bluuebunny/crossref_metadata_2025 huggingface dataset:
Micro-Engineering the Stressed Macro-Interface and Enhancing the Performance of Mg/Al Bimetal Macrocomposites
Authors: Paramsothy Muralidharan , Hassan Syed Fida , Srikanth Narasimalu , Gupta Manoj
Published: August 2009

New bimetal magnesium/aluminium macrocomposites containing millimeter-scale Al based core reinforcement were fabricated using solidification processing followed by hot coextrusion. The initial macrocomposite consisted of a combination of pure Mg shell and pure Al core. Some problems encountered with the macrocomposite were Mg and Al grain coarsening, an inadequate Mg-Al interface (macrointerface) and consequent reduction in strength, compared to monolithic Mg. To rectify these problems, three approaches were taken in the following order primarily to widen (strengthen) the Mg-Al interface: (a) pouring of pure Al at 900°C (higher temperature approach), (b) pure Mg shell substitution with AZ31 shell (single substitution approach) and (c) pure Mg shell and pure Al core substitution with AZ31 shell and AA5052 core, respectively (double substitution approach). The evolution (strengthening) of the Mg-Al interface and its effect on microstructure and mechanical properties in each macrocomposite is investigated in this paper.
Formability of Twin-Roll Cast Age-Hardenable Mg-Zn Alloys
Authors: Venkatesan Kishore , Borbidge Wendy , Kellam Michael , East Daniel R. , Gibson Mark A. , Liang Daniel
Published: August 2009

The suitability of a twin-roll cast (TRC) age-hardenable alloy for wrought applications is explored. A Mg-4Zn (wt.%) alloy, 3mm thick, was cast using the TRC route. Deviating from the traditional practice of homogenization followed by age-hardening in die/sand cast parts, the TRC sheet, cut into small strips, was hot rolled and annealed after homogenization. They were then deep drawn and subsequently age-hardened. The rollability, mechanical properties and microstructure of the alloy at different stages of processing and after forming, are presented and discussed.
Fine Grained AZ31 by Conventional Thermo-Mechanical Processing
Authors: Stanford Nicole
Published: August 2009

The magnesium alloy AZ31 was processed by severe hot rolling and annealing. This processing was optimised to produce recrystallised grain sizes as small as 2.2μm. Specimens in the as-rolled condition had a grain size of 0.5μm, and exhibited a yield strength in excess of 350MPa. In the fully recrystallised condition, with a grain size of 2.2μm, the material had a yield strength of 260MPa which is almost twice that of the as-received plate. The ductility of the annealed specimens was also increased compared to the as-received condition. The combination of specific strength and ductility brings this newly processed material into a new property space compared to the other light metals.
Rotary Welder for Hot Billets
Authors: Jenista David
Published: August 2009

The use of two-piece billets in aluminium extrusion is often viewed as a necessary evil. A heating system that provides two-piece billets to the press can provide better ingot utilization than a heater which provides single-piece billets. The issues associated with the handling and extruding of two-piece billets are accepted as the price of improved ingot utilization.
With the rotary welder, the end of each log segment is joined to the front of the following log by friction welding. The combination of the rotation of the short piece and the pressure applied creates a bond that will maintain one-piece integrity as the billet is conveyed to the press and loaded into the container. The handling issues associated with two-piece billets are eliminated.
A unique re-cut cycle removes contaminants from the two weld faces immediately prior to welding. The two ends are precisely aligned and the saw makes a cut that removes the face of the remaining piece and the face of the following log. This re-cut removes debris, oxide and potential trapped air from a less than perfect cut at the cast house.
The welding is then performed with the two freshly cut faces. The metallurgical performance is improved by the removal of debris and oxide on the faces. This allows the use of welded billets in some applications that previously required single-piece billets to achieve the necessary structural integrity.
Development of High Performance Magnesium Alloys via Microstructure and Texture Control
Authors: Choi Jung Woo , Shin Kwang Seon
Published: August 2009

The mechanical properties of extruded ZA (Mg-Zn-Al) alloys with different Al contents were examined. The effects of Al on deformation behaviour were examined by tensile and compressive tests. The changes in texture due to plastic deformation were examined using the X-ray diffraction method. It was found that the basal poles of the extruded ZA alloy were parallel to the normal direction with a slight tendency to incline toward the extrusion direction. The degree of inclination increased with increasing Al content. The inclination degree of the basal poles was found to be closely related to the change in the deformation behaviour of the ZA alloy. Computer simulations were also carried out using the VPSC (visco-plastic self-consistent) theory in order to predict the contributions of various deformation modes to the plastic deformation behaviour of the ZA alloy.
Influence of Laser Surface Melting on the Microstructure and Corrosion Behaviour of ZE41 Magnesium Alloy
Authors: Banerjee Parama Chakraborty , Raman R.K. Singh , Durandet Y. , McAdam Grant
Published: August 2009

In the present study, surface melting of a magnesium alloy, ZE41 (4%-Zn, 1%-RE) is performed by an Nd:YAG laser (operating in a continuous wave mode). The degree of microstructural refinement and the depth of the laser melted zone is a strong function of laser processing parameters (laser power, beam diameter, scan rate). The corrosion properties of the laser treated and untreated zone is investigated by potentiodynamic polarization method. The microstructural changes on the surface due to laser surface melting were analysed by optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy to understand their effect on the corrosion behaviour of ZE41.
An Electroless E-Coating Bath Sealing Technique for a Phosphated Magnesium Alloy
Authors: Song Guang Ling
Published: August 2009

The corrosion resistance of phosphated Mg components is very low. A low cost and high corrosion resistant sealing technique is particularly desired. In this study, a new sealing technique was proposed and validated in laboratory trials. Phosphated AZ91D was simply dipped in an E-coating bath solution for a few seconds. After baking, the specimens were found to have considerably improved corrosion resistance.
In Situ X-Ray Microtomography Investigation of the Deformation Mechanisms of Al-Cu Alloys in the Semi-Solid State
Authors: Terzi Sofiane , Salvo Luc , Suéry Michel , Adrien Jérôme , Maire Éric , Boller Elodie
Published: August 2009

This paper is concerned with an investigation of the deformation behaviour of an Al-Cu alloy during tensile testing in the semi-solid state. It was carried out by fast in-situ X-Ray microtomography at ESRF, Grenoble. Deformation was performed at constant velocity, which was chosen to be small enough so as not to affect the acquisition of the images. It is observed that deformation is accompanied, initially, by some liquid flow from the adjacent regions towards the deformed zone. Then pores form in the liquid films and grow until they occupy a significant part of the cross section of the specimen. Quantification of this phenomenon was carried out thus leading to a better understanding of pore formation in semi-solid mixtures.
A Novel Micro-Arc Anodising Process for Aluminium Alloys Containing High Silicon
Authors: Shi Zhi Ming , Zhang Ming Xing
Published: August 2009

Although the anodising process has been widely used in surface treatment of Al alloys, the well known sulphuric acid anodising process produces inhomogeneous and highly porous anodised coatings on Al alloys containing high Si due to the inertness of the silicon particles. The present work reports a novel micro-arc anodising process for such high-silicon aluminium alloys. Uniform and thick anodising coatings can be obtained through an anodising process in an alkaline electrolyte under high voltage and low current density conditions. The microstructure examination in SEM indicates that most pores in the coatings have been sealed during the anodising process, thus post-treatment that is normally needed for the currently used anodising process can be eliminated. The coating is very promising in the improvement of corrosion resistance for cast high-silicon aluminium alloys.
Laser Welding of Titanium and its Alloys for Medical Applications: Current Knowledge and Future Direction
Authors: Buddery Alexander , Dargusch Matthew S. , StJohn David H. , Drennan John , Nabulsi Samih
Published: August 2009

This paper outlines the current state of research into laser welding of titanium and its alloys for medical applications. The differences that exist between the medical and other industries are described and a direction for advancing research in this field is proposed.
The Surface Modifications of Dental Implants that are made of a Near-β Type Titanium Alloy
Authors: Han Jian Ye , Yu Zhen Tao , Yu Sen , Ma Xi Qun , Niu Jin Long , He Xin Jie
Published: August 2009

Abstract
Titanium and its alloys are widely used as dental implant materials due to their excellent biocompatibility, mechanical properties and erosion resistance. The b type titanium alloys are becoming more promising dental implant materials for their low elastic modulus and suitable mechanical properties. Because the titanium alloys are bioinert. The dental implant’s surfaces that contact with bone tissues need modification. To bioactivate the implants, hydroxyapatite/TiO2 composite material was coated onto dental implants by sol-gel and micro arc oxidation (MAO) methods. The HA (Hydroxyapatite) was employed to enhance the bioactivity of the Ti substrate. Owning to TiO2, the HA/TiO2 composite coatings adhered tightly to the dental implants and no longer existed cracks.
Development of Biomedical Near β Titanium Alloys
Authors: Yu Zhen Tao , Wang Gui , Ma Xi Qun , Dargusch Matthew S. , Han Jian Ye , Yu Sen
Published: August 2009

The effects of alloy chemistry and heat treatment on the microstructure and mechanical properties of Ti-Nb-Zr-Mo-Sn near  type titanium alloys have been investigated. Near β titanium alloys consisting of non-toxic alloying elements Mo, Nb, Zr, Sn possess a low Young’s modulus, and moderate strength and plasticity. As the hot rolled TLM alloy (Ti-25Nb-3Zr-3Mo-2Sn) possesses high strength and low Young’s modulus a detailed investigation is performed for this alloy. Solution treatment of the hot rolled TLM alloy reduces strength and increases ductility without affecting the Young’s modulus. Ageing of the solution treated TLM alloy reduces elongation and increases the Young’s modulus with little change in strength. Both solution treated and aged conditions show features of two stage yielding associated with a strain induced martensitic transformation.
Biomimetic Coating on Pure Titanium Submitted to Different Surface Treatments
Authors: Wang Xiao Jian , Li Yun Cang , Hodgson Peter  D. , Wen Cui E
Published: August 2009

Titanium (Ti) plates were firstly treated to form various types of oxide layers on the surface and then immersed into simulated body fluid (SBF) to evaluate the apatite forming ability. The surface morphology and roughness of the different oxide layers were measured by atomic force microscopy (AFM), and the surface energies were determined based on the Owens-Wendt (OW) methods. It was found that Ti samples after Alkali-Heat treatment (AH) achieved the best apatite formation after soaking in SBF for 3 weeks, compared to those without treatment, thermal or H2O2 oxidation. Furthermore, contact angle measurement revealed that the oxide layer on the alkali-heat treated Ti samples possessed the highest surface energy. The results indicate that the apatite inducing ability of a titanium oxide layer is linked to its surface energy. Apatite nucleation is easier on a surface with a higher surface energy.
Latest Developments in Understanding the Grain Refinement of Cast Titanium
Authors: Bermingham Michael J. , McDonald Stuart D. , Dargusch Matthew S. , StJohn David H.
Published: August 2009

Grain refinement of cast titanium alloys is believed to have many benefits. However, literature on how to control and manipulate β-grain size during the solidification of cast components is scarce. This paper discusses the current state of research in grain refining practices in cast titanium alloys.
Fabrication of an Apatite/Collagen Composite Coating on the NiTi Shape Memory Alloy through Electrochemical Deposition and Coating Characterisation
Authors: Banerjee Parama Chakraborty , Sun Tao , Wong Jonathan H.W. , Wang Min
Published: August 2009

To improve the biocompatibility and bioactivity of NiTi shape memory alloy (SMA), apatite/collagen composite coatings were fabricated on the surface of NiTi SMA at room temperature using the electrochemical deposition technique. Spherical apatite particles and fibrous collagen that formed the composite coating were visible under scanning electron microscope (SEM). The Ca/P ratio of the apatite component in the coating, as determined by energy dispersive X-ray spectroscopy (EDX), was about 1.38 which is slightly higher than that of octocalcium phosphate (OCP). X-ray diffraction result showed that the apatite was amorphous, which was due to the low temperature (i.e., room temperature) deposition process. The structure of the composite coatings was further characterized using Fourier transform infrared reflection spectroscopy (FTIR). It was also found that, compared to bare NiTi SMA samples, the wettability of as-deposited samples was increased because of the formation of the composite coating.
Bioactive Hydroxyapatite Coating on Titanium-Niobium Alloy through a Sol-Gel Process
Authors: Xiong Jian Yu , Li Yun Cang , Hodgson Peter  D. , Wen Cui E
Published: August 2009

Hydroxyapatite (HA) was coated on the surface of a titanium-niobium (Ti-Nb) alloy by a sol-gel process. Triethyl phosphite and calcium nitrate were used as the phosphorus (P) and calcium (Ca) precursors respectively to prepare a Ca/P sol solution. The Ti-Nb alloy was dip-coated in the sol and heated at 600°C for 30 minutes. X-ray diffraction (XRD) analysis indicated the major phase constituent of the coating after heat treatment was HA. Scanning electron microscopy (SEM) observation showed that a few cracks were distributed on the HA coating. The in-vitro bioactivity of the HA coated Ti-Nb alloy was assessed using a cell culture of SaOS-2 osteoblast-like cells. The density of cell attachment was determined by MTT assay; the cell morphology was observed by SEM. Results indicated that the density of cell attachment on the surface of the Ti-Nb alloy was significantly increased by HA coating. Cell morphology observation showed that cells attached, spread and grew well on the HA coated surface. It can be concluded that the HA coating improved the in-vitro bioactivity of Ti-Nb alloy effectively.
Die Casting Improvements through Melt Shear
Authors: O'Donnell Robert G. , Gunasegaram Dayalan R. , Givord Michel
Published: August 2009

Melt flow and solidification within a die casting cavity is a complex process dependent in part on melt pressure (with or without intensification), melt velocity, melt flow path, thermal gradients within the die, die lubrication and melt viscosity. Casting defects such as short shots, cold shuts and shrinkage porosity can readily occur if casting conditions are not optimised. Shrinkage porosity in particular is difficult to eradicate from castings that comprise thick sections, since these sections will usually solidify late in the casting cycle and may be starved of melt supply during the critical solidification (and contraction) stage. The current work seeks to elucidate the influence of the melt shearing on the die casting process and demonstrates that the modifications made to the melt through introduction of a local constriction in the melt path can generate improvements in casting microstructure and reduce shrinkage porosity.
Alloy Design for Heat Treatment of High Pressure Diecastings
Authors: Lumley Roger N. , Gershenzon Maya , Gunasegaram Dayalan R.
Published: August 2009

Recently, heat treatment technologies have been developed by the CSIRO Light Metals Flagship in Australia that allow the yield stress in conventional aluminium HPDC’s to be more than doubled without encountering problems with blistering or dimensional instability. These procedures involve a severely truncated solution treatment step conducted at lower than normal temperatures followed by quenching and artificial ageing. Typically, heat treated HPDC’s may display increases to the yield stress of around 80 to 100%, but a range of other properties may also be improved such as fatigue resistance, thermal conductivity and fracture resistance for some tempers.
However, the HPDC alloys currently used worldwide have not been developed specifically for heat treatment or the optimization of specific properties. In particular, recent work in Al-Si-Cu HPDC alloys has identified ranges of alloys specifically for achieving yield strengths exceeding 400 MPa, or for high strength combined with elevated ductility levels. The role of alloying elements, composition limits and effects on microstructure development are discussed.
Towards a More Holistic Approach to Quality Improvements in Aluminium Die Casting
Authors: Zanna Sandrine , Frayman Yakov , Gunn Bruce , Nahavandi Saeid
Published: August 2009

This work evaluates the feasibility of using a holistic approach, based on dynamical system theory, to reduce porosity defects in high pressure aluminum die casting. Quality improvements, from a dynamical system perspective mean the ability to move the die casting process out of its natural equilibrium to a more beneficial state and the ability to maintain this new process state. This more beneficial state may be achieved in several ways. One way is to increase the amount of forcing to overcome natural process resistance. This forcing approach is represented by typical continuous intervention policy, with modifications in die/part design and/or process parameters. An alternative approach is to reduce the amount of natural process resistance, in particular the amount of process disturbance, allowing the process to move out of its natural equilibrium with much less forcing. This alternative uses the self-regulating ability of dynamical systems thus decreasing the amount of human intervention required. In this respect, the influence of vacuum on time on chattering at the first stage of the casting shot was identified as a good process candidate for testing using dynamical system theory. A significant reduction in porosity defects was achieved, which also set the process on a path of slow but consistent self-improvement.
Decision and Design Methodologies for the Lay-Out of Modular Dies for High-Pressure-Die-Cast-Processes
Authors: Queudeville Yann , Ivanov Todor , Nußbaum Christopher , Vroomen Uwe , Bührig-Polaczek Andreas
Published: August 2009

Within the project “Decision and design methodology for the lay-out of modular dies” which is part of the Cluster of Excellence “Integrative Production Technology for High-Wage Countries”, established and financed by the German Research Foundation (DFG), the main objective is setting guidelines for cost-effective and high quality high pressure die casting (HPDC) moulds.
The strong increase in product variants and the growing demand for individualised products results in a growing complexity of all related products. The main objective of this project is bridging the existing gap between individual manufacturing and mass production. A new perspective on the value creation chain of HPDC-dies has to be established. First of all, the methodology for the lay-out of modular dies consists in an analysis of the already produced die cast moulds. For the development of modules, standard parts, and different die types, a wide range of HPDC-dies will be compared with each other and subsequently clustered along specific criteria such as size or number of core sliders. Another step consists in optimising setting-up time and maintenance. The as-is state in different companies will be examined. With this knowledge, new concepts will be developed, keeping a modular configuration of the different parts involved in mind. Concepts for modular core sliders, guides and ejectors will be developed and will be investigated for further use.
Based on this information, the decision and design methodology for the lay-out of modular HPDC -dies will be examined and developed throughout the process.
Classification of Streaking Defects on Anodized Aluminium Extrusions
Authors: Zhu Han Liang , Zhang Xin Quan , Couper Malcolm J. , Dahle Arne K.
Published: August 2009

Streaking is a common problem on anodised extrusions of 6xxx series soft alloys. This paper presents various types of streaking defects on the basis of industry practice and experimental results. The streaking defects are classified according to their root causes. This provides a basis for developing effective methods for preventing the formation of these defects for the extrusion.
Optimisation of the Solution Heat Treatment of Rheo-Processed Al-Cu-Mg-(Ag) Alloys A206 and A201
Authors: Masuku E.P. , Möller Heinrich , Knutsen R.D. , Ivanchev L. , Govender Gonasagren
Published: August 2009

The traditional solution treatment cycles that are currently applied to rheo-processed A201 are mostly those that are used for conventional castings. These solution treatments are not necessarily the optimum solution treatments for rheo-processing. As a result, DSC analysis was done to optimize this heat treatment. The new solution treatment, which consists of higher temperatures and shorter times (515°C/5h, followed by 570°C/10h), resulted in slightly higher hardness values for both alloy A206 and A201.
Thermal Fatigue Studies Using HF Induction Heating of Die Materials for Light Metals Casting
Authors: Gulizia Stefan , Jones Darryl , Jahedi Mahnaz Z. , Kearney Trevor , Koltun Paul
Published: August 2009

In this study a new thermal fatigue test rig has been developed that can apply a net energy input to materials with different physical properties using HF induction heating. Several commercially available hot work ferrous and non-ferrous die materials were evaluated with the aim of providing a basis for selecting an appropriate die material with good thermal fatigue resistance for a given HPDC application. The results show materials with high thermal conductivity such as tungsten-based materials are more resistant to thermal fatigue cracking than conventionally used hot work tool steels for HPDC dies. The initiation and growth of thermal fatigue cracks were examined and periodically evaluated using computer image analysis, for crack morphology, and hardness on each material tested.
Microstructural Modification of A206 Aluminium via Friction Stir Processing
Authors: Sun Ning , Apelian Diran
Published: August 2009

Friction stir processing (FSP) is a post-processing method that locally manipulates microstructure by imparting a high level of energy in the solid state giving rise to improved mechanical properties. FSP was applied to 25.4 mm thick, sand casting A206 aluminum workpiece under different parameters. Effects of FSP on microstructure evolution will be described and discussed. Specifically, through optical microscopy and SEM measurements the attained refinement in the stirred zone will be reviewed; porosity is significantly reduced and second phase particles are fragmented. Thermal conditions of the FSP zone have been measured as well as studying the effect of the temperature gradients on the resultant structure.
Cold Spray of Al-MMC Coatings on Magnesium Alloys for Improved Corrosion and Wear Resistance
Authors: Spencer Kevin , Fabijanic Daniel , Zhang Ming Xing
Published: August 2009

Cold spray coatings are considered promising for surface protection of Mg alloys from wear and corrosion since the process temperature is low enough to avoid oxidation of the Mg or any adverse affects on artificial ageing heat treatments.
A special version of cold spray known as Kinetic Metallization has been used to produce pure Al and Al alloy metal matrix composite (MMC) coatings on AZ91 Mg alloy substrates in the present work. This surface treatment produces dense coatings with high adhesive and cohesive strength, which have substantially higher hardness and wear resistance than the AZ91 substrate material.
The influence of coating composition and subsequent heat treatment on wear and corrosion performance have been investigated, using pin-on-disc wear tests, salt spray testing and electrochemical polarisation techniques. The heat treatment of the cold spray coatings is compatible with the solutionising and T6 ageing heat treatment of AZ91Mg.
The results show that cold spray deposition of MMC coatings is a simple and effective technique for improving the surface properties of Mg alloys, both in the as-cast and in the heat treated condition
Characterization of Magnesium Automotive Components Produced by Super-Vacuum Die Casting Process
Authors: Sadayappan K. , Kasprzak W. , Brown Zach , Quimet L. , Luo Alan A.
Published: August 2009

Magnesium automotive components are currently produced by high pressure die casting. These castings cannot be heat-treated to improve the strength and ductility mainly due to the casting imperfections such as porosity and inclusions created by the air entrainment during the turbulent mold filing. These imperfections also prevent magnesium components to be used for highly stressed body components. Efforts were made to produce high integrity magnesium castings through a Super-Vacuum Die Casting process. The AZ91D castings were found to have very low porosity and can be heat-treated without blisters. The tensile properties of the castings were satisfactory. The mechanical properties and thermal analysis indicate that the conventional heat treatment procedure needs to be optimized for such thin sectioned and rapidly solidified castings which have very fine microstructures.
Rapid Manufacture in Light Metals Processing
Authors: Singamneni Sarat , McKenna Nicholas , Diegel Olaf , Singh Darius , Choudhury A. Roy
Published: August 2009

As several of the free form fabrication processes progress with continuous process and material improvements, the feasibility of Rapid Manufacturing becomes more and more of a reality. Defined as the use of a Computer Aided Design (CAD) based automated additive manufacturing process to construct parts that are used directly as finished products and components, some of the rapid manufacturing processes are already competing with traditional processes such as injection moulding and progress is being made in applying the new technologies to the processing of metals, envisioning additive manufacture of high strength parts of unlimited complexity. While there have been quite a few successful attempts in the rapid production of complex medical implants using titanium alloys, 3D printing of sand moulds opens up yet another rapid manufacturing front, allowing for the rapid casting of aluminium and magnesium alloys. The effectiveness of such processes is yet to be researched in terms of process and product characteristics and the overall economy. This paper attempts to review some of the promising rapid manufacturing technologies for light metals processing and presents results of experimental investigations conducted to evaluate the effectiveness of the rapid casting process currently researched at the Rapid Product Development Centre of AUT University.
Mechanism of Improved Hydrogen Absorption Kinetics in Cast Mg-Ni Alloys
Authors: Nogita Kazuhiro , Ockert Sean , Duguid Andrew , Pierce Jordan , Greaves Matthew
Published: August 2009

The potential for Mg and Mg-Ni alloys to be used as hydrogen storage alloys has been known for some time. Although the maximum storage capacity in these alloys is high (7.6wt%H2 for Mg and 3.4wt%H2 for Mg2Ni), they have, until recently, been disregarded for practical applications due to their slow kinetics and high reaction temperatures. This paper discusses the recent discovery that the non-faceted/faceted hypo-eutectic Mg-Mg2Ni system can, similar to Al-Si eutectic alloys, be modified by trace additions and that this results in improved hydrogen storage properties. The hydrogen storage properties depend on the composition, including trace levels of modifying elements, and processing conditions. In alloys of optimal composition it has been shown that the reversible storage of 6.5-7wt% H2 is possible at a rate of reaction that is far better than that previously documented. In addition, the alloy can be satisfactorily processed in air, as opposed to controlled atmospheric conditions. This paper discusses the mechanism of improved hydrogen absorption/desorption kinetics when eutectic Mg-Ni hypo-eutectic alloys are modified. This discussion is based on atomic scale analysis using electron microscopy and examination with synchrotron radiation.
Overview of Lightweighting Materials Research & Development in the United States Freedomcar and Fuel Partnership
Authors: Paxton Dean M. , Carpenter Joseph A. , Sklad Philip S. , Smith Mark T.
Published: August 2009

The United States of America’s (USA’s) transportation system is strongly dependent on petroleum as an energy source. Petroleum is used to satisfy 95 percent of the USA’s transportation energy needs, consuming two-thirds of all the petroleum used in the USA. Since roughly 60 percent of the petroleum is imported, the implications of this dependency on energy security are readily apparent. Since 2002, the United States Department of Energy (USDOE) and the United States Council for Automotive Research (USCAR) have worked cooperatively through the FreedomCAR and Fuel Partnership (FC&FP) to fund high-risk, high-payoff research and development (R&D) into advanced automotive technologies with the potential for lowering this dependence. The FC&FP succeeded and built upon the Partnership for a New Generation of Vehicles (PNGV) initiative that ran from 1993 to 2001. The long-term transition of vehicles from gasoline to non-petroleum energy sources is viewed as critical in lowering the dependence of the USA economy on foreign oil, and in reducing the environmental impact of the personal transportation sector. The FC&FP supports research on technologies with the potential for energy-efficiency and renewable energy benefits, such as new engine concepts, lightweight materials, alternate non-petroleum based fuels, and hybrid propulsion components. This paper will highlight the research in the lightweight metals portion of the FC&FP. Cooperative R&D projects will be discussed which focus on processing and manufacturing technologies such as casting of magnesium (Mg) and aluminium (Al) alloy components, advanced forming techniques for Al sheet, and warm-forming of Mg sheet. The overall objective of these efforts is not only to demonstrate new technologies, but to reduce the cost of manufacturing lightweight materials and enable implementation of the technologies in high-volume automotive applications.
Effect of Welding Parameters on Microstructure and Tensile Properties of Friction Stir Welded 6061 AL Joints
Authors: Feng Ai Han , Chen Dao Lun , Ma Zong Yi
Published: August 2009

The present investigation is aimed at evaluating the influence of tool rotation rate and welding speed on the microstructure, tensile properties, and fracture mode of 6061 Al-T651 alloy after friction stir welding (FSW). TEM results revealed that in the nugget zone (NZ), FSW resulted in the dissolution of fine needle-shaped precipitates that previously existed in the base metal. At a given rotation rate of 1400rpm, the yield strength (YS) and ultimate tensile strength (UTS) of the welded joints increased with increasing welding speed from 200 to 600mm/min. However, the UTS of the joints was nearly independent of the rotation rate. Furthermore, the relationship between the hardness distribution and fracture location has also been identified.
Mass Decompounding and Vehicle Lightweighting
Authors: Verbrugge Mark , Lee Theresa , Krajewski Paul E. , Sachdev Anil K. , Bjelkengren Catarina , Roth Richard , Kirchain Randy
Published: August 2009

Although mass reduction can be associated with additional costs, a decision to lightweight a structural subsystem may, depending on when in the vehicle development process the decision is taken, result in secondary (additional) mass savings such that the value of lightweighting is substantially increased. This paper overviews a method to estimate the potential for secondary mass savings in different vehicle subsystems. We close by describing current research efforts aimed at developing new lightweight product solutions for both body and powertrain applications along with commensurate manufacturing processes.
Processing of High Pressure Die Casting Alloys and Engineering Polymers to New Hybrid Metal/Plastic Products in a Combined Process
Authors: Jakob Matthias , Queudeville Yann , Vroomen Uwe , Bührig-Polaczek Andreas
Published: August 2009

Within the project “Advanced Processes for Hybrid Metal/Plastic Products” which is part of the Cluster of Excellence “Integrative Production Technology for High-Wage Countries”, established and financed by the German Research Foundation (DFG), new hybrid processes for the production of metal/plastic-composites will be developed. The activities of the Foundry Institute focus on the processing of structural parts with excellent mechanical properties and special integrated functions by combining two original mould operations. In the long term, the metal/plastic-composites are to be produced in a single step process, using one mould and one machine. Beside the combination of the two processes, high pressure die casting and injection moulding, preliminary test geometries will be manufactured in separate moulds. The operation using the two moulds consists in the production of the aluminium metal part in a pressure die casting mould, and subsequently the injection of the plastic component into an injection mould. The basics needed to define the adhesion mechanism between metal and plastic were investigated under experimental conditions in order to determine appropriate results for tests, carried out under the process conditions of high pressure die casting. It is proposed to find and to develop new concepts to join these two different materials. The best bonding mechanism will be chosen to obtain the first metal/plastic hybrid products in the so-called One-Step-Process. A selection of promising results concerning the bond strength of different joining concepts under application terms are presented in this paper.
Selective Enhancement of Tensile/Compressive Strength and Ductility of AZ31 Magnesium Alloy via Nano-Al2O3 Reinforcement Integration Method Alteration
Authors: Paramsothy Muralidharan , Hassan Syed Fida , Bau Nguyen Quy , Srikanth Narasimalu , Gupta Manoj
Published: August 2009

Two new AZ31 nanocomposites containing Al2O3 nanoparticle reinforcement were fabricated with different reinforcement integration methods using solidification processing followed by hot extrusion. Each nanocomposite had similar composition (Al and Zn contents), microstructure (grain and intermetallic particle sizes, Al2O3 nanoparticle distribution) and hardness. However, the first nanocomposite had better overall tensile properties compared to the second nanocomposite. Also, the second nanocomposite exhibited better overall compressive properties compared to the first nanocomposite. On the whole, the second nanocomposite was more deformable in tension and compression than the first nanocomposite. The effect of reinforcement integration method on the tensile and compressive properties of the AZ31- Al2O3 nanocomposites is investigated in this paper.
Influence of Ultrasonic Processing on Nano-Sized Particle Dispersion in Magnesium Matrix Nanocomposites
Authors: Liu Shi Ying , Gao Fei Peng , Zhang Qiong Yuan , Li Wen Zhen
Published: August 2009

The parameters of ultrasonic processing have important effects on the distribution and dispersion of nano-sized particles in magnesium matrix nanocomposite (MMNC) fabrication. In order to learn more about the above effects and produce guidelines for the fabrication of MMNC, the acoustic cavitation and streaming effects produced by high intensive ultrasonic method with different frequency and power were experimented with water, glycerol, soybean oil and oil-water mixture respectively. The results showed that the acoustic cavitation and streaming were influenced by ultrasonic frequency and power as well as the depth of waveguide dipped into melts. The ultrasonic processing of the MMNC melts with 20kHz and 1.4kW greatly improved the dispersion and distribution of nano-sized reinforcement particles in MMNC.
Effect of Structure Relaxation on the Plastic Deformation Behaviour in a Zr-Based BMG under Indenter
Authors: Xie Hao Wen , Hodgson Peter  D. , Wen Cui E
Published: August 2009

Vickers and nano indentations were performed on a structurally relaxed Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG), and the evolution of the shear bands in the relaxed BMG was investigated and compared to that in the as-cast alloy. Results indicate that the plastic deformation in the BMG with structure relaxation is accommodated by the semicircular (primary) and radial (secondary) as well as tertiary shear bands. Quantitatively, the shear band density in the relaxed alloy was much lower than that in the as-cast alloy. The annihilation of free volume caused by the annealing was responsible for the embrittlement of the sample with structure relaxation.
Mechanical Properties and Microstrutures of Nano-Sized SiC Particles Reinforced AZ91D Nanocomposites Fabricated by High Intensity Ultrasonic Assisted Casting
Authors: Liu Shi Ying , Gao Fei Peng , Zhang Qiong Yuan , Li Wen Zhen
Published: August 2009

A high intensity ultrasonic assisted casting method was used to fabricate SiC nanoparticles reinforced magnesium matrix nanocomposites (n-SiCp/AZ91D). The microstructures and mechanical properties of the nanocomposites were investigated. The results show that n-SiCp are well dispersed in the matrix and the grain size was refined. A HRTEM study of the interface between n-SiCp and the matrix suggests that SiC bonds well with matrix without forming an intermediate phase. With the lower addition of n-SiCp, the mechanical properties of nanocomposites are greatly improved. As compared to an unreinforced magnesium alloy matrix, the tensile and yield strength were improved by 43.6% and 117% respectively.
Residual Stresses and Distortions in Aluminum Alloy Sheet after Welding under Pre-Tension
Authors: Li Jing Yong , Lu Ya Ming , Liu Zhi Peng , Zhang Ming Ming
Published: August 2009

By applying the elastic pre-tension method, 5A05 aluminium alloy sheets with 4mm thickness were welded. It is shown that the peak value of residual stresses and their distribution vicinity, the longitudinal buckling distortions and plane deformations of specimens after welding under pre-tension were obviously reduced. It is considered that pre-tension counteracts the compression stress in regions close to the weld generated by thermal expansion, consequently reduces the compression plastic deformations and the tensile stresses in these regions when cooling down, and accordingly diminishes the compressive stresses far from the weld.
Room Temperature Formability of Mg Alloys
Authors: Kang Dae H. , Kim D.W. , Kim S. , Bae Geun Tae , Kim K.H. , Kim Nack J.
Published: August 2009

Room temperature formability of twin-roll cast Mg alloys has been investigated and correlated with their work hardening behavior. Tensile properties of these alloys were measured and their work hardening behaviour was analysed by using constitutive equations. Room temperature formability of the alloys was evaluated by the limiting dome height (LDH) value, obtained by the Erichsen cupping test. It shows that there is a linear relationship between LDH value and the inverse of yield ratio, which is a function of work hardening exponents. An increase in grain size increases work hardening exponent and concurrently increases LDH.
Role of Solute Content on the Intermetallic Structure Development in HPDC Mg-Al Binary Alloys
Authors: Nagasekhar A.V. , Cáceres Carlos H. , Easton Mark
Published: August 2009

Scanning electron microscopy has been used to characterize the intermetallic structure development across the tensile cross-section of binary Mg-Al alloys with solute content between ~0.5 and 12 mass%Al. The alloys which contain less than 1 mass%Al exhibited a single phase grain structure. For compositions greater than 1 mass% Al, an eutectic network with a discontinuous distribution of intermetallics across the cross-section became apparent. In alloys with greater than 8.77 mass%Al, the intermetallics form a continuous network over the entire cross-section. The scale of the intermetallics network is finer at the surface and corner regions of the cross section in comparison with the core regions.
Microstructure and Texture of AZ80 Magnesium Alloy Sheet Rolled by High Speed Warm Rolling
Authors: Sakai Tetsuo , Watanabe Yohei , Utsunomiya Hiroshi
Published: August 2009

The present authors have succeeded in single pass large draught rolling of AZ31 and ZK60A magnesium alloy sheet below 200°C without heating rolls by raising the rolling speed above 1000m/min. Maximum reduction attained in single pass rolling was 60%. Among magnesium alloys, AZ31 is known as the most ductile alloy. It remains uncertain whether the high limiting reduction by high speed rolling can be attained in other magnesium alloys that are less ductile but stronger than AZ31.
In this study, AZ80A (Mg-8.1%Al-0.63%Zn) sheets with the thickness of 2.7mm cut from the extruded sheets were used. Rolling temperature was varied from RT to 350°C. Rolling speed was 1000m/min. The limiting reduction in thickness increases with rolling temperature, and the maximum reduction of 52% is obtained at 250°C. The fracture surface of sheet rolled at 100°C shows ductile fractured surface, while it shows brittle fracture surface at 350°C. This difference in fracture mode is attributed to the precipitation of -particles at grain boundaries during holding at 350°C before rolling. From this result, high speed rolling can also be an effective tool for improving the rolling deformability of AZ80 sheet. The hardness of the rolled sheets measured on the transverse plane increases with increasing temperature and reduction. The variation of hardness with rolling temperature and reduction indicates the occurrence of dynamic recrystallization (DRX). The sheet rolled at 200°C with the reduction of 50% shows the tensile strength of 353MPa and the elongation of 29%, which is an excellent strength-ductility balance. By applying high-speed rolling process to AZ80 magnesium alloy, we can obtain a remarkable improvement in the material characteristics as well as rolling deformability.
Solute Partitioning to Enhance Mechanical Properties of Aged Aluminium Alloys
Authors: Polmear Ian J. , Lumley Roger N.
Published: August 2009

Deliberate partitioning of solute elements between the matrix solid solution and dispersed precipitates in aged aluminium alloys can be facilitated by underageing during heat treatment. Although this practice may cause some reduction in tensile properties, it has been shown that significant improvements may be achieved in creep resistance, fatigue strength and fracture toughness. Exploitation of secondary precipitation can allow simultaneous increases to be obtained in tensile and fracture properties.
Structural Bonding for Lightweight Construction
Authors: Hornung Martin , Hajj Michael
Published: August 2009

The demand for safer, lighter and more fuel efficient vehicles has led to the market entry of light weight construction, with the use of advanced high strength steels, engineering plastic and light weight metals. Maximum weight savings potential will be limited if these are used in isolation. Chemistry based structural adhesives and foams enable the intelligent use of all three weight saving methodologies to overcome the problems of safety, quality and high processing cost.
Direct Manufacturing of Titanium Parts by Cold Spray
Authors: Jahedi Mahnaz Z. , Zahiri Saden H. , Gulizia Stefan , Tiganis Bill , Tang C. , Fraser Darren
Published: August 2009

Titanium has excellent properties as an engineering material such as light weight, high strength and high resistance to corrosion and fracture. However, the high cost associated with the materials and current process technologies is not conducive to higher-volume production for consumer industry. It appears near net shape manufacturing has to be used to manufacture titanium and titanium alloys parts. Investigators are exploring several near net shape technologies. However, most of these technologies involve melting and solidification. Each new layer starts out molten, solidifies, and must eventually cool to room temperature. Oxygen sensitive material such as titanium needs to be processed under vacuum. There is a great need for revolutionary coating and direct Manufacturing technology to extend the application of titanium and titanium alloys from top end, aerospace and biomedical to lower end consumer use. It appears Cold Spray Technology can deliver a suitable and cost effective coating and direct manufacturing solution for titanium industry. CSIRO Light Metals Flagship has pioneered in developing direct manufacturing technologies to fabricate titanium parts using Cold Spray. Mechanical properties of Cold Spray titanium in as sprayed and heat treated conditions are presented and compared with wrought titanium. Some of technologies such as Cold Spray for direct manufacturing of seamless titanium pipes are discussed.
Sintering of Titanium Powder Compacts for Containerless Hot Isostatic Pressing
Authors: Low Ray J. , Robertson Ian M. , Qian Ma , Schaffer Graham B.
Published: August 2009

The liquid-phase sintering of Ti-Si binary alloys using mixed elemental powders has been explored. Sintering at low liquid contents avoids excessive porosity and bulging of compacts, and leads to development of a densified surface. Compacts made in this way can be HIPped without a container to full or near full densities. Exploiting the surface densification phenomenon may enable cost-effective net shape manufacturing of full density titanium components.
Consolidation of Titanium, and Ti-6Al-4V Alloy Powders by Powder Compact Forging
Authors: Zhang De Liang , Raynova Stella , Nadakuduru Vijay , Cao Peng , Gabbitas Brian , Robinson Barry
Published: August 2009

Consolidation of titanium and titanium alloy powders using thermomechanical powder metallurgy (TPM) processes (powder compact forging, extrusion and rolling) is one way that can lead to cost-effective production of high value-added consolidated titanium and titanium alloy products such as near-net shaped components, tubes and plates. This paper provides an overview of the quality, microstructure (to limited depth), porosity level and mechanical properties of disks produced using open die forging of powder compacts of CP titanium and Ti-6Al-4V alloy powders. The general materials science principles underlying the relationships between processing conditions, microstructure and the mechanical properties of the disks made by using the powder compact forging are discussed.