bluuebunny/crossref_metadata_2025 huggingface dataset:
Refining of Metallurgical-Grade Silicon by Thermal Plasma Arc Melting
Authors: Tsao Shen , Lian Shuang Shii
Published: March 2009

The refining of MG-silicon (MG-Si) is closely related to the cost and purity of solar-grade silicon (SoG-Si) as well as semiconductor-grade silicon (SeG-Si). Plasma arc refining of MG-silicon is one of the alternative and effective route to remove the impurities in silicon. In this study, a 60KW transfer-arc plasma melting furnace operated in105Pa was used to purify the MG-Si by different kinds of working gas, which was composed of 100%Ar, 95%Ar+5%O2, 95%Ar+5%H2, and
70%Ar+30%H2 respectively. During the processing, an optical spectrometer was used to monitor the changes of compositions. The experimental results show that the removal rate of impurities of aluminum, calcium, sodium, barium...etc. in silicon with plasma working gas containing oxygen, and hydrogen are higher than pure Ar plasma. Especially with 30% H2 plasma, the removal rate of the Na and Ba could reach 100% and the removal rate of Ca and Al could also achieve to 99.5% and 89.5% respectively. For the impurities of boron in the MG-Si, the elimination rate of hydrogen-mixed plasma could be as high as 76%.The in-situ monitoring of plasma refining is accomplished with the monochromators in the range of visible light’s wavelength. From the results of chemical analysis and optical spectrograph, it revealed that elimination rate of Fe and Al was higher in hydrogen-contained plasma arc than in pure Ar plasma, As to the refining of carbon, the hydrogen and oxygen mixed plasma arc are also efficient to reduce the carbon content in silicon, which could be decreased from 310 ppm to 60~70 ppm.
Directional Solidification of Undercooled Hypoeutectic Silver-Copper Alloy Melt
Authors: Lu Yu Ying , Zheng Hong Xing , Xie Fa Qin , Li Jian Guo
Published: March 2009

Directional solidification of the undercooled melt which combines melt undercooling with conventional directional solidification is a new method of obtaining directional structure. This method is used to realize the directional solidification of the undercooled Ag70.3Cu29.7 melt. The experiment is performed in two steps: The undercooled melt is obtained by glass fluxing, and the above specimen is remelted and excited with Ga-In-Sn coolant. By this method, directional solidification dendrites of Ag70.3Cu29.7 alloy are achieved successfully. The columnar dendrites are straight and fine. The primary arm spacing is 21µm in average for a 65K undercooling, as compared to 38µm for a 32K undercooling. This confirms that higher undercooling promotes finer dendritic microstructures.
Damping Capacity of the Fe-Cr-Al Based Alloys
Authors: Lin Renrong , Cao Ming Zhou , Yang Rui
Published: March 2009

Based on the damping alloy Fe-13Cr-6Al, five types of alloys are prepared in the present study with 1 at.% of Cr replaced by Mo, Mn or Nb, and 0.5 at.% of Al replaced by Cu. The effects of annealing temperature, vibrating frequency, strain-amplitude and static load on the damping capacity of these alloys are studied through damping capacity measurement and optical microscope observation. The following results were obtained: (1) The damping capacity of Fe-13Cr-6Al based
alloys increases with increasing annealing temperature. (2) The replacing elements demonstrate different effects on the damping capacity of Fe-13Cr-6Al based alloys. The damping capacity of the alloys with Cu or Mn substitution increases, while that of alloys with Nb substitution decreases significantly as compared with Fe-13Cr-6Al. (3) The damping capacity of Fe-13Cr-6Al based
alloys is not sensitive to frequency. It decreases with increasing in static load, and increases rapidly with strain before reaching a steady state.
Unidirectionally Solidified Al-Cu Eutectic Alloy under High Intensity Pulsed Magnetic Field
Authors: Zhao Zhi Long , Zhang Rong , Liu Lin , Tseng Ampere A.
Published: March 2009

The pulsed electric current produced by discharging of capacitors pass through the
double solenoids with ferrosilicon core, the instant strong pulsed magnetic field with the oscillating and declining characters was made between two ferrosilicon cores. The effect of high-pulsed magnetic field on the unidirectionally solidified Al-Cu eutectic microstructure with 10µm/s withdrawn velocity was investigated. Under the high intensive pulsed magnetic field, the Al-Cu eutectic solidified morphology experience three evolution stages that are regular columnar structure to breaking off fine grain, coarsening dendrite to newly regularization columnar structure with
increasing of 0～15.5J charge energy. It is found that rich copper phase evidently come out inter eutectic cells and the eutectic spacing decrease in newly regularization specimen. The induced electric field caused by high pulsed magnetic field in metallic melt brought into oscillating solute electro-migration in front of solidification interface, which has the effect of promoting solute diffusion and reducing the constitutionally supercooling region.
The Microstructure and Mechanical Properties of Directionally Solidified NiAl-15Cr Alloy at Various Temperatures
Authors: Zhang Guang Ye , Guo Jian Ting , Zhou Lan Zhang , Li Gu Song , Ye Heng Qiang
Published: March 2009

The microstructure and tensile mechanical properties of directionally Solidified
NiAl-15Cr alloy at various temperatures have been investigated in this paper. The results reveal that the microstructure consists of dendritic β-NiAl phase, interdendritic γ/γ’, γ’ phase transient layer and α-Cr precipitation in β-NiAl phase. With the increase of temperature obvious Brittle-Ductile-Transition (BDT) behavior is observed and the BDT temperature (BDTT) is sensitive to initial strain rate. When the initial strain rate increases by two-order magnitude, the BDTT has an approximate 150K increase. In the temperature range of 1123-1373K, the alloy exhibits good tensile plasticity and poor strength comparing with the NiAl/Cr(Mo,Hf) alloy. Superplastic-like deformation behavior with large elongation (exceed 200%) is achieved at 1323K. The balance between strain hardening (by dislocation glide) and strain softening (dynamic recover and recrystallization) is responsible for the large tensile elongation of this alloy.
Fitness-for-Purpose Assessment of Misaligned Welds
Authors: De Waele Wim , Denys R.M. , Lefevre A.
Published: March 2009

Despite many years of research, an understanding of the effect of misalignment is far from complete. This study is focused on an experimental assessment of the interaction between high-low misalignment (hi-lo) and defect tolerance of girth welds subjected to remotely applied plastic strains. The paper highlights the beneficial effect of weld strength overmatch on straining capacity and inherent conservative assumptions made in a standard ECA analysis.
A Bonding Map for Cu and Al Plates by Pressure Welding at Cold and Warm Temperatures
Authors: Sim K.-S. , Lee Yong Shin
Published: March 2009

This paper is concerned with pressure welding, which has been known as a main bonding mechanism during the cold and warm formings such as clad extrusion or bundle extrusion/drawing. Bonding characteristics between the Cu and Al plates by pressure welding are investigated focusing on the weak bonding. Experiments are performed at the cold and warm temperatures ranging from the room temperature to 200°C. The important factors examined in this work are the welding pressure,
pressure holding time, surface roughness, and temperature. A bonding map, which can identify the bonding criterion with a weak bonding strength of 1MPa , is proposed in terms of welding pressure and surface roughness for the cold and warm temperature ranges.
Numerical and Experimental Study of the Electromagnetic Continuous Casting of Silicon
Authors: Shin Je Sik , Kim H.S. , Lee Sang Mok , Moon B.M.
Published: March 2009

For the preparation of multi-crystalline Si ingot, an EMC (Electromagnetic Continuous Casting) technique using a segmented Cu cold crucible under a high frequency alternating magnetic field was utilized. Numerical and experimental works were systematically carried out in order to optimize the effect of Joule heating and electromagnetic pressure. A Si melt of 5.5 cm height was able to be kept non-contact with the crucible wall when the induction coil current of 970 A was applied. A
segmented graphite crucible, which was attached at the upper part of the cold crucible, was introduced to enhance significantly the heating efficiency of Si melt keeping non-contact condition.
Development of the SAW Wire for High Strength TMCP Steel
Authors: Xue Xiao Huai , Lou Song Nian , Qian Bainian , Yu Shaofei
Published: March 2009

The wire for high strength and toughness TMCP steels of submerged arc welding was developed. The low carbon and micro-alloying with Ti-B system was adopted to obtain the acicular ferrite dominated deposited metals. Experimental results show that the carbon equivalent (Pcm) should be higher than 0.17, which can ensure the high strength and high toughness of the deposited metals. In the alloy system, Oxygen and Nitrogen contents, micro-alloyed elements (C, Mn) and its mixture ratio are the key factors that affect the deposited metals toughness. With increasing C, Mn content, the acicular ferrite is increased and toughness is improved. Oxygen and Nitrogen are deleterious to the toughness of deposited metals.
Prediction of Solid-Liquid Interface Stability and Dendritic Growth in Multi-Component Alloys with Calphad Method
Authors: Zhang Rui Jie , He Zhi , Jie Wan Qi
Published: March 2009

A method to predict the solid-liquid interface stability and the constrained dendrite
growth of multi-component alloys was developed based on the Calphad method. The method was applied to several industrial Al-Si-Mg alloys, and the predicted results were compared with some former experimental data. The good agreement between the calculation results and the experimental data demonstrates the superiority of the present method to the classical one based on constant parameter assumptions.
Manufacturing and Oxidation Property of Steel and Ti Metal Fibers
Authors: Lee Dong Bok , Kim T.H. , Ko J.H.
Published: March 2009

Stainless steel and Ti metal fibers having a diameter of 3 µm were produced from wires by multiple extrusions. The suitable sheath coating for stainless steel to extrude the core wires to fibers was the Cu coating having ~30 µm thickness. Zinc was not a suitable sheath coating, because Zn of the low melting point had diffused into the stainless steel wires during extrusion. The oxidation of stainless steel fibers produced using the Cu sheath coating oxidized rapidly above 750°C due to the high surface area of fibers. The utilization of the Cu coating as a sheath material to extrude the core Ti wires to fibers was not possible, because the highly reactive Ti wires resisted deforming to fibers.
Prediction of the Tolerable Defect Size for Strain Based Design
Authors: De Waele Wim , Denys R.M. , de Baets Patrick
Published: March 2009

By using data of Curved Wide Plate (CWP) tests, a simple procedure to derive tolerable girth weld defect sizes is presented. The procedure involves prediction of the maximum tolerable defect size as a function of the applied remote plastic strain and the actual pipe and weld metal properties. Application of the methodology requires a reliable non-destructive testing technique that can detect the critical defect dimensions.
A New Approach to Calculate Liquid-Vapor Surface Energy Using Sessile Droplet Test
Authors: Mázur Lauricella Christiane , Shang Xiaogang , Brandi Sérgio Duarte
Published: March 2009

In this work an applicable mathematical method is described in the analysis and
description of the profile of the drop obtained in the sessile droplet test. The proposed method bases on the study of the differential geometry of surfaces and in the analysis of phenomena related with the creation, expansion and contraction of interfaces to calculate the surface tension of metals. Liquid vapor surface energy of tin and indium were calculated by using sessile droplet method. Tests were carried out at 280 and 350oC temperature over a titanium nitride substrate. Results showed a very good agreement between both methodologies. For example, Sn at 280oC presented a surface tension of 545 mN/m, which is closer to the value reported in the literature (550 mN/m).
Weldability Approach to Duplex Stainless Steels Using Multicomponent Phase Diagrams
Authors: Ramirez Antonio J. , Brandi Sérgio Duarte
Published: March 2009

Welding is a non-equilibrium process. However, some weldability issues, as the extension of the heat-affected zone (HAZ) can be addressed using equilibrium phase diagrams. The 70 wt% Fe-Cr-Ni pseudo-binary phase diagram is commonly used to establish the phase transformations during welding of duplex stainless steels. The predicted results are assumed to be reasonably good for most of the duplex stainless steels. Thermodynamic calculations were used to determine
multicomponent phase diagrams and volumetric fraction of phases present as a function of temperature several commercial duplex stainless steels. Results showed that simplified pseudobinary phase diagram approach is valid to estimate welded joint microstructures only for the low alloy duplex stainless steels as UNS S32304, but phase transformations and mainly solidification paths of high alloy duplex stainless steels should predicted only using a multi-component phase diagram.
Spray Forming and Thermal Processing for High Performance Superalloys
Authors: Zhang Guo Qing , Li Zhou , Liu Zhong Wu , Zhang Zhi Hui , Zhang Yifei , Yuan Hua , Yao Rui Ping , Xu Shibin , Tian Shi Fan , Yan Ming Gao
Published: March 2009

A unique pilot low-pressure spray forming plant was established and its spray
atomisation and deposition process developed to study the new processing methods for high performance materials and to develop spray forming technology suitable for making sound superalloy preforms. The results indicated that high density (>99%) preforms (billets and rings) with little gas pick-ups and with the microstructural features of rapidly solidified superalloys, i.e. refined equiaxed grains and uniform microstructure, could be achieved after the optimisation of the spray atomisation and deposition process. The effects of subsequent thermal processing on the density, microstructure and mechanical properties of the spray formed superalloy were investigated. Compared to the turbine disks and rings made by wrought superalloys, the spray formed superalloys with identical chemistry showed significantly improved metallurgical quality, higher mechanical properties, and better hot workability.
Research on Ultra-High Strength Al-11Zn-2.9Mg-1.7Cu Alloy Prepared by Spray Forming Process
Authors: Xiong Bai Qing , Zhang Yong'an , Zhu Bao Hong , Liu Hong Wei , Zhang Zhi Hui , Shi Li Kai
Published: March 2009

An ultra-high strength Al-11Zn-2.9Mg-1.7Cu alloy has been prepared by spray forming process. The microstructures of as-cast and as-deposited alloys have been studied. XRD analysis result shows that the phases of spray formed Al-11Zn-2.9Mg-1.7Cu alloy consist of a-Al, MgZn2, Al2Cu and Al2CuMg. T6 heat treatment process is used to strengthen the alloy. The ultimate tensile strength reach up to 810MPa, and the elongation is about 9~11%. This kind of aluminum alloy is an ideal structural material for the aerospace and automobile industries.
Spray Forming of AZ91 Magnesium Alloys with and without Si Addition
Authors: Chen C.Y. , Tsao Chi
Published: March 2009

ray forming was employed to refine the microstructures of AZ91 and AZ91-3.34wt%Si Mg alloys during solidification by means of rapid solidification generated at atomization and droplet flight stages. The process parameters of spray forming were varied to reduce the porosity level and improve the morphology of the billet preforms. As-spray-formed microstructures were characterized using OM, SEM/EDS, and XRD, which were compared with as-cast microstructures. The significant differences of grains, Mg2Si and Mg17Al12 in morphology and in size between as-spray-fromed and as-cast materials are mainly due to fast cooling and solidification rates of spray forming process. Supersaturated matrix is found in as-spray-formed materials due to rapid solidification generated by spray forming. Overall, spray-formed materials are shown to have four characteristics, which are
much finer microstructures, uniformly distributed phases, equiaxed-shaped phases, and supersaturated matrix.
Spray Forming of Homogeneous Bearing Steel of Minimized Distortion Potential
Authors: Cui Cheng Song , Fritsching Udo , Schulz Alwin , Bauckhage Klaus , Mayr Peter
Published: March 2009

To minimize the distortion potential of bearing steels, 100Cr6 steel has been spray
formed for the manufacture of ring shape components in this study. Structure characteristics of the spray formed bearing steel have been investigated. Evaluation of distortion of bearing components after machining and heat treatment have been made in comparison with continuous cast material. Spray forming has been approved to be an alternative approach to conventional continuous casting for the production of homogeneous 100Cr6 bearing steel of lower distortion potential.
The Flow Characteristic Study of Gas Spray Process in Baosteel Spray Forming Equipment
Authors: Fan Jun Fei , Zhang Yin , Ren San Bing , He You Duo , Zhang Jing Guo , Sun De Sheng , Le Hai Rong
Published: March 2009

The simulation software of compressible gas flow process in spray forming equipment was developed under three-dimensional cylindrical coordinates. When the gas flow strands sprayed from some definite angles into the atomizer chamber, they converged at the definite height in axial line then expanded outside which showed the jet current characteristic. The substrate stagnated the divergence jet strands of gas and then separated the flow strand into two big recycle zones in whole space. One of the recycle flow zone directed downwards, the other recycle flow zone, directed upwards and reached the inlet area, which is the main reason caused the bonding of small liquid drop in the delivery hole.
Influence of Aging Treatment on the Microstructure and Properties of Spray Formed CuNi15Sn8 Alloy
Authors: Shi Hai Sheng , Fan Jun Fei , Zhang Jing Guo , Le Hai Rong , Peng Yong , Jin Bing Zhong , Mi Xiao-chuan
Published: March 2009

The CuNi15Sn8 alloy has quite potential applications in the field of the electrical
appliance industry. However, this alloy is prone to generate the segregation of alloying elements at the grain boundaries because of the high content of Sn element with the low melting point by conventionally processing route. Although the CuNi15Sn8 alloy can be obtained by powder metallurgy or mechanical mixing techniques, it is hard to avoid the formation of oxidation in the alloy. As compared with these techniques, spray forming technique has obvious advantages in preparing the CuNi15Sn8 alloy. The spray formed CuNi15Sn8 alloy has indicated that the elements of Sn and Ni were very uniformly distributed in matrix with the fine equiaxed grains. Influence of aging treatment on the microstructure and properties of spray formed CuNi15Sn8 alloy was studied.
Research on Preparation of Al-Fe-V-Si Alloy Enhanced by In-Situ TiC Particles
Authors: Zhu Bao Hong , Zhang Yong'an , Xiong Bai Qing , Liu Hong Wei , Shi Li Kai
Published: March 2009

Heat-resistant Al-Fe-V-Si aluminum alloys enhanced by in-situ TiC particles have been prepared by spray forming process with suitable process parameters. Research results show that the microstructure of as-deposited alloy is fine and homogeneous. In-situ TiC particles prevent the unsteady phases from coming into being. On the other hand, the TiC particles increase the volume fraction of heat-resistant phases. So the mechanical properties of the enhanced alloy by in-situ TiC
particles are better than that of Al-Fe-V-Si alloy without TiC particles. The hot extrusion temperature is also an important parameter to understand. Under the permission, it is better to extrude the alloy at lower temperature. The tensile strength of the alloy without TiC particles is about 435MPa at room temperature and is about 204MPa at 350°C. However, when the alloy is enhanced by in-situ TiC particles, the strength of alloy is about 482MPa at room temperature and is about 224MPa at 350°C temperature.
High-Temperature Infiltration of Non-Metallic Articles Produced via Selective Laser Sintering
Authors: Bourell D.L. , Evans R.S. , Barrows S.L.
Published: March 2009

There are several commercial processes for producing metallic parts by selective laser sintering (SLS) followed by infiltration of a molten metal at 700-900C. These parts are used in rapid manufacturing and rapid tooling applications. The present work centers around research to produce non-metallic parts infiltrated with materials at temperatures exceeding 1300C. Specific systems include siliconized silicon carbide. Of primary concern are: process control during the high-temperature infiltration; the binder system which must bind powder together during SLS, provide structural strength continuously from room temperature to the infiltration temperature, and react favorably with the infiltrant. This research was funded by State of Texas Technology Development and Transfer Grant Number 003658.
Comparative Analysis of Different Methods of Rapid Tooling
Authors: Martin Charles , Sasutil J.V. , Kouhkan M. , Lorea E. , Noorani Rafiq
Published: March 2009

The purpose of this experiment was to compare different techniques that help improve conventional tooling. The methods investigated were chosen from both the methods of Rapid Tooling: direct and indirect. Six different methods were selected including, Sand Casting, Investment Casting, Fused Deposition Modeling (FDM), Direct Composite Manufacturing (DCM), Selective Laser Sintering (SLS), and Stereolithography (SLA). Several industrial corporations were contacted to help complete all six tests. Five parameters were selected for the comparison of these
samples: dimensional accuracy, tensile strength, surface roughness, time for completion, and weight. Through comparison the strengths and weaknesses of each method was determined. It was found that different methods did better in various parameters. However, Selective Laser Sintering (SLS) seemed to have the best overall performance.
Effect of Thermal Spray Processing Techniques on the Microstructure and Properties of Ni-Based Amorphous Coatings
Authors: Lee Sang Mok , Moon B.M. , Fleury Eric , Ahn H.S. , Kim Do Hyang , Kim Won Tae , Sordelet Daniel J.
Published: March 2009

Metallic amorphous materials have been widely developed thanks to the outstanding
properties including high chemical stability, mechanical strength, and magnetic properties. However, with the exception of a few compositions, the limiting factor is the critical cooling rate for the formation of the amorphous phase. For many applications, it is only the contact surface properties that are important, thus the use of coating techniques such as thermal sprayings has several attractive features. In this paper, we present the microstructure of Ni-based amorphous coatings prepared by laser cladding and vacuum plasma spraying. The utilization of plasma spraying to deposit atomized powder enabled the formation of fully amorphous coating, laser cladding resulted in mostly crystallized structures. Glass forming ability and wear properties of the coatings were discussed as a function of the coating microstructure.
Correlation of Yield Ratio with Materials Constants of Constitutive Equation
Authors: Kim Young Min , Kim Sung Kyu , Kim Nack
Published: March 2009

The yield ratio of various HSLA steels has been correlated with the materials constants of Swift equation. It has been shown that the materials constants, b and N, of Swift equation can be related to microstructural features such as the dislocation density and volume fraction of constituent phases. In particular, the constant b can be expressed as a function of volume fraction of constituent
phases. It has also been shown that the yield ratio has a linear relationship with ln(b/N2). Since the microstructural features often have opposing effects on the values of b and N, careful control of microstructure is necessary to optimize the yield ratio and other properties. The possible way of decreasing the yield ratio without sacrificing other properties of HSLA steels is suggested based on the relationship between yield ratio and the materials constants of Swift equations.
A Feasibility Study on Advanced Methodology to Produce High-Performance Nano WC-Co Granule Feedstock for Thermal Spraying
Authors: Jun H.W. , Seok Hyun Kwang , Kim Joo Sun , Lee Hai Won
Published: March 2009

A feasibility study was conducted, in order to fabricate WC-Co powder granule as
high-performance feedstock for thermal spraying process, by spray drying weakly flocculated nano-particulate slurries under various conditions. The defects were evaluated with respect to the amount of additives to prepare spherical WC-Co feedstock powders with few morphological defects and homogeneous microstructures. The characteristics of feedstock powders heat-treated at 850~ 1200ı were analyzed using SEM, EPMA, and Hg-porosimetry. The microstructure investigation revealed that the relative portion of larger pores around 10 µm increased with increasing heattreatment temperature. On the other hand, the relative portion of smaller pores of 1 µm decreased due to the coalescence of WC particles, leading to dense feedstock powders with less defects such as hollow or craters. The hardness of thermal-sprayed coat developed with the feedstock in this study, which had exceptionally high feedstock strength, was superior to that of any other sprayed coat obtained with commercial feedstock powders.
Effect of a-CNx Coating on Tribological Properties of SiC Ceramic in Water
Authors: Zhou Fei , Kato Koji , Adachi Koshi
Published: March 2009

The tribological behaviors of a-CNx/SiC tribo-pairs in water at low velocity were
investigated and compared with SiC/SiC at room temperature. The results showed that the mean value µ of friction coefficients at steady state for a-CNx/SiC tribo-pairs (µ=0.075~0.12) was lower than that of SiC/SiC systems (µ=0.24~0.27). At a constant sliding speed, µ for two kinds of tribo-couples decreased with an increase in normal load, but at a constant normal load, µ for SiC/SiC system was nearly independence of sliding speed, whereas that of a-CNx/SiC tribo-pair decreased with sliding speed. The specific wear rates (ws) of ball and disk for a-CNx/SiC tribo-couples were considerably reduced by a factor up to 10 in the comparison to those of SiC/SiC systems. The observations of wear scars showed that the wear mechanism of CNx coating was micro-fracture of irregularities on the film surface for build-up of tribolayer, while that of SiC/SiC system was dominated by mechanical wear.
Microstructural Observation of Diamond Like Carbon Film Prepared from C2H2 / C5H6CH3 Plasma Beam Source
Authors: Liu Li , Yamamoto Atsushi , Oka Yoshihiro , Yatsuzuka Mitsuyasu , Tsubakino Harushige
Published: March 2009

In this study, the microstructure of two kinds of diamond-like carbon films was studied. These films were produced during the deposition of two kinds of hydrocarbon gas plasma by a newly developed technique called plasma based ion implantation (PBII). Microstructural analysis was performed by means of high resolution transmission electron microscopy (HRTEM). An amorphous DLC film was obtained by using C2H2 plasma. The crystal structure of carbon ( (C 168H ) was generated inside the DLC film when C5H6CH3 plasma was used. The effect of the precursor gases used in the present experiment on the microstructure of the DLC film was also studied.
Selection of Binder Materials for Salt Powder Lamination
Authors: Marutani Yoji , Kamitani Takayuki , Tomita Masuyoshi
Published: March 2009

A new technology for manufacturing expandable salt patterns to fabricate metallic parts by investment casting is presented and the results of experiments are reported to find out the binder substances suitable for the method. Solid models made by this method are also reported.
An Experimental Study on Superplastic Behaviors of Magnesium Alloy Sheet
Authors: Jin Quan Lin , Wu Huiying
Published: March 2009

An experimental study on superplastic forming behaviors and microstructure characters of commercial magnesium alloy sheet AZ31B is presented in this paper. The main experimental results show that the commercial magnesium alloy AZ31B sheet has superplastic capability. For the received sheet without any pre-processing, the maximum elongation is 295%. The dynamic recrystallization and grain refinement can be found, In the case of temperature <350°C, and the grain growth appears if temperature ≥ 350°C. The superplastic behaviors can be improved by controlling the dynamic recrystallization and grain refinement. Some experimental results of free superplastic bulging are presented in this paper. The results show that influence of temperature on forming capability is much less than the influences of temperature on elongation. In addition, the maximum principle strain
Superplastic Behavior of As-Equal Channel Angular Pressed 5083 Al and 5083 Al-0.2 Sc Alloys
Authors: Park Kyung Tae , Lee Chong Soo , Shin Dong Hyuk
Published: March 2009

An ultrafine grained structure was obtained in the two grades of a 5083 Al alloy with or without scandium by using equal channel angular pressing and its superplastic behavior was characterized. For the alloy without scandium, low temperature superplasticity was obtained but high strain rate superplasticity was unlikely to occur. By contrast, the alloy containing a small amount of scandium exhibited high strain rate superplasticity. It was found that, in both cases, the strain rate region
showing superplasticity was very limited, i.e. one order of magnitude. From the mechanical data, the deformation mechanisms were examined.
Superplasticity and Deformation Mechanism of LD10 Aluminium Alloy
Authors: Guo Hong Zhen , Duan Chunyan , Yao Ze Kun , Zhang Wei
Published: March 2009

The commercial hot-rolled bars of LD10 alloy (grain size 25~75µm) are pretreated via proper recrystallization annealing (temperature 380°C, 420°C and 460°C) and solution annealing (temperature 500°C). The average elongation is increased from 158% to 270%, 223%, 219% and 233% respectively and the maximum elongation is 321% (500°C, 3.3×10-4s-1). The test results show that the alloy can present certain superplasticity owing to structural effect of dynamic
recrystallization refining during superplastic deformation of coarse-grained LD10 alloy. Large and deep cavities form in grain boundaries and result in intergranular fracture after larger superplastic tensile deformation. And a large amount of metal filaments appear on grain surfaces. The formation of filaments is attributed to viscous flow of solid-liquid mixture in grain boundaries caused by grain-boundary sliding. The appearance of solid-liquid mixture makes grain-boundary sliding easier.
Developing High Strain Rate Superplasticity in Aluminum Alloys
Authors: Xu Cheng , Furukawa Minoru , Horita Z. , Langdon Terence G.
Published: March 2009

The conventional materials used in superplastic forming operations generally have grain sizes of ~2 µm or larger and they exhibit superplasticity at relatively low strain rates. Processing by equal-channel angular pressing (ECAP) produces materials having ultrafine-grain sizes, usually in the submicrometer range. If these ultrafine grains show reasonable stability at elevated temperatures, the alloys may exhibit a capability for achieving superplastic elongations at high strain rates. This paper examines the development of ultrafine-grained structures and superplastic ductilities in a spray-cast aluminum 7034 alloys through ECAP. The results show that ECAP is a very effective procedure for achieving grain refinement and superplasticity at rapid strain rates.
Superplasticity and Fracture Morphologies during Superplastic Deformation of a Commercial TC6 Titanium Alloy
Authors: Li Miao Quan , Xiong A.M. , Zhang Z.Q.
Published: March 2009

Deformation behavior of a commercial TC6 titanium alloy at elevated temperature has
been investigated using isothermal tension tests. By SEM, the fracture mechanism has been analyzed through the morphologies of failure surface. The superplasticity of the TC6 titanium alloy improves with an increase of deformation temperature and a decrease of initial strain rate. The optimal process parameters are the combination of 950 c o and 0.001s-1, and the limit elongation could reach 267%. The tough fracture is main pattern in the failure of the TC6 titanium alloy. The fracture begins at the boundaries between the matrix and the impurity, and it presents the much more tough fracture characteristic with an increase of deformation temperature and a decrease of initial strain rate.
Superplastic Extrusion of Al2O3-YTZ Nanocomposite and Its Deformation Mechanism
Authors: Chen Guo Qing , Zhang Kai Feng
Published: March 2009

Using Al2O3-YTZ(3mol% yttria stabilized tetragonal zirconia) nanocomposite,
superplastic extrusion under different conditions was adopted to form blade models. The results demonstrate that desired microstructure is achieved through the addition of 20mol% YTZ which acts as a second-phase pinning agent. At temperature range of 1650°C to 1700°C the material shows good deformability. At this elevated temperature the maximum extrusion pressure is lower than 25MPa,
and the maximum punch speed is about 0.35mm·min-1. In superplastic extrusion the dominating deformation mechanism is grain sliding and rotation, the accommodating mechanism is intergranular zirconia coordinated deformation. Meanwhile static and dynamic grain growth also plays an important role in deformation.
Crystallization during Superplastic Deformation in a Zr65Al10Ni10Cu15 Glass Metallic Alloy
Authors: Kim Woo Jin , Kim H.S. , Jeong Ha Guk
Published: March 2009

Superplastic behavior of the Zr65Al10Ni10Cu15 glass metallic alloy produced by powdermetallurgy method was examined in the supercooled liquid region. Stress-strain and stress-strain rate relationships showed that Newtonian viscous flow governed the plastic flow until strain hardening took place. The large strain hardening was proved to a result of occurrence of crystallization during deformation.
Superplasticity and Sinter-Forging of Fine-Grained Si3N4-Si2N2O Composite
Authors: Luo Jun Ting , Zhang Kai Feng , Wang Guo Feng , Han Wen Bo
Published: March 2009

The Si3N4- Si2N2O composites are fabricated with amorphous nano-sized silicon nitride powders by the liquid phase sintering(LPS) method in this article. XRD analysis shows that the sintered body consists of β-Si3N4 and Si2N2O. SEM experiment conforms that the average grain size of sintered body is less than 300nm. The superplastic deep-drawing forming can be proceed at a low temperature of 1550°C with a forming velocity of 0.2mm/min. There are only a few small sintered defects before forming, but there are a lot of cavity groups after forming. Cavitation failure occurs by nucleation, growth and interlinkage of cavities. The complex-shape gears can be formed by a sinter-forging technology when the sintering temperature is 1600°C and the superplastic forging temperature is 1550°C.
Superplastic Behavior and Cavitation for WC-Co Cemented Carbides
Authors: Hosokawa Hiroyuki , Shimojima Koji , Kawakami Masaru , Sano Shoken , Terada Osamu , Mabuchi Mamoru
Published: March 2009

Superplastic behavior and cavitation were investigated for WC-15 mass % Co cemented carbides with the WC grain sizes of 0.7 µm (A) and 5.2 µm (B), WC-10 mass % Co cemented carbide with the WC grain size of 1.5 µm (C) and WC-5 mass % Co cemented carbides with the WC grain sizes of 0.5 µm (D) and 2.5 µm (E) by tensile tests at 1473 K. WC contiguity were 0.51, 0.31, 0.27, 0.56 and 0.49, respectively. The large elongations about 200 % were obtained for the B and the C having smaller values of WC contiguity compared to the other cemented carbides. The values of cavity volume fraction for them were less for the other cemented carbides, furthermore, cavities formed at WC/WC interfaces. Therefore, it is noted that the distribution of the Co phase is important for superplasticity of the cemented carbides.
Microstructural Evolution and Deformation Mechanisms for Superplasticity of NiAl Intermetallic
Authors: Guo Jian Ting , Chen Rongshi , Du Xing Hao , Li Gu Song , Zhou Lan Zhang
Published: March 2009

The microstructural evolution during superplastic deformation of the extruded
stoichiometric NiAl polycrystals were systemically investigated in various conditions of temperature, strain rate and strain by means of optical microscopy (OM) and
transmission electron microscopy (TEM). Consequently, The deformation microstructures corresponding to the large tensile elongation consisted of subgrains,
low angle grains as well as high angle grains, which indicated that continuous dynamic recrystallization (CDRX) process was operating during superplastic deformation.
Threshold Stress for Super Plastic Flow in Spatially Extended Crystalline Systems
Authors: Muñoz-Andrade Juan Daniel
Published: March 2009

In general, the mechanical behavior of superplastic spatially extended crystalline systems (SP-SECS) is characterized by a sigmoidal relationship between the applied stress and the steady state strain rate. The sigmoidal curve is defined by three regions: low stress - region I, intermediate stress or superplastic - region II and high stress - region III. The region I is known as the region where the threshold stress exists, but there are controversies on their existence. In this way, some
experimental results reported in the past are analyzed. Earlier investigations have reported the apparent activation energy for creep in SP-SECS as a function of the applied stress, where it is exhibited a marked dependence of impurities or precipitates concentration. In addition, recent experimental evidences have revealed that the unified interpretation of creep, plasticity and superplasticity is the deductive rule [1]. In order to describe the interaction between precipitates at
grain boundaries and dislocations during deformation processes a phenomenological expression for the threshold stress at the Grain Boundary in SP-SECS is described in this work.
Influence of Stress State on Superplastic Deformation Behavior in a Zn-Al Eutectoid Alloy
Authors: Nakano S. , Motohashi Yoshinobu , Itoh Goroh
Published: March 2009

A Zn-Al eutectoid alloy known as a fine-grained superplastic material is tested both in
tension and compression under superplastic conditions, and the influence of the stress state on superplastic deformation behavior, such as flow stress, is investigated. In the compression test, deformation is interrupted and turning is performed to remove a barreled portion so that the gauge section becomes uniform, and then the deformation is continued. Microstructural change during the deformation is also investigated. As a result, flow stress in the compression becomes higher than that in tension even after the barreled portion is removed. After deformation, grain growth is observed both in the tension and compression, and growth rate in the compression is larger than in the tension.
Correlation between the Microstructure and Forces Generated during Friction Stir Processing of AA5052
Authors: Khraisheh Marwan K. , Darras Bassil M. , Kalu Peter N. , Adams-Hughes M. , Chandra Names
Published: March 2009

The microstructure of friction stir processed AA5052 sheets is investigated using
Scanning Electron Microscopy (SEM) and Orientation Imaging Microscopy. The correlation between the generated forces during processing and the microstructure is evaluated. Observations indicate that the finest microstructure are achieved when the plunging forces are at minimum.
Application of Processing Method Enlarging a Partial Diameter to Shaft Parts of Practical Size
Authors: Mori Kazuki , Okabe Nagatoshi , Zhu Xia , Iura Tadashi
Published: March 2009

. A novel processing method was proposed to enlarge a partial diameter in the middle of a round bar with an experimental size of 10mm in diameter. To confirm that the processing method is applicable also to shaft with a practical size of 25mm-60mm in diameter for general industrial machine, a large-scale processing machine was developed. Deformation behavior of diameter in a processed part during processing process was made to an expression. The several influences, such as bending angle θ, axial-compressive stress σc, diameters D0, rotation number N of shaft and curvature radius ρ, on the increase behavior of diameter were estimated quantitatively.
Analysis of Porosity Characteristics in Weld Metal of High Strength Aluminum Alloy and the Effect of Mixed Shielding Gas
Authors: Zhang Xiao Mu , Zhang Zhi Yong , Peng Yun , Tian Zhi Ling , He Chang Hong , Xiao Hong Jun , Ma Cheng Yong
Published: March 2009

Aluminum alloy has being widely used in modern automobile and aeronautic industry.
However, the welding of aluminum alloy, especially high strength aluminum alloy，is difficult. Porosities are usually brought in the weld metal. In this paper, MIG welding using mixed gas shielding is carried out. The characteristic shapes of porosity in weld metal are described, the mechanism of porosity formation is analyzed, and the factors that influence the tendency of porosity formation are studied. Experiment results indicate that by the use of mixed shielding gas of 38%He+62%Ar, the number of porosity is reduced, the width of HAZ and softened zone is decreased, and the mechanical properties of welded joint is increased.
First-Principles Calculations of Titanium Dopants in Alumina
Authors: Matsunaga Katsuyuki , Mizoguchi Teruyasu , Nakamura Atsutomo , Yamamoto Takahisa , Ikuhara Yuichi
Published: March 2009

First-principles pseudopotential calculations were performed to investigate atomic and electronic structures of titanium (Ti) dopants in alumina (Al2O3). It was found that a substitutional Ti3+ defect induced an extra level occupied by one electron within the band gap of Al2O3. When two or more substitutional Ti3+ defects were located closely to each other, the defect-induced levels exhibited strong bonding interactions, and their formation energies decreased with increasing
numbers of Ti3+ defects. This indicates that association and clustering of substitutional Ti3+ defects in Al2O3 can take place due to the interaction of the defect-induced levels.
Density Functional Calculations on Electronic and Magnetic Properties of Fe-Pt Systems
Authors: Gu You Song , He Jian , Ji Zhen , Zhan Xiao Yan , Zhang Yue , Zhou Cheng
Published: March 2009

The electronic structures and magnetic properties of Fe-Pt systems were calculated by CASTEP codes, which employed density functional theory, generalized gradient approximation (GGA), Perdew Burke Ernzerh exchange correlation, Pulay density-mixing scheme and Ultra Soft pseudo potential. The band structures and density of states (DOS) were calculated, together with band
populations and magnetic properties. The calculated results of α-Fe show the validatiy of this method in predication magnetic properties. It is found that as the Pt concentration increases, Fe 4s and 3d electrons decrease while 4p electrons increase, and the magnetic moment of Fe atom increases. Pt atoms also contribute to the magnetic moment due to polarization. The calculated magnetization agrees with experimental values quite well.
Theoretical Investigation of Fe-Based Phase Equilibria from the First-Principles
Authors: Chen Ying , Iwata Shuichi , Mohri Tetsuo
Published: March 2009

Theoretical investigation of the phase equilibira of three kinds of Fe-based alloys,
Fe-Ni, Fe-Pd and Fe-Pt systems is attempted by combining FLAPW total energy calculations and Cluster Variation Method. It is revealed that the magnetism plays a crucial role in the phase stability and spin polarized calculation is indispensable. The experimental L10-disorder transition temperatures are reproduced with fairly high accuracy. Thermal vibration effects incorporated based on the Debye-Gruneisen model further improve the calculated transition temperatures. Furthermore,
the influence of the various effective cluster interactions on phase stability is calculated systematically.
The Behavior of AlTiC Master Alloys in Grain Refining of Commercial and High Pure Aluminum
Authors: Li Jian Guo , Huang Min , Shi Zimu , Liu Dong Yu
Published: March 2009

The AlTiC master alloy has been prepared in different components to refine 99.8%Al
and 99.98％Al, then compared to two typical Al5Ti1B in refining efficiency and the grain nuclear. The result showed that the refining efficiency seemed better if the nucleation of high pure aluminum revealed complexity and variety. It may due to that the latency heterogeneous nucleation was efficient on the whole, consequently accelerated refining efficiency.
Modeling of Dendritic Structure during Solidification Process Based on Cellular Automaton Model
Authors: Xu Qing Yan , Liu Bai Cheng , Liang Zuo Jian
Published: March 2009

Dendritic is the most observed microstructure in metallic materials. Traditional Cellular Automaton model can only predict the grain structure and grain size. It is necessary for us to modify the original model to reflect the real shape of dendrite. In the paper, a mathematical model was established to describe the evolution of the dendritic shape, in which the influence of microsegregation and curvature on undercooling was taking into account. In addition, the growth model was proposed based on the minimum free energy principle. Modeling results indicated the
proposed models can predict not only grain structure, but also dendritic morphology. Free growth of equiaxed grains and the competitive growth of columnar grains were simulated. The modeling results were also validated with experiments.
Monte Carlo Simulation of Cube-Texture Evolution during Grain Growth of High-Purity Nickel
Authors: Godfrey Andrew , Zhang Yong Bin , Lin F. , Miodownik Mark A. , Liu Qing
Published: March 2009

A Monte Carlo Potts model has been used to investigate cube-texture strengthening during grain growth in rolled high-purity Ni-tapes. The initial conditions for the simulations have been taken from electron back-scatter pattern (EBSP) orientation maps of already fully recrystallized samples. Experimentally, grain growth leads to an increase in the cube volume fraction to >95% , accompanied by an approximately ten-fold increase in the grain size. High cube volume fractions can be predicted under a number of conditions, though a small surface energy advantage of just 2% for cube-oriented grains is required to match the texture strengthening to the grain size change. An additional issue of interest is the influence on the grain growth of the large area-fraction of twin boundaries in the fully recrystallized condition. The presence of boundaries with low energy has a strong influence on the
simulated microstructural evolution.
Monte Carlo Simulation of Configurational Anisotropy of Magnetic Cluster
Authors: Huang Zhi Gao , Feng Qian , Li Yong Shen , Zhang Feng Ming , Du You Wei
Published: March 2009

In this paper, the spin configuration and the configurational anisotropy of the clusters
were studied by Monte Carlo simulations. An easy magnetization directions and a configurational anisotropy were found for the clusters using the hysteresis and spin configurations in different magnetization processes, and the simulated natural angle and energy distribution. It is considered that the configurational anisotropy is mainly attributed to the non-uniformity in spin configurations.
The Ground States of the FCC Alloy Films
Authors: Xu Yan Lin , Ni Jun , Iwata Shuichi
Published: March 2009

We have investigated the ground states of the fcc alloy films in the (001) direction
using the Monte-Carlo simulation. The surface field is introduced to describe the surface effects such as surface segregation. The variation of the ground states as a function of the film layer number is determined. The ground states for the films with even layer numbers and odd layer numbers show different variation tendency as the layer number increases. The phase diagrams of the ground states are obtained.