Showing papers in "JOM in 2003"
TL;DR: JMatPro as discussed by the authors is a multi-platform software program for calculating the properties and behavior of multi-component alloys, including thermophysical and physical properties, from room temperature to the liquid state.
Abstract: This article describes the development of a new multi-platform software program called JMatPro for calculating the properties and behavior of multi-component alloys. These properties are wide ranging, including thermophysical and physical properties (from room temperature to the liquid state), time-temperature-transformation/continuous-cooling transformation diagrams, stress/strain diagrams, proof and tensile stress, hardness, coarsening of γ′ and γ″, and creep. A feature of the new program is that the calculations are based on sound physical principles rather than purely statistical methods. Thus, many of the shortcomings of methods such as regression analysis can be overcome. With this program, sensitivity to microstructure can be included for many of the properties and the true inter-relationship between properties can be developed, for example in the modeling of creep and precipitation hardening.
368 citations
TL;DR: An overview of selective laser sintering (SLS) work can be found in this article, where the authors present an overview of SLS work as reported in various journals and proceedings.
Abstract: This article presents an overview of selective laser sintering (SLS) work as reported in various journals and proceedings. Selective laser sintering was first done mainly on polymers and nylon to create prototypes for audio-visual help and fit-to-form tests. Gradually it was expanded to include metals and alloys to manufacture functional prototypes and develop rapid tooling. The growth gained momentum with the entry of commercial entities such as DTM Corporation and EOS GmbH Electro Optical Systems. Computational modeling has been used to understand the SLS process, optimize the process parameters, and enhance the efficiency of the sintering machine.
319 citations
TL;DR: In this paper, various physical processes that occur due to the interaction of the heat source with the metal during welding add a new dimension to the understanding of the weld pool solidification.
Abstract: Parameters that control the solidification of castings also control the solidification and microstructure of welds. However, various physical processes that occur due to the interaction of the heat source with the metal during welding add a new dimension to the understanding of the weld pool solidification. Conventional theories of solidification over a broad range of conditions can be extended to understand weld pool solidification. In certain cases, because of rapid cooling rate effects, it is not unusual to observe nonequilibrium microstructures. Recent developments in the application of computational thermodynamics and kinetic models, studies on single-crystal welds, and advanced in-situ characterization techniques have led to a better understanding of weld solidification and microstructures.
245 citations
TL;DR: In this paper, the authors reviewed two types of cracking, including the factors that affect cracking and the remedies, and proposed a method to deal with the problems of these two types.
Abstract: Solidification cracking can occur in the fusion zone during the solidification of the weld metal Liquation cracking, on the other hand, can occur in the partially melted zone during the solidification of the liquated material These two types of cracking are reviewed in this article, including the factors that affect cracking and the remedies
211 citations
TL;DR: In this article, the formation of plate-like, pro-eutectic Ag3Sn structures can grow rapidly within the liquid phase, potentially adversely affecting the mechanical behavior and reducing the fatigue life of solder joints.
Abstract: Near-ternary eutectic Sn-Ag-Cu alloys are leading lead-free candidate solders for various applications. These alloys yield three phases upon solidification: β-Sn,Ag3Sn, and Cu6Sn5. Large, plate-like, pro-eutectic Ag3Sn structures can grow rapidly within the liquid phase, potentially adversely affecting the mechanical behavior and reducing the fatigue life of solder joints. This article reports on the formation of such plates in Sn-Ag-Cu solder balls and joints and demonstrates how large Ag3Sn plate formation can be minimized.
178 citations
TL;DR: In this paper, the authors show that about 75% of end-of-life vehicles, mainly metals, are recyclable in the European Union and the rest (∼25%) of the vehicle is considered waste and generally goes to landfills.
Abstract: Vehicles, essential to society, are continually increasing in use. However, throughout their life cycle vehicles impact the environment in several ways: energy and resource consumption, waste generation during manufacturing and use, and disposal at the end of their useful lives. About 75 percent of end-of-life vehicles, mainly metals, are recyclable in the European Union. The rest (∼25%) of the vehicle is considered waste and generally goes to landfills. Environmental legislation of the European Union requires the reduction of this waste to a maximum of 5 percent by 2015.
164 citations
TL;DR: Robo-Met.3D as discussed by the authors is a fully automated robotic serial sectioning device that was custom-built for three-dimensional (3D) characterization of advanced microstructures at the Air Force Research Laboratory's Materials and Manufacturing Directorate.
Abstract: Robo-Met.3D is a fully automated robotic serial sectioning device that was custom-built for three-dimensional (3-D) characterization of advanced microstructures at the Air Force Research Laboratory’s Materials and Manufacturing Directorate. The machine is capable of automatically performing metallographic serial sectioning at unprecedented rates and at slice thicknesses between 0.1 µm and 10 µm. Imaging is also fully automatic, using either bright-field or polarized light microscopy, and the high-resolution digital images are combined using custom software to produce accurate 3-D datasets of the material microstructure in near-realtime. Robo-Met.3D is U.S. patent pending.
150 citations
TL;DR: In this paper, a mechanism was proposed whereby the creep resistance decreases with the strontium level but the tensile strength and ductility increase in Mg-Al-Sr-α(Mg) alloys.
Abstract: Mg-Al-Sr-based alloys (AJ alloys) have shown superior creep performance and tensile strength at temperatures as high as 175° with stresses up to 70 MPa. Mg-6Al-2.4Sr (AJ62x) exhibits an optimum combination of creep resistance and excellent castability, while AJ62Lx (strontium <2.1) has better ductility than other AJ formulations. The AJ alloy microstructure is characterized by the Al4Sr-α(Mg) lamellar phase that forms at the interdendritic/grain boundary region of the primary magne sium matrix. Mg-5Al-2Sr (AJ52x) contains a ternary phase that was tentatively named Al3Mg13Sr. When the strontium level is low in AJ62x, the volume fraction of Al4Sr is reduced, the aluminum supersaturation of the magnesium primary phase increases, and Mg17Al12 forms. In this article, a mechanism is proposed whereby the creep resistance decreases with the strontium level but the tensile strength and ductility increase.
148 citations
TL;DR: Scandium-reinforced aluminum alloys represent a new generation of highperformance alloys that display numerous advantages over high-strength aluminium alloys as discussed by the authors, such as grain refinement and grain refinement, strengthen welds and eliminate hot cracking in welds.
Abstract: Scandium-reinforced aluminum alloys represent a new generation of high-performance alloys that display numerousadvantages over high-strength aluminum alloys. Scandium-reinforced alloys are much stronger than other high-strength alloys, exhibit significant grain refinement, strengthen welds, and eliminate hot cracking in welds. These alloys also exhibit a good resistance to corrosion as shown by recent studies. A review of their mechanical, microstructural, and corrosion characteristics shows that scandium-reinforced alloys can be usefully employed in aerospace, sports, transportation, and process industries. The information on scandium-reinforced alloys is scanty; very little has been published on the mechanical, microstructural, and corrosion behavior of these alloys. The following fills this gap.
133 citations
TL;DR: In this article, a review of the current processing and resultant properties of Nitinol for medical device applications is presented. And the effects of the final shape-setting heat treatments on transformation temperature and mechanical properties for medical devices will also be reviewed.
Abstract: The purpose of this paper is to review the current processing and resultant properties of Nitinol for medical device applications. The melting and fabrication of Nitinol present a number of unique challenges because of the strong sensitivity of the alloy system to chemistry and processing. The first part of this paper will summarize the effect of alloy fabrication on key material properties, vacuum-melting techniques, hot working, and cold working. The effects of the final shape-setting heat treatments on transformation temperature and mechanical properties for medical devices will also be reviewed.
120 citations
TL;DR: Several new magnesium alloys have been developed recently for high-temperature applications to obtain an optimal combination of die castability, creep resistance, mechanical properties, corrosion performance, and affordability as discussed by the authors.
Abstract: Several new magnesium alloys have been developed recently for high-temperature applications to obtain an optimal combination of die cast-ability, creep resistance, mechanical properties, corrosion performance, and affordability. Unfortunately, it is difficult to achieve an adequate combination of properties and, in fact, most of the new alloys can only partially meet the required performance and cost. The ZE41 alloy, which is used for most gravity-casting applications, has moderate strength and creep resistance combined with good cast-ability. Although this alloy exhibits poor corrosion resistance, it is still preferred for certain applications.
TL;DR: In this article, a short overview of a large and diverse activity in multifunctional materials aims to highlight the wide spectrum of opportunities available for the design of revolutionary material systems. But it is too early to predict the impact of various technologies and approaches investigated in this program, it is clear that multifunctionality is an enabling step in optimally designing each material system for its intended use.
Abstract: This short overview of a large and diverse activity in multifunctional materials aims to highlight the wide spectrum of opportunities available for the design of revolutionary material systems. Although it is too early to predict the impact of the various technologies and approaches investigated in this program, it is clear that multifunctionality is an enabling step in optimally designing each material system for its intended use.
TL;DR: In this paper, the authors investigated the solution heat treatment response of a second generation, single-crystal nickel-based superalloy, CMSX-4, and found that the resulting microstructure can be characterized for both the as-cast and fully solution-annealed conditions.
Abstract: Understanding of the solution heat treatment response of a second generation, single-crystal nickel-based superalloy, CMSX-4, is necessary before the process can be shortened in an effort to save money. The current solution heat treatment used for CMSX-4 involves high temperatures for long durations and can be quite expensive. This investigation helps to characterize the heat-treatment process for this alloy. The achieved microstructure is described for both the as-cast and fully solution-annealed conditions. In addition, an alternate, less expensive heat treatment was selected for its lower temperatures and shorter overall duration. Microstructures and differential thermal analysis are presented for all three conditions.
TL;DR: In this paper, the thermodynamic properties of the ternary Mg-Al-Ca system were investigated based on the Al-Ca, Al-Mg, and Ca Mg binary systems.
Abstract: The thermodynamic properties of the ternary Mg-Al-Ca system are investigated in this article, based on the Al-Ca, Al-Mg, and Ca-Mg binary systems. The equilibrium phases in the Mg-Al-Ca alloys studied are the primary magnesium matrix and Cl5-Al2Ca, as indicated by the calculated ternary phase diagrams. The experimental results are in good agreement with the thermodynamic calculations using Thermo-Calc software.
TL;DR: In this paper, the authors used the technique of nanoindentation coupled with an atomic force microscope to measure mechanical properties of Cu-Sn and Ag-Sn intermetallics at length scales similar to those observed in real solder joints.
Abstract: The technique of nanoindentation coupled with an atomic force microscope has been used to measure mechanical properties of Cu-Sn and Ag-Sn intermetallics at length scales similar to those observed in real solder joints. This article describes the experiment and discusses the results in terms of the effect of intermetallics on the reliability of microelectronic packages. The results show that, despite their high hardness, the intermetallics deform plastically without cracking at the small loads and length scales of nanoindentation testing.
TL;DR: In this paper, the microstructure, tensile, and creep behavior of bulk Sn-3.5Ag solder were studied as a function of cooling rate, which significantly affected secondary dendrite arm size and spacing of the tin-rich phase.
Abstract: The microstructure, tensile, and creep behavior of bulk Sn-3.5Ag solder were studied as a function of cooling rate. Controlled cooling rates were obtained by cooling specimens in different media: water, air, or furnace. The cooling rate significantly affected secondary dendrite arm size and spacing of the tin-rich phase, as well as the morphology of Ag3Sn. Ag3Sn was relatively spherical at the fastest cooling rate and had a needle-like morphology at the slowest cooling rate. Both the yield strength in tension and creep resistance of Sn-3.5Ag solder increased with increasing cooling rate while the strain-to-failure decreased. In this study, the mechanical behavior was correlated with the observed microstructure, creep-stress exponents, and fracture behavior, in order to understand the underlying damage mechanisms.
TL;DR: A number of standard powder production techniques have been developed to meet the increasing demand for high-purity metal powders as discussed by the authors, and they have been discussed in detail in this paper.
Abstract: Production of high-quality metal powders is becoming important to meet the increasing demand for manufacturing advanced materials. A number of standard powder production techniques have been developed to meet the increasing demand for high-purity metal powders. This paper discusses the different techniques of producing metal powder.
TL;DR: In this article, the reduction, refining/recycling, and electroplating of aluminum from room-temperature molten salts are reviewed, and the characteristics of several non-conventional organic solvents, electrolytes, and molten salt are evaluated, and applicability of these melts for production of aluminum is discussed with special attention to ionic liquids.
Abstract: In this article, the reduction, refining/recycling, and electroplating of aluminum from room-temperature molten salts are reviewed. In addition, the characteristics of several non-conventional organic solvents, electrolytes, and molten salts are evaluated, and the applicability of these melts for production of aluminum is discussed with special attention to ionic liquids. Also reviewed are electrochemical processes and conditions for electrodeposition of aluminum using ionic liquids at near room temperatures.
TL;DR: The Reduced Enrichment for Research and Test Reactor (RENER) program as mentioned in this paper aims to enable the conversion of test reactors using fuel containing high-enriched uranium to fuel that employs low enriched uranium.
Abstract: The objective of the Reduced Enrichment for Research and Test Reactor program is to enable the conversion of test reactors using fuel containing high-enriched uranium to fuel that employs low-enriched uranium. This paper describes the development of this low-enrichedfuel, including fabrication, characterization, and testing of the fuel.
TL;DR: In this paper, the authors summarized the evidence for hydrogen uptake in a low-strength alloy, AA5083, and its contribution to the stress-corrosion cracking of this alloy.
Abstract: There is growing evidence for hydrogen uptake in aluminum alloys and its contribution to the crack growth of high-strength aluminum alloys, but less evidence for low-strength alloys. This paper summarizes the evidence for hydrogen uptake in a low-strength alloy, AA5083, and its contribution to the stress-corrosion cracking of this alloy. A key factor is the anodic dissolution of grain boundary β phase (Al3Mg2) and the associated hydrogen reduction that accompanies this dissolution.
TL;DR: In this article, a leaching process was established based on the ability of platinum-group metals to form stable chloro-complexes in acidic chloride solutions. But this process was not applied to the extraction of rhodium.
Abstract: A leaching process was established based on the ability of platinum-group metals to form stable chloro-complexes in acidic chloride solutions. Industrial catalyst losses were examined for the recovery of platinum, palladium, and rhodium by leaching with a mixture of sulfuric acid and sodium chloride to avoid using aqua regia or autoclave conditions. Extraction of platinum and rhodium in 60% H2SO4 at 135°C steadily increased with increasing NaCl concentrations reaching 95% and 85%, respectively, at 0.1 M NaCl after two hours. By comparison, palladium was dissolved more quickly but also reached 85% under the same conditions. Extraction of each metal increased with temperatures up to 125°C but plateaued at higher temperatures. Similar behavior was observed with increasing H2SO4 concentrations up to 60%. More than 99% extraction of each metal was obtained after ten hours using 0.1 M NaCl and 60% H2SO4 at 125°C.
TL;DR: PANDAT as mentioned in this paper is a software package for multicomponent phase-diagram calculation, based on the principle that stable phase equilibrium is uniquely determined by the thermodynamic properties of the system, such as the Gibbs energy functions of the phases.
Abstract: Knowledge of phase equilibria or phase diagrams and thermodynamic properties is important in alloy design and materials-processing simulation. In principle, stable phase equilibrium is uniquely determined by the thermodynamic properties of the system, such as the Gibbs energy functions of the phases. PANDAT, a new computer software package for multicomponent phase-diagram calculation, was developed under the guidance of this principle.
TL;DR: There are numerous approaches to the treatment of both copper and lead anode slimes as discussed by the authors, however, few of them have described the environmental impact of these activities, and especially selenium emissions are a problem both in the internal working environment and in the external environment.
Abstract: There are numerous approaches to the treatment of both copper and lead anode slimes. Although the chemistry and metallurgy has been described and discussed by many authors, few, if any, have described the environmental impact of these activities. Dust and especially selenium emissions are a problem both in the internal working environment as well as in the external environment.
TL;DR: In this paper, the prices at which primary magnesium becomes competitive with aluminum and steel are examined, including magnesium production cost estimates for current and future scenarios using electrolytic and thermal processes.
Abstract: Production technologies must be cost effective for primary magnesium to become an economically viable alternative material for wide spread automotive applications. In this article, the prices at which magnesium becomes competitive with aluminum and steel are examined, including magnesium production cost estimates for current and future scenarios using electrolytic and thermal processes. The economic viability of the industry for automotive applications is also examined in the context of magnesium market price, taking into consideration the dynamics of its supply and demand as well.
TL;DR: In this paper, the yield stress behavior was investigated for the 95.5Sn-4.7Cu ternary lead-free solders using the compression stress-strain test technique.
Abstract: The yield-stress behavior was investigated for the 95.5Sn-4.3Ag-0.2Cu (wt.%), 95.5Sn-3.9Ag-0.6Cu, and 95.5Sn-3.8Ag-0.7Cu ternary lead-free solders using the compression stress-strain test technique. Cylindrical specimens were evaluated in the as-cast or aged (125°C, 24 h) condition. The tests were performed at −25°C, 25°C, 75°C, 125°C, and 160°C using strain rates of 4.2×10−5s−1 or 8.3×10−4s−1. Specially designed Sn-Ag-0.6Cu samples were fabricated to compare the yield stress of the dendritic microstructure versus that of the equiaxed microstructure that occurs in this alloy.
TL;DR: In this paper, a review of shape-memory alloys with high martensite transformation temperatures is presented, with an emphasis on sputtered films in the NiTiX group, a name for the ternary ordered substitutional solutions of Hf, Zr, Au, Pd or Pt in the β-NiTi lattice.
Abstract: Many applications of shape-memory alloys (SMAs) are likely to require development of alloys having much higher martensite transformation temperatures than are currently available. This article reviews recent reports on a few promising systems, with emphasis on sputtered films in the NiTiX group. NiTiX is a name for the ternary ordered substitutional solutions of Hf, Zr, Au, Pd, or Pt, in the β-NiTi lattice. These have been the most extensively studied compounds and the only high-temperature SMAs yet fabricated as thin films. For films, the exaggerated kinetics of physical vapor deposition and the generous surfaces of the planar form confer economic and technical advantages, especially in cases involving costly additions or troublesome solidification issues. The outlook for technically useful SMAs operating at up to 240°C is quite good. Operation at temperatures above 500°C may be possible, but issues of thermal stability will pose significant challenges.
TL;DR: In this article, the thermodynamics and application of chloride metallurgy for the extraction of precious metals, such as gold and silver, and platinum-group metals, are examined in detail.
Abstract: This paper examines in detail the thermodynamics and application of chloride metallurgy for the extraction of precious metals, such as gold and silver, and platinum-group metals. The advantages with regard to the solubilities of metal ion species and their reduction potentials in chloride media are discussed with examples. The use of chloride media for the extraction of platinum-group metals from spent autocatalysts and for the production of high-purity pigment-grade TiO2 and titanium metal from ilmenite feed stocks is discussed in the case studies provided.
TL;DR: In this paper, the semi-empirical modified embedded atom method is used to develop a model of Pu-Ga alloys, which is then used to predict thermodynamic properties of these alloys.
Abstract: In this article, the semi-empirical modified embedded atom method is used to develop a model of Pu-Ga alloys. Employing classical calculations, the model is used to predict thermodynamic properties of these alloys as well as the complex Pu-Ga phase diagram.
TL;DR: In metals processing, residue streams are routinely generated containing recoverable metallic compounds, and these metallics represent both valuable materials and potential disposal problems to the producer as discussed by the authors. But they represent both useful and potentially dangerous materials.
Abstract: In metals processing, residue streams are routinely generated containing recoverable metallic compounds. These metallics represent both valuable materials and potential disposal problems to the producer. Midrex, primarily involved in ferrous conversion for many years, has developed a variety of new processing techniques for ferrous and non-ferrous recovery. The processing technologies involve either shaft or rotary hearth furnaces, and can be both hydrocarbon or coal based. Recent developments have included conversion studies for ferrous and non-ferrous residual streams that are energy efficient and environmentally friendly. The technologies to be presented, predominantly coal based, include FASTMET®, FASTMELT®, and Itmk3®.
TL;DR: In this article, the effects of electromigration on intermetallic compound growth in lead-free solder joints are examined. And the authors demonstrate that electromigration is an important factor in the interfacial reactions at the joints with the passage of electric currents.
Abstract: At the joints in microelectronic products, electric currents pass through interfaces of dissimilar materials At these joints, atomic fluxes are driven by both the compositional gradients and electromigration effects Although interfacial reactions at these joints appear to be affected by both of the driving forces, most often only compositional gradients are investigated when interfacial reactions are concerned This study examines the effects of electromigration upon interfacial reactions together with the effects of compositional gradients, primarily in lead-free solder joints It is found that electromigration significantly affects intermetallic compound growth in various systems Growth rates of the intermetallic compounds are either enhanced or retarded depending upon the diffusion directions of the primary moving species and those of the applied electric currents This study demonstrates that electromigration effect is an important factor in the interfacial reactions at the joints with the passage of electric currents