Showing papers in "JOM in 2006"
TL;DR: In this article, an overview of recent achievements and new trends in the production of bulk ultrafine-grained (UFG) materials using severe plastic deformation (SPD) is presented.
Abstract: This overview highlights very recent achievements and new trends in one of the most active and developing fields in modern materials science: the production of bulk ultrafine-grained (UFG) materials using severe plastic deformation (SPD). The article also summarizes the chronology of early work in SPD processing and presents clear and definitive descriptions of the terminology currently in use in this research area. Special attention is given to the principles of the various SPD processing techniques as well as the major structural features and unique properties of bulk UFG materials that underlie their prospects for widespread practical utilization.
1,345 citations
TL;DR: In the past decade, natural fiber composites with thermoplastic and thermoset matrices have been embraced by European car manufacturers and suppliers for door panels, seat backs, headliners, package trays, dashboards, and interior parts as mentioned in this paper.
Abstract: In the past decade, natural-fiber composites with thermoplastic and thermoset matrices have been embraced by European car manufacturers and suppliers for door panels, seat backs, headliners, package trays, dashboards, and interior parts. Natural fibers such as kenaf, hemp, flax, jute, and sisal offer such benefits as reductions in weight, cost, and CO2, less reliance on foreign oil sources, and recyclability. However, several major technical considerations must be addressed before the engineering, scientific, and commercial communities gain the confidence to enable wide-scale acceptance, particularly in exterior parts where a Class A surface finish is required. Challenges include the homogenization of the fiber's properties and a full understanding of the degree of polymerization and crystallization, adhesion between the fiber and matrix, moisture repellence, and flame-retardant properties, to name but a few.
1,272 citations
TL;DR: In this article, the authors present a review of recent progress in tailoring the nanostructure to achieve coexisting high strength and high ductility at room temperature, focusing on a summary of the strategies currently being pursued as well as the outstanding issues that await future research.
Abstract: Nanostructured metals and alloys are under intensive research worldwide and being developed into bulk forms for application. While these new materials offer record-high strength, their ductility is often inadequat. This article reviews recent progress in tailoring the nanostructure to achieve coexisting high strength and high ductility at room temperature. The focus is on a summary of the strategies currently being pursued as well as the outstanding issues that await future research.
384 citations
TL;DR: Integrated computational materials engineering (ICME) as mentioned in this paper is a field of study whose time has come to link manufacturing and design via advanced materials models in a seamless, integrated computational environment.
Abstract: Integrated computational materials engineering is a field of study whose time has come. It promises to link manufacturing and design via advanced materials models in a seamless, integrated computational environment. The feasibility of ICME and its benefits have been demonstrated by several projects that have developed methods which are in use in the aerospace and automotive industries. To fully realize the potential of ICME, anumber of technical, cultural, and organizational challenges have been identified and must be overcome.
214 citations
TL;DR: This short review provides insights into the physical, chemical, and interfacial parameters on the toxic potential of nanomaterials.
Abstract: Nanotechnology has attracted considerable attention in the scientific community ever since its emergence as a powerful basic and applied science tool. While beneficial aspects of nanomaterials are well visioned, several reports have suggested the negative impact of nanomaterials on living cells. The diverse array of surface properties achieved due to reduction in particle size that catalyzes the surface chemistry of nanoparticles is responsible for their toxic potential. Physical parameters such as surface area, particle size, surface charge, and zeta potential are very important for providing mechanistic details in the uptake, persistence, and biological toxicity of nanoparticles inside living cells. This short review provides insights into the physical, chemical, and interfacial parameters on the toxic potential of nanomaterials. While nanotechnology has promised invaluable progress in science and technology, the onus rests on the scientific community to predict the unknown outcome on the biological system for its safe proliferation.
209 citations
TL;DR: The importance of understanding and predicting the interactions of oxides with water vapor at high temperatures is demonstrated in this paper, where methods for observing volatilization phenomena and identifying the chemical formulae for volatile metal hydroxides are discussed.
Abstract: The importance of understanding and predicting the interactions of oxides with water vapor at high temperatures is demonstrated in this article. Methods for observing volatilization phenomena and identifying the chemical formulae for volatile metal hydroxides are discussed. In addition, techniques for obtaining accurate thermodynamic data for gaseous metal hydroxide species are described. Detailed examples of the stability of the principle structural and/or protective oxides chromia (Cr2O3), silica (SiO2), and alumina (Al2O3) in high-temperature water vapor are included.
173 citations
TL;DR: A brief overview of the major applications of metal-matrix composites in ground transportation can be found in this paper, where the main attractive features of MMCs are: high strength-to-weight ratio, enhanced mechanical and thermal properties over conventional materials, improved fatigue and creep characteristics, better wear resistance, and general tailorability of properties.
Abstract: Metal-matrix composites (MMCs) are used in a variety of automotive and other ground transp ortation applications. This article provides a brief overview of the major applications of MMCs in ground transportation. The main attractive features of MMCs are: high strength-to-weight ratio, enhanced mechanical and thermal properties over conventional materials, improved fatigue and creep characteristics, better wear resistance, and general tailorability of properties. Because the transportation industry is extremely cost-sensitive, reducing the manufacturing costs of MMC components will aid in the use of MMCs.
135 citations
TL;DR: In this article, the overall design principles in biological structural composites and illustrates them for five examples; sea spicules, the abalone shell, conch shell, the toucan and hornbill beaks, and the sheep crab exoskeleton.
Abstract: Biological materials are complex composites that are hierarchically structured and multifunctional. Their mechanical properties are often outstanding, considering the weak constituents from which they are assembled. They are for the most part composed of brittle (often, mineral) and ductile (organic) components. These complex structures, which have risen from millions of years of evolution, are inspiring materials scientists in the design of novel materials. This paper discusses the overall design principles in biological structural composites and illustrates them for five examples; sea spicules, the abalone shell, the conch shell, the toucan and hornbill beaks, and the sheep crab exoskeleton.
131 citations
TL;DR: In this article, it is shown that fly ash can be incorporated into an aluminum-alloy matrix using stir casting and pressure infiltration techniques to decrease energy content, material content, cost, and weight of selected industrial components, while also improving selected properties.
Abstract: This paper summarizes attempts to incorporate fly ash into aluminum castings to decrease the energy content, material content, cost, and weight of selected industrial components, while also improving selected properties. It is shown that fly ash can be incorporated into an aluminum-alloy matrixusing stir casting and pressure infiltration techniques. The sand and permanent mold castings, which included differential vovers, intake manifolds brake drums, and outdoor equipment castings including post caps, demonstrate adequate castability of aluminum melts containing up to 10 vol.% fly-ash particles. The potential cost, energy, and pollution savings as a result of incorporation of fly ash in aluminum are discussed in the paper.
125 citations
TL;DR: The World Nonferrous Smelters Survey (TMS) as discussed by the authors was the first edition of the TMS program, which was intended to develop a database of all known nonferrous smelters.
Abstract: In June 2004 JOM published the first installment in an ambitious TMS program: the World Nonferrous Smelters Survey. The program is intended to develop a database of all known nonferrous smelters. This paper, the third installment in the project, presents a survey for nickel smelters processing lateritic or other types of oxidic nickel ores. Data for nickel sulfide smelting is scheduled to be published by JOM in the second half of 2006.
112 citations
TL;DR: In this paper, a review of the advantages and limitations of rigid bonded sealing, compressive sealing, and compliant bonded sealing is presented, highlighting some of the leading concepts, and outlines the future steps that need to be taken in their development.
Abstract: One of the keys to developing viable solid oxide fuel cell (SOFC) systems is to first develop reliable and inexpensive stack sealing technology. Three general approaches are currently being pursued: rigid bonded sealing, compressive sealing, and compliant bonded sealing. This review highlights the advantages and limitations of each option, discusses some of the leading concepts, and out-lines the future steps that need to be taken in their development.
TL;DR: The Virtual Aluminum Castings methodology as mentioned in this paper was developed and implemented at Ford Motor Company and demonstrates the feasibility and benefits of integrated computational materials engineering for cast aluminum engine blocks and cylinder heads.
Abstract: The automotive product design and manufacturing community is continually besieged by Hercule an engineering, timing, and cost challenges. Nowhere is this more evident than in the development of designs and manufacturing processes for cast aluminum engine blocks and cylinder heads. Increasing engine performance requirements coupled with stringent weight and packaging constraints are pushing aluminum alloys to the limits of their capabilities. To provide high-quality blocks and heads at the lowest possible cost, manufacturing process engineers are required to find increasingly innovative ways to cast and heat treat components. Additionally, to remain competitive, products and manufacturing methods must be developed and implemented in record time. To bridge the gaps between program needs and engineering reality, the use of robust computational models in up-front analysis will take on an increasingly important role. This article describes just such a computational approach, the Virtual Aluminum Castings methodology, which was developed and implemented at Ford Motor Company and demonstrates the feasibility and benefits of integrated computational materials engineering.
TL;DR: In this article, the authors compared the room-temperature sheet formability of conventional alloy AZ31B with alloys containing lithium oryttrium solid solutions and found that the lithium alloy has comparable or better deep-drawing capacity.
Abstract: The sheet formability of current magnesium alloys at ambient temperatures is poor; however, the formability at moderately elevated temperatures can be excellent. Cylindrical cup drawing tests are used to compare the warm forming characteristics of conventional alloy AZ31B with alloys containing lithium oryttrium solid solutions. While both types of experimental alloy can have better room-temperature ductility (ef∼25–30%) than AZ31B, only the lithium alloy has comparable or better deep-drawing capacity. The results are discussed in terms of the sheet anisotropy. Particular attention is drawn to the fact that magnesium alloys exhibit poor bending ductility due to their anisotropy and mechanical twinning-induced tension-compression strength asymmetry.
TL;DR: In this article, the U.S. Department of Energy FreedomCAR goals for hydrogen storage, storage capacities of important hydrides, and current developments in light-metal complex hydride.
Abstract: Recent developments in light metal complex hydrides show that there is a potential for hydrogen storage using these hydrides in fuel cells for on-board vehicular and other applications. The search for new alloys promises to have practical significance with the realization that hydrogen as a fuel holds the key to filling energy needs and solving environmental problems. This review presents the U.S. Department of Energy FreedomCAR goals for hydrogen storage, storage capacities of important hydrides, and current developments in light-metal complex hydrides.
TL;DR: In this article, a study of the reaction of solder with the electrolessnickel with immersion gold (ENIG) plating system, and the resulting interfacial structures was performed. But the results of the analysis were limited.
Abstract: This paper reports on a study of the reaction of solder with the electrolessnickel with immersion gold (ENIG) plating system, and the resulting interfacial structures. Aforcused-ion beam (FIB) was used to polish the cross sections to reveal details of the microstructure of the ENIG-plated pad with and without soldering. High-speed pull testing of solder joints was performed to expose the pad surface. Results of scanning-electron microscopy/energy-dispersive x-ray analysis of the cross sections and fractured pad surfaces support the suggestion that black pad is the result of galvanic hyper-corosion of the plated electroless nickel by the gold plating bath. Criteria are proposed for diagnosing black pad of ENIG plating.
TL;DR: In this paper, the authors developed a coating for titanium aluminides based on the intermetallic γ-TiAl phase as lightweight structural materials to be used at moderately elevated temperatures.
Abstract: Engine designers show continued interest in titanium aluminides based on the intermetallic γ-TiAl phase as lightweight structural materials to be used at moderately elevated temperatures. Although alloy development has made significant progress in terms of mechanical properties and environmental resistance, protective coatings have been developed that help to extend the lifetime of these alloys significantly. The major challenge of coating development is long-termstability of aprotective oxide scale that forms during service for which purpose alumina formation is essential. Furthermore, changes of coating chemistries at high temperatures must be controlled to avoid rapid degradation of the coatings due to diffusional losses into the substrate material and vice versa.
TL;DR: A review of the principal mechanisms responsible for the plastic deformation of nanocrystalline metals can be found in this article, where the authors show that with a decrease in grain size there is a gradual shift in the relative importance of the deformation mechanisms away from the ones operating in the conventional polycrystalline domain.
Abstract: This article presents a review of the principal mechanisms responsible for the plastic deformation of nanocrystalline metals. As the concentration of grain boundaries increases, with a decrease in grain size there is a gradual shift in the relative importance of the deformation mechanisms away from the ones operating in the conventional polycrystalline domain. This is predicted by molecular dynamics simulations that indicate a preponderance of dislocation emission/annihilation at grain boundaries and grain-boundary sliding when grain sizes are in the range 20–50 nm. Experiments show, in general, a saturation in work hardening at low strains, which is indicative of a steady-state dislocation density. This saturation is accompanied by an increased tendency toward shear localization, which is supportive of dislocation generation and annihilation at grain boundaries. Dislocation analyses recently proposed corroborate the computational predictions and provide a rational foundation for understanding the mechanical response.
TL;DR: In this paper, two main approaches can be taken to prevent reversion and allow recovery of the metal product: rapid quenching of the vapor and dissolving the magnesium directly in a suitable metal solvent before reversion can occur.
Abstract: The carbothermic reduction of magnesia to produce magnesium offers the potential of a lower energy and higher productivity route for metal production compared to existing industrial routes. The reaction of magnesia and carbon produces a magnesium and carbon monoxide vapor. Slow cooling of that vapor will allow the reaction to quickly revert and the prevention of this reversion reaction is a major technical challenge. Two main approaches can be taken to prevent reversion and allow recovery of the metal product: rapid quenching of the vapor and dissolving the magnesium directly in a suitable metal solvent before reversion can occur. The commercial viability of either carbothermic route to magnesium is closely connected to the physical chemistry of each system.
TL;DR: In this article, the failure mechanisms and reliability performance of indium solder TIM as a function of integrated heat spreader metallization thickness, TIM bond line thickness, and die size were investigated.
Abstract: Developing new thermal interface materials (TIMs) is a key activity to meeting package thermal performance requirements for future generations of microprocessors. Indium solder is capable of demonstrating end-of-line performance to meet current technology targets due to its inherent high thermal conductivity. However, improving its reliability performance, particularly in temperature cycling, is a challenge. This study describes the failure mechanisms and reliability performance of indium solder TIM as a function of integrated heat spreader metallization thickness, TIM bond line thickness, and die size. Also studeited were the steps taken to improve its temperature cycle performance. Analyses were performed using thermal resistance measurements, scanning-electron microscopy, scanning-acoustic microscopy, and transmission-electron microscopy to characterize the solder TIM thermal performance, interfacial microstructure, and failure mechanisms.
TL;DR: The selective gas nitridation of model nickel-based alloys was used to form dense, electrically conductive and corrosion-resistant nitride surface layers, including TiN, VN, CrN and Cr2N, as well as a complex NiNbVN phase.
Abstract: The selective gas nitridation of model nickel-based alloys was used to form dense, electrically conductive and corrosion-resistant nitride surface layers, including TiN, VN, CrN, Cr2N, as wellas a complex NiNbVN phase. Evaluation for use as a protective surface for metallic bipolar plates in proton exchange membrane fuel cells (PEMFC) indicated that CrN/Cr2N based surfaces holdpromise to meet U.S. Department of Energy (DOE) performance goals for automative applications. The thermally grown CrN/Cr2N surface formed on model Ni−Cr based alloys exhibited good stability and low electrical resistance in single-cell fuel cell testing under simulated drive-cycle conditions. Recent results indicate that similar protective chromium nitride surfaces can be formed on less expensive Fe−Cr based alloys potentially capable of meeting DOE cost goals.
TL;DR: In this article, the methods employed in the hydrometallurgical production of ammonium paratungstate (APT), the main tungsten compound used in the manufacturing of Tungsten metal powder, are reviewed.
Abstract: Tungsten is one of the most important refractory metals. It is used in the production of numerous end-use items such as incandescent lamps and hard materials. From its ore concentrates and oxidized scrap, tungsten is processed via a hydrometallurgical route. In the last 100 years there has been a significant change in its processing. This paper reviews the methods employed in the hydrometallurgical production of ammonium paratungstate (APT), the main tungsten compound used in the manufacturing of tungsten metal powder. In addition to discussing tungsten feeds, the paper will review all hydrometallurgical steps typically used in the modern methods of APT production.
TL;DR: The challenges facing engineering education and the profession are confronting a challenging crossroad in the 21st century as mentioned in this paper, and it would be fair to say that none of us are very satisfi f with the status quo and what seems to be facing us in the near term.
Abstract: Engineering education and the profession are confronting a challenging crossroad. Some of us see it as a crisis, others, as an opportunity for positioning our community and our society for the 21st century. It would be fair to say, however, that none of us are very satisfi ed with the status quo and what seems to be facing us in the near term. As Charles Dickens wrote in the opening of A Tale of Two Cities, “It was the best of times, it was the worst of times”. Author and journalist Thomas Friedman has declared that the world is now fl at. Globalization of the economy has amplifi ed the impact of technology on modern societies in ways that could not have been predicted. The connectivity provided by the Internet has generated new markets for products and services, but has also made available labor that is often both educated and cheap. This is likely to have a profound impact on the distribution of wealth in both the developed and the developing parts of the world and may, in particular, alter the socioeconomic structure of countries where the general well-being of the population has been taken for granted. That education plays a role in the prosperity of nations is not debated, but many authors, like Landes, for example, argue that it is specifi cally the presence of both knowledge and know-how that determines how well off societies are. The education of engineers is therefore critical to every nation to ensure the prosperity of its citizens. The modern professional identity of engineers emerged in the early 18th century with the establishment of the Ecole Polytechnique in France and the foundation of professional engineering societies in England. The current way Re-Engineering Engineering Education for the Challenges of the 21st Century
TL;DR: The use of a higher-strength aluminum alloy for the construction of military vehicles will reduce their weight substantially and lead to improved fuel consumption, range, reliability, and speed as discussed by the authors.
Abstract: Mechanical millingat cryogenic temperatures produces a nanostructured powder that can be used to manufacture a bulk, ultrafine-grained (UFG), non-heat-treated aluminum alloy with an attractive combination of physical and mechanical properties. The use of a higher-strength aluminum alloy for the construction of military vehicles will reduce their weight substantially and lead to improved fuel consumption, range, reliability, and speed. By introducing coarse grains and creating a multi-scale microstructure, the ductility of the cryomilled aluminum alloy can be increased above that achieved with a fully UFG structure while still retaining high strength levels. The addition of reinforcing ceramic, in the form of particulate addedduring the milling process, has the ability to increase strength levels even further.
TL;DR: In this paper, the common lead alloys associated with insoluble anodes in different metal deposition operations were reviewed and a detailed discussion of Alloy additions and manufacturing processes were examined as appropriate methods to meet the performance needs of a lead anode.
Abstract: This paper reviews the common lead alloys associated with insoluble anodes in different metal deposition operations. Metallographic techniques were used to evaluate microstructures as they relate to physical and mechanical properties. Alloy additions and manufacturing processes are examined as appropriate methods to meet the performance needs of a lead anode.
TL;DR: In this paper, an integrated framework for sustainable materials management that will help to address these critical challenges from a systems perspective is presented. But the authors do not consider the impact of material consumption on economic value creation.
Abstract: Achieving global sustainability will require a decoupling of material consumption from economic value creation While industrialized societies have achieved gains in resource efficiency and waste recycling, total material through-put continues to rise Environmental pressures will only be exacerbated as the world's developing economies increase their consumption rates This paper describes an integrated framework for sustainable materials management that will help to address these critical challenges from a systems perspective
TL;DR: In this article, the enhancement of osseointegration by means of anodized microporous titanium surfaces, functionally macroporous graded titanium coatings, nanoscale titanium surfaces and different bioactive factors is discussed.
Abstract: Osseointegrated dental implants are used to replace missing teeth. The success of implants is due to osseointegration or the direct contact of the implant surface and bone without a fibrous connective tissue interface. This review discusses the enhancement of osseointegration by means of anodized microporous titanium surfaces, functionally macroporous graded titanium coatings, nanoscale titanium surfaces, and different bioactive factors.
TL;DR: The discovery of y' hardening early in the 20th century seeded a continuous evolution of a remarkable family of alloys known as the superalloys as discussed by the authors, and the sequence of their development will be traced in this article.
Abstract: The discovery of y' hardening early in the 20th century seeded a continuous evolution of a remarkable family of alloys, known as the superalloys. The sequence of their development will be traced in this article. The theories of alloying and hardening mechanisms will be discussed as each played an essential role in the progressive development of the superalloys, as did a number of processing discoveries that are reviewed here.
TL;DR: In this paper, the effect of the addition of lanthanum on the melting behavior, microstructure, and shear strength of an Sn-3.9Ag-0.7Cu alloy was investigated.
Abstract: Severallead-free material systems are availableas replacements for traditional lead-based solders in microelectronic packaging, including near-eutectic combinations oftin-rich alloys. Although these materials have superior mechanical properties as compared to the Pb-Sn system, much work remains in developing these materials for electronic packaging. Small additions of rare-earth elements have been shown to refine the microstructure of several lead-free solder systems, thus improving their mechanical properties. This study investigated the effect of the addition of lanthanum on the melting behavior, microstructure, and shear strength of an Sn-3.9Ag-0.7Cu alloy. The influence of LaSn3 intermetallics on microstructural refinement and damage evolution in these novel solders is discussed.
TL;DR: In this paper, the most important aspects of cobalt recycling and application are discussed, and new cobalt purification and electrodeposition developments are described, and the most relevant aspects of the cobalt reuse and application for mixed ore are also presented.
Abstract: Although cobalt is one of the least abundant elements compared to copper and nickel, it is an important part of the composition of nearly all alloys developed since the 19th century and has been of considerable interest in recent years. In this paper, cobalt processes that were developed for mixed ore are summarized. New cobalt purification and electrodeposition developments are described, and the most important aspects of cobalt recycling and application are also presented.
TL;DR: In this article, a two-level composite of a co-continuous alumina-aluminum structure that surrounds SiC particles that provide thermal conductivity was tested. But the results showed that the materials showed friction and wear properties similar to cast iron, but with half the density and better thermal conductivities.
Abstract: Reactive infiltration of precursor ceramics (e.g., the formation of an alumina-aluminum composite by reaction of silica in liquid aluminum) is a low-cost and versatile method of creating materials with interpenetrating co-continuous ceramic and metal phases. By controlling the composition and microstructure of the precursor and the composition of the reaction bath, one can control the structure and properties of the resulting material. This paper summarizes preliminary attempts to use these routes to create next-generation materials for automotive brake rotors. Two types of materials were tested. The first is a two-level composite of a co-continuous alumina-aluminum structure that surrounds SiC particles that provide thermal conductivity. For higher-temperature use, the aluminum alloy is replaced with aluminum-bronze. Both materials show friction and wear properties similar to cast iron, but with half the density and better thermal conductivity.