bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic Field-Enhanced Shape Memory Effect in Ni51.6Mn23.4Ga25 Single Crystals
Authors: Cui Y.T. , Zhu Z.Y. , Chen J.L. , Liao K.J. , Wang W.L. , Wu G.H.
Published: March 2009

We have performed the various measurements of the transformation strain with and
without the different external magnetic fields on the Ni51.6Mn23.4Ga25 single crystals. A stress-free and two-way thermoelastic shape memory, with -1.15% strain (negative sign represents the shrinkage) and 6 K temperature hysteresis, has been found in the single crystal. The deformation can be enhanced up to -2.35% with a bias field 1.2 T applied along the measurement direction of the parent phase [001] crystallographic axial direction. Turning the field laterally applied to [010] and [100] directions of the parent phase, however, the strain was suppressed by the field of 1.2 T to 0.56% and –0.55%, respectively, a different deformation scene. Moreover, it is found that even the field of 1.2 T does not have a significant influence on the phase transition temperature and the temperature hysteresis, which indicates that the mechanism of field-enhanced strain in this material is the twin boundary motion.
Characterization of Martensitic Transformation in Ferromagnetic Shape Memory Alloys Co-Ni-Ga Melt-Spun Ribbons
Authors: Meng F.B. , Li Yang Xian , Liu H.Y. , Qu J.P. , Zhang M. , Liu G.D. , Liu Z.H. , Dai X.F. , Chen J.L. , Wu G.H.
Published: March 2009

The martensitic transformation in Co50Ni20Ga30 ribbon has been characterized in detail by means of X-ray diffraction and magnetic measurements. The sample showed a structural transition from the body-centered cubic with indexed lattice parameters of a=5.743 Å to martensite with a tetragonal structure with lattice parameters of a=b=5.422 Å and c=6.401 Å. (c/a>1). By comparing the results of the diffraction intensity and the magnetic susceptibility measurements, we found that the proceeding of the martensitic transformation can be divided into several different
steps during cooling from 283 K to 213 K. During heating from 673 K to 833 K, the peak width became very wide and the intensity became very low. It reveals an order-disorder transformation.
New Piezoelectric Composites-Design, Fabrication and Characterization
Authors: Wakashima Kenji , Nishida T. , Inamura Tomonari , Hosoda Hideki
Published: March 2009

A new route to designing smart active composites, which deals with fiber-reinforced
in-plane anisotropic piezoelectric lamina and laminates, is proposed and its quantitative procedure formulated. Two examples of design are highlighted: unidirectionally active laminate and twist bimorph. Some progress in experimental work on the latter is briefly described.
The Novel Method of Structural Health Monitoring Using FEM and Neural Networks
Authors: Zheng Shijie , Wang Hong Tao , Liu Lifeng
Published: March 2009

In this paper, a new method of combining computational mechanics and neural networks for prediction of composite beam delamination is proposed. One beam with delamination, as well as a ‘healthy’ beam with no delamination, had a four-ply symmetric carbon/epoxy composite design, were fabricated simultaneously. The delamination was assumed at different location of the beam, and then the finite element analysis was performed and the modal frequencies of the composite beam were obtained, which were used to train the neural network. The piezoelectric patch was attached to the top of the composite beam to measure its modal frequencies. A feedforward backpropagation neural network was designed, trained, and used to predict the delamination location using the experimental modal values as inputs. The experimental results demonstrate that the predicted delamination location and size error is small.
Magnetic Properties of Fe-Pt Nanoparticle Protected by PVP Polymer
Authors: Ohmori Kazuhiko , Umeda Tomonori , Sakaguchi Takuya , Doi Masaaki , Huayong Pan , Asano Hidefumi , Tanaka Nobuo , Matsui Masaaki
Published: March 2009

Annealing effect on the magnetic properties of Fe-Pt nanoparticle was investigated. Fe-Pt nanoparticles were synthesized by the chemical reduction of H2PtCl6 and the decomposition of Fe(CO)5 in the presence of PVP polymers. The samples were annealed at several temperatures from 350°C to 600°C and the structural and magnetic properties were studied by TEM, XRD and magnetization measurements. FePt nanoparticles as-synthesized showed super-paramagnetism and annealed samples at temperatures more than 400°C, ferromagnetism. The crystal structure of
as-synthesized sample was disordered fcc, but chemically ordered fct, when it was annealed at more than 400°C. The annealing effects are the concatenation or agglomeration of nanoparticles accompanied with the increase in particle diameter and with the ordering of the FePt superlattice. The critical diameter for emergence of ferromagnetism of FePt particle has been considered to be 3.6 to 5.6 nm in mean diameter, under the existence of the ordered L10 phase The blocking temperature as a function of the annealing temperature was investigated.
The Effect of Antiferromagnetic Element Manganese on the Magnetic Properties of α-Fe/Nd2Fe14B Magnets
Authors: Xie Guo Zhi , Wang Zhi , Wu Yu Ping , Lin Ping Hua , Du You Wei
Published: March 2009

The addition of manganese into Nd9Fe85-xMnxB6（X=0,0.5,1） was found to enhance the magnetic properties of a -Fe/Nd2Fe14B magnets. After optimal annealed, the coercivity and remanence ratio increased from 0.34MA/m to 0.4MA/m and from 0.70 to 0.72, respectively, for the increase of x from 0 to 1. The XRD patterns indicated the addition of manganese could promote crystallization of as-spun samples. Moreover, the XRD spectra showed almost same grain sizes
obtained for the optimal annealed samples. Thermomagnetic analysis (TMA) measurement indicated that the doping of Mn reduces the Tc of the Nd2Fe14B phase and raises that of a-Fe phase in the system. It is believed the exchange coupling between the Nd2Fe14B phase and a-Fe phase was partly changed by Mn addition, which is the reason for the enhanced magnetic properties and the change of Tc.
Magneto-Transport Study on Ni1-xMnx(0.23<x<0.3) in High Fields up to 30T
Authors: Yamada Koji , Honda Zentarou , Luo Jiao Lian , Okazaki Teiko
Published: March 2009

Giant negative magnetoresistance (MR) up to 15 % were observed for nano-scaled grains of Ni1-xMnx(0.23<x<0.3) in high fields up to 30 T. The crystal grain size (≈5nm) was obtained by an adequate annealing condition of 630 K, 200hrs. The sample resistance decreased linearly with magnetization increases in each magnetization range for different x, and decreased with the same slope even for different x. The observed negative MR is plausibly explained by the scattering of carriers by the anti-parallel spin pairs of residual Mn-Mn clusters.
Exchange-Bias of NiFe/NiO Bilayer
Authors: Noh Eun Sun , Lee Hyuck Mo
Published: March 2009

Exchange-bias (Hex) of NiFe/NiO bilayers grown epitaxially on MgO(100) and MgO(111) have been measured in order to understand exchange biasing phenomena more clearly. According to HRXRD, the separate reflections of MgO and NiO were observed, which implied that NiO layers grew epitaxially on MgO
substrates. The rms roughness (Rrms) of NiO on MgO(100) measured by AFM was 1.79 Å while that of NiO on MgO(111) was 17.85 Å. Despite a higher Rrms, the value of Hex, 85 Oe in the case of NiFe/NiO on MgO(111) was larger than that of NiFe/NiO on MgO(100), 47 Oe, probably due to stronger effect of (111) texture of NiO surface. But low Hex of NiFe/NiO on MgO(111) implied that exchange biasing was generated by not only upcompensated spins but also compensated spins of NiO. Hex of NiFe/NiO bilayer grown on Si(100) was 118 Oe. According to SEM, grain size of NiO surface grown on Si(100) was very small, which mean its domain size was also very small. The explanation of the effect of domain size was consistent with random field model.
A Study on the Preparation of PEG/FeOx Ferrofluids
Authors: Hu Shuchun , Zhou Zuo Wan
Published: March 2009

As FeOx particles were prepared by oxidation-reduction reaction, the surfactant of
polyethylene glycol (ab. PEG) was used to cover the FeOx particles, thus the PEG/FeOx ferrofluids were obtained. The morphology, structure and composition of the ferrofluids were investigated. The results show that the product is spheric in the shape, and the diameter of the product is obviously influenced by PEG content and slightly influenced by the stirring rate. When the content of PEG increases in the range of 50～350g/L, the diameter of the product decreases. However, when the content of PEG is in the range of 350～750g/L, the diameter increases with the
increasing of PEG content. When the stirring rate is between 50 and 150r/min, the diameter of the product slightly decreases as the stirring rate increases. Moreover, the results demonstrate that the products are mainly constituted of PEG and FeOx, and the value of x in the formula of FeOx can be adjusted by controlling the molar ratio of H2O2 to Fe2+. Further analysis indicates that the organic and inorganic components of the PEG/FeOx ferrofluids are combined by both physical adsorption and coordinate combination.
Role of Alloying Elements on the Cytotoxic Behavior and Corrosion of Austenitic Stainless Steels
Authors: Kim Young Sik , Yoo Y.R. , Sohn C.G. , Oh Keun Taek , Kim Kyoung Nam , Yoon Jae Hong , Kim H.S.
Published: March 2009

Super stainless steel has been used to solve corrosion problems of biomaterials because it shows the excellent corrosion resistance as like Ti and Ti alloys and has better mechanical properties than Ti and Ti alloys. We designed high Mo and Ni bearing super austenitic stainless steel. To obtain desirable microstructure, Cr, Ni, Mo, N contents were controlled. This work focused on the role of alloying elements on cytotoxic behavior and corrosion of stainless steel. In acidic chloride solution,
when the alloys had high PRE values, the alloys showed high pitting resistance and low critical current density. However, in Hanks’ solution, the higher PRE’s alloys showed high critical passive current density. Namely, it was revealed that EDTA among Hanks’ solution played an important role to increase the critical passive current density of high Mo and Ni bearing super stainless steels, regardless of PRE’s value of the alloys. Therefore, even if the PRE values of the alloys were higher, high Ni and Mo bearing alloys would reveal more cytotoxic and high metal ion release rate than 316L stainless steel.
Origin of the Hydrogen Absorbed by Incoherent TiC Particles in Iron
Authors: Tsuzaki Kaneaki , Wei Fu Gao
Published: March 2009

Hydrogen absorption of incoherent TiC particles that were once reported to be strong hydrogen traps in iron at room temperature was investigated by means of thermal desorption spectrometry (TDS). The results indicated that incoherent TiC particles in iron do not trap hydrogen at all at room temperature even they are cathodically charged for a long time. Only at high temperatures and in atmosphere containing hydrogen source, incoherent TiC particles can trap hydrogen. The origin of hydrogen trapped by incoherent TiC particles was justified to be water vapor in the atmosphere during heat treatment.
Influence of Trace Boron and Cooling Rate on the Thermal Embrittlement of 2.25Cr-1Mo Steel
Authors: Guo A.M. , Yuan Z.X. , Yuan W.X.
Published: March 2009

The influence of trace boron and cooling rate on the thermal embrittlement of 2.25Cr -1Mo steel was investigated by thermo-mechanical simulator and SEM analysis. It was proved that the trough in the thermo-ductility curve located between 1000°C and 700°Cand shifted to lower temperature and the temperature range of the trough became shallow and narrow as the boron content increased. When the cooling rate decreased, the ductility trough became shallow and narrow too. This made the steel free of surface crack in CC process.
Recent Advances in Lithium-Based Complex Hydrides for Solid-State Hydrogen Storage
Authors: Nakamori Yuko , Kitahara G. , Kudo T. , Yamagishi T. , Orimo Shinichi
Published: March 2009

Fundamental researches on complex hydrides are recently of great importance to
develop practical hydrogen storage materials with higher gravimetric hydrogen densities than those of conventional materials. First, in this paper, we clarify the correlation between B-H atomistic vibrations in [BH4]－-anion and melting temperatures of MBH4 (M = Li, Na, and K) as indexes of hydrogen desorption temperatures. This investigation implies that partial cation substitutions using smaller sized- and/or higher valenced-cations with higher electronegativities might provide higher energy modes of Raman spectra, and then, lower hydrogen desorption
temperatures. Next, as an example, LiNH2 and its partial cation substitution materials are examined. At the start of the reaction, the hydrogen desorption temperature for LiNH2 with partial cation substitution drastically decreased, with the increase in Mg concentration, to around 370K for the sample with x = 30.
Fatigue Property of High-Strength Carbon Steel Deformed by Repetitive Side Extrusion Process
Authors: Aoki Koshiro , Azushima Akira , Kondo Yoshiyuki
Published: March 2009

The development of an ultrafine grained carbon steel during repetitive shear deformation of side extrusion and the properties after heat treatment were investigated. Side extrusions were carried out at room temperature and the used material was 0.50% carbon steel. The repetitive side extrusions with a constant lateral pressure were carried out up to 3 passes without rotation. The specimens of these steels after 3 passes were annealed at a constant temperature of 600°C changing the treatment time. After side extrusion and heat treatment, the fatigue property was better than that of the as-received material.
Degrading Mechanism on Hydrogen Absorbing-Desorbing Cycle Durability of V- and Ti-Cr-Based BCC-Type Solid Solutions
Authors: Tanaka H. , Kuriyama Nobuhiro , Ichikawa S. , Senoh H. , Naka N. , Aihara K. , Itoh H. , Tsukahara Makoto
Published: March 2009

V- and Ti-Cr-based solid solutions with body-centered cubic (BCC) type
structure were investigated on hydrogen absorbing-desorbing cycle durability by using H2 without and with 10ppm CO (Hereafter they are expressed as H2 and CO/H2, respectively.). The solid solutions showed excellent cycle durability even after 1,000 cycles of hydrogen absorption and desorption under H2 atmosphere. On the other hand, the capacities decreased rapidly during hydrogen absorbing-desorbing cycles in the beginning of the tests under CO/H2 one. The solutions were not disproportionate though the stable monohydride phase increased, that is, stored hydrogen increased gradually. It was observed that not only microscopic pulverization but also nanoscopically fine-grained crystallization occurred in degraded particles. It is considered that the impurity CO influences bulk structure as an intrinsic factor as well as surface area as an extrinsic factor as regarded as ever. This causes the degradation of the cycle capacities.
Study on Thermal Fatigue Behavior of Boride Layer of H13 Steel
Authors: Wu Xiao Chun , Peng Wen Yi , Min Yong An
Published: March 2009

With the Uddeholm self-restricted thermal fatigue method, the transformation of phase constitutions and morphology of boride layer after 3000 cycles of thermal fatigue test was studied by XRD and SEM and the surface residual stress in the process of thermal fatigue test was researched by X-ray Stress Analyzer; the formation of the heat checking of boride layer was also analyzed. The results show that with the high strength and excellent thermal stability of boride layer, morphology of heat checking alters. Therefore, boronizing treatment of H13 steel improves its thermal fatigue behavior.
Evaluation of Thermal Degradation of 2.25Cr-1Mo Steel by High Frequency Ultrasonic Attenuation Measurement
Authors: Byeon Jai Won , Kim C.S. , Kwun S.I. , Hong S.J.
Published: March 2009

It was attempted to assess nondestructively the degree of isothermal degradation of
2.25Cr-1Mo steel by using high frequency longitudinal ultrasonic wave. Microstructural parameter (mean size of carbides), mechanical property (Vickers hardness) and ultrasonic attenuation coefficient were measured for the 2.25Cr-1Mo steel isothermally degraded at 630°C for up to 4800 hours in order to find the correlation among these parameters. The ultrasonic attenuation coefficients at high frequencies (over 35MHz) were observed to increase rapidly in the initial 1000 hours of degradation time and then slowly thereafter, while the ones at low frequencies showed no noticeable increase. Ultrasonic attenuation at high frequencies increased as a function of mean size of carbides. Ultrasonic attenuation coefficient was found to have a linear correlation with the hardness, and suggested accordingly as a potential nondestructive evaluation parameter for assessing the mechanical strength reduction of the isothermally degraded 2.25Cr-1Mo steel.
Damping Behavior of the High Strength Aluminum Alloy Prepared by Rapid Solidification and Powder Metallurgy Process
Authors: Zhao H.T. , Yao Junchen , Ma Yue , Xu Hui Bin
Published: March 2009

The effect of aging treatment on the damping capacity of the high strength damping
aluminum alloy prepared by RS/PM process was investigated. The damping properties of the alloy were examined with dynamic mechanic thermal analyzer (DMTA). The damping capacity, as well as the dynamic Young’s modulus was measured at different temperatures and different loading frequencies. The analysis of microstructure characteristics was performed using transmission electron microscopy (TEM) and X-ray diffraction (XRD). It was found that the damping capacity of the alloy did not change significantly after aging treatment, but changed remarkably with the variation of measurement temperature and loading frequency. Grain boundaries in the alloy became clear and sharp with aging treatment proceeded and contributed to the total damping capacity.
Effect of Electrical Pulse Ageing on Microstructure and Properties of Cu-2.5Fe-0.03P-0.1Zn Copper Alloy
Authors: Huang Jin Liang , Li Qiang , Liu Ping , Dong Qi Ming
Published: March 2009

Milisecond high density electrical pulse was used to age one of the typical IC lead frame materials Cu-2.5Fe-0.03P-0.1Zn copper alloy. The effects of electrical pulse aging on the microstructures, electrical conductivity and microhardness of this alloy were systematically investigated. The experimental results shown that the alloy phase precipitated in Cu-2.5Fe-0.03P-0.1Zn copper alloy during electrical pulse aging could be controlled to the order of nano-size and the ideal match of electrical conductivity and microhardness could be achieved in the condition of optimized parameters of electrical pulse. The electrical conductivity of the alloy was kept at above 60%IACS while the microhardness reached to HV115. A preliminary theoretical analysis was made to explain the unique action of electrical pulse.
Interface Morphology and Solute Partition during Directional Solidification Process of Al-1.5Cu-3Zn Alloy
Authors: Chen Fu Yi , Jie Wan Qi
Published: March 2009

Interface morphology and solute partition during directional solidification process of
Al-1.5Cu-3.0Zn alloy were investigated at temperature gradient of 80K/cm and growth rate between 0.1 and 7.1µm/s. The solid-liquid interface was quenched during directional solidification and the micromorphology at the longitudinal section was examed by optic microscope and SEM. The cellular growth interface and dendritic growth interface were observed and characterized. The distribution of
Cu and Zn was measured by EDS, the equilibrium solute partition coefficients for Cu and Zn in Al-1.5Cu-3.0Zn alloy were obtained to be 0.31 and 0.58. The activity model and concentration model, developed by present authors, were used to calculate the equilibrium solute partition coefficients in Al-1.5Cu-3Zn alloy. The model-calculated results were compared with experimental data.
Electromigration Induced Metal Dissolution in Flip-Chip Solder Joints
Authors: Lin Y.H. , Tsai C.M. , Hu Y.C. , Lin Y.L. , Tsai J.Y. , Kao C.R.
Published: March 2009

The failure of flip chip solder joints through the dissolution of the Cu metallization was
studied. From the location and geometry of the dissolved Cu, it can be concluded that current crowding played a critical role in the dissolution. It can also be concluded that temperature, as an experimental variable, is not less import than the current density in electromigration study. Experimentally, no evidence of mass transport due to thermomigration was observed.
Physical Simulation and Metallurgical Evaluation of Heat-Affected Zone during Laser Welding of Ultrafine Grain Steel
Authors: Wang Qing Feng , Shang Cheng Jia , Fu R.D. , Wang Ya Nan , Chen Wayne
Published: March 2009

Two major challenges in relation to laser welding are abrupt change in metallurgical
aspects and actual assessment of the mechanical properties due partly to very narrow heat affected zone (HAZ) and partly to high mechanical properties gradient. The rapid thermal cycle of laser welding imposed on the HAZ was physically simulated using a Gleeble™ dynamic simulator equipped with a special isothermal quenching device (ISO-Q™), and a relatively large volume of HAZ with a homogeneous microstructure was obtained. The thermal cycles were determined from actual laser welding followed by laser tempering. Estimations of microstructure and mechanical properties of the simulated HAZs of an ultrafine grain steel imposed by laser welding with or without post-weld laser tempering were performed. The results indicate that the simulated HAZs, depending on the thermal history, are composed of lathy martensite with different pocket size and dislocation
density. The impact toughness of as-welded HAZ is improved in contrast to the base material, but is further degraded by a following laser tempering, which, however, alleviates the abrupt change in hardness of as-welded HAZ.
Effect of Sb on the Graphite Morphology and Mechanical Properties in Heavy Section Ductile Iron
Authors: Li Zhen Hua , Li Yan Xiang
Published: March 2009

In order to clarify the effect of antimony on graphite morphology and mechanical
properties in heavy section ductile iron, experiments were carried out using a newly developed thermal simulation system. Results show that with 0.011% addition of antimony, tensile strength of heavy section ductile iron are obviously improved by elimination of graphite degeneration in it, and the effect of antimony is increased when the addition is increased to 0.02%. In the range of 0.01~0.04%, antimony is beneficial to graphite morphology and tensile strength although the advantageous effect on them become not so obvious when addition is exceed 0.02%.
Determination of Optimum Parameters Effect on Kerf Width of 316L Stainless Steel Tube in Nd:YAG Laser Cutting
Authors: Ahn J.M. , Kim H.Y. , Kim T.H.
Published: March 2009

The effects of following four factors, which are laser power, assist gas pressure, cooling rate and scanning speed on the quality characteristics of laser cut 316L stainless steel tubes have been studied. 24 full factorial design and central composite design were used to evaluate optimum condition of process parameters. Regression analysis was used to develop empirical models for the combined effects of the independent process parameters on laser cut quality. As the results, it was
observed that laser power, assist gas pressure and scanning speeds did the major effects on kerf width. The smallest kerf width was obtained with the condition of low laser power, assist gas pressure, scanning speed and moderate cooling rate. Calculated regression model was kerf width = 64.47 + 0.91W + 1.25P + 0.41S + 0.41C2 - 0.45P2
Recent New Development of Spray Formed Ultrahigh-Carbon Steels
Authors: Zhang Jing Guo , Luo Guang Min , Li Xiao Jun , Wang Jun , Yan Biao , Lin Yi Jian , Shi Hai Sheng , Zhang Hao
Published: March 2009

The recent investigations on spray formed ultrahigh-carbon steels (UHCSs) are reviewed. A satisfactory combination of strength and ductility in spray formed UHCSs can be obtained by hot rolling and annealing. The composition and hot rolling have a marked effect on the formation of graphite in UHCSs. The possibility of achieving high strain rate superplasticity in the spray formed UHCS was first revealed by very recent investigations in Shanghai Baosteel Research Institute. The
UHCS processed by a combination of spray forming and hot rolling exhibited high strain rate superplasticity.
The Electromagnetic Confinement and Shaping Process of Liquid Metal
Authors: Song Changjiang , Xu Zhen Ming , Li Jian Guo
Published: March 2009

The Electromagnetic Confinement and Shaping (EMCS) process is a crucibleless melting and mouldless shaping technology by alternating magnetic field. In this paper, stability of the shaping, effect factors of the electromagnetic force and the temperature field and the procedure of the EMCS process are systemically analyzed. The Results indicate that a good coupling of the temperature field and the electromagnetic force is important to stably shape for liquid metal, and the gravity force of liquid metal is more sensitive to change of the temperature (or the current through the inductor) than the electromagnetic force does above the melting point of the sample. Several stainless steel samples were obtained by EMCS process.
The Study of Statistical Model of Mass Liquid Drop during Metal Spray Forming Process
Authors: Zhang Yin , Fan Jun Fei , He You Duo , Ren San Bing , Zhang Jing Guo , Sun De Sheng , Le Hai Rong
Published: March 2009

Through the probability simulation method, the statistical model of mass metal liquid
droplets during metal spray forming process was developed and the ejecting process of molten steel was studied. The distribution of metal liquid droplets, their different initial velocity and the original appear location during spray forming were obtained based on the above computation. After made statistic and analyzed on large number of metal liquid droplets, the forming and motion of liquid drop in whole space were defined in detail, which provided the precondition and reference for further study of liquid droplets deposition process on substrate.
Microstructure and Mechanical Property of Al 5083 Alloy Produced by Spray Forming and Hot Extrusion
Authors: Kim Won Yong , Yeo In Dong , Ra Tae Yeub , Kim Mok Soon
Published: March 2009

The microstructure and mechanical property of Al 5083 alloy produced by spray forming and then subsequent hot extrusion at 693 K were investigated. In order to compare the mechanical property and microstructure permanent casting and hot extrusion was also carried out in air. The spray formed Al 5083 alloy showed the microstructure consisting of Al matrix phase, MnAl6, FeAl6 and Mg2Al3 dispersoids. This microstructural feature analyzed is quite similar to Al5083 alloy prepared by conventional casting. However, a noticeable difference in grain size appeared between those alloys with different processing. It is found that spray forming plays an effective role to reduce the grain size of the present Al 5083 alloy. At room temperature, the yield strength of spray formed alloy was higher than that of permanent casting alloy. At high temperature, spray forming appeared to display a higher elongation value than conventional casting. It is therefore suggested that spray forming of the present Al 5083 alloy promotes to increase yield strength at room temperature and to increase elongation at high temperature. Details will be discussed in relation with the results obtained.
Blow Forming of Recycled 5083 Al Alloy and AZ31 Mg Alloy by Solid State Recycling
Authors: Chino Yasumasa , Mabuchi Mamoru , Hoshika Tetsuji , Lee Jae Seol , Shimojima Koji , Hosokawa Hiroyuki , Yamada Yasuo , Iwasaki Hajime
Published: March 2009

Blow forming characteristics of 5083 Al alloy and AZ31 Mg alloy recycled by solid state recycling were investigated. Scraps with different volume were recycled by hot extrusion and hot rolling in air. Oxide layers, which were contaminants from scrap surface, were distributed parallel to the extrusion direction in the recycled specimens. In the blow-forming test, the specimen from smaller scraps exhibited lower formability. The oxygen concentration in the recycled specimens was
approximately proportional to the total surface area of scraps in the recycled specimen per unit volume. The low formability of the recycled specimens is likely to be attributed to contamination level of oxide.
Investigations on the Photoprotection Ability of TiO2 Coated on Copper
Authors: Subasri Raghavan , Shinohara Tadashi
Published: March 2009

A TiO2 coating when directly applied on copper plate showed an instantaneous ptype behavior, i.e. ennoblement of electrode potential on ultraviolet (UV) illumination though a copper plate when galvanically coupled to an ITO glass coated with TiO2 showed immediate lowering of electrode potential (‘n’-type effect) on illumination under deaerated conditions. The instantaneous p-type effect in the former case was attributed to the presence of a copper oxide layer present between the copper plate and the TiO2 coating. However, a prolonged exposure of the TiO2 coated copper plate showed an n-type effect under illumination after nearly 24 h, following which the electrode potential appeared stable and highly negative. This observation indicated that the photogenerated electrons in TiO2 are capable of reducing the copper oxide layer to ultimately realize the n-type effect of TiO2. The
n-type effect could not be observed in aerated electrolyte solutions. The effect of different conditions in the ambience on the photoeffect of copper coated TiO2 will be discussed.
The Influence of Deformation Condition on Microstructure and Properties of GH4169 Alloy
Authors: Wang Yong Wei , Yang Lu Yi , You Wei , Bai Bing Zhe
Published: March 2009

The influence of temperature, strain rate, strain on mechanical parameters and
microstructure evolution in isothermal deformation of GH4169 alloy were investigated. Lower resistance is obtained under higher temperature and or lower strain rate. However, coarser microstructure also is gained under such condition. The tensile property at room temperature and elevated temperature, permanent properties at elevated temperature of the GH4169 alloy with the treatment of “direct aging after isothermal deformation” are better than those of the same alloy with
the treatment of solid-solution+direct aging after isothermal deformation. Isothermal forming was undertaken for a 1/4 size simulated part of a kind of turbo disk of an aviation engine. Its external is fine and the microstructure of the material was fine and homogeneous for both straightly after forming and after direct aging.
Application to Seismic Dampers in High-Strain-Rate Superplastic Zn-Al Alloy
Authors: Kushibe Atsumichi , Makii Koichi , Chiang L.F. , Tanaka Tsutomu , Kohzu Masahide , Higashi Kenji
Published: March 2009

High strain rate superplasticity has been realised at room temperature for the first time with a ultra fine grained Zn-22wt%Al alloy. Zn-Al alloys have some advantages over low-yieldpoint steels in their low work-hardening rate and high ductility. In addition, Zn-Al alloys are environment-conscious because of no harmful metal like Pb. However, when Zn-Al alloys are subjected to plastic deformation, the strain is localised and local fracture can take place because of their low work-hardening property. In this study, a seismic damper was designed with a Ultra fine
grained Zn-Al alloy. As a result, an ecological and high performance seismic damper, the so-called “maintenance-free seismic damper”, has been successfully developed.
Material Flow Characteristics on the Forward and Backward Solid Extrusion Process
Authors: Kim S.H. , Ryu T.K. , Choi Hyoung Jin , Koo H.S. , Hwang Beong Bok
Published: March 2009

FE simulations were carried out to analyze the influence of die geometry and process condition on the material flow. Deformation pattern and its characteristics in a combined forward and backward solid extrusion process were analyzed in terms of forming loads as the primary parameter, volume ratio of backward solid to forward solid and die pressure between tool-workpiece interfaces. Major parameter is the outer diameter ratio (ODR) of backward solid radius to forward solid radius
with constant outer diameter of forward solid. Furthermore, extensive simulation works were conducted to investigate the effect of minor design parameters on stable material flow such as punch corner radius. The deformation pattern of material flow in a combined solid extrusion process is also presented. The results from the process simulation predict the flow modes of workpiece material and
the die pressure occurring at the contact surface between workpiece and punch. The process of a combined forward and backward solid extrusion was analyzed using a rigid plastic finite element code to get information about the forming load and die pressure distribution, etc.
Modeling of Columnar-to-Equiaxed Transition in Solidified Al-Si Alloys
Authors: Yao X. , Wang H. , He B. , Zhou X.
Published: March 2009

A Cellular-Automaton Finite-Volume-Method (CAFVM) algorithm has been
developed, coupling with macroscopic model for heat transfer calculation and microscopic models for nucleation and growth. The solution equations have been solved to determine the timedependent constitutional undercooling and interface retardation during solidification. The constitutional undercooling is then coupled into the CAFVM algorithm to investigate both the effects of thermal and constitutional undercooling on columnar growth and crystal selection in the columnar zone, and formation of equiaxed crystals in the bulk liquid. The model cannot only simulate microstructures of alloys but also investigates nucleation mechanisms and growth kinetics of alloys solidified with various solute concentrations and solidification morphologies.
Reorientation Phase and Striped Domain Patterns of Thin Films
Authors: Feng Qian , Ye Qing Ying , Wen Zhen Zhen , Jiang Li Qin , Huang Zhi Gao , Zhang Feng Ming , Du You Wei
Published: March 2009

A ferromagnetic monolayer with competing long-range dipolar interaction, short-range interaction and magnetic uniaxial anisotropy is studied using Monte Carlo simulation. Striped domain patterns are found and reveal the microstructure of the magnetization transition at the ground state via the competing between dipolar interaction and uniaxial anisotropy. We present the finite temperature phase diagram and find a temperature-induced magnetization reorientation from out-of-plane to in-plane phase. The influence of the various interactions on the structure of the
striped phase and reorientation behavior has been discussed.
Grain Growth Simulation Based on Potts Model with Different Parameters
Authors: Qin Xiangge , Liu Guo Quan
Published: March 2009

Potts model was often used to simulate grain growth without necessary evaluation of the effect of lattice scale and simulation temperature. It is found in this paper that such parameters may affect the simulation results markedly. The results show that simulations at zero temperature or on a small scale lattice (say, the number of sites on one edge of the square lattice L=1000) cannot reach the steady-state period of grain growth, while large-scale simulations (say, L=2000) at a much higher
simulation temperature can. The steady-state grain size distribution so obtained may be well described by Weibull function other than log-normal or Rayleigh functions.
FE Simulation of Grain Size during the Isothermal Forging of a TC6 Titanium Alloy Disc
Authors: Xiong A.M. , Huang Wei Chao , Chen S.H. , Li Miao Quan
Published: March 2009

Isothermal compression tests were conducted at Thermecmaster-Z simulator, and grain size of the prior a phase was measured at a Leica LABOR-LUX12MFS/ST microscope for quantitative metallography. A methodology to establish a constitutive equation with grain size was proposed with the help of the experimental results. Combining FEM and the present constitutive equation at high temperature deformation, grain size of the prior a phase was simulated during the isothermal forging of a TC6 titanium alloy disc. The present results illustrate grain size and
distribution of the prior a phase in the forging process of TC6 titanium alloy disc in detail. The maximum difference between the calculated results and the experimental is not more than 15%.
Modelling of Solid-State Diffusion Bonding with a Real Rough Surface
Authors: Wu G.Q. , Huang Z. , Li Han Yun
Published: March 2009

By using the real information of the intended bonding surface and considering the effect of the diffusion distance in a definite time, a new theoretical model for diffusion bonding was proposed. The model, reflecting the characteristic of real bonding process effectively, realizes the visualization and simulation of the bonding process in which many voids disappear dynamically. The results show that the simulation is close to those experimental results from the phenomena of voids closure.
Analytic Model for Non-Steady State Heat Transfer of Powder Pressing Roller
Authors: Chang H.J. , Han Heung Nam , Moon M.W. , Lee Kwang Hee , Oh Kyu Hwan
Published: March 2009

An analysis for non steady state heat transfer of a hot pressing roller was suggested in 1-dimensional model. The surface temperature on hot pressing roller was predicted by using surface contact heat transfer coefficient calculated with induced analytic solution. We calculated the size of iron powder, influencing on surface contact heat transfer coefficient. Since coarse iron powder has reduced heat transfer coefficient during contacting on roll surface with smaller contact area,
temperature on roller surface has been expected to decrease. This predicted temperature by the analytic model was fairly reasonable in comparison with experimental data and finite element model.
An Analysis of the Riveting Process as 2-D Frictional Contact Problem
Authors: Jang D.H. , Hwang Beong Bok , Hwang Sun Keun , Min Kyung Hoon , Choi Hyoung Jin
Published: March 2009

A frictional contact model is adopted for the analysis of conventional solid rivet setting. Material properties for the selected plates and rivets are obtained from analytical method using elastic constants and tensile strengths for each material. Rigid- and elasto-plastic models are selected for process analysis in this paper. Process variables are selected to investigate the effect of variables on
the successful rivet setting and servicing in any structure as force transmitting member. Major variables in riveting process are material variables such as material properties and geometrical variables, which are dimensions of head, shank, and blank diameters. Analysis in this study is concentrated on the influence of variety of materials and of shank dimensions on the contact area after rivet setting, i.e. after forming process of rivet head. Soft and hard materials are selected as mother
materials to investigate how the selection of material influences on the riveting process in quantitative manner. The geometry of head is closely investigated through simulation in terms of contact status, i.e. contact area between rivet head and mother material, which would affect the snap fit joint by riveting.
A Marco-Homogenous and Micro-Heterogeneous Model for Self-Propagating High Temperature Synthesis (SHS)
Authors: Zhang Jin Yong , Fu Zheng Yi , Wang Wei Min , Zhang Qing Jie
Published: March 2009

Recently research shows that heterogeneous model is needed to explain some complex combustion behaviors in SHS. However, more heterogeneous details be considered more difficulties will be faced. A micro-heterogeneous & macro-homogeneous model is proposed in this paper based on some previous works for this problem. Combustion compact is divided into lots of little units, which are composed of a large number of small particles. Considering a well-mixed situation, properties of every unit must be almost the same, so the compact can be
treated as a macro-homogeneous system on the scale of these little units. During the combustion, every unit will have a heterogeneous properties and change; it can be gotten by a micro-heterogeneous model. Therefore, the micro-heterogeneous characters are connected with the Marco-combustion behaviors. Combustion dynamics of Ti-C-Fe system was studied to certify this model. Results show well consistency with experiments results.
Optimization of Tube Hydroforming Process by Using Fuzzy Expert System
Authors: Park K.S. , Kim B.J. , Moon Young Hoon
Published: March 2009

In the tube hydroforming process, a tube is placed into the die cavity and the ends of the tube are sealed by fixing the axial cylinder piston into the ends. Then the tube is pressurized with a hydraulic fluid and simultaneously the axial cylinders move to feed the material into the expansion zone. In this study, the empirical and the quantitative relationship between process parameters and hydroformabillity are analyzed by fuzzy rules. Fuzzy expert system is an advanced expert system
which uses fuzzy rule and approximate reasoning. Many process parameters are converted to the quantitative relationship by use of approximate reasoning of fuzzy expert system.
Finite Element Analysis for the Transverse Mechanical Behavior of Fiber-Reinforced Three-Phase Metal-Matrix Composites
Authors: Zhang M. , Zhang W.L. , Gu M.Y.
Published: March 2009

To improve the transverse properties of fiber-reinforced metal matrix composites, a
three-phase material model was proposed. In the model the reinforcing fibers are surrounded by a weak metal matrix, which in turn is encircled by another strong metal matrix. The weak matrix acts as a role to protect the fibers from damage and the strong matrix acts as a role to improve the transverse properties of the composite. Based on the material model, FEM model was established
and parameter analysis was carried out to determine the influence of matrix strengths and fibers spatial distribution on the transverse mechanical behavior of the three-phase composite. It was found that the yield strength of the three-phase composite was mainly dictated by the matrix directly surrounding fibers and the effect from another matrix on the yield strength can be neglected. The three-phase composite has a higher transverse strength with hexagonal fiber arrangement than
with regular square fiber arrangement.
Fuzzy Modeling of the Magnetostrictive Hysteresis for TbDyFe Actuator
Authors: Mao Jian Qin , Ding Hai Shan , Xu Hui Bin , Jiang Cheng Bao , Zhang Hu
Published: March 2009

A mechanical properties prediction model for cobalt-free maraging steel was built upon the experimental data by fuzzy identification method. A method of fuzzy identification based on fuzzy clustering and Kalman filtering is proposed. The results showed that good correlations between the predicted result and the experimental data. The technique proposed could be served as a reliable tool for cobalt-free maraging steel mechanical properties control and design.
Compressive Properties and Energy Absorption of Hollow Sphere Aluminum
Authors: Yamada Yasuo , Wen Cui E , Asahina Tadashi , Katou Kiyotaka , Sonoda Tsutomu , Mabuchi Mamoru
Published: March 2009

Manufactured cellular aluminums have been developed for a wide range of automotive applications where weight savings, improved safety, crashworthiness and comfort are required. The plateau deformation behavior of cellular aluminums under compressive loading makes this new class of lightweight materials suitable for energy absorption and comes close to ideal impact absorbers. In the present study, aluminum hollow hemispheres were firstly processed by pressing. Hollow sphere aluminum samples with a body-centered cubic (BCC) packing were then fabricated by bonding together single hollow spheres, which were prepared by adhering together hollow hemispheres. Hollow sphere aluminum samples with various kinds of sphere wall thicknesses of 0.1 mm, 0.3 mm and 0.5 mm but the same outside diameter of 4 mm were investigated by compressive tests. The effects of the sphere wall thickness on the mechanical properties and energy absorption characteristics were investigated.
Aging Properties Prediction of the Lead Frame Cu-Cr-Sn-Zn Alloy via Neural Network
Authors: Li He Jun , Su Juan Hua , Dong Qi Ming , Liu Ping , Ren Feng Zhang
Published: March 2009

The aging process of lead frame Cu-Cr-Sn-Zn alloy has only been studied empirically by trial-and-error method so far. This paper builds up the prediction model of the aging properties via a supervised artificial neural network(ANN) to model the non-linear relationship between parameters of aging process with respect to hardness and electrical conductivity properties of the alloy. The improved model is developed by the Levenberg- Marquardt training algorithm. The predicted
values of the ANN coincide with the tested data. So the ANN system is effective and successful for predicting and analyzing the properties of Cu-Cr-Sn-Zn alloy. The optimized processing parameters are available at 475 C ° -520 C ° aging for 2h-1h.
Synthesis and Mechanical Properties of Conventionally Cast Icosahedral Particle-Reinforced Al-Mn(-Cu)-Be-Si Alloys
Authors: Fleury Eric , Chang H.J. , Kim D.H. , Kim Do Hyang , Kim Won Tae
Published: March 2009

The microstructure of the Al-Mn(-Cu)-Be-Si alloys analyzed by X-ray diffraction and TEM consisted of icosahedral (i) quasicrystal particles embedded in aAl matrix. The conjoint addition of Si and Be elements enabled the i-phase formation in Æ10 mm specimens prepared by conventional casting technique. The size, volume fraction and stability of the i-phase were found to be dependent on the Mn content. The addition of 2 at.% Cu did not affect the formation and stability of the i-phase but
contributed significantly to the enhancement of the mechanical properties.
Synthesis and Properties of GaN Nanostructures
Authors: Ma Hong-Lei , Xue Cheng Shan , Yang Ying Ge , Zhang Hui Zhao , Ma Jin , Liu Jian Qiang , Xiao Hongdi , Zong Fu Jian
Published: March 2009

One-dimensional GaN nanostructure films were successfully synthesized by the recently developed sputtering post-nitridation technique. The morphology and structure of GaN nanowires are investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The results indicate that the crystalline GaN nanostructures
have a hexagonal wurtzite structure, and there is not any other phase such as Ga2O3 or Ga in the specimen. It also confirms that high quality crystal was obtained in the resulting sample due to the lattice defects decreased and the crystallinity improved in the process of nitridation at high temperature. The growth mechanism of the GaN nanostructures is briefly discussed.
Effect of Alloy Composition on the Glass Forming Ability in Ca-Mg-Zn Alloy System
Authors: Park Eun Soo , Kim Won Tae , Kim Do Hyang
Published: March 2009

The effect of alloy composition on the glass forming ability (GFA) of the Ca-Zn-Mg alloys has been investigated in the present study. The alloy compositions investigated are near Ca-rich ternary eutectic composition; Ca60Mg15Zn25, Ca65Mg10Zn25, Ca65Mg15Zn20, Ca65Mg20Zn15, and Ca70Mg15Zn15. Bulk
metallic glass (BMG) samples with the diameter larger than 5 mm are fabricated by conventional copper mold casting method in air atmosphere. Among the parameters representing the glass forming ability, Trg and γ parameters exhibit good correlation with the maximum diameter of the fully amorphous structure in the alloy compositions investigated in the present study.
Nucleation Barrier for the Precipitation in Nanosized Al-4wt%Cu Alloy
Authors: Xu Shan Qing , Guo Zheng Hong , Hsu T.Y.
Published: March 2009

The possibility of Al2Cu( q) precipitation in nanosized Al-4wt%Cu alloy is predicted based on the theory of homogeneous nucleation. The result indicates that the initial concentration of Cu in parent phase has little influence on the nucleation event when the grain size is larger than a critical size. On the other hand, when the grain size is smaller than the critical size, the formation of a stable Al2Cu nucleus will be prohibited completely due to the insufficient initial concentration of Cu.