bluuebunny/crossref_metadata_2025 huggingface dataset:
The Microstructures and Their Stability of β Base Mg-13Li-X Alloys
Authors: Feng Lin Ping , Chen Bin , Liu Pei Ying , Zhou Tie Tao , Li Huan Xi
Published: March 2009

In the present work Mg-Li-X alloys with different alloying are investigated and the
studies are focus on the stability of microstructures and properties of β base Mg-13Li-X alloys. The alloying elements concerned are aluminum, zinc, zirconium, rare earth. The microstructure and corresponding mechanical properties are examined with the aid of DSC analyses, X-ray diffraction and OM observation. The results showed that the hardening effect and the stability of the alloys varied with different
addition of aluminum, zinc, zirconium, rare earth elements. The mechanical properties of the alloys greatly depend on the additional elements.
Ab Initio Study of Phase Stability for (Mg1-xAlx)2Sn Alloys
Authors: Bai Kewu , Wu Ping
Published: March 2009

Mg2Sn is a well known anode material used in rechargeable lithium batteries, and a
principal component of low melting tin-based alloys. In order to improve its anodic as well as anti corrosion performance, alloying of selected metals like aluminum into Mg2Sn was recommended in the literature. In this research,phase stability of a series of tin based (MgxAl1-x)2Sn alloys was studied by DFT calculations. Structural and thermodynamic properties of Al in Mg2Sn was disclosed, which may be of interest to the design of new anode materials or low melting alloys for industrial
applications
Development of a High Strength and High Ductility Magnesium Alloy
Authors: Ma Y.Q. , Chen Rongshi , Han En-Hou
Published: March 2009

A new steel mold gravity casting magnesium alloy of low-cost, high strength, and high
ductility has been developed and studied. This new magnesium alloy, which is designated as IMR-41, exhibits high strength (Yield Tensile Strength≈145 MPa, Ultimate Tensile Strength≈280 MPa) and high ductility (Elongation≈8%) at room temperature. The alloying elements are inexpensive ones and the cost of IMR-41 is similar to AZ91 series. The influence of small X element addition and heat treatment on the microstructures and mechanical properties are discussed. The IMR-41 combines the virtues of AZ91 series and AM60 series to some extend and shows great potential application on wheels of lightweight vehicles or motorcycles, etc. which require high strength and high ductility simultaneously.
Preparation Technologies and Applications of Strontium-Magnesium Master Alloys
Authors: Liu Xiang Guo , Peng Xiao Dong , Xie Wei Dong , Wei Qun Yi
Published: March 2009

In this paper, effects of strontium on Mg alloys and preparation technology of Mg-Sr and Mg-Sr-Al master alloys were summarized respectively. Prospects and applications of Sr-Mg master alloys were analyzed too. The results showed that thermodynamics calculation of reaction between SrO and Mg(l) showed that molten Mg can reduce SrO, in which excess of molten. The microstructure of hypoeutectic Mg-Sr binary alloys is composed of primary Mg matrix, and laminary eutectic phase(Mg-Mg17Sr2),but the microstructure of Mg-Sr-Al alloy consists of
plate-like primary Al4Sr, laminary eutectic phase (Mg-Mg17Sr2 or Mg-Mg17Al12 or
Mg-Mg17Sr2-Mg17Al12) embedded in primary dendrites of magnesium matrix. Additive strontium in Mg alloys can refine it grains, reduce degree of porosity, improve mechanical and thermal properties, therefore, Mg-Sr master alloys can be served widely as an additive for modification or as a constituent of Mg alloys, Al alloys, Zn alloys, etc.
Microstructure Evolution of Deformed Magnesium Alloy in Semi-Solid State
Authors: Yuan Sen , Wang Wu Xiao , Jiang Bai Ling
Published: March 2009

Magnesium alloy slurry was prepared using Strain-Induced Melt Activation(SIMA)
technique. The samples were quenched into water so as to fix the high temperature instantaneous microstructures. The microstructure evolution of compressed deformation Mg alloy is studied in the process of continuous heating and iso-temperature of semi-solid state. The results indicate that deformed Mg alloy (AZ91) has first occurred to have the conversion of dendrite crystal-oriented
isometric crystals in the continuous heating process. When the temperature rises to the range of semisolid state, the region with high energy at the pressed stripes begins to melt, showing that the cellular structures emerge in the crystal boundary and melting micro-pool phenomena appear within the crystals. With the iso-temperature time in semisolid state prolongs, the isometric crystals can be gradually converted into spherical crystal grains.
The Latest Technology Trends on Thixomolding® of Magnesium Alloys
Authors: Tsukeda Tadayoshi , Saito Ken , Takeya Kengo , Kitamura K.
Published: March 2009

We developed the new technology for Thixomolding® of magnesium alloys to meet latest market requirements as the following. (1) Flood feed screw to stabilize chips feeding and its melting. (2) High speed and quick response new series machine to improve injection performance. (3) Long nozzle to increase the yield ratio about parts per shot.
Characterization of Magnesium Plates Produced by Wheel-Band Casting and Horizontal Continuous Casting
Authors: Chang Dong Yim , You Bong Sun , Kam Bum Sik , Park Won Wook
Published: March 2009

AZ31 magnesium plates with 1mm in thickness were fabricated by casting and
subsequent hot rolling process. Both wheel-band continuous casting (modified Properzi) and horizontal continuous casting (HCC) machine were designed and employed to produce AZ31 alloy plates. The plates with 5x50mm in size produced by modified Properzi process exhibited good surface qualities that were sustained during following rolling process. Surface qualities of HCC plates with 120x30mm in size were very sensitive depending on the processing parameters. Homogenization treatment or surface machining before rolling was effective to get good thin plate. By means of rolling process, microstructures were refined effectively to the size of 7~10µm.
Material-Specific Joining Techniques for Magnesium Body Structures
Authors: Hahn Ortwin , Schumann S. , Meschut G. , Fuhrmann T.
Published: March 2009

In order to achieve further reductions in the weight of the body-in-white, efforts are being made in the field of car design to replace structural elements by magnesium components. In addition to the use of extrusion and sheet metal processes, die casting in particular is an especially important method of producing thin-walled, highly integrative components, because of the very good casting properties of magnesium. Integrating of die casted components into a vehicle structure calls for joining techniques which offer the maximum utilization of the materials of the joined parts under operating loads. This article discusses the necessity for material-specific joining techniques for future magnesium body structures. Using the example of aluminium/magnesium joints, the article describes the benefits of different joining techniques with regard to their efficient use of material in the case of both quasi-static and dynamic loads.
Thermally Supported Mechanical Joining of Magnesium Components
Authors: Hahn Ortwin , Tan Y. , Schroeder M. , Horstmann Magnus
Published: March 2009

In modern car concepts the aspect of lightweight constructions becomes more and more important. Lightweight materials, as aluminum and magnesium, get in the spotlight, thereby. Particularly because of the enormous potential for lightweight constructions industrial interests in magnesium wrought- and casting materials have increased in recent years. Against this background new alternative methods in the range of joining techniques are necessary which consider the specific mechanical-technological properties, such as limited deformability at room temperature and high
corrosion-affinity of magnesium. The present article discusses the integration of heating principles in a mechanical joining process of magnesium components without an additional pre-punch operation. In this connection, feasibilities and limits of the considered joining techniques are shown and a concept for thermal support is presented.
Production of Magnesium Metal from Turkish Calcined Dolomite Using Vacuum Silicothermic Reduction Method
Authors: Yucel Onuralp , Yiğit Selen , Derin Bora
Published: March 2009

In the present study, the production of magnesium metal from Turkish calcined dolomite containing 43.20 % MgO and 47.46 % CaO via Pidgeon process was studied under the pressure of 1 mbar. In the experiments, Turkish ferrosilicon containing 75 % Si and 24 % Fe was used as reducing agent. Effects of FeSi addition (90-150 % of stoichiometric requirement of silicon) and time (60-240 min.) were investigated on recovering of metallic magnesium from calcined dolomite
(dolime) at the temperature of 1200 °C. Effects of fluxing additive (CaF2), calcined magnesite and different temperatures on Mg recoveries and concentrations were also studied using with 100 % of stoichiometric requirement of silicon for 180 min. It was found that magnesium recovery increases with increasing FeSi addition, temperature, time, CaF2 addition and decreases with increasing calcined magnesite additions under the pressure of 1 mbar.
Processing and Characterization of Magnesium Alloys
Authors: Jung Hwa Chul , Shin Kwang Seon
Published: March 2009

Magnesium has the lowest density among the commercially available structural metals and its superior physical and mechanical properties make magnesium alloys extremely attractive for applications requiring lightweight, good castability and damping capacity. In recent years, due to the demand for lightweight magnesium components in the automobile and electronic industries, the world market for magnesium alloys has increased rapidly. At the same time, the research activities on
manufacturing process and characterization of magnesium alloys have also increased significantly. The research activities have been concentrated on many different fields, including the development of high pressure die casting process and semi-solid processing, development of high strength wrought alloys and components, and characterization of microstructure, mechanical properties as well as corrosion properties. In this article, the recent progresses achieved in these research areas at Seoul National University will be introduced.
Properties of AZ31 Magnesium Alloy Sheet Produced by Twin Roll Casting
Authors: Nakaura Yusuke , Ohori Koichi
Published: March 2009

Twin roll casting has been used to produce AZ31 magnesium alloy strip. The size of the cast strip is 5mm thick and 250mm wide. The microstructure of the as-cast AZ31 alloy strip consists of columnar zones from the surface to mid-thickness region and equiaxed zones in the mid-thickness region. The secondary dendrite arm spacing varies from 5.0 to 6.5 μm through the thickness and width of the strip and is much smaller than 34μm of an AZ31 alloy DC ingot used for comparison. In the temperature ranging from room temperature to 400°C, the tensile strength and elongation of the as-cast strip are higher and smaller than those of DC ingot, respectively. Elongation is evidently improved by homogenization treatment and becomes more than that of the DC ingot. Such an improvement of elongation is though to be caused by homogenization of segregation of Al and Zn atoms in the dendrite cell boundaries. The non-homogenized and homogenized strips were subsequently hot rolled. Their hot rolled sheets have much higher value of elongation with equivalent strength, compared to the hot rolled sheet of flat-bar extruded from DC ingot in the temperature ranging from 200°C to 300°C.
Development of a Moderate Temperature Bending Process for Magnesium Alloy Extrusions
Authors: Luo Alan A. , Sachdev Anil K.
Published: March 2009

An appropriate temperature (150-200°C) bending process has been developed for AZ31 and AM30 magnesium alloy tubes, and the optimum bending process parameters were obtained using a Design of Experiments (DOE) method. The development of this process was one of the key factors for use of magnesium tubes in automotive components for vehicle weight reduction. The tensile properties and deformation microstructure of magnesium alloys at elevated temperatures indicated
that temperature of 150-200°C which might be suitable for hydroforming and other forming processes.
Research on Technology and Microstructure Performance in Profile Extrusion of AZ31 Mg-Alloy
Authors: Wang Qiang , Li Bao Cheng , Feng Zai-xin
Published: March 2009

Aimed at characteristics of the profile such as complex shape, high dimensional accuracy and mechanical properties, the reduction zone length and devided flow taper of female die were designed by FEM and extrusion experiments were carried out for as-cast AZ31 magnesium alloy. Technological parameters were determined and microstructure and properties of the extruded profile were examined. The results show that magnesium alloy profile can be extruded if technological parameters such as deformation temperature, tool temperature and ratio of extrusion
are controlled strictly. Each of the above mentioned technological parameters has its different influence on microstructure and properties of extruded profile. In comparison with as-cast alloys, microstructure is refined from 120～140μm to about 10μm and tensile strength is enhanced from 171～200MPa to above 260Mpa. This suggests that fine grain and high strength are attained for AZ31 magnesium alloy by extrusion deformation. The extruded profile can meet high properties demands for carrying parts. It provides a possibility for broader usage of magnesium alloy profiles.
Density Functional Theoretical Study on Dehydration Process of MgCl2·6H2O
Authors: Liu Gou Sheng , Song Xing Fu , Yu Jian Guo
Published: March 2009

Anhydrous magnesium chloride (MgCl2), the dehydration product from bischofite
(MgCl2•6H2O) and as industrial raw material for preparation of electrolytic magnesium, is now the most advanced and perfect technological process. For long, the detailed dehydration process was not known due to its dehydration complexity and lack of appropriate experimental conditions. In this paper, quantum chemistry method based on density functional theory (DFT) was used to study the whole dehydration processes. The molecular geometries of MgCl2•6H2O, MgCl2•4H2O, MgCl2 •2H2O, MgCl2•H2O and MgCl2 were all optimized at level of B3LYP/6-31G*, the optimized geometrical parameters and correspondent energies corrected by the second order Møller-Plesset perturbation theory (MP2) were thus obtained. Results show that the energy variations corresponding to the whole dehydration steps from MgCl2•6H2O via intermediates MgCl2•4H2O, MgCl2•2H2O and MgCl2•H2O, to anhydrous product MgCl2 are 35.55, 41.30, 28.55, 31.08kcal/mol, respectively. For steps of 2H2O removal, the energy variation from MgCl2•2H2O to MgCl2 is 59.63kcal/mol, bigger than the steps from MgCl2•6H2O to MgCl2•4H2O (35.55kcal/mol) and from MgCl2•4H2O to MgCl2•2H2O (41.30kcal/mol), which means the last two water molecules are the
most difficult to be removed. All these results are significant for mechanism study of bischofite dehydration and are helpful for industrial production of anhydrous magnesium chloride.
Strengthening Behaviours of AZ31 Mg-Alloy during Warm Forming
Authors: Zhang Zhi Min , Wang Qiang , Zhang Bao Hong
Published: March 2009

In order to study the warm forming strengthening behaviours of AZ31 magnesium alloy, plane strain compression tests were carried out at the temperatures ranged from 210 to 330°C for as-cast and pre-forged Alloys. Tensile specimens were machined from the compressed samples. Room temperature mechanical testing was conducted according to the specifications. Microstrutres were investigated using scanning electron microscope. The analysis revealed that there is an excellent warm forming strengthening effect for as-cast AZ31 alloy with hexagonal close-packed structure. The increments of the tensible strength is about 40～50%. With decreasing temperature, the tensible strength increases during warm forming. The deformation extent and deformation mode has its different influence on strengthening effect. The high strength was attributed to the fine-grain strengthening and work hardening. This suggests that fine grain and high strength are attained for AZ31 alloy by means of rational combined action of work hardening and fine-grain strengthening during warm forming.
Dynamic Analysis on Thermal Deformed AZ61B Magnesium Alloy
Authors: Peng Jian , Zhang Ding Fei , Ding Pei Dao , Pan Fu Sheng , Yu Xiang
Published: March 2009

In this paper, the flow stress curves during thermal deformation of AZ61B magnesium
alloy have been measured by isothermal compression tests on Gleeble-1500D thermal simulation instrument, and effects of deformation temperature and strain rate on flow stress were analyzed. The thermal deformation activation energy of AZ61B alloy could be work out at 185.64 KJ/mol by means of empiric dynamic equation of elevated temperature deformation. The softening mechanism of AZ61B alloy under the testing condition of thermal deformation has been identified to be dynamic recrystallization.
The Effect of Thermomechanical Treatment on the Mechanical Behavior of Mg-Al-Zn Alloys
Authors: Sohn Keun Yong , Ha Ryeo Sun , Kang Min Cheol , Kim Kyung Hyun
Published: March 2009

In this study, the effect of thermomechanical treatment (TMT) on the aging and
mechanical behavior of Mg-Al-Zn alloys has been investigated. Three Mg-Al alloys AZ31, AZ61, and AZ91 were mold cast into a block under a CO2 and SF6 gas mixture atmosphere. The cast specimens were hot-swaged to a rod after homogenizing treatment at 400°C for 4 hours. The prestrain was applied by cold swaging up to 10% RA after solution treatment. From the aging curves obtained at 150°C, it was identified that the hardness of TMT-processed AZ31 and AZ61 did not
increase during aging, while that of AZ91 remarkably increased. The tensile strength and elongation of the TMT-processed AZ31 and AZ61 remarkably increased depending on the amount of applied prestrains, indicating the introduction of dislocations prior to aging significantly improved the mechanical properties.
Effect of Temperature on the Superplasticity of AZ81 Magnesium Alloy Processed by Hot Extrusion
Authors: Lin Li , Chen Li Jia , Liu Zhen
Published: March 2009

An AZ81 magnesium alloy, which was processed by hot extrusion in advance, was tested in the temperature range of 473 ~ 623 K and at various initial strain rates, ranging from 1×10-1 to 1×10-4 s-1. True stress-true strain curves under various temperatures and activation energy within different temperature range were investigated for the analysis of effect of temperature on superplastic behaviors. Elongation of the as-extruded AZ81 alloy increased with temperature when tested at the same initial strain rate. Elongation values, obtained at the same initial strain rate of
1×10-3 s-1, were 94% at 473K and 446% at 623K, respectively. Deformation mechanisms varied with increasing temperature, from the grain boundary sliding (GBS) accommodated by grain boundary diffusion to the GBS accommodated by lattice diffusion, transition temperature was 573 K.
Effect of Equal Channel Angular Extrusion on the Microstructure and Mechanical Properties of Magnesium Alloy Containing Quasicrystallines
Authors: Zheng Ming Yi , Qiao Xiao Guang , Xu Shi Wei , Wu Kun , Kamado Shigeharu , Kojima Yo
Published: March 2009

Equal channel angular extrusion (ECAE) was applied to an extruded ZW1101 (Mg - 11wt%Zn - 0.9wt%Y) Mg alloy containing quasicrystallines. The as-extruded ZW1101 alloy had an initial grain size of about 12 µm and bands of quasicrystalline phases parallel to the extrusion direction. After the extruded alloy was subjected to ECAE processing, the grain size was refined to about 0.5 µm, and the quasicrystalline phases were further broken and dispersed in the matrix. After
the ECAE processing, the micro-hardness and yield strength of the alloy were increased, however, the ultimate tensile strength and the ductility of the alloy were slightly decreased.
Preparation of Anhydrous Magnesium Chloride from MgCl2·6H2O Ⅱ Thermal Decomposition Mechanism of the Intermediate Product
Authors: Song Xing Fu , Wang Jin , Wang Xiang Tian , Yu Jian Guo
Published: March 2009

Magnesium chloride hex-ammoniate (MgCl2·6NH3) is an intermediate to produce
anhydrous magnesium chloride (MgCl2) by method of reaction crystallization. MgCl2·6NH3 is decomposed at 670K to produce anhydrous magnesium chloride. The process of thermal decomposition and its non-isothermal kinetics of MgCl2·6NH3 is studied. Results show that the thermal decomposition process is made up of three stages, the thermal decomposition functions and the thermal decomposition kinetics parameters, such as activation energy (E), pro-exponential factor (A) of MgCl2·6NH3 for each step are obtained by means of the Acher differential, the Coats-Redfern integral and multi-accelerated heating rate method. This study provides a valuable theoretical basis for MgCl2·6NH3 decomposition process on industrialization.
The Influence of Twinning on the Hot Working Flow Stress and Microstructural Evolution of Magnesium Alloy AZ31
Authors: Beer Aiden G. , Barnett Matthew R.
Published: March 2009

The microstructural evolution during compression (at 350°C and a strain rate of 0.01s-1) was examined for magnesium alloy AZ31 received in the "as-cast" condition. It was revealed that at low strains, many twins are produced and dynamically recrystallized (DRX) grains form as a necklace along pre-existing grain boundaries. At higher strains, DRX stagnates, most likely due to the
accommodation of deformation in the DRX fraction of the material. It was also observed that twin boundaries act as sites for the nucleation of DRX grains. The analysis was repeated for samples pre-compressed to a strain of 0.15 at room temperature prior to the hot deformation step. The idea of these additional tests was to increase the degree of twinning and therefore the density of sites for the
nucleation of DRX. It was found that statically recrystallized (SRX) grains developed at the twins during heating to the test temperature. When these samples were deformed, the peak flow stress was reduced by approximately 20% and the development of DRX was enhanced. This can be attributed to the accelerated nucleation of DRX in the refined SRX structure.
New Processing Technology of Twin Roll Strip Casting of AZ31B Magnesium Strip
Authors: Di Hong Shuang , Li Yong Lin , Ning Zhong-liang , Li Zheng , Liu Xianghua , Wang Guo Dong
Published: March 2009

In order to improve the poor workability and solve the problem of difficult roughing
rolling of magnesium billet, the twin roll strip castor (TRSC) was used for the manufacture of magnesium thin strip directly from its molten metal. Since the cooling rates achieved by TRSC casting process are in the range of five hundred to several thousands of degrees per second and the strip is formed under the pressure, therefore, this near- rapid solidification process can leads to homogeneity of microstructures, refined grain size and increased solid solubility. The experiments
were carried out on the existing equipments at State Key Laboratory of Rolling and Automation (RAL), Northeastern University. Strip samples 200~350 mm wide and 1.5~3.5 mm thick have been successfully cast in standard AZ31B alloy. The surface of the as cast magnesium strip was smooth and the edge was tidy. The microstructure analysis of the as cast magnesium strip showed that the gain size was much refined compared to that of ingot samples, and there was no segregation in the strip. The tensile strength of the strip in the cast state was about 220 MPa. The as cast magnesium strips were cold rolled directly on a two-high rolling mill, the total reduction up to 40% can be reached. X- ray diffraction result showed that the main phase in the as cast state AZ31B magnesium strip was a (Mg), the g (Mg17Al12) phase existing in the conventional wrought magnesium AZ31B sheet was vanished, therefore, the ductility of the strip increased.
Constitutive Model Development and the Numerical Study on the Drawability of AZ31 Sheet
Authors: Peng Ying Hong , Luo Ying Bing , Li Da Yong , Yin Ji Long
Published: March 2009

To examine the formability of a magnesium-based alloy AZ31 sheet, a temperature and strain rate related constitutive model for AZ31 sheet was developed based on tensile experiments. The relative parameters were obtained by fitting the equation to the experimental data. The comparison between the fitted and the experimental data proved the effectiveness of the model. Based on this model, the deep drawing process has been simulated with the finite element method and the limit drawing ratio (LDR) of AZ31 sheet was numerically studied. The study result was helpful to the
application of the stamping technology for the magnesium alloy sheet.
Two-Step Anodization of AZ91 Magnesium Alloy
Authors: Zhang Rong Fa , Shan Da Yong , Han En-Hou
Published: March 2009

Among four AZ91 samples, two were once anodized and the others were twice anodized in two electrolytic baths. After twice anodization, two coatings coexist on the base metal. Surface morphology showed that for one of twice anodic coatings (sample 2), the second coating only existed on some places and sealed some pores of the first coating after short time on the second anodizing. However, for another twice anodic coating (namely sample 4), the second anodization spent very long time and the coating was thick and loose. Salt spray testing showed that sample 2 had the most excellent corrosion resistance and the reason is discussed.
Preparation of Ceramic Membrane by Micro Arc Oxidation on Mg-Alloy
Authors: Dong Qing , Xiao Liang Tao , Luo Qin
Published: March 2009

The article introduces the ceramic membrane technology by micro arc oxidation on
Mg-Alloy surface and its properties. The important factors of technical parameters on the properties of ceramic membrane are analyzed. The formation and prevention of defects during the process are also discussed.
The Effect of Inverse Macro-Segregation on Fatigue Behavior of Die-Cast AM60 Magnesium Alloy
Authors: Lee Soon Gi , Patel Gautam R. , Gokhale Arun M.
Published: March 2009

The normal and inverse solute macro-segregation are known to occur in Al and other
nonferrous alloy castings and have been well studied and documented. However, these phenomena have not been investigated in the high-pressure die-cast Mg-alloys. Consequently, the effects of macro-segregation on the mechanical properties of cast Mg-alloys have not been characterized. The objective of this contribution is to investigate the effects of inverse macro-segregation and porosity on the fatigue behavior of high-pressure die-cast AM60 alloy. It is observed that the inverse macro-segregation of eutectic phase at the cast surfaces adversely affects the fatigue behavior: the fatigue resistance decreases substantially due to the presence of the surface segregation.
Addition of B4C to AZ91 via Diecasting and Its Effect on Wear Behaviour
Authors: Kaya Ali Arslan , Kayali E.S. , Eliezer Dan , Gertsberg G. , Moscovitch N.
Published: March 2009

The dry sliding wear behavior of magnesium-matrix-composites (MMC) reinforced by boron carbide particulates (B4Cp) has been investigated. Magnesium is the lightest structural material and is a good choice as a metal matrix for boron carbide and silicon carbide addition. Magnesium and its alloys, without reinforcement, are generally not suitable for mechanical applications due to their low wear resistance. The MMCs used in this study were produced via highpressure die-casting technique. The wear resistance of B4C/AZ91D composite reinforced with 12 and 25 wt% B4C were studied, compared with unreinforced diecast AZ91D. As-cast microstructures of the materials and boron carbide particules were characterized by using Scanning Electron Microscopy (SEM). The hardness values of the control sample and the composites were determined via Vickers hardness measurements. Pin on disk dry sliding wear tests were carried out to study wear rate and wear mechanisms. The magnesium matrix composites were used as pins while mild steel as disc material. The worn surfaces of pins were examined by using SEM. The wear
performance of magnesium matrix composites was improved with increasing volume fraction of B4C up to a certain level.
A Comparative Study on the Fretting Wear Resistant Properties of AZ91D and AM60B Magnesium Alloys
Authors: Huang Wei Jiu , Zeng Rong Chang , Chen An Hua
Published: March 2009

The paper studied the fretting properties and the fretting mechanism of AZ91D and
AM60B magnesium alloy. The results showed that the AZ91D alloy displayed lower friction coefficient and smaller wear volume than those of AM60B alloy, and also showed superior ability than those of AM60B in resisting crack nucleation and propagation. The fretting wear mechanisms of AZ91D and AM60B alloy were similar, including adhesion wear, surface fatigue wears and abrasive wear.
A Model on the Correlation between Composition and Mechanical Properties of Mg-Al-Zn Alloys by Using Artificial Neural Network
Authors: Liu Hai Ding , Tang Aitao , Pan Fu Sheng , Zuo Ru Lin , Wang Ling Yun
Published: March 2009

A model was developed for the analysis and prediction of correlation between
composition and mechanical properties of Mg-Al-Zn (AZ) magnesium alloys by applying artificial neural network (ANN). The input parameters of the neural network (NN) are alloy composition. The outputs of the NN model are important mechanical properties, including ultimate tensile strength, tensile yield strength and elongation. The model is based on multilayer feedforward neural network. The NN was trained with comprehensive data set collected from domestic and foreign
literature. A very good performance of the neural network was achieved. The model can be used for the simulation and prediction of mechanical properties of AZ system magnesium alloys as functions of composition.
Optimization of Mg-Zn-Al-Ca-La Alloys for the Improvement of Casting Properties and Creep Resistance
Authors: Anthony Anyanwu Ifeanyi , Suzuki Atsuya , Kamado Shigeharu , Kojima Yo
Published: March 2009

Mg-0.5%Zn-4%Al-0.5~2.0%Ca-0.5~2.0%La alloys are investigated in order to determine the optimum composition with superior casting properties and excellent creep resistance for automatic transmission case applications. The results show that regardless of the La content, the hot-tearing susceptibility of alloys containing 0.8%Ca or more is low. However, at 0.5%Ca content, hot-tearing occurs in alloys containing more than 1.2%La. The creep resistance of the alloys increases as the Ca content increases and Mg-0.5%Zn-4%Al-0.9%Ca-0.8%La alloy is found to be the
optimum alloy exhibiting good casting properties and adequate heat resistance for automatic transmission cases.
The Effect of RE and Ca on Corrosion Resistance of AZ91
Authors: Fan Yu , Wu Guo Hua , Gao Hong Tao , Zhai Chun Quan
Published: March 2009

The effects of RE and Ca on the mechanical properties and corrosion behavior of AZ91 have been studied by Zwick electronic universal material testing machine, X-ray diffraction, corrosion test and polarization experiment. The results showed that the addition of RE and Ca could improve the mechanical properties and corrosion resistance of AZ91 alloys. The ultimate tensile strength of AZ91 with addition of 1%RE and 1%Ca increased by 15.9%. The addition of 1%RE in AZ91 made the corrosion rate decrease from 0.453mg·cm-2·d-1 to 0.178mg·cm-2·d-1. Furthermore,
with adding 1%Ca in AZ91+1%RE, the corrosion rate of AZ91 decreased to 0.086mg·cm-2·d-1 due to the formation of reticular Al2Ca phases, which acts as an effective barrier against corrosion.
Study of Grain Refinement and SiC Nanoparticle Reinforced Magnesium Alloys
Authors: Wang Zhao Hui , Kang Yong Lin , Dong Wenchao , Zhao Hongjin , Liu Jin Wei , Xu Yue
Published: March 2009

Magnesium alloys offer advantages of low density, high specific strength, machinability and availability. So it has been used more and more in many fields, such as automobile, communication etc. In this paper, grain refinement process and SiC nanoparticles reinforcement process are investigated for the purposes of increasing ultimate tensile strengthen and ductility of AM60B magnesium alloys. We find that after grain refinement process the ultimate tensile strength of AM60B alloys with permanent casting increase to 241MPa, which is about 27MPa higher than that of original alloys, and the elongation of it increases up to 20.1%, which is about 8.7% higher than that of original alloys. We added SiC nanoparticle into AM60B alloys in liquid state and found it could increase strength and ductility of alloys. By SiC nanoparticle reinforced process the ultimate tensile strength of magnesium alloys can increase up to 255MPa with the elongation of 19%.
Study on Properties of Carbon Nanotube/Magnesium Matrix Composite
Authors: Zhang You Shou , Xue Yi Yu , Li Sinian , Huang Jin , Huang Cai Hua
Published: March 2009

Under the protection of argon gas, carbon nanotube reinforced magnesium metal matrix composite was made by stirring carbon nanotube into magnesium melts and formed by die casting. TEM and EDS methods were introduced to analyze boundary structure and chemical composition between carbon nanotube and magnesium metal matrix. The mechanical carbon nanotube properties of the composite were tested. Nickel chemical plating surface of carbon nanotube is favorable to adhesion of carbon nanotube to magnesium. Tests show that carbon nanotube, especially chemical nickel-plated one, has excellent role in strengthening the magnesium. The structure of magnesium was fined .The tensile strength, elongation, hardness and elastic modulus of the composite are improved.
Magnesium Motorcycle Applications
Authors: Cao Jianyong , Zhang Zhong He , Xiang Dongxia , Wang Jun
Published: March 2009

Magnesium, the lightest engineering structural metal, has been comprehensively used in castings of aviation and aerospace, communication and transportation, and IT components. This paper introduced the history, advantages and difficulties of magnesium castings for motorcycle application as well as its application state in China. It also indicated the production situation of magnesium motorcycle components in CQMST and difficulties need to overcome for further development.
Alternative Mechanical Surface Treatments for Fatigue Strength Enhancement
Authors: Altenberger I.
Published: March 2009

In this paper, The effects of laser-shock peening and high temperature deep rolling on nearsurface microstructures, residual stress states and fatigue behavior of various metallic materials are investigated and discussed. Similar to warm peening (shot peening at elevated temperatures), high temperature deep rolling may induce several favourable effects, especially in ferritic steels, where dynamic strain aging by carbon atoms can be exploited as a major strengthening mechanism. But also in materials without ‚classical‘ strain aging high temperature deep rolling is effective in improving the fatigue behaviour by inducing favourable, e.g. precipitation-hardened, nearsurface microstructures. As a consequence, these modified near-surface microstructures directly alter the thermal and mechanical relaxation behaviour of residual stresses. Laser-shock peening is already used in the aircraft industry (as a mechanical surface treatment for fan-blades) and owes its benefial effects to deep layers of compressive residual stress and work hardening and a relatively smooth surface roughness. Characteristic examples of microstructures and residual stress profiles as generated by laser-shock peening are presented. Moreover, the impact on the fatigue behavior of steels and a titanium alloy is outlined and discussed.
Residual Stress Prediction in Dissimilar Metal Weld Pipe Joints Using the Finite Element Method
Authors: Katsareas Dimitrios Elias , Youtsos Anastasius
Published: March 2009

Dissimilar metal welds are commonly found in the primary piping of pressurized water nuclear reactor power plants. The safety assessment practice for such welds requires residual stresses to be taken into consideration. In the present paper the finite element method is utilized for the simulation of the welding process and prediction of the residual stress field in a dissimilar metal weld pipe joint. Although it is common practice to develop in-house finite element codes for weld simulation, the ANSYS commercial finite element code is selected. This is mainly due to the fact that industry focuses on commercial software, since residual stress analysis procedures based on them can be readily transferred to industrial applications. A simplified 2-D axi-symmetric model, in which residual stresses are produced due to the thermo-mechanical properties mismatch during cooling of the weld, is compared with a detailed model in which the complete multi-pass welding procedure is simulated. The latter incorporates the “birth & death of elements” technique, temperature dependant material properties and kinematic hardening material behavior. The aim of this comparison is to establish the degree of model detail and complexity, necessary to obtain satisfactory results and consequently to define a golden rule between computational cost and practically accurate predictions. Identifying the specific simulation parameters and variables, that have the highest impact on the accuracy of the computed results, is also important. It is concluded that, a bead-by-bead or lump-by-lump detailed simulation is necessary in order to obtain reasonably accurate residual stresses that cannot be predicted by a simplified model. A general conclusion is that the proposed method, being simple in implementation and cost effective concerning model complexity and analysis time, is a potential weld residual stress prediction tool.
Electrically Conductive and Wear Resistant Si3N4-Based Composites with TiC0.5N0.5 Particles for Electrical Discharge Machining
Authors: Jiang Dongtao , Vleugels Jef , Van der Biest Omer , Liu Wei Dong , Verheyen Raf , Lauwers Bert
Published: March 2009

Electrically conductive and wear resistant Si3N4-based composites were developed in order to facilitate electrical discharge machining (EDM). The microstructural and mechanical properties of Si3N4-based composites with different amounts of TiC0.5N0.5, fabricated by hot pressing at 1650°C for 1 hour, are investigated and evaluated. The hardness of the micron-sized TiC0.5N0.5 powder based composites increased with increasing TiC0.5N0.5 content from 20 up to 40 vol. %, whereas the bending strength decreased. The fracture toughness reached a maximum at 30 vol. % TiC0.5N0.5 and exhibits a strong anisotropy with respect to the hot-pressing direction. The EDM behaviour of the composites is strongly influenced by the TiC0.5N0.5 content. The composites with a higher TiC0.5N0.5 content have a lower material removal rate but a better surface quality.
Mechanical Properties of TiO2-Kaolin FGM Produced by Progressive Lamination Method for NOx Reduction
Authors: Uchida Yoshihisa , Higa Shuntaro , Uchida Yoshiyuki , Hayashi Niichi
Published: March 2009

Mechanical properties of TiO2-Kaolin Functionally Graded Materials (FGMs) that
combined TiO2 and Korean kaolin (Al2Si2O5(OH)4) in a graded distribution were experimentally investigated. TiO2 is an excellent photocatalysis material, however, it does not have the mechanical strength sufficiently. Therefore, FGMs were used as the photocatalysis materials with mechanical strength. To improve the mechanical properties, Korean kaolin was selected as a binder. Bulk FGMs were produced by vacuum filtration and compression involving wet filtration, mechanical
compression and sintering. By this process, it is easy to control the thickness of FGMs. The porosity in FGM depends on the content of TiO2. The porosity in FGM decreases with increasing pressure of the compressor. The shrinkage decreases with increasing compression pressure at all ratios of TiO2 and kaolin. The materials have almost no shrinkage at 10 MPa. The bending strength and the Young’ modulus depends on content of TiO2. The bending strength of material was found to be approximately 2.5 MPa for 10 MPa compression pressure at TiO2 side. The bending strength and the Young’ modulus increases with increasing compression pressure. These results indicate that kaolin particles are useful to improve the strength of FGM. These properties of FGM, such as porosity, shrinkage, mechanical strength, etc., can be controlled by content of TiO2 and compression pressure. Based on an optimal design of production conditions, FGMs were developed for the nitrogen oxides (NOx) removal. The NOx reduction increases with increasing compression pressure. NO of 11.7 mg/m2h was removed under present conditions. The sintering temperature ensured the optimal removal of NOx
was 800 oC. After NOx removal test, the FGMs were found to be free from erosion due to photocatalysis. And kaolin particles do not interfere in photocatalysis effect of TiO2. It can be concluded that TiO2-Kaolin FGM have a possibility for application to the air purification.
Functionally Graded Coatings of Carbon Reinforced Carbon by Physical and Chemical Vapour Deposition (PVD and CVD)
Authors: Maile Karl , Berreth K. , Lyutovich A.
Published: March 2009

This paper reflects our R&D results in the field of functionally graded coating processes. For industrial applications a special architecture for coatings is necessary: because the surface has to withstand environmental attacks, specific physical and mechanical functions and characteristics are required. In the interface region to the substrate additional stresses and strains occur due to the different
materials combined. Consequently, the coatings have to be chemically and mechanically adjusted to the substrates. For this challenging problem, a concept named Materials Adapter has been developed within the frame of different research programs at MPA. For optimisation of the interface region an ion bombardment-activated inter-diffusion process ("ion mixing") was employed by using ion assisted electron beam PVD (IA EB PVD). Several Cr, Ti, Al and Zr coatings have been produced. An automated precursor inlet has been installed for CVD processes to obtain preset composition profiles for graded systems. Especially multilayer stacks of PyC-SixCy-SiC-Si3N4-Al2O3 have been deposited in a single growth process. The structure and composition of the coatings and interfaces were investigated by XRD, AFM, SEM, EDX, EPMA, ESCA and the micro-Raman
spectroscopy. The characterisation confirms the gradual transition between Si and Cr, as well as between Cr and Al deposited by IA EB PVD and between C and Si grown by CVD.
Precipitation in Plasma Nitrided Fe-M(M=Ti, V, Al) Alloys
Authors: Miyamoto G. , Tomio Y. , Furuhara Tadashi , Maki Tadashi
Published: March 2009

Microstructures of the plasma nitrided ferritic Fe-M (M = 0.5, 0.7, 1.0mass%Ti, 1.0mass%V, 1.0mass%Al) binary alloys were studied mainly by TEM. Metastable clusters are uniformly formed in the Ti added alloys. Near the surface of the specimen, transition from the clusters to the equilibrium B1-type TiN is observed. The microstructure formed in the 1%V alloy is similar to that of the Ti added alloy. In contrast, no cluster is formed in the 1%Al alloy and B1-type AlN is observed to nucleate on dislocations.
Seebeck Scanning Microprobe for Thermoelectric FGM
Authors: Platzek D. , Karpinski G. , Drasar Cestmir , Müller Eckhard
Published: March 2009

The FGM principle plays an important role in enhancing the efficiency of thermoelectric devices. While a thermoelectric generator (TEG) is typically operating in a large temperature difference, attractive conversion efficiency of a particular semiconductor is restricted to a small temperature range. Hence, when employing a semiconductor with its highest possible efficiency at the respective temperature in the internal temperature field along a stacked TEG, the overall
conversion efficiency of the device may be considerably enhanced. Similarly, the FGM principle can be employed for linearization of thermal sensors. The output voltage (response) of the sensor is proportional to the Seebeck coefficient of the material the sensor is made of. Since the Seebeck coefficient is strongly temperature-dependent, the sensor response is not linear with temperature.
However, combining in a stack two or more semiconductors which temperature dependence of the Seebeck coefficient are complementary to each other, results in a sensor with linear response (i.e. its output is proportional to the temperature difference, or heat flux, respectively.) Stacking of several materials to each other or grading a semiconducting sample requires a technique which can scan the Seebeck coefficient profiles S(x) along the stack. Accordingly a Seebeck micro-probe technique has been developed for scanning the surface of a sample monitoring
S with a resolution of down to 10 µm within the temperature range from -15°C to 60°C. An additional option of such a device is the scanning of the electrical potential along the stack under current flow [1]. Thus, related experimental data on the local profiles of the electrical conductivity and Seebeck coefficient along the stack (or continuously graded FGM) will be available. The apparatus has been automated so that extended areas may be scanned providing two-dimensional images. Additionally, several samples can be scanned in one automatic run.
Local Graded Structure in 6.5wt%Si-Fe Alloy and the Effect on Ductility
Authors: Shen Qiang , Li Ran , Zhang Lian Meng
Published: March 2009

The changes of phase composition and structure evolvement of Fe and Si powders with the ratio of 6.5wt%Si to 93.5wt%Fe were mainly studied. It is found that, the local graded structure, Fe-Fe(Si)-Fe3Si-(FeSi)-Si, forms due to the obvious diffusion and the alloying reaction between Fe and Si powders when sintering at 900-975oC. The graded structure, in which the high silicon phase based on Fe-Si alloys is packed by the low silicon solution based on Fe, exhibits a graded concentration of Si distribution. And most of the Fe-containing phase remains a state of lower Si
content, less than that of 3wt%Si-Fe alloy, thus provides the good deformation behavior of rolling and cutting for the compacts. Therefore, it is feasible for the high silicon iron sheets to be produced by the powder metallurgy method.
Stress Relaxation on Polished Cross-Sections of Al2O3/ZrO2 FGM Discs Measured by Raman Spectroscopy
Authors: Anné Guy , Vanmeensel Kim , Vleugels Jef , Van der Biest Omer
Published: March 2009

The residual stresses were measured on polished cross-sectioned Al2O3/ZrO2 FGM discs by means of Raman spectroscopy. The experiments revealed that it is possible to measure the residual stresses caused by the thermal expansion mismatch between the alumina and zirconia phase as a function of the position in the FGM. These experimental data are in excellent agreement with the thermal stresses calculated from the local composition using the model of Taya. However, the stresses due to the generated FGM profile could not be measured by means of Raman spectroscopy, due to stress relaxation upon cross sectioning of the FGM disc.
Microstructure of Al2O3-Fe FGM Obtained by Modified Slip-Casting Method
Authors: Ozieblo A. , Wejrzanowski Tomasz , Konopka K. , Szafran Mikolaj , Kurzydlowski Krzysztof Jan
Published: March 2009

This paper describes the technology and microstructure of Al2O3-Fe functionally graded composites, FGM, obtained by slip-casting under magnetic field. Alumina a-Al2O3, provided by Alcoa (symbol A16SG), with average grain size of 0.5 µm, and iron powder, (symbol Distaloy AB) from Hoganas, with average grain size of 35 µm, were used to produce a series of specimens which differed in contents of Fe particles in Al2O3. As a source of magnetic force a permanent magnet was used. Preforms were sintered in a vacuum at temp. 1470oC. The microstructures of the specimens were quantitatively described via stereological methods. Sections, parallel to the magnetic field lines were analyzed using special image analysis software. Stereological methods presented in this work have been used to determine gradient in the volume fraction of the Fe particles and variation in their size and dispersion. These parameters are essential for controlling the technological process of interest and to design microstructure for needed properties (fracture toughness).