bluuebunny/crossref_metadata_2025 huggingface dataset:
The Shape Memory Effect in Melt Spun Fe-15Mn-5Si-9Cr-5Ni Alloys
Authors: Druker Ana , La Roca Paulo , Vermaut Philippe , Ochim Patrick , Malarría Jorge
Published: March 2013

At room temperature, Fe-15Mn-5Si-9Cr-5Ni alloys are usually austenitic and the application of a stress induces a reversible martensitic transformation leading to a shape memory effect (SME). However, when a ribbon of this material is obtained by melt-spinning, the rapid solidification stabilizes a high-temperature ferritic phase. The goals of this work were to find the appropriate heat treatment in order to recover the equilibrium austenitic phase, characterize the ribbon form of this material and evaluate its shape memory behaviour. We found that annealing at 1050°C for 60 min, under a protective argon atmosphere, followed by a water quenching stabilizes the austenite to room temperature. The yield stress, measured by tensile tests, is 250 MPa. Shape-memory tests show that a strain recovery of 55% can be obtained, which is enough for certain applications.
Determination of the Characteristic Parameters of Tension-Compression Asymmetry of Shape Memory Alloys Using Full-Field Measurements
Authors: Chemisky Yves , Echchorfi Rachid , Meraghni Fodil , Bourgeois Nadine , Piotrowski Boris
Published: March 2013

In this work, a method for the identification of the transformation surface of Shape Memory Alloys based on full field measurements is presented. An inverse method coupled with a gradient-based algorithm has been developed to determine the characteristic parameters of the transformation surface. The constitutive equations of the chosen model that capture the macroscopic behavior of Shape Memory Alloys are first presented. The material parameters, to be identified, that are characteristic of the tension-compression asymmetry of the alloy are detailed. The identification algorithm, based on full field measurements obtained by Digital Image Correlation (DIC) and numerical simulation by Finite Element Analysis are introduced. The identification algorithm is validated using a numerically generated strain field on a Meuwissen-type specimen.
Fundamental Achievements of the Dynamic Theory of Reconstructive Martensitic Transformations
Authors: Kashchenko Mikhail P. , Chashchina Vera G.
Published: March 2013

Basic directions in the theory of martensitic transformations are briefly listed. Solutions of several important problems in the context of dynamic theory of reconstructive martensitic transformations are reviewed. The FCC-BCC (BCT) transformation in iron alloys is used as an example. Main attention is paid to concept links. In particular, the key role of the concept of initial exited state for realization of transformations with crystal growth at supersonic speed is shown. The leading value of this concept both for calculation of critical rates of austenite cooling and for estimation of scales of incubatory times at bainitic transformation is marked as well.
Structure, Phase Transformations and Properties of Rapidly Quenched Ti2NiCu Alloys
Authors: Pushin A.V. , Popov A.A. , Pushin V.G.
Published: March 2013

Methods of X-ray diffraction, transmission and scanning electron microscopy, and electron diffraction have been used to study phase and chemical compositions and structure of Ti2NiCu alloys. The alloys of the quasi-binary section TiNi–TiCu, which exhibit in the initial as-cast state thermoelastic martensitic transformations B2↔B19 and related shape memory effects, have been produced by rapid quenching of the melt (melt spinning technique). The chemical composition of the Ti2NiCu alloys was varied with respect to titanium and nickel within x ≤ ±1 at. %. The mechanical properties of the alloys have been measured in the initial state and after subsequent heat treatment. The kinetics of the crystallization from the amorphous state, devitrification processes and the forward and reverse thermoelastic martensitic transformations were investigated. Their characteristic temperatures have been determined by measuring temperature dependences of the electrical resistivity of the alloys. The diagram of the dependence of the critical temperatures on the chemical composition has been constructed.
Recent Progress and Future Perspectives in Magnetic and Metamagnetic Shape-Memory Heusler Alloys
Authors: Planes Antoni , Mañosa Lluís , Acet Mehmet
Published: March 2013

Magnetic shape-memory properties refer to the ability of certain materials to show strong response in strain to an applied magnetic field. This strain is caused by either inducing the martensitic transition or rearranging martensitic variants. In the first, case a superelastic effect is possible, while in the second, the system is able to show the shape-memory effect. The complex behaviour displayed by these materials is mainly a consequence of a strong interplay between magnetism and structure which is driven by a martensitic transition. This interplay is the source of many other observed effects such as giant magneto-resistance, exchange bias and magnetocaloric effects. In this paper, we will overview the present state of the art, discuss present challenges and outline some future perspectives in the field.
Effect of Magnetostatic Energy on the Magnetic Driving Forces and Field Induced Superelastic Behavior in Ni-Mn-Ga
Authors: Likhachev Alexander A.
Published: March 2013

Abstract. Present publication gives a general theoretical concept and also presents the relevant experimental results concerning the effect of the magnetostatic coupling between the twin layers on the magnetic-field-controlled superelastic behavior during the mechanical cycling in magnetic field in Ni-Mn-Ga.
Microstructural Studies of NiCoMnIn Magnetic Shape Memory Ribbons
Authors: Prusik Krystian , Bałdys Katarzyna , Stróż Danuta , Goryczka Tomasz , Lelątko Józef
Published: March 2013

In present paper two ribbons of the Ni44Co6Mn36In14 (at.%) were prepared under different melt-spinning technique conditions. Microstructure of the ribbons was studied by scanning electron microscopy (SEM). Depending on the liquid ejection overpressure two types of ribbons microstructures were observed. Ribbon T1 for which ejection overpressure was 1.5 bar showed typical melt-spun ribbon microstructure consisting of a top layer of small equi-axial grains and columnar grains below. For T2 ribbon (ejection overpressure 0.2 bar) only a small fraction of the columnar grains were observed. Structure analysis of the ribbons performed by XRD showed that at room temperature both ribbons have B2 parent phase superstructure. No gamma phase precipitates were observed. In order to determine the orientation of the grains the EBSD technique was applied.
Adiabatic Temperature Change in Metamagnetic Ni(Co)-Mn-Al Heusler Alloys
Authors: Khovaylo Vladimir , Lyange Maria , Skokov Konstantin , Gutfleisch Oliver , Chatterjee Ratnamala , Xu Xiao , Kainuma Ryosuke
Published: March 2013

Two representatives of Ni(Co)-Mn-Al metamagnetic shape memory alloy system, Ni45Co5Mn31Al19 and Ni35Co15Mn35Al15, have been studied with respect to their magnetocaloric properties. Experimental study of the magnetocaloric effect by a direct measurement of the adiabatic temperature change ΔTad revealed that in both the samples ΔTad depends on the measurement protocol as well as on the magnetic prehistory of the samples. For the applied magnetic field µ0H = 1.93 T, the largest adiabatic temperature change, |ΔTad| ~ 0.7 K, has been observed in the Ni35Co15Mn35Al15 sample at T = 464 K.
Mechanocyclic and Time Stability of the Loading-Unloading Diagram Parameters of Nanostructured Ti-Nb-Ta and Ti-Nb-Zr SMA
Authors: Prokoshkin Sergey , Brailovski Vladimir , Petrzhik Mikhail , Filonov Mikhail R. , Sheremetyev Vadim
Published: March 2013

The Ti-21.8Nb-6Zr and Ti-19.7Nb-5.8Ta (at.%) shape memory alloys are thermomechanically treated by cold drawing and post-deformation annealing at 550-600°C forming a nanosubgrained structure in the β-phase. Cyclic mechanical testing using a “loading-unloading” mode with 2% tensile strain in each half-cycle reveals the non-perfect superelastic behavior of both alloys during the very first cycles of testing, which becomes perfect during further mechanocycling. The Young’s modulus of thermomechanically-treated alloys is low (about 45 GPa), and it decreases during mechanocycling (n=10 cycles) down to 25-35 GPa, approaching the Young’s modulus of cortical bone tissues. The Young’s modulus obtained in the 10th cycle is stable or changes only slightly during a further 40-day pause at room temperature and then during repeated mechanocycling. The residual strain per cycle, the transformation yield stress and the mechanical hysteresis decrease during mechanocycling. Subsequent to a 40-day pause at room temperature, they restore their initial values. Repeated mechanocycling is accompanied by a repeated decrease of these parameters.
Thermo- and Deformation Induced Martensitic Transformations in Binary TiNi-Based Alloys Subjected to Severe Plastic Deformation
Authors: Kuranova Natalia N. , Makarov Vladimir V. , Pushin Vladimir G. , Uksusnikov Alexey N.
Published: March 2013

Results of investigations of structure and phase transformations and properties of the TiNi-based alloys with a shape memory effect (SME) after severe plastic deformation (SPD) by cold rolling, cold drawing, high pressure torsion and subsequent annealing are reported. It is found that the baroelastic effects related to the highly reversible martensitic transformations can occur in alloys, subjected to high pressure. The evolution of fine structure of the alloys into nanocrystalline and then amorphous state during SPD and after subsequent annealing have been studied. The effect of grain size on the martensitic transformations and properties of the alloys is discussed.
Structural-Mechanical Control of Bypass Reactivity in LISB for Space Application Using Alloys with Shape Memory Alloys
Authors: Protsenko N.A. , Blednova Zhesfina
Published: March 2013

Keywords: Lithium-ion storage battery (LISB), bypass device, shape memory effect (SME) thermal treatment, reactivity, reliability Abstract. Deformation and strength characteristics of a thermal drive spring made of alloy with shape memory effect (SME) оn the base of TiNi in bypass device (BD) of Lithium-ion storage battery (LISB) for space application were investigated. A technique was developed for this spring thermal preparation for a certain magnitude of shape memory deformation, due to which during reverse martensite transformation a spring generates reactive force, sufficient for BD operation. It allowed to develop small-sized multiple action BDs for LISBs intended for “Glonass-K” spacecrafts. Study of technological and operational factors’ impact proved high level of BD failure-free operation.
High Temperature Martensitic Transformation and Shape Memory Behavior in Hfir Intermetallic Compound
Authors: Koval Yuri N. , Firstov Georgiy , Odnosum Valeri V.
Published: March 2013

The present paper is dedicated to the first observation of the martensitic transformation (MT) and associated shape memory effect (SME) in HfIr equiatomic intermetallic compound. Differential scanning calorimetry allowed determining MT temperatures, which are above 700 K. It was also shown that MT taking place at such high temperatures is associated with SME measured in 3 point bending. MT temperatures and crystal structure changes in the homogeneity range of HfIr compound were also studied. SME behavior changes in the homogeneity range of HfIr compound are discussed
The Application of the Steel Slag in the Radiation Shield Heavy Concrete
Authors: Li Ru Guang , Zhou Sheng Yin , Tian Kun , Yao Peng
Published: March 2013

The steel slag was broken into steel slag powders and sands. The performance of the radiation shield heavy concrete was studied in this work by mixing different content of steel slag sand and powder. The results showed that the water requirement of normal consistency and setting time increased with the increase of the content of the steel slag powder. The strength reduced in the early stage of the experiment. The strength increased firstly and decreased later. The optimal content of steel slag powder for strength was 20%. For the steel slag powder and sand, whether the concrete added one or two components, the concrete slump loss increased and strength reduced at 3 days. The steel slag powder and sand added into concrete improved the performance of the concrete effectively, solved the heavy aggregate subsidence and improved the concrete homogenous.
Effect of Aluminium Sulfate on Cement Properties
Authors: Kan Chang Yu , Lan Ming Zhang , Kong La Mei , Yang Jin Bo
Published: March 2013

The effect of aluminium sulfate on cement properties was studied systematically and the mechanism was analyzed using XRD and SEM tests. Experimental results showed that the addition of aluminium sulfate will shorten the setting time of cement, increase the drying shrinkage and improve the early strength; however it will weaken the late strength of cement and reduce the fluidity. Micro-research showed that the addition of aluminium sulfate will change the morphology and location of aluminium sulfate distinctly.
The Oxidation State of Sulfur on the Air Side Surface of Soda-Lime Float Glass as Determined by X-Ray Absorption near Edge Structure Spectra
Authors: Meng Zheng , Hong Wang , Huang You Rong , Wang Jin Zhen , Li Yao Hui , Shi Di , Jiang Hong
Published: March 2013

Three ways were used to prepare sulfide in soda-lime-silicate glass samples, i.e., glass heat-treated in N2/H2 (90/10 volume ratio), doped with different Carbon/Sulfur in mol ratio, as well as different sulfur source respectively. The oxidation state of sulfur on the air side surface of float glass heat-treated in N2/H2 and the bulk samples of the other two were determined by X-ray absorption near edge structure spectra (XANES). It was observed on the air side that: 1) A weak pre-edge exhibits at 2466.8eV which appears only with sulfite at high temperature and related to sulfur source; 2) A typical peak of sulfate at 2482.4eV decreases with increasing the temperature and heating duration. 3) Two peaks associated with sulfide, a broader one at about 2476.3eV and a sharper one with an accurate position at 2473.7eV. The S2- content at air side of glass heat-treated at 750 is higher than that of the glass treated at other temperatures, and increases with the heating duration, which is just the reverse at 1050, because the S2- volatilizes to the atmosphere easily at higher temperature. In addition, the content of S2- increases with increasing C/S ratio. The local environment of S2- in the glass with Na2S is different from that of with FeS, as indicated by the broader resonance. The spectra indicate that the glass heat-treated in N2/H2 (90/10), doped with different C/S ratio and with Na2S have the same sulfites or sulfites.
Synthesis and Electrochemical Performances of Nanoparticle FePO4 and Ce-Doped FePO4 Cathode Materials for Lithium Ion Batteries by Microemulsion Method
Authors: Zhang Shi Ming , Zhang Jun Xi , He Bo Cheng , Xu Suo Jiong , Yuan Xu Ji
Published: March 2013

nanosized FePO4 and Fe1-xCexPO4 (x=0.02, 0.04, 0.08) cathode materials were synthesized by microemulsion method. The samples were prepared via a microemulsion system in a H2O/cyclohexane/Triton x-100/n-butyl alcohol at different temperatures (30 , 45 , 50 , 60 ) and then sintered at 380 and 460 for 3 h. The thermal stability, structure and morphology were investigated by means of TG/DCS, X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), and the electrochemical properties were characterized by cyclic voltammetry (CV) and galvanostatic charge and discharge tests. Results show that synthesis temperature has a great influence on the performances of FePO4, and the sample synthesized at 45 shows the best performances with a diameter of about 20 nm and a high discharge initial specific capacity of 142mAh/g and retaining 123mAh/g after 20 cycles at 0.1 C. The Ce-doped FePO4, Fe1-xCexPO4 (x=0.02, 0.04, 0.08), can effectively improve the electrochemical properties of FePO4 cathode materials. The Fe0.96Ce0.04PO4 exhibits an initial discharge capacity of 158.2mAh/g and retains 152mAh/g after 20 cycles at 0.1 C. Hence, Fe0.96Ce0.04PO4 is a promising candidate for cathode materials of lithium ion batteries.
Design and Preparation of Cement-Based Composite with Electromagnetic Protection
Authors: Tian Kun , Zhou Sheng Yin , Xiao Jiang Rong , Li Ru Guang , Yao Peng
Published: March 2013

Using space electromagnetic wave propagation principle, environment requirements of building protective engineering structure and performance characteristics of cement-based composites, a design idea of cement-based composite with electromagnetic protection is presented in the present study. This design idea was tested and verified. According to the proposed new designed method, by optimizing and selecting the wave-transparent aggregate and absorbing agent material, the absorbing composite materials of cement-based electromagnetic protection, electromagnetic wave absorbent, energy saving and environmental protection can be improved. A new cement-based composite with electromagnetic protection and microwave absorbing properties (the minimum reflectivity is-8.4dB), wide frequency bandwidth, and letter mechanical properties was prepared by using a 20 mm sample between 8-18 GHz. The results provide a basis design and preparation of cement-based composite with electromagnetic protection.
The Effect of Cooling Process on the Microstructure and Electrical Transport Properties of AgSbTe2 Compound
Authors: Fu Liang Wei , Yang Jun You , Xiao Ye , Peng Jiang Ying , Zhang Ming Yang
Published: March 2013

AgSbTe2 compounds have been synthesized via melting and subsequent cooling processes. The effect of cooling process, from air-cooling, water quenching to liquid nitrogen-quenching, on the microstructure and the electrical transport properties of AgSbTe2 has been investigated by means of powder X-ray diffraction, electron microscope, electrical resistivity, and Hall coefficient measurements. It has been found that the cooling process has apparent influence on the microstructure and corresponding electrical properties. The phase components and morphology changed as the cooling process altered. The electrical resistivity and the Seebeck coefficient of the as-prepared samples increased from air-cooled to liquid nitrogen-quenched sample.
BiFeO3 Nanoparticles Prepared by NaNO3-Assisted Low-Heating Temperature Solid State Reaction Method
Authors: Wang Lei , Chen Xue Ying , Xu Jin Bao , Bian Liang , Gao Bo
Published: March 2013

BiFeO3nanoparticles were synthesized by a NaNO3-assisted low-heating temperature solid state reaction method. The effects of the molar ratio of added NaNO3and the calcination temperature on the characteristics of the products were discussed. The structure, morphology, magnetic, optical and electrical properties of BiFeO3were characterized by XRD, SEM, VSM and UV-VIS. The experimental results showed that the introduction of leachable inert inorganic salt as a hard agglomeration inhibitor in the mixture precursor led to the formation of BiFeO3nanoparticles with uniform size. With the addition of NaNO3in the process, the particle morphology decreased from a diameter of 300-500 nm to 80-100 nm. The BiFeO3attained at 600 °C showed a smaller band gap (2.12 eV) and weak ferromagnetism at room temperature with a remnant magnetization value (Mr) of approximately 3.1×10-5emu/g and a coercive filed value (Hc) of nearly 20 Oe.
Study on the Rolling Process of 1J22 Soft Magnetic Alloy
Authors: Gan Chao , Zhu Jie
Published: March 2013

The nearly stoichiometric Fe-Co alloy is well known as soft magnetic materials with high saturation magnetization and Curie temperature. However, the application is restricted by its brittleness and poor machinability. For this reason, we studied the rolling process of this alloy. Firstly, the effect of final thickness of hot rolling on the cold rolled samples showed that there was little difference for these cold rolled samples, and the thinner hot rolling samples were not so easy to crack during the cold rolling. Secondly, the soft magnetic properties were found to be better under the 1050 water quench when we studied the influence of different solution temperature on soft magnetic properties. Thirdly, with the increase of annealing time, grain size and soft magnetic properties of 1J22 alloy increased, whereas mechanical properties decreased.
Annealing Effects on the Microstructure and Mechanical Properties of Cu-Nb Microcomposites
Authors: Xu Xiao Yan , Lu Ya Feng , Liang Ming , Wang Peng Fei , Ma Xiao Bo , Li Cheng Shan
Published: March 2013

The annealing effects on the microstructure of Cu-Nb microcomposites fabricated by bundling and drawing process have been studied. During annealing at temperature as high as 800, the intensity of (110) diffraction peak of Nb became sharper and higher. The significant cylinderization and coarsening phenomenons of the niobium filaments were observed. The influence of microstructural changes on the hardness and the tensile strengths of Cu-Nb wires were discussed.
Preparation of Multi-Core Bi-2212/Ag Wires
Authors: Hao Qing Bin , Li Cheng Shan , Zhang Sheng Nan , Li Gao Shan , Bai Li Feng , Liu Guo Qing , Zhang Ping Xiang
Published: March 2013

The core breaking mechanism of the traditional Bi-2212 wires with filament configuration of 85×7 during the drawing process was analyzed, and the solution of these problems was given. The results showed that the major reason of core breaking occurs was that the tensile stress was bigger on the center than the edge of Bi-2212 wires during the drawing, and the silver-superconductor ratio was smaller of the center than the edge of the traditional Bi-2212 wires. It was effective to avoid the core breaking of Bi-2212 wires using the Ag core strengthener, and the uniformity of distortion of Bi-2212 wires during the drawing was improved, and the critical current of Bi-2212 wires increased 40% than that of traditional wires. If the diameter of the filament of Bi-2212 wires decreased further, there would be lots of bridging between core and core, which provided routeway for current. So the critical current of Bi-2212 wires was improved further.
Mechanical and Superconducting Properties of NbTi Reinforced MgB2 Wires
Authors: Sun Yu Yan , Zhang Ping Xiang , Wang Qing Yang , Qi Ming , Yang Fang , Jiao Gao Feng , Yan Guo
Published: March 2013

The strengthening abilities of NbTi for 6-filamentary MgB1.9(TiC)0.08/Nb/Cu wires and the electrical properties have been investigated. The NbTi reinforcing core was suitable for manufacturing MgB2 wires. It was observed that with the sintering temperature increasing, the yield strength decreased. The plasticity improved while the strength changed little by introduction of intermediate annealing during the cold processing of the wires. The transport properties of the wire degraded to some degree due to intermediate annealing. The mechanical properties have already met the application requirements of superconducting magnets in low field with the critical engineering current Ic above 90 A (Jce exceeding 7.9×103 A/cm2) at 35 K in self-field.
Analysis of the Permanent Magnet Guideway of High Temperature Superconducting Maglev
Authors: Ye Chang Qing , Deng Zi Gang , Wang Jia Su
Published: March 2013

t was theoretically and experimentally proved that High Temperature Superconducting (HTS) Maglev had huge potential employment in rail transportation and high speed launch system. This had attracted great research interests in practical engineering. The optimization design was one of the most important works in the application of the HTS Maglev. As the NdFeB permanent magnet and HTS materials prices increased constantly, the design optimization of the permanent guideway (PMG) of HTS maglev became one of the indispensable works to decrease the cost of the application. This paper first reviewed four types of PMGs used by the HTS Maglev, then disucssed their structures and magnetic fields. Finally, the optimization methods of these four PMGs were compared. It was suggested that with better optimization methods, the levitation performance within a limit cost got better. That would be helpful to the future numerical optimization of the PMG of the HTS maglev.
Effect of Various C Sources Co-Doping on Transport Critical Current Density and Grains-Connectivity of MgB2/Fe Tapes
Authors: Pan Xi Feng , Yan Guo , Liu Xiang Hong , Feng Yong , Zhang Ping Xiang , Zhao Yong , Mastumoto Akiyoshi , Kumakura Hiroshi
Published: March 2013

In this paper, we have prepared a series of Fe sheathed MgB2 tapes with SiC, Malic acid and C9H11NO mono-and co-doping by in-situ powder-in-tube (PIT) method, and studied the effects of various C sources co-doping on transport critical current density and flux pinning of MgB2/Fe tapes. The results suggest by various C sources co-doping, the amount of C substitution for boron largely increase, comparing to SiC, Malic acid or C9H11NO mono-doped sample. For MgB2/Fe tapes with 5 mol% SiC+10 wt% Malic acid and 4 wt% C9H11NO+10 wt% Malic acid co-doping, the transport Jc at 4.2 K and 10 T are 14.8 and 13.5 kA/cm2, respectively, which are clearly higher than the Jc of these dopants mono-doped samples. Furthermore, it is found that at the 4 wt.% C9H11NO doped MgB2, the poor in-field Jc should be attributing to the cracks at grains boundary, which results in the bad grains-connectivity.
A Review of the Ion Beam Assisted Deposition Researches towards Industrialization for the Second Generation High Temperature Superconducting Wire Fabrication
Authors: Feng Feng , Qu Ti Ming , Shi Kai , Huang Rong Xia , Wu Wei , Zhang Yan Yi , Xiao Shao Zhu , Wei Jun Jun , Wang Xiao Hao , Han Zheng He
Published: March 2013

on beam assisted deposition (IBAD) is an important technique to fabricate the second generation high temperature superconducting (2G HTS) wires. Among the fabrication routes of 2G HTS long wires, IBAD route achieved the best performance in recent years. IBAD was adopted in this field in 1991 to obtain biaxially textured buffer layers, which helped to deposit high quality YBCO superconducting films on metallic substrates for the first time. Series of experimental and industrial researches on IBAD were carried out by many groups worldwide. And in the researches lasting for over two decades, the focused material for IBAD was changed from Yttria-Stabilized Zirconia (YSZ), Gd2Zr2O7 (GZO) to MgO. In this paper, the research progresses and the main achievements were briefly reviewed.
Effect of Firing Temperature on Microstructure and Superconductivity of YBCO Films Derived from Low-Fluorine Solution
Authors: Wu Chuan Bao , Zhao Gao Yang , Chen Yuan Qing
Published: March 2013

Using a low-fluorine solution, YBa2Cu3O7-x (YBCO) superconducting films were prepared on LaAlO3 (LAO) substrates by dip-coating method. YBCO films were fired at different temperatures with same oxygen pressure of 1.3 vol% and water vapor pressure of 7.4 vol%. Effect of firing temperature on film microstructure and superconductivity was investigated. The results indicated that YBCO films with high-degree c-axis orientation (the degree of c-axis orientation reached 96%) can be obtained when heat treated at 800 °C. At this temperature YBCO films were grown on LAO with cubic-on-cubic mode, resulting in a high critical transition temperature (Tc) of 91.5 K, and critical current density (Jc) of lager than 1 MA/cm2. However, when fired at lower temperatures, YBCO films trended to form a-axis grains, which degraded Jc of films. And a higher heat treatment temperature also depressed superconductivityof YBCO films.
Influence of Electron-Beam Annealing Duration on MgB2 Film Superconductivity
Authors: Kong Xiang Dong , Dai Qian , Li Han , Feng Qing Rong , Chu Ming Zhang , Xue Hong , Li Jian Guo , Wang Fu Ren
Published: March 2013

A novel method to fabricate Magnesium diboride ( MgB2) film by electron beam annealing was presented. The MgB2thin films could be prepared in a second or sub-second without any toxic diborane gas, extra Mg vapor or argon gas. The method has the advantages of short formation time and high efficiency. Based on this, the relationship between MgB2conductivity and electron beam annealing duration was investigated experimentally with an accelerating voltage of 40 × 103V, a beam current of 3×103A and different annealing durations of 0.1796s, 1860s, 0.2108s, 0.2200s and 0.2332s. The experimental results showed the MgB2film with 0.2200s has the highest Tconset, the most dense structure and the strongest diamagnetic signal. Its zero-fieldJc at 5 K was 5.0 × 106A/cm2. Also the variation of the film superconducting properties with the annealing duration was found, it will provide an important reference for the preparation of high-quality MgB2thin films.
Effect of Hot Extrusion and Cyclic Extrusion Compression Progress on the Microstructures and Properties of Mg-Zn-Y-Nd Alloy
Authors: Zhu Shi Jie , Wu Qiong , Wang Li Guo , Liu Qian , Yue Gao Chao , Guan Shao Kang
Published: March 2013

Magnesium alloys are promising candidate materials for cardiovascular stents due to their good biocompatibility and degradation property in human body. However, in vivo tests also show that improvement in mechanical property and corrosion resistance is necessary for wide application. In this study, hot extrusion and cyclic extrusion compression (CEC) were used on Mg-Zn-Y-Nd alloy, the effects of hot extrusion and CEC process on the microstructures, mechanical properties and corrosion properties of alloy were studied. The results showed that the microstructures of CEC treated Mg-Zn-Y-Nd alloy became finer and more homogenous, some nanoparticles which came from the cluster phase uniformly precipitated inside grains, alloy had good mechanical properties and corrosion resistance. The immersion test results in SBF solution at 37 for 24h showed that the alloy after CEC treatment is uniform corrosion.
Preparation and Characterization of HGM-Ni0.5Co0.5Fe2O4 Core-Shell Particles by Homogeneous Coprecipitation
Authors: Yu Mei , Hu Jing Zhi , Liu Jian Hua , Li Song Mei
Published: March 2013

HGM-Ni0.5Co0.5Fe2O4 core-shell particles were prepared by plating Ni0.5Co0.5Fe2O4 magnetic film on hollow glass microsphere (HGM) from the aqueous solution containing NiCl2·6H2O, FeCl2·4H2O, CoCl2·6H2O and HGMs without sintering. Urea was used as precipitator, and air was used as oxidizer in homogeneous coprecipitation process. The morphologies, phase structures, shell thickness, chemical compositions and magnetic performances of the core-shell particles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and vibrating sample magnetometer (VSM), respectively. The results showed that a compact and continuous film with thickness at about 250 nm was coated on the HGM by the homogeneous coprecipitation process. The film was spinel ferrite phase, and was determined as the Ni0.5Co0.5Fe2O4. The saturation magnetization (Ms) and the coercivity (Hc) of as-synthesized HGM-Ni0.5Co0.5Fe2O4 core-shell particles were 20.886emu/g and 97.174G, respectively.
Microstructures and Properties of Biological Mg-Zn-Y-Nd Alloy by Friction Stir Processing
Authors: Zhu Shi Jie , Wang Li Guo , Jin Jin , Wang Jing , Sun Yu Feng , Chen Juan , Hidetoshi Fujii , Guan Shao Kang
Published: March 2013

In order to improve the mechanical properties and processing performance of the Mg alloys, and to prevent magnesium alloy from non-uniform corrosion and too fast degradation in the degradation process, the biological medical Mg-Zn-Y-Nd alloy was modified by the friction stir processing (FSP) technique in this paper. The microstructural evolution and phase constitute of the stir zone of Mg-Zn-Y-Nd alloy were investigated, the microhardness and the corrosion properties of the alloy after FSP process was studied. The results showed that the FSP parameters had significant influence on the stir zone and thermo-mechanically affected zone. The stir zone experienced severe plastic deformation and complete dynamic recrystallization after FSP. The stir zone consists of fine equiaxed recystallized grains, and thermo-mechanically affected zone (TMAZ) has deformed grain structure. The second phase distributed along grain boundaries in as-cast state was broken during the FSP and transformed into fine, uniform and dispersed particles in the grains. After FSP, the size of grains was reduced from 50μm (as-cast alloy) to 1-2μm. However, the second phase constitution didnt change. The alloy obtained good comprehensive mechanical properties after FSP. The microhardness of alloy after FSP increased from 39HV (as-cast alloy) to 64HV(FSPed alloy). The results of electrochemical tests in simulated body fluid showed that the corrosion potential of FSP alloy increased and corrosion current density decreased, which confirmed the uniform corrosion of FSPed alloy.
Microstructural Evolution of Fe-Based Metallic Glass/2024-Al Powder during High Energy Ball Milling Process
Authors: Zheng Rui Xiao , Zhang Yi Tan , Ge Su Jing , Yang Han , Ma Chao Li
Published: March 2013

Nanostructured Al alloy powder was prepared by ball milling of a mixture of Fe-based metallic glass (FMG) powder and 2024-Al alloy powder. Microstructural evolution and mechanical properties of the milled composite powder were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and micro-hardness test. It is revealed that after 24h milling, the grain size of the Al alloy powder reduced to about 30nm, and the FMG particles were uniformly distributed throughout the Al matrix. The mechanical test indicated that the micro-hardness of the powder was significantly improved.
High-Cycle Fatigue Behavior of Pure Iron with Gradient Structures Layer
Authors: Feng Yan Peng , Zhao Si Cong , Xie Ji Jia , Wu Xiao Lei
Published: March 2013

In the present study, surface mechanical grinding treatment method was developed to induce a gradient nanograined structures in commercial pure iron bar. The gradient structures and hardness were characterized by optical microscope and micro-indentation. Fatigue behaviors of samples in gradient nanograined structures and in as-annealed state were examined at room temperature, and the fatigue fracture behavior was characterized with scanning electron microscope. The result showed that the thickness of deformation layer was about 300 μm, and the fatigue strength of the treated case was 252 MPa based on fatigue life of 107cycles, but the fatigue strength of the as-annealed sample was 186 MPa. Fatigue cracks source of samples in gradient nanograined structures gradually transformed into the internal of gradient structures layer, but cracks sources of as annealed samples were observed to be initiated at surface.
Microstructural Characterizations of Maraging Steel Processed by Equal-Channel Angular Pressing
Authors: Yang M.X. , Yang Gang , Liu Z.D. , Wang C. , Huang C.X.
Published: March 2013

Microstructures of a maraging steel subjected to equal-channel angular pressing (ECAP) up to 16 passes at room temperature were investigated. Electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) examinations showed that the microstructures of the as-processed samples were characterized by a well-defined lamellar structure. With increasing the number of ECAP passes from 1 to 16, the lamellar spacing was significantly decreased from ~323 nm to ~54 nm, while the volume fraction of high-angle lamellar boundaries (HALBs, having the misorientation larger than 15o) was obviously increased form ~46% to ~80%. The real lamellar-type nanostructured microstructures were completely accomplished in the tested steel after 8 or more ECAP passes. In addition, the grain refinement mechanism of maraging steel during the processing was discussed in detail.
Mechanical Properties of Poly(3-hydrobutyrate-co-hydroxyvalerate)/ Biodegradable Hyperbranched Poly(ester amide) Blends
Authors: Liu Pei , Chen Long , Xu Jun , Zhu Mei Fang , Qin Zong Yi
Published: March 2013

Biodegradable composites were prepared by adding hyperbranched poly (ester amide) (HBPs) into poly (3-hydroxybutyrate-co-3-hydrovalerate) (PHBV) through melt blending method. It was found that the tensile strength and toughness of PHBV were simultaneously enhanced by the addition of HBPs. Compared with neat PHBV, the tensile strength of the composite increased about 23% from 20.96 to 25.87 MPa for the content of 2.5 wt.% HBPs, and more remarkable enhancement in tensile elongation at break can be achieved by about 88% for 5 wt.% HBPs. The influences of HBPs on crystallization, thermal and fracture morphologies of PHBV were further evaluated by using differential scanning calorimeter and scanning electron microscope, respectively. The decrease in the crystallinity of PHBV and high dispersion of the HBPs in PHBV matrix were observed, which should contribute to the improvement on the mechanical properties of PHBV.
Synthesis and Characteristics of Dental Composites with Novel Bis-GMA Derivate as a Resin Base
Authors: Wang Rui Li , Zhu Mo , Liu Sheng , Liu Feng Wei , Jiang Xiao Ze , Zhu Mei Fang
Published: March 2013

2,2-bis [4-(2-hydroxy-3-methacryloyloxypropoxy) pheny propane (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) have been commonly used as a viscous monomer and a reactive diluent in the organic phase of dental restorative composites, respectively. The purpose of addition of TEGDMA is mainly to decrease the high viscosity of Bis-GMA caused by hydrogen bonding between hydroxyl groups. However, some adverse effects will accompany with increased amounts of the TEGDMA, such as higher values of polymerization shrinkage, which is not undesirable for the clinical application. Therefore, substituting hydroxyl groups of Bis-GMA might be an appropriate and effective way to reduce the amount of diluents and weaken the accompanied adverse effects. This work focuses on the synthesis of a novel Bis-GMA derivate, substituting acetyl groups for hydroxyl groups in Bis-GMA. The viscosity of Bis-GMA characterized with rotational rheometer was significantly decreased from 820 Pa.s to 11 Pa.s by substitution of acetyl group, leading to the low amount of TEGDMA in resin matrix. Differential Scanning Calorimeter (DSC) was used for investigating the reaction kinetics of this novel monomer with different mass ratios of TEGDMA. The results suggested that the maximum conversion of the Ac-Bis-GMA can reach 88% while the corresponding value for Bis-GMA is 75%. Dental composites were prepared from 2,2-bis [4-(2-acetyl-3-methacryloyloxypropoxy) pheny propane (Ac-Bis-GMA) or Bis-GMA resin mixtures with TEGDMA filled with 70 wt% silica co-fillers. The results presented that dental composites prepared from new resin matrixes exhibited adequate mechanical properties.
Preparation and Application of Nano Ce-Zr Mixed Oxides Supported H3PW12O40 in Nitrogen Oxide Capture and Decomposition
Authors: Cheng Lin , Wang Rui
Published: March 2013

In this study, nanoCe-Zr mixed oxides (CeZrO) were prepared, and XRD, BET surface areas, TEM and TPD-MS were employed for characterization and mechanism analysis. CeZrO was initially used as support for solid tungstophosphoric acid (H3PW12O40 or HPW) and was found to have promotion effect on the adsorption and decomposition of NOx. After loading with HPW, the NOx adsorption efficiency increased, and the highest efficiency of HPW/CeZrO was 98%, much higher than that of pure HPW (ca. 60%). With the increase of HPW loading, the NOx adsorption efficiency tended to reach a peak value before dropping down. The mechanical grinding method was much more suitable than the incipient impregnation method for CeZrO to load HPW. Furthermore, the adsorbed NOx was found to decompose into N2, O2 and N2O, and yields of N2 of 29.7% for HPW/CeZrO was obtained upon heating at a ramp rate of 50 °C/min.
Properties of h-Bn/Si3N4 Composite Ceramics Fabricated by Gel-Casting
Authors: Liu Chang , Jia De Chang , Wang Sheng Jin , Cui Wang
Published: March 2013

h-BN/Si3N4 composite ceramics were fabricated by gel-casting method and pressureless sintering using Si3N4 and h-BN as raw materials. The effect of h-BN on the microstructure and comprehensive properties of h-BN/Si3N4 ceramic were investigated. The results showed that the introduction of h-BN hindered the densification of h-BN/Si3N4 ceramic as well as the transformation of α-Si3N4 to β-Si3N4. The mechanical properties of Si3N4 based ceramics decreased with the increase of h-BN content, while the thermal property, dielectric properties and machinability increased.
Preparation of Poly (MMA-S-DVB) Microspheres by Suspension Polymerization Method
Authors: Chen Si Qun , Sun Zi Cai , Wang Xiao Wei , Chen Xiao Hui , Chen Jian Jun
Published: March 2013

In this work, Poly (methy methacrylate-styrene-divinyl benzene) (MMA-S-DVB) microspheres were prepared by suspension polymerization approach in the presence of n-dodecane as porogenic agent. Various types of measurements,such as binocular biological microscope with micrometer, fourier transform infrared (FT-IR) and N2 absorption analysis (BET) were conducted to characterize the MMA-S-DVB microspheres. The effect of the amount of surfactants (PVA and NaCl), porogenic agent and crossing agent (DVB) on the morphology of microspheres was investigated and mass ratio of oil/water and the stirring speed were also discussed. Finally, according to the experimental results,the optimum experimental condition was obtained as follow: the mass ratio of S:MMA:DVB=3:3:4, the concentration of PVA in the water phase is 2.2 wt %, the concentration of NaCl is 5 wt %, the mass ratio of oil/water is 1:11, the stirring speed is 500rpm.Via controlling the optimum reaction conditions of the suspension polymerization, the crosslinked macroporous resin polymer MMA-S-DVB microspheres with excellent sphericity and controllable diameter in a range of 200~400 μm can be gained.
Preparation of Stable Pt Nanoparticles Supported by Mesoporous Silica SBA-15
Authors: Zhang Xin , Wang Lian Jun , Jiang Wan
Published: March 2013

A simple two-step procedure towards the Pt nanoparticles and mesoporou silicate SBA-15 composite was developed in this work. The ultrasonic irradiation and the calcinations involved in the preparation did not destroy the size and morphology of prepared Pt nanoparticles, and no agglomeration of Pt nanoparticles was observed, thus stable Pt nanoparticles supported by SBA-15 host were formed. The hexagonal ordered structure of SBA-15 also remained. This stable composite are mainly used as the starting material in fabricating stable Pt nanoparticles doped glass.
Mechanical Properties of NanoSiC Reinforced ZrB2-Based Ceramic Composite
Authors: Han Wen Bo , Wang Peng , Hou Yang
Published: March 2013

ZrB2-based ceramic composites were prepared through hot-pressing at a temperature of 1880°C. An intragranular microstructure was achieved because of the existence of nanoSiC. In this paper, the mechanical properties of ceramic materials of ZrB2-SiC-G were studied, and the influence of intragranular microstructure on the mechanical properties was analyzed. The values of flexural strength and fracture toughness of ZrB2-20vol%SiCnp-15vol%G reached 551.9MPa and 5.25MPa·m1/2, respectively. Compared to ZrB2-20vol%SiC-15vol%G with micro-SiC, the fracture toughness was improved.
Mechanism of Self-Propagating High-Temperature Synthesis of MoSi2
Authors: Gao Jian Ying , Wang Lian Jun , Jiang Wan
Published: March 2013

The reaction mechanism of self-propagating high-temperature synthesis of MoSi2was investigated by means various methods. The result of activation energy calculation indicates that the synthesis reaction is controlled by a single mechanism. Analysis on the microstructure of Mo/MoSi2and Si/MoSi2interfaces reveals that Mo reacts with Si to directly form MoSi2without any transient product (s). Morphology comparison between the reactants and the product demonstrates that the reaction mechanism is not reactive diffusion. Microstructural observation on the materials from quenched zone shows MoSi2particles precipitate from liquid phase. A mechanism may be proposed based on the above results: Mo particles are covered by molten Si and dissolve into the melt, and then MoSi2particles precipitate from the melt due to super saturation.
Effects of Al2O3 Species and Particle Sizes on Properties of Al2O3-Cr2O3 Refractories
Authors: Sun Hong Gang , Li Peng Tao , Yan Shuang Zhi , Wang Gang , Li Jian Qiang , Wang Han
Published: March 2013

The microstructure of Al2O3-Cr2O3 refractories is an important factor to affect its high temperature performance. The Al2O3-Cr2O3 green bodies were prepared by hot pressing using aluminum oxide and Cr2O3 powder mixture by adding a binder. And then the specimens were sintered at 1650 for 4h in the electric muffle furnace. Properties of specimens with different species of Al2O3 powders were studied, including α-Al2O3 powder, ρ-Al2O3 powder, and fused corundum powder. Moreover, three sizes of α-Al2O3 powder (D50=0.8 μm, 1.4 μm, 4.0 μm) were used as additive. Properties of specimens, including apparent porosity, bulk density, cold modulus of rupture, pore size distribution were tested. The morphology of sintered specimens was analyzed by the Scanning Electron Microscope. The results showed that the specimens adding α-Al2O3 powder had the better properties since α-Al2O3 powder has higher sintering activity, and it was more efficient for Al2O3-Cr2O3 solid solution. The specimens with α-Al2O3 had lower porosity, higher bulk density and cold modulus of rupture, and more uniform pore distribution. There were great differences in sintering activity for specimens with different particle size of α-Al2O3 powder. And the microstructure of Al2O3-Cr2O3 was significantly dissimilar. The specimen with the addition of the activated alumina powder of D50 with the size of 1.4 μm and bimodal size distribution showed the perfect performance, including high density and high flexural strength. The experimental results showed that the microstructure of this specimen was uniform and its pore size was homogeneous. This special microstructure is beneficial for improving the slag resistance and thermal shock resistance of Al2O3-Cr2O3 refractories.
Comparison of the Luminescence Properties of PbS Quantum Dots Prepared by Different Methods
Authors: Yu Xiang Wen , Wang Ming Hui , Wang Lian Jun , Jiang Wan
Published: March 2013

PbS quantum dots (QDs) were prepared through a two-phase approach and an aqueous method respectively. The reaction conditions of the two-phase approach were mild and highly controllable, but the as-prepared QDs were capped with oleic acid. Although the PbS QDs prepared by the aqueous method did not exhibit excellent photoluminescence properties, it was more facile and environmentally friendly, and furthermore the resulting PbS QDs were more promising in biological labeling without ligand exchange. We have investigated the absorption and luminescent properties of QDs prepared by the two methods. The results showed that the absorption shoulder of oil soluble PbS QDs was at 580nm and water soluble PbS QDs was at 600~700nm. And the emission peaks in the photoluminescence spectra were at 755nm and 970nm, respectively. XRD analysis confirmed that the PbS QDs were cubic phase. The TEM results showed that the size of both types of PbS QDs was smaller than the excitons Bohr radius (18nm).
Microstructure of Short Carbon Fiber/Si3N4-Reinforced BAS Glass-Ceramic Matrix Composites
Authors: Ma Jing Mei , Ye Feng , Hua Zhong
Published: March 2013

Compact short carbon fiber and silicon nitride particles co-reinforced BAS (barium-aluminosilicate) composites were synthesized by hot-pressed. Phase compositions and microstructures of these composites were characterized by means of XRD and SEM methods. The results showed that BAS was benefit to the densification and partially realize the αβ-Si3N4phase transformation. Definite orientation of the carbon short fibers was observed in the BAS matrix.