bluuebunny/crossref_metadata_2025 huggingface dataset:
A Model of Ferroelectric Field-Effect Transistor after Ionizing Radiation
Authors: Li Zheng , Xiao Y.G. , Tang M.H. , Chen J.W. , Ding H. , Yan S.A. , Zhou Y.C.
Published: April 2014

A theoretical model for radiation effect in a metal-ferroelectric-semiconductor (MFS) field-effect transistor was proposed by considering the fixed charges (Qfx) and interface charges (Qit) induced by ionizing radiation. In this model, the energy band-bending and surface charge in Si at a given gate bias were calculated systematically as a function of fixed charges (Qfx) and interface charges (Qit). The drain-source current (ID) was derived in an exact form without any approximation. All modeling done in this work was generalized to both n and p type Si substrates with an easy sign of the Fermi level potential in the formalism. The derived results demonstrate that the symmetry of polarization versus gate voltage curve of the MFS structure degrades when Qfx and Qit increase, which can explain the imprint behavior successfully. Additionally, the residual polarization in the ferroelectric field-effect transistor decreases with increasing Qfx and Qit, which can account for the polarization reduction. As expected, the calculated transfer characteristic of the ferroelectric FET shows that the subthreshold voltage is significantly affected by Qfx and Qit. This investigation may provide some useful insights for the space applications of ferroelectric FET’s.
Research on Annealing Process for Amorphous & Nanocrystalline Soft Magnetic Alloy with High μi and Low Pc
Authors: Lv Wei
Published: April 2014

Recent advance and application about Fe-based amorphous nanocrystalline alloy have been reviewed, the latest achievement of static stress annealing, continuous moving stress annealing, and magnetic field annealing for the alloy discussed, and future tendency of Fe-based amorphous nanocrystalline prospected in the paper.
Effect of Aging on Super-Elastic Response of a Polycrystalline FeNiCoAlNbB Shape Memory Alloy
Authors: Chen Zhao Xia , Peng Wen Yi , Qu Gui Li , Wang Wei Wei , Shi Hai Ping , Wang Wen Jun
Published: April 2014

This study reports the effect of aging duration on the super-elastic response of Fe-30%Ni-18%Co-10.5%Al-2%Nb-0.15%B (at.%) poly-crystals in compression. The aging temperature was 600°C and the aging durations were 20h, 45h, 60h and 72h, respectively. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) were used in the work. The results show that with prolonging the aging duration, the super-elastic strain rises firstly and then descends. The super-elastic strain reaches the maximum 10.5% when the aging duration is 60h. The crisis stress for stress-induced martensite (σM) has no obvious changes, being about 250MPa when the aging duration is between 20h and 60h. But σM increases markedly when the aging duration prolongs to 72h. The hardness of the specimens changes in the same way as the superelastic strain, and reaches the maximum of 497HV10 when the aging duration is 60h. During the aging process, two factors react. One is the decomposing and reducing in size of the undissolved phase (σ). The other is the formation of the precipitation phase (γ'). Nb can dissolve into the matrix phase (γ) adequately and promote the formation of γ'. The combination of the two factors improves the strength and superelasticity of the specimens till the over-aging arises corresponding to the 72h aging duration.
Effect of Ta Addition on Properties and Microstructures of Fe-28Ni-11.5Al Shape Memory Alloys
Authors: Peng Wen Yi , Yang Neng Wu , Qu Gui Li , Wang Wei Wei , Shi Hai Ping , Wang Wen Jun
Published: April 2014

The effects of Ta additions (x=0, 0.5, 1.0, 1.5) in Fe60.5-xNi28Al11.5Tax(at.%) shape memory alloys on microstructure, thermal expansion, and pseudoelasticity of the aged alloys were investigated by metallurgical microscope, X-ray diffraction, SEM, EDS, high-temperature dilatometer spectrometer and pressure test machine. The results showed that with the increment of Ta additions, the γ' phase content increased which strengthened the austenitic matrix, meanwhile the compressive strength, the recoverable strain and the maximum strain of the aging state alloys decreased first and then increased, and the alloy’s residual strain firstly decreased and then increased. When the Ta content was 1.0 at.%, the alloy’s compressive strength, recoverable strain and plastic deformation strain reached its maximum value, 2.5Gpa, 14.4%, and 16.0% respectively. Thus, the alloy had the best pseudo-elastic at this time. The mean thermal expansion coefficient of the alloys decreased with Ta additions, when the Ta content was 1.0 at.%, the mean thermal expansion coefficient was at its minimum.
Influence of Annealing and Pre-Straining on the Coupling Effect of a TiNi-Nb Nanowire Composite
Authors: Liu Zhen Yang , Cui Li Shan , Yu Cun , Jiang Jiang , Jiang Da Qiang , Shi Xiao Bin , Guo Fang Min , Wang Zhong Qiang , Ren Yang
Published: April 2014

The influences of different annealing temperatures and pre-strains on the coupling effect between TiNi matrix and the Nb nanowire were studied by means of synchrotron X-ray diffraction in form of variation in lattice strain of the nanowire upon temperature changing for four groups of samples. For every annealing temperature, variation in Nb (110) lattice strains initially increasing with increasing pre-strain and then decreased after 12% pre-strain. A maximum variation in Nb (110) lattice strain was observed approaching 2.4% within the sample 450°C-20min annealed and 12% pre-strained. Such variations in lattice strain of the embedded nanowires upon temperature changing provided the composite great potentials as structural-functional integrated two-way actuators.
Properties of Low Temperature Fired Ferroelectric/Ferromagnetic Composite Materials
Authors: Zhang Dai Nan , Lin Wei Wei , Zhang Huai Wu
Published: April 2014

In this paper, Ni0.60Cu0.24Zn0.16Fe2O4/BaTiO3composites of BaTiO3(BT)/NiCuZn (NCZ) with mass ratios (x) equal to 5%, 10%, 15% or 20% were synthesised by a conventional solid-state reaction method and sintered at 900oC to adapt to low temperature co-fired ceramic technology. X-ray diffraction results showed that the composites were composed of BT and NCZ phases. The microstructures of the sintered composite materials were observed and analysed using scanning electron microscopy. The dielectric and magnetic properties of the composites were improved effectively with increasing BaTiO3content. The influences of different compositions on the electromagnetic properties of the composites were investigated.
Phase Formation, Microstructure and Magnetic Properties of NiCuZn Ferrites with Bi2O3 Additive
Authors: Li Qiang , Li Yuan Xun , Li Jie , Yu Guo Liang , Zhang Huai Wu
Published: April 2014

The ferrites (Ni0.2Cu0.2Zn0.6)1.02(Fe2O4)0.98 were prepared by standard solid state method and sintered at different temperatures. The effects of different Bi2O3 additives (0<x<5 wt%) on the phase formation, crystal structure and properties were investigated. The results of thermal analysis (DSC) showed that Bi2O3 played an important role in the process of sintering. The magnetization and the permeability were measured at room temperature, with increasing of Bi2O3 amount, the saturation magnetization had no obvious change and the initial permeability decreased from 291.2 to 197.6. SEM micrographs showed that the average grain size decreased with increasing Bi2O3 contents, but more Bi2O3 (x≥4wt %) additives may resulted in the abnormal grain growth.
Magnetic Properties and Microwave Loss of Polycrystalline M-Type Barium Hexaferrite Thick Films by Tape Casting
Authors: Chen Da Ming , Liu Ying Li , Li Yuan Xun , Li Jie , Zhang Huai Wu
Published: April 2014

M-type barium hexaferrite (BaM) is a promising gyromagnetic material for self-biased microwave\millimeter wave devices because of its large uniaxial magnetocrystalline anisotropy and low microwave loss in high frequency. Due to the limitation of growth conditions, it is difficult to deposit BaM films with enough thickness by PLD, MBE and Magnetron Sputtering for practical application. However, it is demonstrated in present experiment that large area polycrystalline BaM thick films (500μm) with self-biasing (high remanence) and low microwave loss can be successfully fabricated by tape casting. X-ray diffraction and Scanning electron microscopy results indicate that these BaM thick films have highly c-axis oriented crystallographic texture with hexagonal morphology. Magnetic hysteresis loops reveal that samples exhibit excellent properties with a saturate magnetization (4πMs) of 3606G, a high squareness ratio (Mr/Ms) of 0.82. In addition, ferromagnetic resonance (FMR) measurement shows that the FMR linewidth is as small as 431Oe at 48GHz. These parameters ensure these BaM thick films are potentially useful for self-biased microwave\millimeter wave devices such as circulator, phase shifter and filter.
Preparation and Property of Alkynyl Substituted Azobenzene Optical Limiting Materials
Authors: Li Lin Feng , Xu Hong Yao
Published: April 2014

An novel nonlinear optical alkynyl substituted azobenzene 4-(propargyl methyl ester)-4'-[(N,N'-diethyl) amino] azobenzene was synthesized and characterized by FTIR, 1HNMR. The linear optical properties were investigated by UV-Vis spectra. The nonlinear optical properties and optical limiting properties were investigated using 21 ps pulse at 532nm and 4ns pulse at 532nm, respectively. The results show that this novel nonlinear optical alkynyl substituted azobenzene possesses large third nonlinear optical coefficient and good optical limiting properties.
Influence of SiO2 Additive on the High-Frequency Magnetic Properties of Sr-Doped Co2Z Hexaferrite
Authors: Gan Li Yun , Liu Ying Li , Wang Yu , Yang Kai , Zhang Huai Wu
Published: April 2014

In this work, SiO2has been selected to be introduced into the system to improve the high-frequency magnetic properties of Ba1.5Sr1.5Co2Fe24O41hexaferrites. The influence of SiO2additive on the phase composition, microstructures and high-frequency magnetic properties of the samples prepared by solid-state reaction were investigated. The results indicate that the major phase of doped samples is Z-type ferrite. The addition of SiO2causes a decrease of the average grain size. Permeability measurements indicate that SiO2doping significantly improves the magnetic characteristics of those samples. With the doping content of SiO2increasing from 0 to 8wt%, the initial permeability decreases from 5.8 to 2.6, and the cut-off frequency rises up from 1.5GHz to over 1.8GHz. Meanwhile, the quality factor of the samples sintered at 1200°C varies with the SiO2content, and a maximum quality factor at 1GHz of Q=14 was found for x=4wt%. The improvements of magnetic properties and the high quality factors are crucial for applications of Z-type hexaferrites in high-frequency communication systems.
High-Frequency Performance of Co2FeAl Half-Metallic Films Prepared by Oblique Sputtering under Various Deposition Conditions
Authors: Cai Zhi Yi , Li Shan Dong , Cao Xiao Qin , Du Hong Lei , Xue Qian , Gao Xiao Yang , Xie Shi Ming
Published: April 2014

Co2FeAl full-Hesuler alloys show good soft magnetic properties, implying a promising high ferromagnetic resonance frequency. In this study, Co2FeAl films were deposited on Si (100) substrates using an oblique sputtering method. As expected, a good high-frequency performance was achieved in the as-deposited Co2FeAl films without any annealing. An obvious uniaxial magnetic anisotropy over 200 Oe with the magnetic hard axis along the radial direction of the sample turntable was obtained. As a result, the self-bias ferromagnetic resonance frequency reaches more than 4 GHz for the Co2FeAl films prepared under an integrated circuits compatible process. These results indicate that the Co2FeAl films are promising in integrated circuits RF/microwave devices.
Surface Roughness in Alumina Thin Film Deposited on Silica Using Oblique Incidence
Authors: He Li Jun , Li Chuan , Liu Xing Zhao
Published: April 2014

The main characteristics of a surface are physical and chemical structure, surface tension and surface roughness. Surface roughness is one of the critical factors, which could cause instability in quality performance. In this paper, surface roughness of alumina thin films deposited on a silicon substrate by using electron beam evaporation with oblique angle deposition were studied. It has been found that the surface roughness of the alumina thin films was dependent on the substrate temperature, the deposition rate, the film thickness and the inclined angle. The experimental results showed that increasing the substrate temperature reduced the surface roughness at a low inclined angle and enhanced the surface roughness at a high inclined angle, and the surface roughness increased with increasing deposition rate and film thickness. By choosing the appropriate film preparation parameters, the film surface roughness was effectively controlled.
Highly Sensitive Room Temperature Hydrogen Sensors Based on Photochemically Deposited SnO2
Authors: Ichimura Masaya , Ao Dengbaoleer
Published: April 2014

Highly sensitive room temperature hydrogen sensors based on undoped and Fe-doped SnO2films were fabricated. The SnO2films were deposited by the photochemical deposition using an aqueous solution containing SnSO4. For deposition of doped and undoped SnO2films, a small amount of an aqueous solution was dropped on a glass substrate and irradiated by UV light. The sensors annealed at 200oC showed extremely high sensitivity to hydrogen, but the initial resistance was very high. The sensors annealed at 400oC had a much lower resistance, and thus the sensor response was able to be measured even by a pocket multimeter. The Fe-doped sample showed higher sensitivity compared with the undoped sample.
Synthesis of Nanogels of Poly Methyacrylic Acid Using Methyl Cellulose as a Template
Authors: Zhang Jun Li , Wang Peng , An Dong , Li Xue Ting , Wu Qian , Zhao Di , Lu Xi Hua , Qiu Gao
Published: April 2014

In recent decades, thermo sensitive polymer system has been intensively studied due to significant importance in fundamental studies and various applications. Methyl cellulose (MC) is a thermo sensitive natural polymer, having a phase transition temperature or a lower critical solution temperature of about 65 °C. When methacrylic acid (MAA) was added to the MC solution, the phase transition of MC occurred at a lower temperature less than 65°C, and a higher concentration of MAA leds to a lower phase transition temperature of MC. Based on the phase transition of MC solution triggered by MAA, the surfactant-free poly (methacrylic acid) nanogels were synthesized by using methyl cellulose as a template in an aqueous media. The resulting PMAA nanogels characterized by using dynamic light scattering (DLS) and Fourier Transform Infrared Spectroscopy (FTIR). The nanogels of poly methyacrylic acid (PMAA) were affected by the concentration of both MC and MAA. A higher concentration of MAA led to a higher polymerization rate, and the higher concentration of MC resulted in the formation of the samller size of PMAA nanogels.
Stability of NbCl5 and ZnMg Intercalated Graphite
Authors: Meng Xiu Qing , Tang Shuang Shuang , Han Cong , Wu Feng Min
Published: April 2014

NbCl5and ZnMg intercalated graphite have been successfully synthesized by two-zone vapor transport method with the reactants sealed in the vacuum. The incorporation of NbCl5and ZnMg results in randomly intercalation confirmed from the X-ray diffraction (XRD) analysis, and the doping effect change with the variation of intercalation time, the evolution of the doping is confirmed by X-ray photoelectron spectroscopy (XPS) and Raman analysis. The doped graphite is relatively stable at room temperature for up to 60 days from the Raman observations.
Characterisation of YSZ Layers Deposited on Y2O3 Buffered Textured Tapes for Coated Conductors
Authors: Xia Yu Dong , Xiong Jie , Zhang Fei , Xue Yan , Hu Kai , Zhao Xiao Hui , Tao Bo Wan
Published: April 2014

Yttria-stabilized zirconia (YSZ) films were deposited on Y2O3/Ni-5at.%W substrates serving as the barrier layers for coated conductors by reel-to-reel direct-current (D.C.) magnetron reactive sputtering. The deposition parameters, such as the substrate temperature and tape moving speed, were systematically investigated. X-ray diffraction analysis confirmed that optimized YSZ/Y2O3buffer layers showed excellent in-plane and out-of-plane textures. Atomic force microscope revealed a smooth, dense and crack-free surface. The subsequent CeO2cap layer and 1μm-thick YBa2Cu3O7-δfilm sequentially prepared, showing the critical current densityJcunder 77K, self-field of 1.4MA/cm2.
Levitation Performance of Multiple YBaCuO Blocks with Different Arrays above a Permanent Magnet Guideway
Authors: He Da Bo , Zheng Jun , Gou Yan Feng , Sun Rui Xue , Che Tong , Deng Zi Gang
Published: April 2014

Bulk high temperature superconductors are usually used as arrays due to the limited size and performance of a single bulk. To find a reasonable array pattern for the superconducting maglev vehicle, we studied the levitation force of four multi-seeded rectangular YBaCuO blocks with three possible arrays above a permanent magnet guideway (PMG). Experimental results show that the levitation force can be improved through an optimal array pattern of the bulk superconductor. The method is to avoid the joint gaps of bulk arrays in a strong magnetic field area of the PMG thus improving the utilization rate of the applied magnetic field. The optimal array pattern will be helpful to improve the levitation performance and reduce the quantity of onboard superconductors.
Photocatalytic Activity of Ce-Doped Hematite for Hydrogen Production
Authors: Cai Jia Jia , Li Song , Wang Jian Sheng , Mei Yu Dong , Ren Yu Ping , Cao Feng , Qin Gao Wu
Published: April 2014

Hematite is one of the most promising photoanodes for water splitting, but its photoelectrochemical (PEC) efficiency is still low. This work proved that the PEC efficiency of hematite can be improved by Ce doping. The Ce doped hematite was successfully prepared by co-sputtering CeO2and Fe2O3, and followed by thermal oxidation treatment. The results of J-V test showed that the photocurrent of 5 at.% Ce doped α-Fe2O3film can reached 1.35mA/cm2in 1 M NaOH (pH=13.6) at 1.23V vs. NHE, which is nearly 15 times higher than the undoped one. The enhancement of PEC efficiency was proved by the enhancement of absorbance of visible light, as well as increased carrier density after Ce doping.
Degradation of Sodium Dodecyl Benzene Sulfonate in Surface Water or Clothes Laundering Drain Water with and without Anion via TiO2-Bentonite
Authors: Wen Shu Yao , Sun Xiao Chun , Chen Su Yun
Published: April 2014

Previous studies predominantly degraded organic matter in simulated water samples containing one or two organic components, while a few literatures reported organic matter degradation in natural and actual sewage water samples. This is likely due to the ingredient of surface water or actual sewage coexisted with many kinds of organic pollutants being complex. The relationship among coexisting organic materials is complex during photocatalytic degradation. Moreover, the coexistence of many kinds of inorganic pollutants in natural or actual sewage water samples is also common. Thus, the influence of coexisting inorganic pollutants on degradation is also worthy of study. This work explored these influences of TiO2-bentonite composite catalysts. 8.6%~11.5% sodium dodecyl benzene sulfonate (SDBS) in surface water or clothes laundering drain water was degraded by 3‰ TiO2-bentonite within 6h under 6W ultraviolet light. Under the same conditions, 86.5% of the SDBS in aqueous solution was degraded. The difference was obvious, but the causes were complicated. For example, the influence of , , and on the degradation was discussed. The results show that the influence of on the above degradation was obvious, while and was not obvious. In addition, and were captured by resulting a decrease of degradation speed. Competition of , and SDBS for surface active sites decreased the efficiency of the degradation. Based on these results, pretreatment such as filtering, deposition and impurity removal before actual sewage is degraded could improve the degradation efficiency. Further study, such as on the reasons for efficiency reduction, on new pretreatment methods and on the application of multi-treatment measures, is needed to conduct.
Variation Law Analysis of the Latent Heat of Al-Si Alloys
Authors: Xu Jun , Yu Si Rong , Liu En Yang , Wang Hai Yan , Zhang Shan Bao
Published: April 2014

Currently, Al-Si alloy is one of the most widely studied aluminum alloy for the phase change thermal storage materials which can be used in solar thermal power generation. However, there still exist some problems to be solved on Al-Si alloy in the present researches. For instance, the latent heat of Al-20%Si alloy is lower than that of Al-12%Si alloy in some papers while the an opposite conclusion was draw in other papers. To solve this problem, five kinds of Al-Si alloy were designed in this investigation, and the mass fraction of silicon was 4%, 8%, 12%, 16% and 20% respectively. The latent heat value of these alloys was determined using an SII TG/DTA 6300 differential thermal analyzer. According to the phase diagram and photomicrographs as well as the measured values, the quantitative expression of the relationship between alloy composition and the latent heat of Al-Si alloy were obtained. And the two quantitative relational expressions (Y1=13.14x+372.05 for the hypoeutectic alloy and Y2=-4.72x+599.01 for the hypereutectic alloy) were validated through the determination of latent heat of Al-6%Si alloy and Al-14%Si alloy.
Effects of Different Acids and pH on the Degradation of Sodium Dodecyl Benzene Sulfonate by TiO2-Bentonite
Authors: Wen Shu Yao , Sun Xiao Chun , Ma Min Li
Published: April 2014

Five types of TiO2-bentonite catalyst, #1, #2, #3, #4, and #5, were prepared separately using hydrochloric acid, nitric acid and perchloric acid by the sol-gel method. The original concentration of sodium dodecyl benzene sulfonate (SDBS) in the aqueous solutions was 20 mg/L. The amounts of SDBS degraded by #1, #2, #3, #4 and #5 under a 6 W ultraviolet lamp were compared, the influences of #1 and #2 on the chemical oxygen demand (COD) of the aqueous solutions studied. And the influences of the initial pH on the degradation of SDBS and on the COD of aqueous solutions were investigated. The results showed as the following. (1) When the catalyst input was 0.5‰ and the solutions were irradiated with a 6 W ultraviolet lamp, 81.0%, 90.5% 47.5%, 39.5% and 26.5% of the SDBS in the aqueous solutions was degraded within 2 hours by catalysts #1, #2, #3, #4 and #5, respectively. The COD was reduced by 8.81% and 50.84%by catalysts #1 and #2, respectively. (2) Under an ultraviolet lamp, 94.5% and 99.3% of the SDBS in the aqueous solutions was degraded and 33.59% and 96.93% of the COD was reduced within 6 hours by catalysts #1 and #2, respectively. TiO2-bentonite catalyst #2 was the best based on the effects on the degradation of SDBS and on the reduction of the COD of aqueous solutions. Using nitric acid was better than using hydrochloric acid or perchloric acid for the preparation of TiO2-bentonite. (3) Under the same conditions (20 mg/L SDBS, 20°C, ultraviolet light irradiation time of 2 h, electromagnetic mixing, 0.5‰ input of TiO2-bentonite #2 ), 90.3% and 90.5% of SDBS was degraded by TiO2-bentonite #2 at pHs 6 and 8, respectively. The optimal pH range for SDBS degradation was 6~8. The COD was reduced by 59.5% and 63.5% pHs 4 and 6, respectively. The optimal pH range for the COD reduction was 4 ~ 6. The pH had a clear effect on SDBS degradation and the COD of the aqueous solutions.
Removal of Indoor Formaldehyde with Nanoscale Catalytic Oxidation
Authors: Chen Zhi Yuan , Yuan Hui Lin , Liu Yong , Wang Ke Jian , Liu Yue Xing , Zhang You Chen
Published: April 2014

Catalytic oxidization has been studied for elimination of indoor formaldehyde. It was found that manganese dioxide (MnO2) is the most effective catalyst among all the tested catalysts at room condition. In the present investigation, the formaldehyde removal efficiency of several commercially available MnO2 catalysts was studied with typical method. Studies showed that the efficiency of MnO2 can be affected by the particle size, the dispersity and the work hours.
Comparison of Environmental Impact Analysis of Two Typical Construction Windows Production
Authors: Wang Shu Ping , Wang Zhi Hong , Chen Wen Juan , Gong Xian Zheng , Liu Yu , Ma Li Ping
Published: April 2014

The energy consumption of window accounts for nearly half of buildings. The purpose of this study is to compare the environmental impact of plastic windows and aluminum alloy windows production, including resource and energy consumption, waste emission. The result shows that energy consumption of plastic window production is only 0.24 times of aluminum alloy window production, and the overall environmental impact of the former is 30% of the later. This study is a quantitative description of energy consumption and environmental impact of two windows production pattern, which intends to fill the blank in LCA field of windows in China.
Process and Property of Superplastic Mould Forged AZ80 Wheel Hub
Authors: Quan Gao Feng , Ren Ling Bao
Published: April 2014

Automobile wheel hub of Mg alloy with single-step extrusion-forging process was developed, and the microstructure and mechanical properties after heat treatment were investigated. The forged hubs have a hub wall of as thin as 3mm, and 4-7kg lighter than that of Al alloy wheel hub with a same size and design of each wheel hub, that would lead remarkable reduction of fuel consumption. The tensile strength larger than 308 MPa, good corrosion fatigue and impacting resistance sampled from the hubs obtained.
Composition-Dependent Collapse of β {111} Planes Leading to ω Precipitation in Ti-Nb Alloys: A First-Principles Study
Authors: Ou Wen Chao , Kou Hong Chao , Meng Cai Si , Tang Bin , Li Jin Shan
Published: April 2014

The effects of Nb content on the collapse of β {111} planes leading to ω phase precipitation were investigated in binary Ti-Nb alloys by first-principles exact muffin-tin orbitals-coherent potential approximation (EMTO-CPA) method. In accordance with the accepted mechanism of the beta to omega transformation occurring due to the collapse of the bcc {111} planes, the total energies of β Ti-Nb binary alloys containing multiple states corresponding to different Nb concentration ranging from 20at.% to 30at.% were calculated. The results indicated that the total energies for the same Nb content are not monotonically decreasing with the z (z denotes the degree of collapse of β {111} planes) value increasing, but keeping an energy barrier to cross. The energy barrier increases gradually along with increasing Nb content. The density of states (DOS) was given to elucidate the changes of electronic structure during the collapse of β {111} planes.
Influence of Various Precipitate Phases on Tensile Properties of an Extruded Mg-Y-Nd Alloy
Authors: Song Bo , Xin Ren Long , Chen Gang , Zeng Ke , Huang Guang Jie , Liu Qing
Published: April 2014

The high strength of Mg-Y-Nd alloy has been achieved primarily by precipitation hardening. Therefore, it is important to investigate the influence of various precipitate phases on the tensile properties of Mg-Y-Nd alloys. In this study, an extruded Mg-Y-Nd alloy was aged at various temperatures to examine the hardening behaviors. The results showed that the as-extruded alloy exhibited remarkable age hardening response at 210°C due to the precipitation of β’, and slight hardening response at 150°C and 280°C due to the precipitation of β’’ and β, respectively. Furthermore, different precipitates exerted different effects on the tensile properties. In comparison with the as-extruded alloy, the yield strength of the alloys aged at 210 °C and 150 °C was increased by 21 MPa and 8 MPa, respectively, whereas the yield strength of the alloy aged at 280°C was decreased by 30 MPa. The elongation of the alloy aged at 210°C and 150°C was also largely reduced by 3.4% and 2.9%, respectively, while the elongation of the alloy aged at 280°C was only slightly reduced (6.3%). Moreover, compared with the as-extruded alloy, the alloy aged at 210°C and 150°C exhibited lower hardening capacity and higher strain hardening rate at the initial stage, but the strain hardening rate decreased more quickly with the increasing stress. The alloy aged at 280°C exhibited similar strain hardening behavior with the as-extruded alloy. The results in this study provide guidelines for determining the heat treatment parameters for the Mg-Y-Nd alloys to improve their tensile properties.
Mechanical Spectra of an Al-12.7Si-0.7Mg Alloy under Extrusion and T6 States
Authors: Yu Ning , He Chang Shu , Wang Dong , Ji Jing Wen , Zhang Lin
Published: April 2014

Mechanical spectra of an Al-12.7Si-0.7Mg alloy under extrusion and the solid solution treatment followed artificial aging (T6) states were measured at different frequencies. It has been found that their spectra present differences. There was an obvious internal friction peak near to 200°C with increasing the temperature. The value of internal friction presented increase started from 300°Cand height of the peak was low, there existed a peak near to 270°C during the cooling processes in the spectrum for the extrusion state. For the T6 state alloy, no peaks could be observed during the heating processes. With decreasing the temperature, the internal friction peaks were again observed near 200°C and 270°C.
Hot Deformation Behavior and Microstructure of 6069 Aluminum Alloy
Authors: Li Hui Zhong , Jiang Jun , Deng Min , Liang Xiao Peng , Ouyang Jie
Published: April 2014

The deformation behavior and microstructure of 6069 aluminum alloy have been studied by isothermal compression at temperature ranging from 300°C to 450°C on Gleeble-1500 machine at strain rates from 0.01 to 10s-1. The results show that the deformation temperature and strain rate is essential to the flow characteristic, and the main deformation mechanism for 6069 aluminum alloy is dynamic recovery at low strain rates. The dynamic recrystallization take place at the strain rates of 10s-1 and deformation temperature ranges of 300~350°C. At constant strain rate, the flow stress and steady-state flow stress decrease with deformation temperature increasing. While at constant temperature, the flow stress and steady-state flow stress increase with increasing strain rate. The processing map at the strain of 0.7 is obtained and the map exhibits two safe deformation domains (300~350°C at 1~10s-1 and 380~450°C at 0.01~0.3s-1).
Microstructure and Mechanical Properties of a 6061 Aluminum Alloy Part Prepared by Casting-Forging Integrated Forming Technology
Authors: Peng Yong , Wang Shun Cheng , Zhou Hai Tao , Zheng Kaihong , Chen He Xing
Published: April 2014

The effect of applied forging pressure on microstructure and mechanical properties of 6061 aluminum alloy was examined. The results showed that the ultimate tensile strength, elongation and hardness of the alloy after heat-treated treatment increase with the applied forging pressure, and the corresponding highest values, 365MPa, 11.52% and 146.53HV, were obtained at the applied forging pressure of 120MPa. Compared to casting condition without forging pressure, the ultimate tensile strength, elongation and hardness can be increased by 22.8%, 98.2% and 48.7%, respectively. The defects such as the shrinkage pores and cracks were absent in the microstructure due to the applied forging pressure. The SEM observation indicated that the fracture mode of 6061 aluminum alloy is more ductile at higher applied forging pressure.
Fracture Toughness and Fatigue Behavior of T7451 Al-Zn-Mg-Cu Alloy Thick Plate
Authors: Wei Li Li , Pan Qing Lin , Wang Yi Lin , Feng Lei
Published: April 2014

The mechanical property, fracture toughness and fatigue behavior of T7451 Al-Zn-Mg-Cu alloy thick plates in different orientations and with various thicknesses were investigated by means of tensile, fatigue and plain strain fracture toughness testing. And the microstructures and fracture morphologies were analyzed with optical microscopy and scanning electron microscopy. The results showed that the samples in longitudinal (L)-transversal (T) orientation possessed better mechanical property, fracture toughness and fatigue resistance than that in T-L orientation. Fractography and optical microanalysis clearly demonstrated that the feature of recrystallized grains is the decisive factor for this anisotropy. On the other hand, values of strength and fracture toughness decreased with the increase of plate thickness, but their fatigue crack growth rate became slower. Combined with the fractography analysis, the increase of recrystallization degree and the coarser grains in the thicker plate should be the main reason for the detrimental to the strength and toughness properties since the main fracture mechanism changes from ductile transgranular fracture to intergranular failure. However, these coarse recrystallized grains play an advantageous role for fatigue resistance from crack deflection and closure perspectives.
Microstructure and Cryogenic Mechanical Properties of AA5083 Joints Prepared by Friction Stir Welding
Authors: Gu Bao Kang , Zhang Da Tong
Published: April 2014

In this study, 5083 aluminum alloy plates with a thickness of 3mm are friction stir welded and the microstructure and mechanical properties of the joints were characterized. In particular, tensile behavior of the joints is examined at 77K. It is found that defect-free joints can be obtained under a tool rotational rate of 800rpm and a welding speed of 60mm/min. The friction stirring welds exhibit finer microstructure and higher hardness than that of the base material due to the grain refinement. The ultimate tensile strength (UTS) and elongation of the joints measured at 298K are 316MPa and 21.3%, which are nearly equal to those of the base material. With the tensile test temperature decreasing to 77K, UTS and elongation of both the base material and joints increase. Comparing with tensile testing at 298K, dimples on the fracture surface of the samples tested at 77K are more uniform in distribution. The improvement of the mechanical properties of specimens at low temperature is related to the inactivation of planar slip and the strengthening of strain hardening.
Production of Primary Magnesium by the Aluminothermic Reduction of Magnesia Extracted from Dolomite Ore
Authors: Deng Peng , Liu Yu Qin , Yao Wen Gui , Ma Hong Wen
Published: April 2014

In this paper, a new process for the production of the primary magnesium is introduced using the dolomite as the raw material. The magnesia and calcium carbonate were prepared from dolomite by acidification. The content of magnesium oxide can reach 98.92% about the magnesia obtained. The magnesia is used to produce primary magnesium by aluminothermic reduction under vacuum condition. The reduction ratio of MgO can be up to 86.14% under the temperature of 1200°C for 5hrs, briquetting pressure of 10MPa and the molar ratio of MgO to Al of 3:2. The content of magnesium is more than 99.90%. The major phases in the briquette residue are corundum and spinel, which can be used as refractory.
Thermodyanmics of CaO in Slag Reduced by Carbon during VD Process of Hollow Steel 95CrMo and its Effect on Inclusions
Authors: Cai Chuan Jie , Zheng Shao Bo , Chen Jing , Ye Zhi Yang , Li Hui Gai , Yang Jie Ming
Published: April 2014

With the help of thermodynamics calculation and kinetic model, the generation mechanism of calcium aluminate inclusions in hollow steel 95CrMo was analyzed. The steel was produced in a certain steelmaking factory whose smelting process is EAF-LF-VD-CC and the micreostructure of the hollow steel 95CrMo samples have been investigated by SEM and EDS. Based on Lumsden’s regular solution model to molten slags, the possibility of CaO in slags reduced by carbon during hollow steel refining in VD furnace was calculated. The influence of furnace vacuum, slag basicity and liquid steel temperature on the reduction of CaO in slag by carbon was discussed. It was showed that the carbon dissolving in liquid steel might reduce CaO in slags to dissolved calcium which could also react with Al2O3 and turn into dot calcium-aluminate inclusions in the steel. The calcium-aluminate existing in the hollow steel easily turned into dot inclusions, which would decrease the fatigue life of the hollow steel. According to the thermodynamic conditions of dot calcium-aluminate inclusions, the influence of slag basicity, temperature of liquid steel, vacuum degree and the Ca treatment process on the quantity of dot inclusions in hollow steel 95CrMo was analyzed.
Effect of V Contents on Microstructure and Mechanical Properties in a Fe-Cr-Ni-Mo High-Strength Steel
Authors: Wen Tao , Hu Xiao Feng , Yan De Sheng , Rong Li Jian
Published: April 2014

The effect of V contents (0, 0.03, 0.08 and 0.14%) on microstructure and mechanical properties was investigated in a Fe-Cr-Ni-Mo high-strength steel. Optical microscope (OM), electron back scattered diffraction (EBSD), transmission electron microscopy (TEM) and electron probe micro-analyzer (EPMA) were used to observe the microstructure varying in this paper. The results show that the prior austenite grain was refined obviously as increasing V content. Simultaneously, the amount of acicular ferrite (AF) increased and the size of that decreased. In addition, the size of carbide gradually decreased with increasing V content, and there appeared M2C, M6C and MC types of carbide after addition of V in the steel, while it is mainly M23C6 in the 0V steel (M is any combination of Cr, Mo, V or Mn). The strength and elongation increased gradually as increasing V content, meanwhile the impact toughness decreased gradually. The excellent combination of mechanical properties can be obtained in the steel with about 0.03% V content.
Effect of Solid Solution Treatment on the Microstructure and Properties of Fe-Mn-Al Light-Weight Steel
Authors: Yang Fu Qiang , Song Ren Bo , Zhang Lei Feng , Zhao Chao
Published: April 2014

A study was made of the effects of solid solution treatment on the properties of hot rolled Fe-Mn-Al steel and on the microstructure transformation. In the steel, the austenite matrix and ferrite duplex phases were confirmed by micrographs and X-ray diffraction. It was indicated that the hot rolled Fe-Mn-Al steel (6.55g/cm3 in density) is with mechanical properties of tensile strength 1315.6MPa, elongation 14.60%. The tensile strength decreases with increasing temperature. The tensile test displays an outstanding combination of high strength and ductility at room temperature due to continuous strain hardening behavior. The product of tensile strength and ductility can reach 46.5GPa·%. Solution treatment contributes to the dissolution of precipitate, austenite grain growth and banded ferrite crushing.
Effect of Strain Induced Martensite for 304M2 Austenitic Stainless Steel Wire
Authors: Jia Yi Su , Song Ren Bo , Pei Yu , Xu Yang , Hu Jian Xiang
Published: April 2014

The impact of deformation and strain rate on the strain induced martensite (SIM) from 304M2 austenitic stainless steel was studied by using X-Ray diffraction, transmission electron microscopy. The results indicate that 304M2 is easy to have SIM because of the chemical component and microstructural characteristic. The amount of SIM has great relationship with the deformation and strain rate. It is found that the amount of SIM is reduced during high speed deformation. The obvious SIM can be observed with higher deformation, but the growth rate slows down. When the deformation rates are 8.3%, 55.0% and 67.3%, the contents of martensite are 6.55%, 15.35% and 16.21%, respectively. Compared with the slow stretching, the quick stretching leads to less martensite transformation. Moreover, the elongation of the specimens decreases. At the stable deformation stage, the temperature increases are 72.8 and 91.9℃, respectively, when the strain rates are 2×10-2s-1 and 5×10-4s-1. Therefore, the martensitic transformation and the deformation behavior of the austenitic stainless are affected by heating.
Working Hardening Mechanism and Aging Treatment Behaviors of D631 Precipitation Hardening Stainless Steel Wire
Authors: Chen Lei , Song Ren Bo , Yang Fu Qiang , Pei Yu
Published: April 2014

Precipitation hardening stainless steel has the advantages of both austenitic stainless steel and martensitic stainless steel, including good corrosion resistance, excellent processability and high strength. With the evolution of microstructure and properties of semi-austenitic precipitation hardening stainless steel (D631) during drawing process and aging treatment, the working hardening behaviors, law of phase transition, dissolution and precipitation state of alloying element are investigated to gain the toughness mechanism of D631. The results show that the tensile strength increases with the increase of the reduction of area, on the contrary, the plasticity decreases gradually. The tensile strength is 1529 MPa while the reduction of area is 54%. By means of X-ray diffraction (XRD) and metallograpic observation, the content of martensite increases with the increase of deformation, and makes the higher strength and lower plasticity. The alloying element dissolved in the matrix precipitates in fine particles by aging treatment, resulting in a higher strength of 1948MPa.
Effect of Austenizing Temperature and Time on Microstructure and Mechanical Properties of Cr12MoVNbRE Steel
Authors: Jiang Chang Hong , Tang Di , Zhao Ai Min , Zhang Yan , Zhang Cong
Published: April 2014

A new-type of Cr12MoVNbRE die steel was designed and investigated. The phase transition temperature was measured by dilatometer. Effects of austenizing temperature and time on the microstructure and mechanical properties of the Cr12MoVNbRE die steel were studied. The results show that the hardness decreases with the increasing austenitizing time. As for the austenitizing temperature, it increases firstly, and then decreases when the austenitizing temperature increases. The most suitable austenitizing temperature and time are 1010 °C and 20 min respectively. The high hardness of the Cr12MoVNbRE die steel is mainly attributed to the martensite with high alloy content and fine uniformly dispersed carbides.
Effects of Processing Parameters on the Evolution of Microstructure and Hole Expansion Property of F/B Dual Phase Steels
Authors: Shen Xin Jun , Zhang Xiang Jun , Ji Feng Qin , Chen Jun , Tang Shuai , Wang Guo Dong
Published: April 2014

With the development of auto industry, the F/B dual phase steels were widely used in wheel and underpan due to their lower cost and higher hole expansion property. In the present investigation, the effects of the finishing rolling temperature and initial cooling temperature of ultra fast cooling (UFC) on microstructure and hole expansion property of a low carbon C-Mn steel were investigated using optical microscope (OM) and scanning electron microscope (SEM). It has been found that lowering the finishing rolling temperature can refine the microstructure and the volume fraction of ferrite is increased as the initial cooling temperature of UFC is lowered. Furthermore, both lowering the finishing rolling temperature and the initial cooling temperature of UFC can improve hole expansion property.
Analysis of Abnormal Fracture Occurring during Full Scale Tension Increasing to Failure Test of High Strength Low Alloy Steel Casing
Authors: Lou Qi , Yu Si Rong , Du Wei , Chu Hong Chao
Published: April 2014

The full scale evaluation test of a set of API Q125 high strength low alloy steel casing specimens was conducted. With the tension increasing to failure, the abnormal fracture occurred on each specimen. A series of testing and analysis including fracture observation, chemical composition analysis, mechanical properties testing, metallographic analysis and SEM analysis were made for the specimen with abnormal spiral fracture. The geometry measurement, visual examination, mechanical properties testing and metallographic analysis were conducted for a new specimen. The mechanical properties of the two specimens are in compliance with the specified material specification. The new specimen has lower external diameter ovality and higher wall thickness eccentricity. The smaller wall thickness is distributed in a spiral shape, similar with the abnormal fracture. The fracture originated in the middle of casing wall, and the fracture position had obvious necking. According to fractography and fracture mechanics analysis, the abnormal spiral fracture was attributed to the metallurgical and geometry imperfection grown out of tubing processing process.
Microstructure and Mechanical Properties of Microalloyed Multiphase Steel
Authors: Zhou Yun , Wang Xue Min , He Xin Lai
Published: April 2014

Multiphase steels were obtained by using Gleeble-1500 simulator and TMCP, and were characterized by optical microscopy, SEM, TEM, EBSD (electron back-scattered diffraction) and other tests to investigate its microstructure and mechanical properties. During the simulation, the deformation temperature is 850°C, and the steels are air cooled to 750-600°C and then quenched to room temperature. The results indicate that the microstructure of the specimen is composed of ferrite and bainite. With the lowering of quenching temperature, the proportion of ferrite increases and the proportion of bainite decreases, and the bainite laths is shorter. The fine (Nb, Ti) C particles and dislocations appear in ferrite and lath bainite, and the amount of high angle grain boundary decrease after the initial increasing. The microaolloyed hot-rolled multiphase steel plate was developed by two-stage rolling, subsequently quenching to room temperature or air cooling to 600°C, then quenching to room temperature. Two typical microstructures: acicular ferrite and ferrite-bainite multiphase were obtained. The ferrite-bainite multiphase steel showed better mechanical properties, and the yield strength, tensile strength, yield ratio, uniform elongation and percentage elongation were 488Mpa, 845Mpa, 0.58, 10.3% and 21% respectively. The refinement of bainite structures, fine (Nb, Ti) C particles and the dislocations in bainite increase the strength.
Nitrogen-Bearing Carbides in K417G Alloy Doped with Different Nitrogen Contents
Authors: Yang Guo Liang , Yu Lian Xu , Jia Dan , Sun Wen Ru , Yang Hong Cai , Hu Zhuang Qi
Published: April 2014

By adding FeNCr6-A, K417G alloys with different nitrogen content from 4 to 32ppm were prepared by using the vacuum induction melting (VIM). The precipitation of the carbonitrides in the virgin alloys was studied. The results show that N mainly exists in Ti (N, C) phase which sometimes served as heterogeneous cores for the carbides in the alloy. Besides, a few isolated regular square blocky Ti (N,C) particles were also found in alloy with 10ppm N, and these isolated particles became larger in the alloy with 21ppm N. Moreover, as N level reaching 32ppm, the Ti (N,C) phase did not grown but these particles usually gathered together and formed many clusters. For the alloy with 4ppm N, the content of N in Ti (N,C) was lower, but for the alloys not less than 10ppm N, the N content of Ti (N,C) was higher and relatively stable.