bluuebunny/crossref_metadata_2025 huggingface dataset:
NIR (Near-Infrared) Driven Carbon Nanotube Modified with Dendrimers
Authors: Gao Ming Jun , Guo Bin , Ma Lu Wei , Zhang Bo , He Xiao Chun , Bian Lin , Ma Xing Fa , Li Guang
Published: March 2016

Dendrimers and carbon nanotube took an important role in transport and delivery of drugs, gene, et al, however, to improve its functional properties is still a great challenge. Carbon nanotube not only has good biocompatibility but also hold optical adsorption in NIR. In biomimetic and biomedical fields, nanorobots or nanocarriers with external stimuli response for removal the organic pollutants and toxins or drugs in the living body are attractive for research and applications. In this paper, the self-assembly with CNTs containing –COOH and dendrimers having –NH2 groups was carried out. A series of characterizations were performed by SEM (scanning electron microscopy), TEM (transmission electron microscopy), XRD (X-ray diffraction), and Fourier-Transform Infrared (FTIR) spectra. The adsorption properties and releasing characteristics of CNTs modified with dendrimers were performed with simulating drugs. Some meaningful results were obtained. The photoconductivity response to visible light and 808 nm laser with low-power were studied based on interdigital electrodes of Au on flexible PET(polyethylene terephthalate) film substrate. The results indicated that CNTs modified with dendrimers showed good photo-response to visible light and 808 nm laser. It would be developing smart nanorobots with external stimuli response for removal the organic pollutants and toxins or drugs in the living body.
Uniform Deposition of Chemical Vapor Deposition Diamond Films on Slender Tungsten Wires
Authors: Wang Xin Chang , Shen Xiao Tian , Zhao Tian Qi , Sun Fang Hong , Shen Bin
Published: March 2016

In the present study, high-quality chemical vapor deposition (CVD) micro-crystalline diamond (MCD) film was successfully deposited on the surface of the Φ0.5 mm×120 mm tungsten wire using a special designed graphitic jig for supporting the substrate and a two-step deposition procedure for guaranteeing the uniformity of as-deposited diamond film. It is proved that as-deposited film indeed presented much more uniform thickness than that obtained using a conventional jig described in the previous literature, and a very thick WC interlayer spontaneously formed between the substrate and the diamond film, which together with as-deposited MCD film have significant effects on mechanical properties of the wire. Generally speaking, the coated wire remains extremely high surface hardness of the MCD film and considerable toughness of the substrate, along with favorable film-substrate adhesion. It is recognized that these the coated tungsten wires have broad application prospects, but the technologies for depositing diamond films that are thick enough on even longer and thinner wires still need further investigation.
Influence of Austenite Grain Size on Martensite Start Temperature of Nb-V-Ti Microalloyed Ultra-High Strength Steel
Authors: Dong Ji , Liu Chen Xi , Liu Yong Chang , Li Chong , Guo Qian Ying , Li Hui Jun
Published: March 2016

In order to investigate the effect of austenite grain size on martensite start temperature of Nb-V-Ti micro-alloyed ultra-high strength steel, the phase transformation features of Nb-V-Ti micro-alloyed steel was investigated. It has been found that martensite start temperature increased with the increase of austenite grain size as a consequence of the increase of austenitizing temperature. Based on microstructure observation, two types of MX carbonitrides with different compositions and morphologies have been identified. With the increase of the austenite grain size, both the volume fraction of precipitates and the dislocation density decreased, which may be induced by the strengthening of the austenite matrix directly and increasing the resistance of austenite to plastic deformation. Hence, the increase of martensite start temperature could be attributed to a decrease in volume fraction of precipitates and dislocation density.
Effect of Iron-Rich Intermetallic and Eutectic Si Accumulation on Al-Si-Mg Alloy
Authors: Chen Ze Hao , Xu Cong , Hu Xiao Liang , Liu Zhi Guo , Yamagata Hiroshi , Ma Chao Li
Published: March 2016

Al-Si-Mg alloys, an important aluminum cast alloys, are excessively used inmanufacturing of critical components due to their high strength to weight ratio, flexibility ofmanufacturing designs, economic processing and capital material cost for automotive industry. Thisresearch is aimed to study microstructure evolution including distribution and morphology ofiron-rich intermetallic, as well as eutectic Si accumulation and their effect on mechanical propertiesof Al-Si-Mg (A356) casting alloy after artificial ageing. The results show that formation of iron-richintermetallic and eutectic Si accumulation resulted in surprisingly opposite mechanical properties,especially ductility. The elongations deceased with increase of area of accumulated eutectic Si and theamount of needle-like iron-rich intermetallic. When the area of accumulated eutectic Si reached 31%of the microstructure of the A356 alloy, the strength and elongation were respectively damaged to129.69 MPa and 1.05%. Moreover, the amount of needle-like iron-rich intermetallic increased, thestrength and elongation respectively decreased.
Preparation and Characterization of Amorphous Fe-B-P Ultrafine Particles
Authors: Zhang Yan Hui , Wang Xing Kui , Yao Cheng , Qin Gao Wu
Published: March 2016

Soft magnetic Fe-B-P ultrafine particles with amorphous structure were prepared by aqueous reduction method with variable pH values. The microstructure, compositions and the soft magnetic properties of Fe-B-P submicron particles were investigated by using field emission scanning electron microscope (FE-SEM), X-Ray Diffraction (XRD), mössbauer spectrum (MS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), vibrating sample magnetometer (VSM). The results showed that a series of Fe-B-P amorphous particles with the average particle size of 0.26~0.42 μm were obtained depending on the pH value of solution. As pH value increased, the contents of B and P increased, and the specific saturation magnetization of the Fe-B-P submicron particles decreased. Some electrons, transferred from p-shell of B atoms and P atoms to 3d-shell of Fe atom, resulted in the decrease of the number of unpaired electron, which in turn led to reduction of the average hyperfine magnetic field of the Fe-B-P particles and the decrease of the magnetic torque of Fe atoms. The relation between hyperfine magnetic field (Hhf) and the specific saturation magnetization was in accord with the Marshall’s equation. At the same time, the enhancement of the shielding effect on 4s electron orbital, i.e., the density of 4s electron reduced, leading to the increase of Isomer Shift.
Electric-Field-Control of Non-Volatile Magnetization Switching in Multiferroic CoFeB/(011)-PMN-PT Heterostructures
Authors: Yang Yuan Jun , Hong Bin , Yang Meng Meng , Wang Liang Xin , He Hao , Zhao Jiang Tao , Hu Kai , Huang Hao Liang , Li Xiao Guang , Luo Zhen Lin , Kang Chao Yang , Li Ming , Zong Hai Tao , Gao Chen
Published: March 2016

The giant converse magnetoelectric coupling (GME) was observed in the multiferroic Co40Fe40B20/(011)-0.7Pb (Mg1/3Nb2/3)O3-0.3PbTiO3 heterostructures at room temperature in this investigation. A tunability of magnetization by electric field along the [100] direction was up to-66.7% at-10 Oe bias magnetic fields. Moreover, the non-volatile magnetization switching was found after removal of bipolar electric field. The corresponding remanent magnetic states even without the assistance of bias magnetic fields were stable and could be modulated synchronously by a sequence of pulse electric fields. The 90o rotation of easy axis and non-symmetrical ferroelastic domain switching contributed to the above results. This work is of great significance in designing ultra-low power and non-volatile magnetoelectric memories and other spintronic devices at room temperature.
Chemical Bonds Properties and Spontaneous Polarization of Orthogonal SrBi2Ta2O9 Crystals
Authors: Xiao Xiao Hong , Li Shi Chun
Published: March 2016

The bonds structure, atomic coordination situation and local cluster structure in SrBi2Ta2O9 were analyzed by means of the Atomic Environment Calculation (AEC), and then the SrBi2Ta2O9 crystal was decomposed into 20 pseudo-binary crystals with the crystal decomposition method. The chemical bonds properties, such as effective valence electron density and iconicity of the individual bond were calculated by the dielectric chemical bonds theory. And the correlation between chemical bonds properties and spontaneous polarization of the bismuth layered ferroelectrics was established. Finally, the spontaneous polarization in ferroelectric SrBi2Ta2O9 and other relevant ferroelectrics were calculated, which are in good agreement with the experimental values and other theoretical calculated values.
Microstructure and Magnetic Properties of RE2.28Fe13.58B1.14 Alloys
Authors: Fu Gang , Wang Jiang , Rong Mao Hua , Rao Guang Hui , Zhou Huai Ying
Published: March 2016

The rare-earth (RE) permanent magnets based on Nd2Fe14B with excellent magnetic properties have been widely used in industrial applications. In this work, the crystal structure, microstructure and magnetic properties of Nd2.28Fe13.58B1.14, Ce2.28Fe13.58B1.14 and Pr2.28Fe13.58B1.14 alloys prepared by arc-melting were investigated. The results show that all alloys are single phase with tetragonal Nd2Fe14B-type (space group P42/mnm). The Curie temperatures (Tc) of RE2.28Fe13.58B1.14 (RE=Nd, Ce, Pr) alloys are 583 K, 423 K and 557 K, respectively. On the other hand, the coercivities of Nd2.28Fe13.58B1.14 and Pr2.28Fe13.58B1.14 alloys are about 1.05 T and 1.23 T, respectively, while that of Ce2.28Fe13.58B1.14 alloy is only about 0.25 T due to the poor squareness of hysteresis loop. Meanwhile, the saturation magnetizations of Nd2.28Fe13.58B1.14 and Pr2.28Fe13.58B1.14 alloys are about 135 emu/g and 113 emu/g, respectively, while that of Ce2.28Fe13.58B1.14 alloy is about 97 emu/g. It was indicated that the Curie temperatures and magnetic properties of RE2.28Fe13.58B1.14 alloys with the same crystal structure are dependent on light rare earth elements.
Random Lasers with Coherent Feedback from Polymer Films Based on Rh6G-PVP
Authors: Liu Xi Yun , Liu Shen Ye , Yi Tao , Wang Chuan Ke , Li Ting Shuai , Xu Min , Huang Deng Feng
Published: March 2016

The observation of random laser (RL) with coherent feedback in transparent polymer films based on Rh6G-PVP by spin-coating was carried out in the present investigation. Some sharp peaks with FWHM identified to be 2 nm appeared on the fluorescent spectra of polymer films which pumped by Nd:YLF pulse laser (wavelength: 526nm, frequence: 1Hz, pulse duration: 1ns, energy power: 1.2mJ/pulse). The threshold of emission spectra is ~35 and the spectra range from 570 ~ 610 nm. Streak camera was used to record the temporal process of RLs and the pulse duration time was measured to ~400ps. Rh6G-PVP transparent films were a kind of polymer films with numerous nanogaps distributed randomly on the surface of the film. The photons will be multiple scatterred and amplified during the spreading in the polymer film owing to the refractive index difference between nanogaps and polymer films. As the Rh6G-PVP polymer films have characters of convenient fabrication processes, low threshold and low cost, it shows great potential application in photoelectron and laser imaging.
Viscoelastic and Morphological Behavior of Stearic Acid Layer on Top of Polystyrene as Immobilisation Matrix for QCM Sensor
Authors: Masruroh  , Djoko D.J.D.H. , Rahayu Susi , Sakti S.P.
Published: March 2016

The effect of different solvents on the acoustic property and morphology of polystyrene (PS) and the stearic acid (SA) layer was investigated in this study. The acoustic property was analyzed by using impedance analyzer and morphology of SA layer in a quartz microbalance (QCM) sensor have been studied to quantify their effects on viscoelasticity within the sensor. The polystyrene coating on a QCM sensor was created by spin-coating with various solvents, such as chloroform and toluene, which contains a 3% polystyrene solution by mass. Then, the SA coating was deposited onto the polystyrene layer using a low-vacuum evaporation method. The viscoelasticity was measured by an impedance analyzer coated with the SA layer to determine whether the material used as a coating will effectively immobilize a biomolecule and whether the material produces an acoustic load. The experimental results showed that the impedance value in the series resonant frequency was small (i.e., near 10 Ω), indicating that the deposited SA coating is rigid and that the SA coating does not produce a loading effect on the QCM sensor. Therefore, the coating technique used on the QCM sensor surface to produce the SA coating is likely to be an effective biosensor material for QCM immunosensor. Additionally, the study shows that the frequency change (Δf) of the SA layer deposited onto the polystyrene coating created with chloroform is larger than that of the coating created with toluene. This also shows that the SA layer deposited onto the polystyrene coating created with chloroform is thicker than the coating created with toluene. The Δf correlates with the mass change (Δm), according to the Sauerbrey equation, which requires that the material be rigid. The Δf value also correlates with the deposited SA mass change. From the calculation of Δf, the SA coating created with the chloroform solvent was shown to be thicker than that created with the toluene solvent. In addition, the roughness of the SA surface using a test of non-contact topography measurement system TMS TopMap-1200 showed that the SA surface roughness with the chloroform solution was 763 nm compared to that with the toluene solution, which was 424 nm.
Preparation and Characterization of a Novel Anti-Dripping Flame Retardant PET/Phosphate Glass Nanocomposite
Authors: Liu Hui Chao , Huang Yi Long , Ma Jing Hong , Gong Jing Hua , Xu Jian
Published: March 2016

In the present study, the effect of phosphorus flame retardation (FR) agent, 2-carboxyl ethyl (phenyl) phosphinic acid (CEPPA), incorporating phosphate glass (Pglass) on the flame retardation and melt dripping behavior of poly (ethylene terephthalate) (PET) has been investigated. The Pglass/FR-PET nanocomposites (P/FR-PET) were prepared by melt blending. The morphology, thermal degradation behavior and flamability of the nanocomposites were investigated by means of scanning electron microscopy (SEM), thermogravimetric analysis (TGA), limiting oxygen index test (LOI) and vertical combustion test. SEM micrographs showed that as the increasing of Pglass contents the morphologies of Pglass in the FR-PET matrix changed from nanoparticles (50 nm to 100 nm) to network structures. The thermal stability of nanocomposites at high temperature increased with the addition of Pglass contents. Meanwhile, the LOI values of the nanocomposites increased from 33.6 for neat FR-PET to 36.1 for 50% P/FR-PET nanocomposites. The vertical combustion test revealed that the P/FR-PET nanocomposites had excellent anti-dripping flame retardant property which can achieve UL-94 V-0 level. The formation of the Pglass network-structured protective layer, which acted as a supporting and heat shield layer, must be crucial for the large reduction in melt dripping. In a word, the experimental results showed that the CEPPA in combination with Pglass has excellent flame retardation and anti-dripping effect.
Influence of a Trace Alloying of Ag on the Ageing Behavior and Mechanical Properties of AZ80M Magnesium Alloys
Authors: Sun Wei Bing , Liu Cu Ming
Published: March 2016

The ageing behavior of AZ80+xAg (x=0;0.3;0.5) magnesium alloys at different temperature were systematically investigated using optical microscopy, scanning electron microscopy and X-ray diffraction analysis. Experimental results demonstrate that the trace amount of Ag accelerated the precipitation of Mg17Al12 phase during ageing at 200°C, AZ80+0.5Ag achieved the peak hardness of 89.7HV after holding for 12h, compared with 80.8HV after 28h for the Ag-free alloy. However, when ageing at high temperature (250°C), the promotion response of Ag was totally vanished. The tensile property of the peak aged alloys at ambient temperature increased with Ag addition, as well as the tensile property at elevated temperature. Further investigation indicates that Ag addition suppresses the discontinuous precipitates, which account for the enhanced property of Ag-containing alloy.
Stress Induced Martensitic Transformation in Ti-1023 Alloys
Authors: Chang Li Li , Liu Jia Peng
Published: March 2016

Mechanical behaviors of isothermal hot forged and solution treated Ti-1023 alloy with different initial microstructures were investigated. After heat treatment at 760°C and 820°C for 1 hour, Ti-1023 alloys mainly consisted of fine α particles and β phase with a large grain size. The CMWP (Convolution Multiple Whole Profile) analysis indicated that the dislocation density in Ti-1023 decreased with increasing heat treatment temperature. Ti-1023 alloy solution treated at 760°C showed high strength and large anisotropy in plasticity. Improved ductility was observed in the alloy with solution treatment at 820°C. Increasing work hardening rate related to stress induced martensite transformation was observed in Stage II of the work hardening rate curves.
Damage Characteristics of Zr-Based Metallic Glasses under Helium Ions Irradiation
Authors: Li Feng Jiang , Xing Jian Shuo , Zhao Zi Qiang , Wei Bing Chen
Published: March 2016

Metallic glasses (MGs) exhibit extremely high strength and superior resistance to corrosion. They are also supposed to be resistant against displacive irradiation due to their inherent disordered structure, and thereby are viewed as potential candidates for applications in irradiation environments. However, the structures and properties evolution of metallic glasses, especially bulk metallic glasses (BMGs), under irradiation has not been fully understood up to now. In this work, the structural stability and damage characteristics of a Zr-based BMG under helium ions irradiation environment were investigated. Meanwhile, the effect of structural relaxation and crystallization on the irradiation response of the BMG was also studied. Results show that the BMG reserves the amorphous structure within the studied range of fluence, and exhibits better irradiation resistance compared to that of the crystalline alloys. In our opinion, the initial free volume concentration affects the damage morphology of the BMG, while partial crystallization will lead to significantly embrittlement under irradiation.
Effect of DC Pulse Patterns on Spark Plasma Sintering Process of [Fe0.8Co0.2B0.05Si0.2]96Nb4  Bulk Metallic Glass
Authors: Sun Yue Ting , Shao Hui Liang , Zhao Zhan Kui
Published: March 2016

The influence of direct current pulse on–off patterns on spark plasma sintering of [Fe0.8Co0.2B0.05Si0.2]96Nb4 on kinetics competition and coordination mechanism of the interface bonding and crystallization has been investigated systematically. No crystallization of metallic glassy matrix and good bonding state between the particles were responsible for good mechanical properties of the fabricated Fe-based bulk glassy alloy at 2:9 (on: off) pattern. The higher local micro area’s instantaneous power and larger cooling time caused by low pulse duty ratio played a vital role in consolidation of amorphous alloy powder and desired structural properties.
Effect of Ta Addition on Structural Evolution and Mechanical Properties of the CoFeNi2W0.5 High Entropy Alloy
Authors: Jiang Li , Dong Yong , Jiang Hui , Lu Yi Ping , Cao Zhi Qiang , Li Ting Ju
Published: March 2016

A series of CoFeNi2W0.5Tax (x = 0-0.6) high entropy alloys (HEAs) were synthesized by arc melting to investigate the alloying effect of Ta element on the microstructure and mechanical properties of the CoFeNi2W0.5 alloy system. Phase constitution, microstructure and mechanical properties of the alloys were analyzed by X-ray diffraction (XRD), scanning electron microscopes (SEM), Vickers hardness and compressive test. It was found that when x = 0, the alloy consists of a single-phase face-centered cubic (FCC) solid solution structure and exhibit excellent ductility, the compressive plastic elongation of which can reach 80% without fracture. While with increasing Ta content, the brittle Co2Ta-type Laves phase appears which leads to a decrease of the plastic strain and an increase of the yield strength, and the Vickers hardness shows an obvious increase from HV 179.5 to HV 753.2.
Low Cycle Fatigue Behavior of TA29 Titanium Alloy at Different Temperatures
Authors: Li Juan , Cai Jian Ming , Duan Rui , Huang Xu
Published: March 2016

The low cycle fatigue behaviour of TA29 titanium alloy blisk forging at 300°C, 400°C, 500°C, 600°C were studied. The cyclic stress response, the stress-strain behaviour, the fatigue life and the fractograph were observed and analyzed. Through the double logarithm linear regression, the Coffin-Manson model parameters of TA29 titanium alloy at different temperatures were obtained. The results showed that the fatigue life decreases as the strain amplitude increases. Also, the testing temperature has a significant effect on the low cycle fatigue properties of TA29 titanium alloy. At the same level of the strain amplitude, the fatigue life and the peak value of cyclic stress decrease, while the plastic strain component in total strain amplitude increases with the increase of testing temperature. On the basis of the fractograph of fatigue specimens, the initiation of crack is mainly on the surface of the specimen. Fatigue striations can be seen clearly at fatigue crack propagation area. The fatigue striations in stable fatigue crack propagation area were broadened, and the propagation area was reduced and the final rupture area was increased with the increase of testing temperature.
Wetting Behavior and Interface Characteristic of Ti32.8Zr30.2Ni5.3Cu9Be22.7/Ti6Al4V
Authors: Liu Ding Ming , Zhu Zheng Wang , Li Zheng Kun , Fu Hua Meng , Li Hong , Wang Ai Min , Zhang Hong Wei , Zhang Hai Feng , Hu Zhuang Qi
Published: March 2016

The wetting behavior and the interaction at the liquid-solid interface are significant in preparation of metallic glass composite. In this paper, the wetting behavior and the interfacial interaction between Ti32.8Zr30.2Ni5.3Cu9Be22.7 (denoted as ZT3) bulk metallic glass (BMG) alloy melt and Ti6Al4V (denoted as TC4) substrate at different temperatures were investigated using sessile drop method. The results show that ZT3 alloy melt wetted the substrate well. With the increase of temperature, the droplet spread out rapidly and then came to equilibrium gradually. The equilibrium contact angle under 1273 K stabilized at about 15°. Dendrite phase generated at the interface during the wetting progress. The composition of the interface product transformed from Ti69.8Zr24.2Al2.2V1Cu2.8 to Ti73.6Zr15.3Al5V2.7Cu2.6Ni0.8 with the temperature rising from 973 K to 1273 K. Meanwhile, the dissolution of the TC4 substrate increased with increasing the temperature.
Fabrication and Strengthening Mechanisms of Al/WC Particles Composite Prepared by Accumulative Roll Bonding
Authors: Liu Chong Yu , Jiang Hong Jie , Wang Chun Xia , Li Yu Ping , Luo Kun
Published: March 2016

Aluminium metal matrix composites reinforced with WC ceramic particles were manufactured through warm accumulative roll bonding (ARB) in this study. The microstructures of the composites exhibited excellent particles distribution in the matrices. Compared with the mechanical properties of ARB monolithic pure Al, the Al/WC composites exhibited higher tensile strength. The shear lag theory modified was used in considering the yield strength of the composites. The results indicated that the effects of WC particles in Al/WC composite lead to the thermal expansion dislocation strengthening, small subgrain strengthening, Orowan strengthening and geometrically necessary dispersion strengthening.
Investigation of Viscosity Measurements of Molten Fe-Si-B-Nb Alloys
Authors: Zheng Hai Jiao , Sun Qi Jing , Zhao Xi , Hu Li Na
Published: March 2016

The properties of Iron-based metallic glasses, such as glass-forming ability and soft magnetic properties, (MGs) have been widely investigated. However, seldom reports are available concerning the properties of these iron-based melts. In the present work, the viscosity of superheated Fe-Si-B-Nb metallic glass forming liquids (MGFLs) was measured by a torsional oscillating viscometer. It has been found that the crucial condition to get viscosity data using graphite crucibles is to reach a superheated degree of at least 250 K for melts prior to measurements. The viscosity increases monotonically with a decrease in temperature before solidification, without distinct changes of dynamic mechanism during cooling. The present work indicates that these iron-based melts are heterogeneous even above the liquidus temperature. This finding helps to understand the melts of iron-based MGs and to improve the production process of iron-based glass ribbons.
The Effect of Remelting on the Microstructure and Mechanical Properties of a Nickel Superalloy
Authors: Zhang Zhi Wei , Niu Yong Ji , Tian Jian Jun , An Ning , Gao Yang , Wang Chao , Shi Shi Feng
Published: March 2016

Effect of remelting processes on the microstructure and mechanical properties of as-cast Nimonic 90 superalloy was investigated by OM (optical micrograph), SEM (scanning electron microscopy), EDS (energy-dispersive X-ray) and tensile tests. The results indicated that the microstructure of the as-cast alloy was mainly composed of γ, γ' and carbides which contain Ti and Cr elements. The average grain size of the alloy tends to increase with mould shell temperature ranging from 350°C to 950°C. The strength of the as-cast alloy decreased with the increasing of mold shell temperature, with constant elongation as the mold shell temperature changes.
Influence of Metallographic Etchant on γ’ Precipitates Characterization in a Single Crystal Nickel-Base Superalloy
Authors: Zhuang Xiao Li , Wu Hong Yu , Si Jia Yong , Jiang Liang
Published: March 2016

Two metallographic etchants were employed to characterize the γ′ precipitates in a single crystal Nickel-base superalloy. One can corrode γ matrix and retain γ′ precipitates, while the other one can remove γ′ and obtain γ. Potentiodynamic polarization curves of γ′ precipitates and γ matrix in these two etchants were measured to examine the electrochemical process of metallographic etching. The results from the electrochemical tests showed that the corrosion potential (Ecorr) of each phase determined the metallographic etching morphology. For γ′ volume fraction evaluation, the quantitative analysis by image analysis software was carried out with the electrolytically extracted γ′ precipitates for the same specimen. Statistics showed that the etchant which selectively etched γ′ precipitates can provide appropriate results.
Microstructure, Mechanical and Tribological Properties of the Rapidly Solidified NiAl/Cr(Mo,Dy) Hypoeutectic Alloy
Authors: Sheng Li Yuan
Published: March 2016

The NiAl/Cr (Mo,Dy) hypoeutectic alloy was fabricated by rapid solidification. The microstructure and mechanical properties as well as tribological properties for the alloy at different temperatures were investigated. The results revealed that the rapidly solidified NiAl/Cr (Mo,Dy) hypoeutectic alloy was composed of primary NiAl, fine NiAl/Cr (Mo) eutectic lamella, Ni5Dy phase and Cr7Ni3 precipitate. The compression test showed that the rapid solidification improved the mechanical properties of the NiAl/Cr (Mo,Dy) hypoeutectic alloy obviously. The dry sliding test results showed that alloy had excellent tribological properties at about 1073 K, which obtained wear rate of 4.9 10-14m3/m·N and friction coefficient of 0.16 μ. The excellent tribological properties at high temperature may be attributed to the continuous and intact protecting lubricant film which was composed of amorphous, Cr2O3 and Al2O3 nanoparticles. Between 700 K to 900 K, the alloy demonstrated bad tribological properties, especially the high wear rate, which may be ascribed to the softening of NiAl and Cr (Mo) phases.
Microstructure and Properties of Fe-Based Amorphous Composite Coating Prepared by Pulse Laser
Authors: Jiang Run Sen , Wang Yong Tian , Tang Jin , Xu Gang , Liu Zong De
Published: March 2016

The Fe-based amorphous composite coatings were prepared by pulse laser cladding method. The amorphous powder with the size ranging from 100 to 200 meshes was cladded on the low carbon steel plate,and the nominal composition of the powder was (wt.%) Cr:14.95, Mo:25.7, B:1.24, C:3.45, Y:3.40, Fe:51.29. The microstructure, phase composition and hardness were characterized by XRD, SEM, DSC and semi-automatic Vickers hardness tester in this study, respectively. The results show that the coating which is composed of amorphous and nanocrystal phases has the dense structure and metallurgical bonding with the substrate. The hardness of coatings was about 5 times higher than that of the substrate. With the increase of cladding layer, the average hardness of coating showed an increasing trend, and the intrinsic mechanism was discussed.
Study on the Corrosion Behavior In Vitro and Mechanical Properties of the FHA Coated Mg-Zn-Zr Alloy
Authors: Li C.G. , Chen Min Fang , Sun S.Z. , Zhang J.
Published: March 2016

The fluorine-doped hydroxyapatite (FHA) coating on the surface of Mg-3wt%Zn-0.8wt%Zr alloy was prepared using a chemical treatment method. The standard tensile samples of coated and uncoated Mg alloy were immersed in the SBF respectively for 1,3,5,10,20 and 30 days. The effect of the FHA coating on corrosion behavior in vitro and mechanical properties of the Mg-Zn-Zr alloy was investigated. Based on the losing weight and the max corrosion depth of the samples, the corrosion rate can be calculated. According to the weightlessness curve of samples, the average corrosion rate of the bare alloy, the alloy of MgF2 coating and the alloy of FHA coating were 4.13mm / y, 1.51mm / y and 0.86mm / y within 30 days in vitro, respectively. It can be seen that the significant difference of mechanical properties between the coated and uncoated samples with the increase of immersing time. This fully revealed that the FHA coating on the Mg-Zn-Zr alloy is beneficial to improve its corrosion resistance.
Effects of Combined Addition of Cr3C2 and NbC on Microstructure and Properties of Cemented Carbides Prepared by WС-Co Composite Powder
Authors: Jiang Ai Min , Li Quan , Yang Feng Jie
Published: March 2016

With addition various contents of combined grain growth inhibitors Cr3C2 and NbC into the ultrafine WC-Co6% composite powder, and the effects of codoped Cr3C2 and NbC addition on microstructure and properties of the alloys have been investigated by X-ray diffraction, scanning electron microscopy. The results showed that increasing the content of inhibitors in the composite powder, the abnormal grain growth disappeared and homogeneous ultrafine grain structure formed, i.e., the grain growth inhibitor promoted sintering densification process. WC grains were refined by the comprehensive effects of the Cr3C2/NbC dissolving in the Co phase to alter the interface energy and interfere the WC solution in the binder phase, which prevents the structure of cobalt change from the face-center-cubic into dense-hexagonal crystal, and to increases the transverse rupture strength.
Structure and Inverse Magnetocaloric Effect of Mn1.2Co0.8Si0.2P0.8 Compound Prepared by SPS
Authors: Ma Lei , Zhou Liang , Li Lin , Gu Zheng Fei , Cheng Gang
Published: March 2016

The single-phase Mn1.2Co0.8Si0.2P0.8 compound was fabricated by the spark plasma sintering (SPS) technology followed by vacuum annealing. The microstructure, Néel temperature (TN) and “inverse” magnetocaloric effect of this compound were investigated. The results show that the structure of Mn1.2Co0.8Si0.2P0.8 compound prepared by SPS is a single phase with precise stoichiometric proportion. Increasing the magnetic field from 0.05 T to 1 T, the TN of the material reduces gradually from 110 k to 45 k, and a splitting of TN appears. The splitting of the antiferro-to-ferromagnetic transition is an intrinsic feature rather than the secondary phase. Though the maxima entropy changes is about 0.6 Jkg-1K-1 at B=5T, the Mn1.2Co0.8Si0.2P0.8 phase synthesized by SPS is more favorable, more overall magnetic moment. In addition to the magnetic refrigeration applications, this compound may be used in thermomagnetic generators.
Eddy Current and Metal Magnetic Memory Testing Nondestructive Evaluation for Superficial Defects of Old Cylinder Barrel
Authors: Shi Chang Liang , Dong Shi Yun , Tang Wei Xue , Zhan Hao
Published: March 2016

Eddy current testing and metal magnetic memory testing, cooperated with special testing devices, were applied to detect the superficial defects of old cylinder barrel. It was indicated that there were three types of the signals, which were non-defect signals, discontinuous peak signals and continuous peak signals. Non-defect signals indicated that there was no defect in cylinder barrel, and the discontinuous peak signals denoted that there was circumferential cracking, and the continuous peak signals showed that there was longitudinal cracking in the surface of cylinder barrel. The amplitude of eddy current testing signals characterizes the depth of cracking, and the gradient of magnetic signals descript the degree of stress concentration. The method mentioned above detects the cracking and stress concentration in the superficial coat of old cylinder barrel, which effectively guarantee the quality of automobile cylinder.
Research on Microstructure and Properties of Co-Si Alloys by Vacuum Suction Casting
Authors: Peng Zhen , Wu Peng Hui , Zhang Jing , Liu Ning , Wang Xiao Jing
Published: March 2016

Rapid solidification of Co-Si alloys was investigated by using vacuum suction casting in this study. Different microstructures and intermediate phases were obtained. Eutectic εCo phase and eutectoid εCo + αCo2Si structures were obtained in the first eutectic Co76.9Si23.1 alloy. The microstructures of hypereutectic Co70Si30 alloys were composed of primary αCo2Si phase and interdendritic lamellar eutectoid εCo + αCo2Si. While for hypoeutectic Co63Si37 alloy at the second eutectic point, CoSi dendrites were the primary phase, and αCo2Si+CoSi eutectoid structures can be seen at the interdendritic region. Especially, a metastable CoSi2 phase was found in Co63Si37 alloy. This indicates that eutectoid decomposition βCo2Si→ CoSi+αCo2Si is restrained in eutectic Co60.3Si39.7 alloy. For rapid solidified Co55Si45 and Co52Si48 alloys, αCo2Si+CoSi eutectoid structures were not observed, while metastable CoSi2 were obtained. The higher hardness achieved in Co-Si alloys at the second eutectic point, for the reason of the higher volume fractions of compound phases.
Surface Stability of NiTi Alloy: A Density-Functional Theory Study
Authors: Li Yong Cheng , Wang Fu He , Shang Jia Xiang
Published: March 2016

The low-index (001), (111) and (110) surfaces of austenitic NiTi were investigated by the use of first principles calculations. The calculated results showed that the non-polar NiTi (110) surface was the most stable under most of the Ti chemical potential. The polar Ni terminated NiTi (001) surface was the most stable under Ni-rich conditions. The Ni-terminated surfaces were more stable than their corresponding Ti-terminated surfaces in the entire range of Ti chemical potential. The surface interlayer relaxations of the Ni-terminated surfaces were much larger than those of the corresponding Ti-terminated surfaces. The Ti atoms in the surface layer of the non-polar NiTi (110) surface were more outward than Ni atoms.
Deformation Twinning in Hexagonal Close-Packed Single Crystals under Uniaxial Compression
Authors: Xiong Kai , Zhang Yi Yang , Gu Jian Feng
Published: March 2016

In this paper, the uniaxial compression of Mg, Ti, Zr and Co single crystals along the direction is performed by molecular dynamics (MD) to investigate the elastic-to-plastic transition in these hexagonal close-packed (hcp) metals. Two deformation twinning modes are observed in these simulations, including the twinning in Ti, Zr and Co and the [0001] twinning in Mg. The underlying atomistic mechanisms of these twinning modes are analyzed in detail.
QSAR Study on Imidazole Derivatives as Corrosion Inhibitors by Genetic Function Approximation Method
Authors: Xiong Sang , Sun Jian Lin , Xu Yang , Yan Xu Dong
Published: March 2016

Quantitative structure and activity relationship (QSAR) method is becoming more desirable for predicting of corrosion inhibition properties. The inhibition efficiency of organic compounds is dependent on many basic molecular descriptors, including structural descriptors, thermodynamic descriptors, information content descriptors, topological descriptors as Wiener index, Zagreb index and molecular connectivity indices. A genetic function approximation approach was used to run the regression analysis and establish correlations between different types of descriptors and measured corrosion inhibition efficiency for imidazole derivatives. A QSAR equation was developed and used to predict the corrosion inhibition efficiency for 18 imidazole derivatives. The prediction of corrosion efficiencies of these compounds nicely matched the experimental measurements.
Synthesis and Characterization of High Purity Ruthenium Sponge
Authors: Yi Wei , Xin Ze Na , Sheng Yue , Tan Zhi Long , Zhang Jun Min , Wang Chuan Jun , Bi Jun , Wen Ming , Guan Wei Ming
Published: March 2016

Ruthenium is widely used as catalyst, magnetic recording and electrode materials. In this study, high-purity (≥99.995 wt%) ruthenium sponge was synthesized from crude ruthenium (≤99.9 wt%) by chemical refining technique. Initially, crude Ru was transformed into H2RuCl6 by distilling treatment. The H2RuCl6 was, then, added with NH4Cl powder to precipitate (NH4)2RuCl6 powder. Afterward, the (NH4)2RuCl6 powder was ignited in air and transformed into RuO2. Finally, RuO2 was changed to Ru by hydrogen reduction method. Impurities included in the starting Ru powder were eliminated after distillation and precipitation treatments. As-obtained ruthenium particles were spherical-like agglomeration, the average size was about 6 μm and the powder density was 11.83 g/cm3. The details of chemical transforming mechanisms in the refining process were described.
Effect of Salt-Deposit Hot Corrosion on Creep Rupture Behaviors of DZ466 Superalloy
Authors: Ding Xian Fei , Chen Xue Da , Li Qing , Xiao Cheng Bo , Ren Wei Peng , Feng Qiang
Published: March 2016

Since gas turbine blades in engines suffer centrifugal stress and gas corrosion during service, a good creep resistance in hot corrosion environment is one of the important considerations to evaluate service performance of the blade materials. In this work, the creep rupture behaviors of the directionally solidified superalloy DZ466 with and without salt deposition at 760°C/765MPa, 850°C/500MPa and 950°C/220MPa are preliminarily investigated based on the creep properties measurement and microstructure observations. The effects of hot corrosion on the creep properties and fracture mode are examined. The results show that the creep-rupture life in salt-deposit environment is lower than that in air-exposure environment at different temperatures. The creep-rupture life reduction caused by hot corrosion is increased with increase of the creep temperature. The fracture mode is exhibited by transgranular fracture in all crepted specimens. The propagation directions of all the secondary cracks are almost perpendicular to the crept specimen surface or the stress axis. The surface cracks are mainly produced in air-exposure environment at low temperature or in salt-deposited environment at high temperature. Induced by the stress concentration, the internal cracks are initiated surrounding the carbides in both air-exposure and salt-deposit environments. The creep-rupture life is dependent on the crack initiation at low temperature but on the crack propagation at high temperature. The reduction of the active load bearing area in transversal direction is the main reason why the creep-rupture life is decreased at 950°C.
Analysis of Preform Annealing Process for the Aluminum Automotive Door Inner Panel
Authors: Yang Yu Juan , Lin Jian Pin , Wang Bin
Published: March 2016

To improve the formability of aluminum alloy, a new forming technique-the preform annealing process is proposed. Based on the mechanical properties of the original aluminum alloy AA5182-O with two experienced preforming annealing treatment, and preforming annealing process of a complex geometric shape aluminum door inner panel was numerical simulated by using LS-DYNA software. As a result, the effects of annealing time at 365°C on stamping height of the panel and the optimum annealing time were obtained. The results showed that the preform annealing process was feasible in the door inner panel. At 365°C, the smooth forming of the door inner panel was achieved after annealing for 20s with the pre-deformation amount 97mm, Which are the most suitable parameters.
Microstructure and Mechanical Properties of 7000 Series Al Alloy via Tiny-Molten-Pool Solidification Forming
Authors: Shen Qi Zhao , Jiao Jing Ye , Cheng Ai Chao , Guo Ren Fei , Zhou Tie Tao
Published: March 2016

As the grains of 7000 series Al alloy prepared by traditional casting method are usually quite coarse, and there exists serious segregation of composition and structure in the alloy, a new forming process for high-alloying alloy is in urgent need. Here we demonstrate a new method called tiny-molten-pool solidification forming to improve the above mentioned problems. In detail, the alloy powder was melt by the plasma and then deposits on the base plate. 7075 Al alloy bulk specimens with the size of about 200 mm × 8 mm × 4 mm were prepared and the effects of homogenizing treatment, cold rolling, T6 heat treatment for the alloy were studied. The results show that there were no oxide film inclusions in the single-pass multi-layers specimen prepared by AC tiny-molten-pool solidification forming, and the microstructure was homogeneous; The grains were homogeneous and mainly equiaxed grains with a uniform size of about 20 μm, which were much smaller than that of traditional casting 7075 Al alloy; After the homogenization treatment (470 °C × 48 h), most of the net-shape eutectic structure in the alloy is re-dissolved. After cold rolling with a total deformation of 60%, the alloy became compact as the stomata were compressed. The hardness of the alloy was HV183.51 after T6 heat treatment (480 °C × 2 h + 120 °C× 15 h). The micro-molten-pool solidification forming is feasible for the forming of bulk 7000 series Al alloy.
Effect of Rapid Thermal Process on the Recrystallization and Precipitation in Non-Oriented Electrical Steels Produced by Twin-Roll Strip Casting
Authors: Han Qiong Qiong , Jiao Hai Tao , Wang Yang , Zhang Yuan Xiang , Qiu Wen Zheng , Zhao Cong Wen , Yu Yong Mei , Xu Yun Bo
Published: March 2016

A Fe-1.3% Si non-oriented silicon steel strip was produced by twin-roll strip casting process, and subsequently treated with cold rolling and annealing. The effect of heating rates on the recrystallization and precipitation behavior of second phase particles (AlN and MnS) was investigated by MMS-200 thermal mechanical simulator. It was found that the recrystallization area fraction decreased obviously with the increase of heating rate. At the heating rate of 5 °C/s, the recrystallization rate gradually decreased with the extension of holding time, but it increased at the rapid heating rates. The particle’s sizes mainly concentrated in 50~200 nm at the heating rate of 5 °C/s during annealing. The number of particles under 50nm increased gradually and the number of precipitates between 50~400 nm reduced significantly when the heating rate was increased to 50~300 °C/s. The results indicated that the rapid heating rate could refine the size of precipitates and decrease the number of particles above 50nm.
Crystal Structure of Al2Cu3Nd Ternary Compound
Authors: Li De Gui , Liang Liu Qing , Qin Ming , Hu Lei , Qin Chang Sheng , Liu Shu Hui , He Bin , Jia Chen Zhong , Zeng Ling Min
Published: March 2016

A new Al-Cu-Nd system alloy, the high-purity Al2Cu3Nd ternary compound, was developed and prepared with the stoichiometric amounts of elemental constituents by arc melting under argon atmosphere. The X-ray diffraction (XRD) data of Al2Cu3Nd was collected by using the Rigaku Smart Lab X-ray powder diffractometer, and all X-ray diffraction peaks of Al2Cu3Nd compound were indexed successfully with the hexagonal structure. The Rietveld refinement results of the XRD pattern for the Al2Cu3Nd compound showed that the Al2Cu3Nd compound is the hexagonal structure, space group P6/mmm (No.191) with a = 5.2397(1) Å, c = 4.1783(1) Å, V = 99.34 Å3, Z = 1. The density of the compound was 6.501 g/cm3, and its reference intensity ratio (RIR) w 1.26.
Study on Heat Treatment of the C-276/Q235-B Bimetallic Composite Plate
Authors: Wang Bin , Xue Xiao Jun , Lei Bo Bo , Wang Liang , Xu Ming
Published: March 2016

For the problem that stress relief annealing has a great effect on corrosion resistance and mechanical properties of the C-276/Q235-B bimetallic composite plate, the microstructure and mechanical properties of the C-276/Q235-B bimetallic composite plate at different heat treatment processes were investigated in the present investigation. The results showed that after 560°C,580°C and 600°C heat treatment, the tensile strength of composite plate was in 515-530MPa and elongation rate was in 25.6-33%, which could meet the requirements for industries. Corrosion tests were conducted according to A and B methods of ASTM G28 standard, corrosion resistance of composite plate after 560°C, 580°C and 600°C heat treatment exhibited a small difference with supplied C-276 alloy. Microstructure of composite plate after 580°C heat treatment exhibited a single austenite without intermediate phase and after 650°C heat treatment with small amounts of intermediate phase. The optimal heat treatment process for the C-276/Q235-B bimetallic composite plate was air cooling after 4 h heat treatment at 580°C.
Influence of Different Conditions on the Precipitation of Metatitanic Acid to Synthesis Rutile TiO2 via Sulfuric Acid Process
Authors: Zhou Qiang , Liu Qing Cai , Yao Lu , Ren Shan , Zhu Bo Hong , Meng Fei , Lu Rui Fang
Published: March 2016

The formation of metatitanic acid particles in the form of rutile TiO2 is an important step in the sulfuric acid process used to manufacture white pigment. F value, temperature and stirring speed were investigated to study their influence on the particle size and distribution in this paper. The results showed that suitable size and narrow particle size distribution were obtained in metatitanic acid on the condition that F value was 2.02, the temperature was 95°C and the stirring speed was 300r/min. Metatitanic acid was calcined above 850°C to form rutile TiO2. The crystal structure and micromorphology of TiO2 were characterized by XRD and SEM, respectively. The results demonstrated that a rutile TiO2 with high crystallinity was prepared.
Thermal Aging Effect of 17-4PH Martensitic Stainless Steel Valves for Nuclear Power Plant
Authors: Bai Bing , Zhang Chang Yi , Wang Jia Sheng , Tong Zhen Feng , Lv Qun Xian , Yang Wen
Published: March 2016

In this work, impact toughness and tensile properties of valve stem used in NPP are obtained. Combining with microstructure analysis of fracture morphology and metallurgical structure, the thermal aging behavior of the martensitic stainless steel is studied. The results show that the thermal aging embrittlement is significant when the valve stem serves in high temperature for a long time. The ductile to brittle transition temperature (DBTT) and the hardness increase, and the upper platform energy decreases.