bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Cold Working on Deformation Behavior and Shape Memory Effect of Ti-Ni-Nb
Authors: Okita Keisuke , Okabe Nagatoshi , Sakuma Toshio , Semba Hiromasa , Mihara Yuji
Published: March 2009

Thermo-mechanical characteristic of shape memory alloy depends on cold working and heat treatment, because these processes can control the amount of defects including dislocation and precipitation [1]. In this study, the influence of cold working on the deformation behavior and the transformation characteristics was investigated on the Ti-Ni-Nb shape memory alloy (SMA). Both the tensile test and the shape recovery test were performed for the wire specimens of 1mm in the diameter with some different rates of cold working. The shape recovery tests were performed for the wire specimens of different cold working rates until the various levels of maximum applied strain, and the reverse-transformation characteristics on the process of heating after unloading were studied. It is clarified that the higher cold-working rate improves the shape memory properties of the alloy.
Anomalies in Physical Properties Related to the Stability of the B2-Phase in Ti-Ni-Co Shape Memory Alloys
Authors: Choi Mi Seon , Fukuda Takashi , Kakeshita Tomoyuki
Published: March 2009

Martensitic transformation behavior of a series of Ti-(50-x)Ni-xCo at% alloys (x = 4, 8, 12, 16, 20) has been examined by electrical resistivity, magnetic susceptibility and specific heat measurements, in order to know the phase stability of the B2-type structure. The 4Co and 8Co alloys exhibit a typical first order B2-R-B19' transformation. The 12Co alloy probably transforms to the R-phase, but its microstructure is composed of small domains with about 10 nm in diameter, being
quite different from the microstructure of a typical R-phase formed by nucleation and growth. The 16Co and the 20Co alloys do not show any martensitic transformation but anomalies of the electrical resistivity and magnetic susceptibility being similar to those of the 12Co alloy appear in these alloys. The diffuse scattering of 1/3<110> is also observed in the 16Co alloy. The Debye temperature decreases and electronic specific heat coefficient increases with increasing Co content.
Crack-Healing Behavior of Mullite/SiC Particle/SiC Whisker Multi-Composite and Mechanical Properties of the Multi-Composite
Authors: Nakao Wataru , Lee Sang Kee , Yokouchi Masahiro , Takahashi Koji , Ando Kotoji
Published: March 2009

For improving fracture toughness as well as endowing with excellent self-crack-healing ability, mullite/SiC particles /SiC whiskers multi-composites were developed. Crack-healing ability and the mechanical properties of the specimens were investigated. Mullite/ 20 vol% SiC whiskers, mullite/ 25 vol% SiC whiskers and mullite/ 15 vol% SiC whiskers/ 10 vol% SiC particles composites can completely heal the pre-crack of 100 ım in surface length by heat-treatment at 1300 oC for 2 h in
air. However, not completeness of the strength recovery was caused for mullite/ 15 vol% SiC whiskers composite by crack-healing. In spite of the same SiC content, the crack-healing ability of mullite/ 15 vol% SiC whiskers/ 10 vol% SiC particles composite is superior to that of mullite/ 25 vol% SiC whiskers composite. Admixing with SiC whisker was effective for improvement in fracture toughness. Additionally, the fracture toughness was not reduced by admixing with SiC particles.
Magnetostrictive Material Actuator Based Active Vibration Control-a Heuristic Iterative Learning Control Method
Authors: Song Zhao Qing , Mao Jian Qin , Li Chao , Xu Hui Bin , Jiang Cheng Bao
Published: March 2009

A heuristic iterative learning control (ILC) design scheme is presented and is applied to the controller design of the active vibration control. A magnetostrictive material actuator is used as experimental equipment for active vibration control in this paper. The merit of the presented ILC scheme is that it is not necessary to build the mathematical model of the magnetostrictive actuator. The experimental result shows that the controller designed is efficient for active vibration control.
On Control of Six Freedom Magnetostrictive Smart Structure
Authors: Mao Jian Qin , Li Chao , Xu Hui Bin , Jiang Cheng Bao , Li Lin
Published: March 2009

A six degree-of-freedom (DOF) Stewart platform is constructed, which consists of six TbDyFe alloy magnetostrictive actuators, and applied to active vibration control. To control the smart structure, a real time computer control system is built. An improved adaptive filtering algorithm is proposed in this paper, which is used for the computer control system. The results of experiments show that the smart structure and the proposed algorithm are efficient for active vibration control. More than 30 dB of vibration attenuation is achieved in real-time experiments.
Electrochemical Impedance Spectroscopy of Nd-Fe-B Magnet Prepared by Spark Plasma Sintering
Authors: Liu Wei Qiang , Yue Ming , Wang Gong Ping , Zhang Jiu Xing , Li Tao , Xiao Yao Fu
Published: March 2009

Electrochemical impedance spectroscopy (EIS) tests of anisotropic Nd-Fe-B magnets prepared by spark plasma sintering (SPS) technique were carried out to investigate their corrosion kinetics in different solutions. According to the Nyquist and Bode diagrams, convenient equivalent circuit was modeled and the values of the proposed equivalent circuit components were calculated. It was found from the EIS plot formats that the electrochemical reaction of SPS Nd-Fe-B magnets was controlled by the step of surface charge transfer i.e. activation polarization in alkaline solution, while controlled by step of active substances adsorption on the magnet surface in salt and acidic solutions. Compared with conventional sintered Nd-Fe-B magnets, the SPS Nd-Fe-B magnets possess better chemical stability in saline and weak acidic environment.
New YDy-Based R2(Fe,Co)14B Melt-Spun Magnets (R=Y+Dy+Nd)
Authors: Tang W. , Dennis K.W. , Kramer Matthew J. , Anderson I.E. , McCallum R.W.
Published: March 2009

The effects of the ratio of Y to Dy as well as the effect of Nd and Co substitutions on
magnetic properties in [Ndx(YDy)0.5(1-x)]2.2Fe14-yCoyB ribbons melt-spun at 22 m/s have been systematically studied. (Y1-zDyz)2.2Fe14B ribbons with a ratio z of 0.25 or 0.5 simultaneously obtains a smaller temperature coefficient of remanence (α ) and coervicity (β ) which are much smaller than those of Nd-based Nd2Fe14B ribbons. In [Ndx(YDy)0.5(1-x)]2.2Fe14-yCoyB ribbons, Nd substitution (x=0 to 0.8) can improve the maximum energy product (BH)max of annealed ribbons but degrades the temperature stability of the magnetic properties. The ribbons with x=0.4 and y=0 yield a (BH)max of 8.7 MGOe. For these ribbons, the α and β are -0.07 and -0.31 %/°C in the temperature range of 27 to 127°C, respectively. Increasing Co (x) from 0 to 3, slightly decreases coercivity Hcj
from 21.5 to 16.3 kOe, but keeps the (BH)max in the range of 8.6 to 10.2 MGOe. The optimal sample with x=0.5 and y=1.5 obtains a (BH)max of 10.2 and 5.0 MGOe at 27 and 250°C, respectively. Its α and β are -0.11 and -0.30 %/°C, respectively. These results show that studied ribbons are very promising to develop into high temperature isotropic bonded magnets capable of operating at or above 180°C.
Study on Two-Phase Nanocrystalline Nd2Fe14B/α-Fe Bonded Magnet
Authors: Ni Jiansen , Wang Zhen , Xu Hui , Wu Yi Seng , Zhou Bangxin , Hou Xueling , Li Ying
Published: March 2009

Two-phase nanocrystalline ribbons were prepared by melt-spun and subsequent heat treatment. Excellent magnetic properties of the bonded magnet were achieved as follows: Br = 0.67 T, JHc = 664.3 kA·m-1, (BH) max = 75.0 kJ·m-3. The mean grain size of the ribbons heat-treated at 710 °C/ 4 min is about 50 nm. After heat-treated the ribbons at 750 °C/ 4 min, the mean grain size is about 100 nm.
The Magnetic Entropy Changes in Gd1-xCrx Alloys
Authors: Huang Song Ling , Wang Dun Hui , Han Zhi Da , Ren S.K. , Su Zheng Hua , Du You Wei
Published: March 2009

A series of Gd1-xCrx (x=0.01,0.03,0.05 and 0.07) alloys have been prepared by arc melting. After introducing a small quantity of Cr into Gd, the Curie temperatures of these alloys increase. Magnetic entropy changes at the Curie temperature of Gd1-xCrx (x=0.01, 0.03, 0.05) alloys are nearly the same as that of Gd. However, compared with Gd, the magnetic entropy changes of Gd1-xCrx (x=0.01, 0.03, 0.05) alloys remain at a high level in a wider temperature range. So Gd1-xCrx (x=0.01, 0.03, 0.05) alloys are more suitable as magnetic refrigerant to be used in Ericsson Recycle for room temperature magnetic refrigeration. Our results and the fact that Cr is quite cheaper than Gd, suggest that Gd1-xCrx alloys maybe utilized as refrigerant in room temperature magnetic refrigeration.
Dental Precision Casting of Ti-29Nb-13Ta-4.6Zr Using Calcia Mold
Authors: Niinomi Mitsuo , Akahori Toshikazu , Takeuchi Tsutomu , Katsura Shigeki
Published: March 2009

Duplex calcia coating method where firstly fine calcia was coated on wax pattern and then fine calcia reinforced silica fiber was coated on the fine calcia coated wax pattern, that is, duplex calcia coating method, was applied for making mold. The surface of Ti-29Nb-13Ta-4.6Zr cast using the duplex calcia coating method show very fine metallic lust. The thickness of alpha case formed on the surface of Ti-29Nb-13Ta-4.6Zr is much thinner comparing with the case where the commercial
magnesia mold for casting conventional titanium and its alloys for dental applications is used. The duplex calcia coating method is highly expected to be put into practical use for dental precision casting of Ti-29Nb-13Ta-4.6Zr. The dental crown of Ti-29Nb-13Ta-4.6Zr is successfully fabricated using duplex calcia coating method.
Ambiguous Transition from Fretting to Sliding of Biomedical Alloys
Authors: Fukui Hisao , Yang W. , Tsuruta Shozo , Kaikawa K. , Sugimura A. , Takeda Shoji , Niinomi Mitsuo
Published: March 2009

An intensive amplitude arrangement for reciprocal tribocontact of biomedical alloys,
Ag-20.0Pd-14.5Cu-12.0Au, Au-5.0Pt-2.0Pd-9.2Ag-15.0Cu and Ti-29Nb-13Ta-4.6Zr was conducted in order to check the details of friction and wear alterations around the transition from fretting to sliding. It is shown that the friction force exhibits stagnation for the Ag alloy and decrease for the Au alloy and the Ti alloy in certain domain of oscillating amplitude. Beyond the domain the friction force increases with the amplitude, and below the lower threshold and above the upper threshold triboevent is complete fretting and sliding respectively. Observation of friction-force waveform and SEM topography found, a hybrid mechanism of fretting and sliding is dominant in the amplitude domain, and the strong adhesion between the self-mated alloys is responsible to this exhibition.
Biomedical Properties of Tantalum Coatings Prepared by Multi Arc Ion-Plating
Authors: Cai Wei , Cheng Y. , Zheng Y.F. , Li Hong Tao , Zhao Lian Cheng
Published: March 2009

Ti-50.6 at.% Ni shape memory alloy was coated with tantalum using multi arc
ion-plating technique with the aim to increase its radiopacity and biocompatibility. The surface characteristics were investigated by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The results of XPS survey spectra show that a thin oxide film are formed inside tantalum coating as a result of natural passivation of Ta in atmosphere. The hemocompatibility was
evaluated in vitro by clotting time and platelet adhesion measurement. The results of our study showed that the clotting time of tantalum was higher than that of the TiNi alloys and no sign of accumulation and only slight pseudopodium was observed on the tantalum coatings, suggesting that the tantalum coatings can improve the biocompatibility of TiNi alloy.
A Novel Way to Prepare Nano-Hydroxyapatite/Poly(D,L-Lactide) Composite
Authors: Xiao Yu Mei , Zhao Hui Chuan , Fan Hong Song , Wang Xin Lin , Guo L.K. , Li Xu Dong , Zhang Xing Dong
Published: March 2009

A composite of needle-like nano-hydroxyapatite (n-HA)/poly (D,L) lactide (PDLLA) was prepared. The n-HA crystals were poorly crystallized and uniformly distributed in the composite with a crystal size of 10–20 nm in diameter by 40–60nm in length，which was smaller than that of pure nano-HA. Molecular interactions and chemical bonds might present between n-HA and PDLLA in the composite, which were revealed by IR and XPS. The synthetic n-HA/PDLLA
composite had a good homogeneity and could be a bioactive material for bone defect especially for load-bearing bone repair, which is more potential than pure HA or pure PDLLA.
Materials Selection and Scaffold Construction for Liver Tissue Engineering
Authors: Feng Qing Ling
Published: March 2009

To design the scaffold with suitable properties for the development of tissue engineered livers, materials design, selection and scaffold construct are three dispensable steps to be followed consequently. Firstly, some natural materials such as collagen, chitosan and alignate as well as some prevailing aliphatic polyester such as poly(lactic acid) (PLA), polyglycolide (PGA) and their copolymers poly(lactide-co-glycolide) (PLGA) are selected and characterized by hepatocyte culture. The experimental results reveal that the natural materials with excellent biocompatibility are not suitable as the scaffold alone because of the poor mechanical properties. At same time, aliphatic polyesters with good mechanical properties and biodegrade abilities are also proved inapplicable for hepatocytes for the lack of right cell recognition sites. Among our study scope, the hybrid materials
such as collagen/chitosan or collagen/chitosan/heparin are the very promising candidates for hepatic tissue engineering scaffold. Secondly, two novel designs composed of collagen and PLGA, namely, the spindle porous scaffold with separated channels for transportation of nutrient, plasma and the one made by dewaxen-casting method are initiated respectively.
Influence of Bone Structure on Mechanical Properties of Bovine and Swine Compact Bones
Authors: Kim Jong Heon , Niinomi Mitsuo , Akahori Toshikazu
Published: March 2009

Recently, more attention has been focused on the research and development of
biomaterials such as an artificial bone because of the rapid-increasing demand for biomaterials from the aging society in the world. However, the study on the bone itself is not enough. In particular, there is little information about the fracture toughness, and fatigue property of bones, and effect of the microstructure on the fracture characteristic. In this study, the fracture toughness of the bovine and swine humerus and femur as well as the fatigue property of the bovine humerus and femur was investigated with relating microstructures. The fracture toughness of plexiform bone is greater than that of haversian bone, and the fatigue strength of the plexiform bone taken from the humerus and femur is a little greater than that of the haversian bone taken from the humerus and femur in particular in high cycle fatigue life regions.
The Electrochemical Characteristics of Mg-Based Alloy Prepared by HT (Heat Treatment) and MG (Mechanical Grinding) for Nickel-Metal Hydride Secondary Batteries
Authors: Kim Young Ha , Chung Uoo Chang , Nam Byungwook , Chung Won Sub , Kim In Gon
Published: March 2009

Mg2Ni powder was heated up to 880°C which is higher than the melting point of Mg2Ni alloys (760°C) for 30 minutes and immediately cooled into water (14°C). And then, mechanical ball milling was conducted for 1,4,8,10,12,24 hours respectively. As milling time increased discharge capacity was increased to maximum of 700mAh/g at 12hours then decreased with increasing milling time. The best high rate dischargeability (HRD) characteristic also obtain at the 12 hours ball milling time. Therefore, the ball milling time could be shorten to 12 hours by heat treatment and rapid cooling. Praseodymium (0,0.2,0.5,0.7,1.0%Pr) was added to Mg2Ni alloys. These alloys were ground for 12 hours to investigate the improvement of cycle life. The cycle life was remarkably improved with increasing the amount of Pr. The best amount of Pr was 0.7 wt%.
Hydrogen Diffusion in Ti-Cr Hydrogen Absorption Alloys by Tritium Radioluminography
Authors: Saitoh Hideyuki , Homma Hirofumi
Published: March 2009

Tritium radioluminography has been applied to Ti50Cr50 and Ti40Cr60 alloys with
two-phase structure of BCC phase and Laves phase by examining hydrogen distributions and by measuring a hydrogen penetration profiles. Hydrogen diffusion coefficients in these alloys have been successfully determined by analyzing the tritium depth profile to be 3.3×10-12 m2/s and 1.3× 10-12 m2/s, respectively. This value has been suggested that the hydrogen diffusion in the Laves phase is slower than that in the BCC phase.
Effects of Rare-Earth Content on the Properties of Co-Free MmxMl1-x(NiCuAlZn5)Hydrogen Storage Alloys
Authors: Wang Yi Jing , Yuan Huatang
Published: March 2009

MmxMl1-xNi4.14Cu0.5Al0.3Zn0.06 (Mm=Ce-rich misch-metal, Ml=La-rich misch-metal, x=0, 0.2, 0.4, 0.6, 0.8, 1) alloys have been synthesized by the inter-media alloy method. The properties of these alloys have been systematically investigated by means of X-ray diffraction (XRD), pressure-composition isotherms (PCT), electrochemical impendence (EIS) and cyclic voltammogram (CV). The X-ray diffraction results indicated that these alloys had a CaCu5-type hexagonal crystal structure. With increasing the Mm content, the plateau pressure and volume expansion of their hydrides were increased, but the volume of unit was decreased.
Determination of Die Design Rules for Semi-Solid Die Casting Process and Its Experimental Investigation
Authors: Kang Chung Gil , Seo P.K. , Kim Byung Min
Published: March 2009

Die design rule for semi-solid die casting (SSDC) with A356 electromagnetic stirring (EMS) aluminum alloy, was proposed. The die design rule included inspection of machine, part requirements, parting line determination, sleeve, plunger, gating system, overflow, air vent, ejector pin, and heating line design. The specification of gating system, overflow, air vent, plunger tip, and sleeve suitable for respective part were regulated. Two steps die system of lower-positioned gate and
three steps die system of center-positioned gate were manufactured for 4 automobile suspension parts, based on the die design rule. For the sound filling pattern and solidification behavior, injection speeds of 4 parts were summarized to the interval (from V1 to V4). As a result of observing the microstructure of 4 parts after T6 heat treatment, primary Al-α phase was globularized and fine Si particles were distributed around the grain boundary. The mechanical properties of 4 parts with T6 heat treatment were investigated and showed ultimate tensile strength (UTS) of 330 MPa, yield strength (YS) of 250 MPa, and elongation of 7.5% as average.
Investment Casting of Titanium Matrix Composites
Authors: Sung Si Young , Park Keun Chang , Kim Myoung Gyun , Kim Young Jig
Published: March 2009

The aim of the present work is to investigate the possibility of in-situ synthesis and
net-shape of the titanium matrix composites (TMCs) using a casting route. From the scanning electron microscopy (SEM), electron probe micro-analyzer (EPMA), X-ray diffraction (XRD) and thermodynamic calculations, the spherical TiC and needle like TiB reinforced hybrid TMCs could be obtained by the conventional casting route between titanium and B4C. No melts-mold reaction could
be possible between (TiC+TiB) hybrid TMCs and the SKKU mold, since the mold is composed of interstitial and substitutional reaction products. Not only the sound in-situ synthesis but also the economic net-shape of TMCs could be possible by conventional casting route.
Effect of Material Properties on the Plastic Straining Capacity of Defective Welds
Authors: De Waele Wim
Published: March 2009

This paper describes the effect of the interrelation between the base and weld metal postyield characteristics on the CMOD (Crack Mouth Opening Displacement) and the straining capacity of a defective weld. The effect is discussed and illustrated by means of test data obtained from standard CTOD and tension loaded wide plate tests.
Nitrogen Porosity in Nitrogen Bearing Austenitic Stainless Steel
Authors: Yang Seong Ho , Lee Zin Hyoung
Published: March 2009

The formation of nitrogen gas pores is affected by various factors such as solidification sequence, solubility of nitrogen, cooling rate, melt pressure, nitrogen content etc. Nitrogen porosity in Fe-16Cr-3Ni-9Mn austenitic stainless steel solidifying to primary d-ferrite that can cause nitrogen gas pores was examined. And also the effect of nitrogen content, cooling rate and melt pressure on nitrogen porosity was investigated.
Microstructure Evolution in a Directional Solidification Process
Authors: Liu Shan , Trivedi R.
Published: March 2009

Models and theories of the microstructure evolution in a directional solidification (DS) process will be firstly addressed. Discrepancies between theories and experiments will be presented. For the thin film sample growth in a temperature gradient stage, the geometrical constraint makes it difficult to compare the experimental primary spacing with theoretical predictions. While for a bulk sample growth, fluid flow always exists in the solidification process despite that the growth interface rejects a lighter or heavier solute. Based on these analyses, the appropriate techniques to conduct DS experiments are proposed that can be used to test models. One is the solidification in a capillary sample where a single cell/dendrite grows. While for array growth in 3 dimensions, long-duration microgravity experiments will be the only viable way to obtain meaningful results.
A Novel Spray Deposition Technology for the Preparation of Aluminum Alloy and Aluminum Alloy Matrix Composite Rings with Large Dimensions
Authors: Chen Zhen Hua , Teng Jie , Yan Hong Ge , Chen Gang
Published: March 2009

A novel spray deposition technology with characteristic of the movable crucible, has been developed to prepare aluminum alloy and aluminum alloy matrix composite rings with large dimensions. The influences of process parameters on the microstructure and properties of the as-deposited rings were systematically investigated and the process parameters were optimized. Up to now, 7075Al/SiCp and A356/SiCp composite rings with the outer diameter of 1200mm, the inner
diameter of 600mm and the thickness of 250mm, and LF6 aluminum alloy ring with the outer diameter of 3500mm, the inner diameter of 3100mm and the thickness of 250mm have been produced respectively. All the as-deposited performs were featured with the grain size about 3~5µm and a homogeneous distribution of ceramic particles the cooling rate up to 104K/s. Moreover, no cracking occurred in the performs because of the lower inner stress. The experimental results indicated that this novel technology was a promising and viable mean for the preparation of metal
rings.
Microstructures of Spray Formed Superalloy GH742
Authors: Li Zhou , Zhang Guo Qing , Tian Shi Fan , Yan Ming Gao
Published: March 2009

Microstructures and hot deformation behaviors of spray formed superalloy GH742 have been studied in this paper. The results indicate that the spray formed superalloy GH742 has high relative density, low oxygen pickup, refined microstructure, and good forgeability. The fully inhibited coarsening of microstructure in spray formed superalloy GH742 has also been found in this study. 32wt% γ¢ and 0.5wt% carbonitrides, (Nb,Ti)(C,N) and Ti(C,N) were found in the as-deposited GH742, and most of them are sub-micrometer.
Experimental and Thermodynamic Modeling of the MnO-SiO2-TiO2-Ti2O3 System
Authors: Kang Youn Bae , Jung In Ho , Lee Hae Geon
Published: March 2009

The MnO-SiO2-TiO2-Ti2O3 system is a key oxide system for well known “Oxide
Metallurgy” for HSLA steel. However, the available thermodynamic data for this system are rare and even the available experimental data are often inconsistent with each other. In the present study, experimental and thermodynamic modeling studies have been carried out on the MnO-SiO2-TiO2-Ti2O3 system. High-temperature equilibration and quenching technique followed by EPMA (electron probe X-ray microanalysis) was used to determine liquidus temperatures and solid solubilities of the crystalline phases such as manganosite, rutile, spinel, pyrophanite, pseudobrookite, tridymite, etc. in the temperature range from 1200°C to 1550°C (1473 to 1823 K) under an atmosphere controlled by CO-CO2 gas mixture. These equilibrium data for the MnO-SiO2-TiO2-Ti2O3 system, combined with previously reported data for this system, were used to obtain an self-consistent set of optimized parameters of thermodynamic models for all phases. In addition, the application of the optimized thermodynamic database to oxide metallurgy was discussed.
The Effects of Free Space in Mould Cavity on Sandglass Extrusion
Authors: Lu W.L. , Wang Y. , Hai Jin Tao
Published: March 2009

Sandglass extrusion is an ultrafine grain size method. Due to the repetitive and multiple extrusions, large strain will be accumulated and ultafine grain size can be obtained. There are some factors that can affect the experimental result of sandglass extrusion. Among these factors, free space in mould cavity is very important, which can affect the forming of the fold during the extrusion. In this paper, the effects of free space in mould cavity on sandglass extrusion have been discussed and theory analysis and experimental results have been reported.
Research and Application of Superplastic Forming Titanium Alloys for Commercial Aircraft Parts
Authors: Gershon B. , Eldror I.
Published: March 2009

Titanium alloys sheets have many attractions for the aerospace industry owing to their high strength, low density, heat resistance and other useful properties. Many of the sheet metal structures in airframes have complex shapes and compound curvatures with intricate details. Superplastic forming (SPF), a most recent advancement in titanium sheet forming technology, exploits the excellent characteristic of >1000% elongation potential for the fabrication of complex
configurations not achievable by conventional methods. SPF technology can also reduce manufacturing cost by shortening the preparation time, eliminating the
need for extensive welding or other joining methods and by reducing the number of manufacturing steps. Consequently, high profit margins may be achieved in serial aircraft production. This paper outlines the research at Israel Aircraft Industries (IAI) of SPF technology and its application in producing complex-shape Ti sheet parts for the new IAI commercial aircrafts, models “G-150” and
“G-200”. Examples of both actual and experimental parts are given, together with details of the manufacturing parameters employed. An economical analysis is also included.
A Study on Gas Pressure for Superplastic Forming of Titanium Alloy Bellows
Authors: Wang Gang , Chen Jun , Ruan X.Y.
Published: March 2009

The complex superplastic forming (SPF) technology applying gas pressure and
compressive axial load is an advanced forming method for bellows made of titanium alloy, which forming process consists of the three main forming phases namely bulging, clamping and calibrating phase. The influence of forming gas pressure in various phases on the forming process are analyzed and models of forming gas pressure for bellows made of titanium alloy are derived according to the thin shell theory and plasticity deformation theory. Using model values, taking a two-convolution DN250 bellows made of Ti-6Al-4V titanium alloy as an example, a series of superplastic forming tests are performed to evaluate the influence of the variation of forming gas pressure on the forming process. According to the experimental results models are corrected to make the forming gas pressures prediction more accurate.
A Modeling Study of Cyclical Phase Transformations
Authors: Lee Jong K.
Published: March 2009

Recent work has shown evidence of cyclical phase transformations taking place during mechanical alloying. Cyclical phase transformations resemble dynamic equilibrium in the sense that both equilibrium and non-equilibrium phases are simultaneously present during milling, but phase fractions vary during cyclical transformations. A brief thermodynamic and kinetic account is first discussed to establish the criteria for cyclical transformations. A two-dimensional molecular
dynamic work is then presented to demonstrate cyclical phase transitions between an equilibrium and a non-equilibrium phase during mechanical alloying. A model binary crystal made of 57 Lennard-Jones atoms is studied to illustrate cyclical transitions between an equilibrium rhombus and a non-equilibrium square phase.
Defect Properties in GaN: Ab Initio and Empirical Potential Calculations
Authors: Gao Fei , Bylaska Eric J. , Weber William J.
Published: March 2009

The defect properties and atomic configurations in GaN have been comparatively
investigated using density functional theory (DFT) and molecular dynamics method with two representative potentials. The DFT calculations show that the relaxation of vacancies is generally small, but the relaxation around antisite defects is large. The N interstitials, starting from any possible configurations, eventually relax into a N+-N< 0 2 11 > split interstitial. In the case of Ga interstitials, the most stable configuration is a Ga octahedral interstitial, but the Ga+-Ga< 0 2 11 >
split interstitial can bridge the gap between non-bounded Ga atoms. The formation energies of vacancies and antisite defects obtained using the Stillinger-Weber potential (SW) are in reasonable agreement with those obtained by DFT calculations, whereas the Tersoff-Brenner (TB) potential better describes the behavior of N interstitials.
The Investigation on Aluminium Alloys Automobile Wheel with Low-Titanium Content Produced by Electrolysis
Authors: Xie Jing Pei , Li Ji Wen , Liu Zhong Xia , Wang Ai Qin , Weng Yong Gang , Song Tian Fu , Liu Zhi Yong , Wang Jie Fang
Published: March 2009

The in-situ Ti alloying of aluminium alloys was fulfilled by electrolysis, and the
material was made into A356 alloy and used in automobile wheels. The results show that the grains of the A356 alloy was refined and the second dendrites arm was shortened due to the in-situ Ti alloying. Trough 3-hour solution treatment and 2-hour aging treatment for the A356 alloy, the microstructures were homogeneous, and Si particles were spheroid and distribute in the matrix fully. The outstanding mechanical properties with tensile strength (σb≥300Mpa) and elongation values (δ≥10%) have been obtained because the heat treatment was optimized. Compared with the
traditional materials, tensile strength and elongation were increased by 7.6~14.1% and 7.4~44.3% respectively. The qualities of the automobile wheels were improved remarkably.
Simulation Study of Thermal Buoyance Influence on Flow Characteristic in Single Outlet Tundish
Authors: Fan Jun Fei , Chen Ya Xian , Ren San Bing , Huang Zong Ze , Zhu Miao-yong
Published: March 2009

The distribution of velocity field in single outlet tundish has been simulated through
numerical solution of turbulent Navier-Stokes equation in conjunction with e − k turbulence model. The theoretical predicted results have compared with experimental ones, and excellent agreement between them has been achieved. Through comparing the computational data using coupled heat and flow method with that of using uncoupled method, it indicated that it’s necessary to utility the coupled heat and flow method in big size tundish since the thermal buoyance should not be ignored in the calculation.
Thermodynamics-Based Constituent Design of Lithium Containing 7000 Series Aluminum Alloys
Authors: Ji Yan-li , Zhou Tie Tao , Liu Pei Ying
Published: March 2009

The influence of Zn content and Zn/Mg ratio on the equilibrium phase amounts of major ageing strengthening phase η’ (MgZn2) in lithium containing 7000 series aluminum alloys has been investigated by means of thermodynamic calculations. The results show that, comparing with Li-free 7000 series aluminum alloys, Zn/Mg ratio is no longer the determinant for the amount of η’ and only increasing Zn content that can increase the amount of η’. And the results were discussed with existing experiments.
Three-Dimensional Finite Element Modeling for Biomaterial Selection and Shape Design of the Nucleus Prosthesis
Authors: Huang Qi Jin , Liu Guo Quan , Li Yong , Gao Jin Ji , Gu Zheng Qiu , Ma Yu Zhen , Xue Hai Bin
Published: March 2009

Nucleus prosthesis replacement is considered as an ideal solution to low back pain. The purpose of this paper is to predict the suitable material properties and shape for the nucleus prosthesis of Chinese people based on biomechanical analysis using three-dimensional (3D) finite element (FE) method combined with experiments. The results suggest that a pillow-shaped nucleus prosthesis made of the polymer biomaterial with a Young’s modulus of 0.1-100 MPa is qualified to replace the degenerated nucleus. Then under the guidance of the FE predictions, a novel nucleus replacement material of polyvinyl alcohol hydrogel was prepared; the mechanical experiment shows that it has a compressive modulus of 1.0-6.8 MPa over a strain range of 10-60 %. The finite element predictions and experimental results have implications for the nucleus prosthesis designs.
Simulation of Structural Parameters and Superconducting Transition Temperature of MgB2 under Pressure
Authors: Shao Yang , Zhang X. , Tang Fu Ling
Published: March 2009

We successfully developed the potential parameters for simulation of MgB2. With these potential parameters, we calculate the lattice parameters and volume variations with pressure up to 240GPa. All these results agree well with experimental data under 40GPa and provide reasonable tendencies from 40GPa to 240GPa. By employing the McMillan expression, it is found that the lattice
stiffening dominants the behavior of Tc under pressure in the scope of BCS theory. Using our calculated Grüneisen parameter G g , the simulated pressure effect on Tc accords well with experimental results. Our result shows that the Tc of MgB2 can be destroyed by high pressure.
Upper-Bound Velocity Limit for Free-Jet Melt Spinning
Authors: Meco H. , Napolitano Ralph E.
Published: March 2009

The upper bound for the production of uniform amorphous ribbons during free-jet melt spinning is predicted by coupling a mass balance condition for the melt-pool with a simple boundary layer model for momentum transfer. The relationships between melt-pool length, ribbon thickness and wheel speed are investigated, and a criterion is developed for the onset of unsteady melt-pool behavior, which has previously been associated with increased surface roughness, porosity, and the formation of crystalline phases at high wheel speeds.
Investigation of the Bulk Nd60-xDyxFe30Al10 (x=0, 2, 5) Amorphous Alloys
Authors: Xu Hui , Tan Xiao Hua , Qi Nannan , Wang Qing , Dong Yuanda
Published: March 2009

The glass-forming ability, thermal stability and magnetic properties of the
Nd60-xDyxFe30Al10 (x=0, 2, 5) bulk amorphous alloys were investigated by x-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscope (SEM) and the vibrating sample magnetometer (VSM). The results show that the glass forming ability of the Nd60-xDyxFe30Al10 (x=0, 2, 5) alloys decrease with increasing Dy content. The as-cast Nd60-xDyxFe30Al10 (x=0, 2, 5) alloys show hard magnetic behavior at room temperature. With
increasing Dy content, the intrinsic coercivity of the alloys increase significantly while the saturation magnetization and remanence of the alloys decrease monotonously. With increasing annealed temperature, the intrinsic coercivity of the Nd55Fe30Al10Dy5 alloy decreased significantly, while the saturation magnetization and remanence decrease monotonously. The Nd55Fe30Al10Dy5 alloy shows soft magnetic behavior after annealed at 773K for 30 min.
Fabrication of Fe-Based Glassy Cores with High Saturation Magnetization and Good Soft Magnetic Properties by Spark Plasma Sintering
Authors: Shen Bao Long , Kimura Hisamichi , Inoue Akihisa
Published: March 2009

Glassy Fe77Ga3P9.5C4B4Si2.5 alloy powders were synthesized in the particle size
range below 125 µm by Ar gas atomization. A glassy alloy disc of 10 mm in diameter and 3 mm in thickness with a high relative density of 99.7 % was synthesized by spark plasma sintering. The resulting glassy magnetic core exhibits good soft magnetic properties, i.e., 1.35 T for saturation magnetization, 5 A/m for coercive force and 9600 for maximum permeability.
Effects of Constraint and Strain Path on Evolution of Ultrafine Grained Microstructure by Multi-Axial Alternative Forging
Authors: Noda Masafumi , Funami Kunio , Suwahara Yutaka
Published: March 2009

For the formation of ultrafine grain in Al alloys, various means have been investigated based on a process of continuous recrystallization using a high-strain technique that employs rigorous plastic working. However, utilization
for practical application is difficult for small specimens that require constraining. In this study, the effects were studied of the use of constraining die walls in the multi-axial alternative forging process (MAF) on the formation of ultrafine
grains and microstructural homogeneity. This technique has possible for scaling up to a practical scale. Our results showed that tensile strength and yield stress in these fabricated materials were tripled over those of the initial materials
when strain was applied. The average grain size after strain application was 0.5 µm. We conclude that a loading technique that uses different applied directions is the key determinant in creating ultrafine grains.
Mechanical Properties of SPD (Severe Plastic Deformation) Processed Copper
Authors: Han S.Z. , Lim Cha Yong , Kim Chang Joo , Kim Sang Shik
Published: March 2009

The mechanical behavior of nano grain-sized pure copper produced by various SPD (severe plastic deformation) processes such as ECAP (equal channel angular pressing) and ARB (accumulated roll bonding) was investigated in relation to the microstructural evolution. These processes promoted the formation of equiaxed nanoscale grains in pure copper. The present observation suggested that the tensile behavior of the specimens prepared by the current SPD processes was influenced by several mechanisms involving strain hardening and dynamic recovery.
The heat flow was measured by using a DSC (differential scanning calorimeter) to elucidate the relationship between the dislocation density and the tensile behavior in the specimens.
Synthesis and Investigation of Micro-Tribological Behavior of WS2 Nanotube
Authors: Li Chang Sheng , Yan Ke Hong , Fan Zhen , Shen Xiao Ping , Chen Kang Ming , Jiang Ting Shun , Hua Yin Qun , Ding Jian Ning , Yang Ji Chang
Published: March 2009

MS2(M=Mo, W, S=S, Se) are often used as solid lubricants in high/low temperature, high load, vacuum, in which oil lubrication is failed. Although WS2 is much more expensive than MoS2, it has better high temperature properties than MoS2. Thermal decomposition method is used to produce fullerence-like WS2 nanotube on Al2O3 template using (NH4)2WS4. The fabricated WS2
nanotube’s diameter is about 100nm and its length is longer than 2µm.The morphology, microstructure and tribological behavior of WS2 nanotube are investigated by means of SEM, TEM, XRD and AFM. The friction force between Si3N4 probe of AFM with WS2 nanotube is lower than that with MoS2 powder. Similar results are also found in pin-disc tester by GCr15 pin and lubricants
coating disc. The results of HETEM show that WS2 nanotube has rolling debris between the two antagonist surfaces, and MoS2 powder only has flattened debris. It may be the fullerence structure brings the chemical stability and leads to low friction.
Mechanism on Growth of Carbon Nanotubes Using CO-H2 Gas Mixture
Authors: Chung Uoo Chang , Chung Won Sub
Published: March 2009

To investigate the catalytic mechanism for the growth of carbon nanotubes (CNTs), carbon materials was synthesized at 680°C with a gas mixture of CO-H2 after reduction at 800°C by H2 gas. The synthesized carbon materials on reduced metallic surface were comprehensively explored by scanning electron microscopy (SEM) and X-ray diffraction patterns (XRD) at various reaction times
of 2, 10, 70, and 150 min, respectively. The carbon materials synthesized by metal Pt were little affected by reaction time, and only the sintered particles were observed without formation of CNTs. From X-ray analysis, iron oxides synthesized for 2 min were completely converted to iron carbide (Fe3C) without Fe peaks. After 5 min, iron carbide (Fe3C) and carbon (C) phases were observed at the
beginning of CNTs growth. It was found that the intensity of carbon(C) peak was gradually increased with the continuous growth of CNTs as reaction time increases. The carbon materials synthesized from the metal Pt were amorphous. It was also found that a catalyst on growth of CNTs was metal carbide.
Low Stress Tetrahedral Amorphous Carbon Films Prepared by Filtered Vacuum Arc Deposition
Authors: Zhang Xu , Zhang Hui Xing , Wu Xiang Ying , Zhang Tong He
Published: March 2009

The tetrahedral amorphous carbon films are attracting materials because of their properties similar to diamond, such as high hardness, resistivity, optical transparency, chemical inertness and low coefficient of friction. These properties make it ideal for wear resistance application on cutting tools, automotive component, aerospace components and orthopedic prosthesis etc. In this paper the
structures, mechanical properties and wear resistance of the tetrahedral amorphous carbon films deposited on silicon under lower pulse bias voltage by filtered catholic vacuum arc deposition system have been investigated. The high quality tetrahedral amorphous carbon film has been obtained. The hardness and elastic modulus of the low stress tetrahedral amorphous carbon films are higher than
60Gpa and 380Gpa respectively determined by nano indentation tests. The friction performance of the tetrahedral amorphous carbon films was also studied by SRV tests, the results show: the tetrahedral amorphous carbon films have much lower wear rate than that of silicon substrate.
Improvement of Adhesion of Cubic Boron Nitride Films: Effect of Interlayer and Deposition Parameters
Authors: He Qi , Li Cheng Ming , Lu Fan Xiu , Pilione Lawrence , Messier Russell F.
Published: March 2009

Diamond and B4C coatings were used as an interlayer for the growth of cubic boron
nitride thin films on c-silicon. By employing a B-C-N gradient layer on top of the B4C interlayer, improved adhesion occured between BN and B4C. A multi-step process after the nucleation of c-BN was found very helpful for improving the adhesion of c-BN on silicon with interlayers. Residual stress of c-BN thin film was significantly decreased by using a new post-deposition annealing treatment.
Dilute Alloy Designs of 7xxx Aluminum Alloys for Thick Forging Applications
Authors: Lim Seong Taek , Lee Yong Yun , Eun Il Sang
Published: March 2009

An effort has been made to present optimum alloy designs of commercial 7175 and 7050 type alloys to be used in thick forgings with proper microstructures and properties. The effects of changing alloy constitutions, primarily [Zn+Mg+Cu] and Zn:Mg ratio, on the evolutions of the coarse equilibrium phases and age hardening response are investigated. As a result, equilibrium phases (M,T,S) are evolved depending on alloy constitutions and cooling rate following solutionizing. The formation of the T- and S-phases is effectively controlled in the novel alloys (dilute and with high Zn:Mg ratio). In the slow quench, the redesign promotes homogeneous precipitation of η-phases, leading to higher mechanical properties than conventional alloys. The novel alloys provide microstructural homogeneity and extended heating range, ensuring 7xxx thick forging applications.
Optical and Electrical Properties of Transparent Conductive ITO Thin Films under Proton Radiation with 100 keV
Authors: Wei Q. , He S.Y. , Liu J.C. , Yang D.Z.
Published: March 2009

Under the simulation environment for the vacuum and heat sink in space, the changes in optical and electrical properties of transparent conductive indium tin oxide (ITO) thin films induced by radiation of protons with 100 keV were studied. The ITO thin films were deposited on JGS1 quartz substrate by a sol-gel method. The sheet resistance and transmittance spectra of the ITO thin films were measured using the four-point probe method and a spectrophotometer, respectively. The surface morphology was analyzed by AFM. The experimental results showed that the electrical and optical performances of the ITO thin films were closely related to the irradiation fluence. When the fluence exceeded a given value 2×1016 cm-2, the sheet resistance increased obviously and the optical transmittance decreased. The AFM analysis indicated that the grain size of the ITO thin films diminished. The studies about the radiation effect on ITO thin films will help to predict performance evolution of the second surface mirrors on satellites under space radiation environment.
Structural Refinement of Interstitial Free (IF) Steel by Deformation and Phase Transformation
Authors: Hansen Niels , Huang X.
Published: March 2009

Structural refinement in interstitial free (IF) steels has been obtained by three different methods: (i) deformation by cold or warm rolling, (ii) martensitic transformation and (iii) a combination of a martensitic transformation and plastic deformation. For all these processes, the refinement is discussed in terms of grain subdivision by high angle boundaries and dislocation boundaries on length scales from the micrometer level to the nanometer dimension. The characteristics of the subdividing boundaries are discussed, leading to the formulation of strength-structural relationship for IF steel in the deformed state.
Microstructural and Magnetic Properties of C/Co/C Pseudo-Sandwich Granular Films by Facing Sputtering
Authors: Feng Shun Zhen , Sun Huiyuan , Yu Hongyun , Gao Fengju , Pan Chengfu , Zhou Hong Juan , Nie Xiangfu , Sun Yuping
Published: March 2009

Granular C/Co/C films have been prepared by magnetron sputtering from C and Co onto glass substrates at room temperature and subsequent in situ annealing. C and Co targets use an RF and DC facing deposition mode respectively. The structural and magnetic properties of films at room temperature were investigated as functions of Co layer thickness, C layer thickness and annealing temperature. X-ray diffraction (XRD) shows the majority Co nanograins are formed as the
hexagonal-close-packed (hcp) structure annealing at 400 °C. Vibrating sample magnetometer (VSM) measurements indicate that the magnetic moment lies well in the film plane. Hc reaches maximum near 20 nm-thick Co layer and 30 nm-thick C layer with annealing temperature of 400 °C for 30 min. Remanent squareness (S) close to 1 was achieved for the film in which C layer thickness is 45 nm.
Scanning probe microscope (SPM) was used to scan surface morphology and magnetic domain structures. The average grain size varies from 10 nm to 15 nm after annealing.
Electric-Pulse-Induced Reversible Resistance Change Effect and Its Fatigue Behavior in Manganite Perovskite Films
Authors: Wang Qun , Dong Rui , Chen Li Dong , Chen Tong Lai , Li Xiao Min
Published: March 2009

A novel electric-pulse-induced reversible resistance (EPIR) change effect was observed in Ag/Ln1-xCaxMnO3/Pt (Ln= Pr, La) sandwich structure at room temperature without applied magnetic field. The Ln1-xCaxMnO3 films were grown on Pt/Ti/SiO2/Si substrate. The resistance of the Ag/Ln1-xCaxMnO3/Pt sandwich structure increases and reaches at a saturated high resistance state after applying a certain number of electric-pulse from Pt bottom electrode to Ln1-xCaxMnO3
layer, while it decreases and switches to a saturated low resistance state when the pulse polarity reversed. It is also found that the EPIR effect in the /Ln0.7Ca0.3MnO3/Pt system exhibits “fatigue” behavior, that is, for the high resistance state activated by electric-pulse, along the time after pulsing, the resistance decreases slowly after a certain stable stage; otherwise, the resistance change ratio decreases as the number of the high-low resistance switching circle increases. For the fatigue phenomenon with time, a resistance change with three stages was observed and a simple mechanism of the EPIR was proposed.