manufactured through the UOE process. The plate is crimped along its edges, formed into a U-shape and then pressed into an O-shape between two semicircular dies. The pipe is welded closed and then circumferentially expanded to obtain a highly circular shape. In this study, the two-dimensional finite element model of the whole processing of the UOE pipe production has been established, including large deformation and complex contact. The deformed geometries of different steps and distribution of the equivalent plastic strain and variation in load are analyzed. This research is helpful in UOE forming process design and evaluating the capability of the pipe mill.
Research on the out of Square of H-Beams
Authors: Zhao Xian Ming , Guo Fei , Gao Xin , Xia Wen Zhen , Wang Li Na , Wu Di
Published: March 2013

H-beam will inevitably produce temperature uneven in cooling process, causing the uneven deformation phenomenon in H-beam cross section, and therefore how to improve H-beam cooling distortion uniformity become a research priority of H-beam. In this paper, the deformation of H-beam was simulated in the cooling process by using finite element analysis software ANSYS, and the simulation results was compared with measured data. Uneven cooling rate between up and down groove of the H-beam caused the out of square. Uneven cooling rate for the R corner and web surface was simulated, the conclusion is that uneven cooling rate for the web is the main reason of the out of square, and that of R corner is the second factor.
Precipitate Behavior and Microstructure Evolution of γ’ Phase in Ni-Al Alloys with the Internal Elastic Strain
Authors: Cheng Xiao Ling , Li Yong Sheng , Zhang Lei , Zhu Hao
Published: March 2013

The microstructure evolution and precipitation behaviors of ordered γ (Ni3Al) phase in Ni-Al alloys were studied using the phase field dynamic model. Under the interactions of internal elastic strain, the γ phase morphology changes from the separated cuboidal to connected rectangle shape with the decrease of the aging temperature or the increase of the Al concentration. It also shows that the ordering of precipitates is finished instantly when they precipitate from the matrix phase. The γ phase volume fraction and the phase transformation velocity are affected by the aging temperature and composition of the Ni-Al alloys.
Indenter Size Effect on the Incipient Plasticity of Al (001) Surface
Authors: Shao Yu Fei , Tang Dan , Li Jiu Hui , Zhao Xing
Published: March 2013

ndenter size effect on the incipient plasticity of Al (001) surface is studied by using the quasicontinuum simulation method. Two cylindrical indenters with the radii 2.5nm and 40nm are used to penetrate the surface respectively, and in displacement-control in steps of 0.02 nm. Results show that the plasticity under the small indenter is activated by discrete dislocation nucleation events, while the plasticity under the large indenter is dominated by a collective dislocation activity. Contact pressure calculations reveal that reversible incipient plasticity occurs under the small indenter, i.e. the plastically deformed surface can completely recover upon withdrawal of the indenter, while the incipient plasticity under the large indenter seems to be irreversible.
Surface Stability of a Biaxially Pre-Tensioned Soft Elastic Film Interacting with a Contactor
Authors: Qiao Ling , He Ling Hui
Published: March 2013

The elastic buckling of a biaxially pre-tensioned soft elastic film in proximity to a rigid contactor was studied. By a linear analysis, it was shown that the critical mode of buckling depended on the two in-plane principal stretches in the respective tensile directions, and the threshold of buckling only depended on the product of two principal stretches. Such a regular effect of pre-tension may be applied in the field of the generation of the precise surface patterns.
Study on the Electrolysis Expansion of Carbon Cathode in [K3AlF6/Na3AlF6]-AlF3-Al2O3 Low Temperature Melts
Authors: Fang Zhao , Xu Peng Fei , Xu Jian , Li Lin Bo , Zhu Jun
Published: March 2013

Electrolysis expansion of carbon cathodes due to alkali metal penetration in [K3AlF6/Na3AlF6]-AlF3-Al2O3 melts was tested. Effect of ampere density and superheating temperature on the electrolysis expansion was studied. A mathematical model was got to numerically describe electrolysis expansion performance of carbon cathode. The results indicated that K and Na penetrate into carbon cathode from outside to inside. Ampere density and superheating temperature had a great effect on the electrolysis expansion of carbon cathode. With the superheating temperature increasing from 10 to 50, electrolysis expansion increased from 1.41% to 2.10% gradually. With the ampere density increasing, the increase trend of electrolysis expansion was not linear. When ampere density was lower than 0.4A / cm2 and greater than 0.7A / cm2, cathode electrolysis expansion obviously increased with the increase of ampere density. Meanwhile, cathode electrolysis expansion tended to be constant as the ampere density changed at the range of 0.4A / cm2 to 0.7A / cm2.The results of the mathematical model in this study had a good agreement with the test results. This model would be helpful to accurately describe the anti-penetration performance of K and Na on the carbon cathode.
Effect of Deposition Temperature on the Structure and Mechanical Properties of Ti-6Al-4V Film
Authors: Li Lei , Lu Ya Feng , Li Wen Xue , Zeng Li Ying , Yang Yi , Hou Zhi Min , Han Dong
Published: March 2013

Ti-6Al-4V films were deposited by direct-current magnetron sputtering at different substrate temperatures. The structure and the surface morphology of the films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The hardness and elastic moduli of Ti-6Al-4V films were measured by nanoindentation test. The results showed that the phase direction of the films deposited at room temperature was (102) orientation, and turned to almost complete (002) preferred orientation at 300°C. For a higher temperature of 500°C, the preferred orientation of the film disappeared and presented a random grain orientation. The hardness and elastic moduli of Ti-6Al-4V films obviously showed the dependence on the temperature. The relationships among temperature, microstructure and mechanical properties of Ti-6Al-4V films were discussed in this paper.
Preparation and Characterization of the Highly Regular Nitrogen Doped Anatase TiO2 Nanotube
Authors: Li Hong Bo , Li Jin Long , Wang Yong Xin , Wang Li Ping
Published: March 2013

Nitrogen-doped TiO2 nanotubes (N-TNTs) were fabricated on the titanium foil by anodic oxidation and followed by annealing at NH3 environment. Highly ordered nanotubes, roughly 150 nm in the diameter and 20 μm in the length, were synthesized on the titanium foil. By controlling oxidation voltage, the thick TiO2 nanotubes were peeled off from the titanium substrate. In one step annealing at NH3 environment, nitrogen replaced oxygen and doped into TiO2, but anatase phase was formed.
Effect of Process Parameters on Hydroforming of Stainless Steel Tubular Components with Rectangular Section
Authors: Xu Yong , Zhang Shi Hong , Zhu Qing Xun , Cheng Ming , Song Hong Wu , Zhang Gui Jie
Published: March 2013

The effects of key process parameters including initial lengths of tube blank, forming velocity and loading paths on hydroformability of stainless steel tubular components with rectangular section were systematically investigated. The results showed that sufficient axial feed must be given before the tube contacting the surface of die in order to prevent the excessive thickness thinning, especially for longer tube blank. The lower loading velocity led to enhanced formability. It is more important that pulsating loading path observably improved the formability of 304 stainless steel.
Hot Deformation Behavior of A390 Hypereutectic Al-Si Alloy
Authors: Hu Xiao Gang , Yang Bi Cheng , Xu Jun , Wang Hai Jun
Published: March 2013

The hot deformation behavior of hypereutectic aluminium-silicon alloy was investigated by thermal simulation test at the deformation temperature of 330-480 and the strain rate of 0.1-10s-1using the Gleeble-1500 thermal mechanical simulator. The relationship of flow stress, temperature and strain rate was appropriately described by the deformation constitutive equation, and the deformation activation energy is 187.418 KJ/mol. In addition, the microstructures of these specimens were analyzed and the result showed that the inhomogeneous deformation enhances with increasing strain rate and decreasing deformation temperature, and the presence of primary silicon had a strong influence on the uneven deformation.
Effect of Crack Initiation Size on Fatigue Strength in 0.85% Carbon Steel
Authors: Makabe Chobin , Miyazaki Tatsujiro , Nakane Naoki , Yamazaki Shinya , Makishi Takashi , Murdani Anggit
Published: March 2013

The fatigue limit of a plain specimen of a tool steel JIS SK85 was investigated. The initial crack length in the fatigue process is related to the size of a single crystal in the case of low carbon steel. However, that is independent of the crystal size in the case of pure aluminum, a lamellar pearlitic steel, etc. In this study, the relationship between the initial crack length and the fatigue limit was investigated. The original microstructure of this material includes a spherical microstructure. However, after heat treatment under some conditions, that microstructure changed to a lamellar microstructure. The fatigue limit of heat-treated SK85 could be evaluated by an equation in which the parameters are the hardness and initial crack length. Finally, this result was discussed based on the observations of crack growth behavior and fracture surface.
Modeling and Simulation of Dynamic Recrystallization of GCr15 Steel Using Cellular Automaton Method
Authors: Deng Xiao Hu , Qu Zhou De , Zhang Li Wen , Ju Dong Ying
Published: March 2013

A modified two-dimensional (2-D) cellular automaton (CA) model was constructed to simulate dynamic recrystallization (DRX) process of GCr15 steel. Particle stimulated nucleation (PSN) was incorporated into the CA model to determine the influence of dispersed particles on the nucleation of DRX. In addition, the model included the effects of particles on increasing the dislocation density and pinning the grain boundaries for accurate determination of micro-structural evolution during DRX. The model was applied to simulate the DRX process of GCr15 bearing steel. DRX grain size and volume fraction were simulated using the CA model. The simulated results indicated that the simulated stable grain size of particle-containing model is closer to measured value than particle-free model. It was observed that DRX kinetics depends on both thermo-mechanical parameters and initial grain sizes. The calculated results were compared with the experimental findings in GCr15 bearing steel, the predictions show very good agreement with the experimental results.
Synthesis of Spherical Carbon Nanoparticles via Sol-Gel and their Electrochemical Properties in Electrical Double Layer Capacitor
Authors: Zheng Guo Bin , Sano Hideaki , Uchiyama Yasuo
Published: March 2013

Spherical carbon nanoparticles were prepared by the polycondensation of resorcinol and formaldehyde using sol-gel method in the presence of cetyltrimethylammonium bromide (CTAB) and subsequent carbonization. Addition of carbon nanotubes (CNTs) in the precursor solution resulted in CNT/carbon porous composites. The effect of carbon nanotubes (CNTs) on the microstructure, pore structure and electrical double layer capacitance of CNT/porous carbon composites was examined based on the field emission scanning electron microscope, transmission electron microscope observation, N2 isothermal adsorption, cyclic voltammetry and charge/discharge tests. The results showed that 20% CNT addition had little effect, but 50% CNT addition significantly changed the microstructure and pore distribution, and charge/discharge properties.
Effect of Chemical Composition on Fracture Behavior in ZrNiAl Metal Glass
Authors: Kawaguchi T. , Li F.W. , Zhu Shi Jie , Wang Y.M. , Dong C.
Published: March 2013

Compressive tests of Zr6Ni3AlX（X=1 to 3），Zr7Ni3AlX（X=1 to 3），Zr8Ni3AlX（X=1 to 3），Zr9Ni3AlX（X=1 to 3），Zr3Ni4AlX（X=1 to 3）and Zr10Ni3AlX（X=1 to 3）bluk metallic glass（BMG） were carried out to investigate the compositional dependence of mechanical properties． The strength increased but the ductility decreased with an increase in Al content．Moreover，it was confirmed that the formation of multiple shear bands became difficult with an increase in glass forming ability．
A Study on Spatial Resolution of the Microwave Atomic Force Microscope Imaging Affected by Scanning Speed
Authors: Zhang Lan , Hosoi Atsushi , Ju Yang
Published: March 2013

Using the microwave atomic force microscope (M-AFM) measuring system, the sample of Au nanowires arranged on glass wafer was sensed with three kinds of scanning speed. As the results shown, the spatial resolution of topographies is increased with the decrease of scanning speed. However, the precision of microwave images is not changed much with decreasing the scanning speed. Since M-AFM with the compact microwave instrument can always implement the real time measurement, the variation of scanning speed will not affect the microwave measurement.
Thermal Residual Stress and Tensile Strength of UACS/Al Laminate with Different Slit Angles
Authors: Xue Jia , Wang Wen Xue , Takao Yoshihiro , Matsubara Terutake
Published: March 2013

This paper focus on the investigation of tensile strength and thermal residual stress in UACS/Al laminates. The UACS (unidirectionally arrayed chopped strands) is made by cutting parallel slits on unidirectional carbon fiber prepreg. Thus all of the carbon fibers in the cut prepreg are 25 mm in length. Six cases of UACS prepregs are prepared with different slit angle θ, which is the angle between slit and fiber direction, including 5.7o, 11.3o, 16.7o, 31o, 45o and 90o. A UACS/Al laminate consists of one UACS layer with four UACS plies and two aluminum layers, such as [Al/UACS4/Al]. Four pieces of UACS prepreg with alternate slit angle [θ/-θ/θ/-θ] are stacked together in the same fiber direction. Then stacked UACS/Al laminate are cured using an autoclave. Tensile tests are performed to investigate the thermal residuals stress using the yielding-point-shift method. Experiment results show that thermal residual stress is reduced in the case of UACS/Al compared with conventional CFRP/Al. Among all the cases, specimen with slit angle of 11.3o is the most impressive one with 37.7% reduction of thermal residual stress.
Structure Simulation Calculation of Impurities B with Fe, Al or Ca in Metallurgical Grade Silicon
Authors: Xie Ke Qiang , Tang Jian Wen , Chen Xiu Min , Ma Wen Hui , Yang Bin , Liu Zi Li
Published: March 2013

Ab initio molecular dynamics (MD) calculations had been performed in this work to simulate the interactions of B with Fe, Al or Ca in metallurgical-grade silicon (MG-Si). The temperature of the MD simulations is 0K, the simulation time is 1ps. All the calculations were performed by using the CASTEP module of Materials Studio 4.3 software package. The geometry optimizations of impurities B with Fe, Al and Ca in MG-Si were performed with density functional theory (DFT) calculation. The Density of States of the optimized structures was calculated and the results have the potential application in guiding the boron removal from MG-Si by acid leaching.
Effect of Microwave Irradiation on Rapid Crystallization of Ferroelectric Lead Zirconate Titanate Thin Films
Authors: Wang Xian Wei , Wang Zhan Jie , Chen Yan Na , Zhang Yu Qing , Zhang Zhi Dong
Published: March 2013

Ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT) thin films rapidly crystallized by microwave irradiation were compared with those obtained by conventional furnace process. The PZT films under microwave irradiation at 650 °C for 60 s were crystallized well in to the perovskite phase, and showed butter electrical properties than those crystallized by conventional furnace annealing at 650 °C for 30 min. It is clear that microwave irradiation is effective for obtaining well-crystallized PZT films with good properties in a short process time.
Optimization of Process Parameters for Unidirectional Solidification of Magnesium Alloy
Authors: Chen Ming , Hu Xiao Dong , Zhao Hong Yang , Ju Dong Ying
Published: March 2013

The unidirectional solidification process of magnesium alloy needs to establish a specific temperature gradient in casting mold, the direction of crystal growth and heat flow are in the opposite direction in the unidirectional solidification. The process can better control the grain orientation, and eliminate the horizontal grain boundary, so to attain columnar grain structure and excellent performance of magnesium alloy. In this paper, Numerical simulation is carried out by orthogonal experiments in order to obtain the optimal process parameters according to the actual experimental device. Different process parameters are taken into account, including pulling speed, cooling time and cooling intensity. FEM (finite element method) is employed to calculate the temperature field and reached a straight shape of temperature gradient distribution which is conductive to achieve unidirectional solidification microstructure. PFM(phase field method) is adopted into the microstructure calculation. The microstructure obtained by PFM is in agreement with the actual pattern by the optical microscope observation.
Notch Effects in High Cycle Fatigue of Ti-6Al-4V
Authors: Shojima Kenji , Weldle Sabine , Okazaki Saburo , Endo Masahiro , Eifler Dietmar , Balle Frank
Published: March 2013

In this study, a series of experimental studies was conducted to investigate the fatigue behavior of Ti-6Al-4V alloy at room temperature. Specifically, by inspecting the cylindrical specimens with a circumferential notch of different depths (20-200µm) and notch root radii (20-100µm), the notch effect was systematically investigated with tension-compression fatigue tests (R = –1). To quantify the effects of small notch, the -parameter model was adopted and its applicability for Ti-6Al-4V alloy was examined. Finally, the fatigue characteristics are discussed in conjunction with the behavior of small fatigue cracks at notches.
Investigation for Small Shear-Mode Fatigue Cracks in Bearing Steels
Authors: Okazaki Saburo , Kusaba Atsushi , Matsunaga Hisao , Endo Masahiro
Published: March 2013

Flaking and spalling caused by rolling contact fatigue associate with a small crack, and a special testing method and machine are required to study the small fatigue crack behavior under shear mode loading. It was found by authors that the behaviors of small shear-mode fatigue cracks from the inclusions and the artificial defects could be successfully observed by applying the fully-reversed torsion coupled with static axial compressive stress. However, the servo-hydraulic fatigue testing machine is quite expensive for purchase and maintenance, and large installation space is necessary for the hydraulic and cooling systems. Moreover, the presence of axial compression significantly lowers the frequency of torsional loading, which consequently results in low testing speed. In this study, a cost-effective, space-saving and high-speed fatigue testing method was newly proposed, and the shear-mode fatigue crack growth tests were carried out by using the developed machine. Based on the obtained experimental data, the potential of the new testing machine is discussed.