Showing papers in "JOM in 1999"
TL;DR: In this article, the main applications for nickel-based superalloys are gas-turbine-engine disc components for land-based power generation and aircraft propulsion, and they have been developed for specific, specialized properties and applications.
Abstract: Superalloys have been developed for specific, specialized properties and applications. One of the main applications for nickel-based superalloys is gas-turbine-engine disc components for land-based power generation and aircraft propulsion. Turbine engines create harsh environments for materials due to the high operating temperatures and stress levels. Hence, as described in this article, many alloys used in the high-temperature turbine sections of these engines are very complex and highly optimized.
254 citations
TL;DR: An overview of the structure and mechanical behavior of polycrystalline terrestrial ice is given in this paper, where the authors present an overview of various structural and mechanical properties of terrestrial ice.
Abstract: Since icebergs were first proposed as potential aircraft carriers in World War II, research has led to a better understanding of the mechanical behavior of ice. While work remains, especially in relating fracture on the small scale to that on the larger scale and to the appropriate structural features, the groundwork in materials science has been laid. This paper presents an overview of the structure and mechanical behavior of polycrystalline terrestrial ice.
244 citations
TL;DR: In this article, a variety of processing schemes have been used to generate these in-situ composites, including solidification and vapor phase processes, and secondary processing, such as forging and extrusion, has also been employed.
Abstract: High-temperature, refractory-metal, intermetallic, in-situ composites consist of high-strength, niobium-based silicides with a niobium-based metallic toughening phase. A variety of processing schemes have been used to generate these in-situ composites, including solidification and vapor phase processes. Secondary processing, such as forging and extrusion, has also been employed. These composites offer an excellent balance of high-and low-temperature mechanical properties with promising environmental resistance at temperatures above 1,100°C.
128 citations
TL;DR: Titanium alloys composed of nontoxic elements are being studied in Japan for use in biomedical applications, including surface treatments to improve biocompatibility and methods of preventing fretting fatigue, a primary cause of failure in biomaterials.
Abstract: Titanium alloys composed of nontoxic elements are being studied in Japan for use in biomedical applications. The alloys being studied are primarily α + s- and s-type titanium alloys. Areas of research include surface treatments to improve biocompatibility and methods of preventing fretting fatigue, a primary cause of failure in biomaterials.
81 citations
TL;DR: In this paper, the authors propose the concept of a forming window in strain space that identifies the strains that can be developed safely in a sheet element, bounded by failure limits corresponding to localized necking, shear fracture, and wrinkling.
Abstract: Developments in the numerical modeling of stamping processes and experimental measurements now make it possible to design stamping processes using sound engineering principles. This article shows how experimental and theoretical contributions have led to the concept of a forming window in strain space that identifies the strains that can be developed safely in a sheet element. It is bounded by failure limits corresponding to localized necking, shear fracture, and wrinkling. A robust stamping process is one in which the strains in the part lie well within the forming window. The nature of the window and the influence of material behavior on its shape can be predicted.
81 citations
TL;DR: In this paper, the presence of Fe(III) is required for combination with As(V) to form the crystalline hydrated ferric arsenate known as scorodite (FeAsO4·2H2O).
Abstract: Experimental testwork has shown that arsenic can be removed from arsenic-bearing solutions by hydrothermal precipitation at temperatures in the 170–200°C range. The presence of Fe(III) is required for combination with As(V) to form the crystalline hydrated ferric arsenate known as scorodite (FeAsO4·2H2O). The contained arsenic is effectively immobilized by incorporation into a crystalline, low-solubility compound. Process options are suggested for disposing of arsenic in copper electrorefinery bleed liquors.
66 citations
TL;DR: In this article, the authors provide an overview of structural changes that occur during the hot working of superalloys and provide insight into the use of precipitated particles and other thermomechanical factors to achieve desired structures.
Abstract: This article provides an overview of structural changes that occur during the hot working of superalloys and provides insight into the use of precipitated particles and other thermomechanical factors to achieve desired structures. Examples will focus primarily on alloys 718 and 720, which are iron-nickel and nickel-based alloys, respectively. The availability of a second phase to control grain size is a characteristic of some iron-nickel-and nickel-based superalloys that is not usually available to cobalt-based superalloys; processing with and without the use of a precipitated phase that influences microstructures will be illustrated by the use of these examples.
61 citations
TL;DR: In the last two decades, the aluminum industry has seen the demise of the ASP chloride process as an alternative production path and a reduction of papers on carbothermal production options as discussed by the authors, and the recent emphasis has been a shift to high amperage technologies that are less energy efficient but more cost efficient.
Abstract: In the last two decades, the aluminum industry has seen the demise of the ASP chloride process as an alternative production path and a reduction of papers on carbothermal production options. At the same time, there has been a steady stream of articles proposing the use of drained-cathode technology (by a wettable titanium-diboride coating) and others extolling the virtues and potential materials for inert-anode technology. There was also a rush of smelter technology papers in the early 1980s claiming an achievable energy consumption of less than 12.5 kWh/kg. However, the recent emphasis has been a shift to high amperage technologies that are less energy efficient but more cost efficient. Current efficiencies in excess of 96 percent can be routinely obtained by new technologies, and even aged technologies can be retrofitted to perform at 95 percent. The challenge is to lower cell voltages, but one of the key limitations is the need to maintain adequate superheat to avoid sludge formation and electrolyte-concentration gradients. Electrochemical technologies face the same problems and challenges as present technology; the requirements are even more acute and demanding. These challenges can probably be met, however, and the industry is undoubtedly faced with interesting times as it continues to strive to be competitive.
61 citations
TL;DR: The advancement of metal-matrix composites in the automotive market is still hampered by the low-volume usage of these materials, which is caused by their high cost in comparison with aluminum alloys and, in some cases, by the lack of theoretically predicted properties.
Abstract: The advancement of metal-matrix composites in the automotive market is still hampered by the low-volume usage of these materials, which is caused by their high cost in comparison with aluminum alloys and, in some cases, by the lack of theoretically predicted properties. Many significant challenges must be met as these materials reach maturity and the technology is scaled-up for automotive-component fabrication. The successful commercialization of metal-matrix composites will ultimately depend on their cost effectiveness for different applications. This requires optimum methods of processing, machining, and recycling, including some very new and advanced forming routes.
58 citations
TL;DR: The important issues in advanced area-array electronic packaging for semiconductor devices are materials driven as mentioned in this paper, and some of the processing-driven materials issues include the effect of introducing a silicon device interface with copper pads and a low-κ dielectric, decreasing pitch and feature size on the package interconnects, and advanced underfills for fine-pitch flip-chip applications.
Abstract: The important issues in advanced area-array electronic packaging for semiconductor devices are materials driven. Some of the processing-driven materials issues include the effect of introducing a silicon device interface with copper pads and a low-κ dielectric, the effect of decreasing pitch and feature size on the package interconnects, the development and implementation of organic substrates, and advanced underfills for fine-pitch flip-chip applications. From a materials reliability aspect, important materials issues include enhanced solder interconnect reliability, α-particle-induced soft errors, and the introduction of lead-free solder alloys.
51 citations
TL;DR: The variation of the experimental formability results found in the literature for aluminum tailor-welded blanks appears to be large, and a combined theoretical tensile instability and statistical analysis of internal weld porosity may explain at least some of the variation reported as discussed by the authors.
Abstract: The application of aluminum tailor-welded blanks offers significant potential for reducing the weight of future automobiles, and improvements are being made in the development and understanding of the welding process. There are several geometric and internal weld features that make the complete numerical description of tailor-welded blank forming challenging. The variation of the experimental formability results found in the literature for aluminum tailor-welded blanks appears to be large, and a combined theoretical tensile instability and statistical analysis of internal weld porosity may explain at least some of the variation reported.
TL;DR: The implementation of improved process control systems has not only underpinned the success of new cell designs, but has also enabled many older technologies to remain competitive.
Abstract: It was primarily the improved understanding and control of magnetic fields, assisted more recently by the use of computer modeling, that made modern aluminum reduction cells more stable and has enabled them to grow larger. However, the implementation of improved process control systems has not only underpinned the success of new cell designs, but has also enabled many older technologies to remain competitive. While there is still much room for improving reduction-cell control systems, this task is increasingly difficult due to the diminishing performance gains available.
TL;DR: In this paper, it was shown that any jarosite-type compound would likely be an effective seed for the precipitation of any other jarosite species, and the implication is that the zinc industry can readily convert from one species to another without concerns about the efficiency of the seed used.
Abstract: The precipitation of jarosite-type compounds [eg, NaFe3(SO4)2(OH)6] is commonly used in the zinc industry to remove iron solubilized in the processing circuit The precipitation reaction is greatly accelerated by the presence of jarosite seed, and the rate increases in a nearly linear manner with increasing seed additions As shown in this study, sodium jarosite, potassium jarosite, silver jarosite, and lead jarosite are equally effective as seed for the precipitation of sodium jarosite By extension, any jarosite-type compound would likely be an effective seed for the precipitation of any other jarosite species The implication is that the zinc industry can readily convert from one jarosite species to another without concerns about the efficiency of the seed used
TL;DR: In this article, a rolling-assisted biaxially textured substrate is used to obtain a near-single-crystal-like, flexible metal substrate in arbitrary lengths on which epitaxial oxide buffer layers and superconductors are then deposited.
Abstract: In order for many large-scale bulk applications of high-temperature superconducting materials to be realized, the cost/performance of the superconductors needs to be optimized. From a performance standpoint, a long, flexible, single-crystal-like wire is required; from a cost-and-fabrication standpoint, an industrially scalable, low-cost process is required. Both of these critical requirements are met by rolling-assisted biaxially textured substrates, a conductor-fabrication technique that employs simple, scalable, thermomechanical processing techniques to obtain a near-single-crystal-like, flexible metal substrate in arbitrary lengths on which epitaxial oxide buffer layers and superconductors are then deposited.
TL;DR: In this article, the activation energies for the oxide formation of each of the alloys used in this work were determined, and the values obtained were compared with those obtained by other researchers for identical alloys.
Abstract: The kinetics and mechanisms of oxidelayer formation on Ti-Al-X alloys, specifically Ti-25Al-18Ta, Ti-30Al-2.7Nb, and Ti-43Al-11Nb have been studied. The activation energies for the oxide formation of each of the alloys used in this work were determined, and the values obtained were compared with those obtained by other researchers for identical alloys.
TL;DR: There are now a number of important production applications for DRA, which span the transportation, aerospace, recreation, and electronics industries and that demonstrate the material's attractive combination of structural, thermal management, an d wear properties as mentioned in this paper.
Abstract: There are now a number of important production applications for DRA, which span the transportation, aerospace, recreation, and electronics industries and that demonstrate the material’s attractive combination of structural, thermal management, an d wear properties. While large materials suppliers have mostly exited the area, many smaller suppliers are forging ahead to make DRA a success.
TL;DR: In this paper, the deformation mechanisms scale with grain size to the nanocrystalline range or whether there are fundamental changes/transitions in deformation mechanism at an extremely fine microstructural scale and the observations of low-temperature and high-strain-rate superplasticity in nanocrystine materials with unique features open up new possibilities for scientific and technological advancements.
Abstract: Nanocrystalline materials provide a unique opportunity to investigate deformation mechanisms at an extremely fine microstructural scale. An intriguing question has been whether the deformation mechanisms scale with grain size to the nanocrystalline range or whether there are fundamental changes/transitions. The observations of low-temperature and high-strain-rate superplasticity in nanocrystalline materials with some unique features open up new possibilities for scientific and technological advancements.
TL;DR: In this article, the authors considered the problem of removing arsenic-bearing SO2 gases from pyrometallurgical process gas using either the dry or wet method, after which final arsenic removal from the process gas to below the required admissible level must take place in a wet electrostatic precipitator.
Abstract: The pyrometallurgical processing of nonferrous minerals found in association with sulfur and arsenic generates arsenic-bearing SO2 gases. Effective process gas cleaning presents technical problems due to the high volatility of the As2O3 compound and the elevated dew point of the sulfur-trioxidecontaining SO2 gas. Critical factors for gascleaning technology selection pertaining to technical feasibility, economic acceptability, and environmental compatibility are the arsenic-to-sulfur ratio in the feed material, the operating parameters of the pyrometallurgical and gas cooling process, the admissible arsenic concentration of the SO2 gas after arsenic elimination, and the most suitable form of the arsenic-bearing output material. Depending on these factors, the bulk of the arsenic can be eliminated from the process gas in concentrated form according to either the dry or wet method, after which final arsenic removal from the process gas to below the required admissible level must take place in a wet electrostatic precipitator.
TL;DR: In this article, a hydrometallurgical method for removing arsenic from copper converter dust is presented, which consists of a selective leaching of the flue dust in which arsenic is dissolved in sodium-sulfide solution and then removed by precipitation methods using various agents: copper sulfate, a mixture of phosphoric acid with calcium hydroxide, calcium oxide, and ferrous or ferric sulfate.
Abstract: Research has been conducted at the Faculty of Metallurgy, Technical University, Kosice, to develop a hydrometallurgical method for removing arsenic from copper converter dust The process consists of a selective leaching of the flue dust in which arsenic is dissolved in sodium-sulfide solution and then removed by precipitation methods using various agents: copper sulfate, a mixture of phosphoric acid with calcium hydroxide, calcium oxide, and ferrous or ferric sulfate In principle, arsenic can be removed as a marketable product (copper arsenate for wood preservation) or as stable precipitate compounds suitable for safe landfill disposal under existing US Environmental Protection Agency regulations
TL;DR: In this article, the effect of recycling the electric arc furnace dust leaching residues to the furnace was investigated and it was shown that the alkaline treatment route is more favorable than the acid one.
Abstract: Simulation programs have been devel oped to study the effect of recycling the electric arc furnace dust leaching residues to the furnace. Residues from sulfuric acid and sodium hydroxide leaching have been tested. Results enable the furnace-leaching response to be defined in accord with the recycling rate and conditions for zero stabilization to be determined. Either of the two alternative treatments eliminates the resulting environmental problem. Regarding the management and minimization of residues, the alkaline treatment route is more favorable than the acid one. The preliminary economic evaluation of the alkaline method is very promising.
TL;DR: In this article, the integration of Dynatec's zinc pressure leach process with existing roast-leach-electrowin plants employing various methods of iron rejection is briefly described, along with the application of two-stage pressure leaching in stand-alone processes.
Abstract: The occurrence of zinc in sulfide ore deposits is generally accompanied by various iron minerals. Hence, even the most efficient concentrators generally produce a zinc concentrate with significant iron content. The efficient recovery of zinc metal from zinc concentrates requires the rejection of iron residue in a form that minimizes the zinc entrainment. Careful control of the iron precipitation step is important, so that the iron residue produced is amenable to efficient liquid-solid separation in order to obtain high zinc recoveries. In hydrometallurgical zinc processes, the coprecipitation of minor impurities along with iron precipitation is also important in producing zinc-sulfate solution from which high-purity zinc cathode can be electrowon. The integration of Dynatec’s zinc pressure leach process with existing roast-leach-electrowin plants employing various methods of iron rejection is briefly described in this article, along with the application of two-stage pressure leaching in stand-alone processes.
TL;DR: A number of solid-state and liquid-state processing techniques are available for tailoring the properties of a ceramic-metal interface as discussed by the authors, but the mechanisms for their microstructural formation are not well understood.
Abstract: A number of solid-state and liquid-state processing techniques are available for tailoring the properties of a ceramic-metal interface. While many of the techniques are successfully used in industry, the mechanisms for their microstructural formation are not well understood. For situations where a liquid metal is in contact with a solid ceramic substrate, the wetting and spreading behavior of the liquid is critical in determining the final microstructure and properties of the interface, which may control the properties of the component or system.
TL;DR: In this article, the authors discuss the mechanisms of transient liquid phase bonding as a reactive liquid process for the joining of structural intermetallic compounds and stress the importance of alloying reactions for successful wetting of the substrates by the liquid interlayer.
Abstract: Transient-liquid-phase bonding provides a method of joining nonweldable materials intended for elevated temperature service. This paper discusses the mechanisms of transient-liquid-phase bonding as a reactive liquid process for the joining of structural intermetallic compounds. The importance of alloying reactions for successful wetting of the substrates by the liquid interlayer is stressed, and the roles of dissolution, isothermal solidification, and homogenization processes in microstructural development are discussed.
TL;DR: In this article, a software is developed to calculate the viscosities of multicomponent oxide slags using a viscosity model, which is linked to a database containing the model parameters and the experimental data, along with their sources.
Abstract: A software has been developed to calculate the viscosities of multicomponent oxide slags using a viscosity model. The software is linked to a viscosity database, which contains the model parameters and the experimental data, along with their sources. The model parameters have been optimized based on experimental data generated in the laboratory and found in the literature. The model parameters enable the calculation of the viscosities of six-component Al
2
O
3-CaO-Fe
n
O-MgO-MnO-SiO
2 slags as well as its subsystems as functions of temperature and composition.
TL;DR: The titanium alloy Ti-5Al-1Sn-1Zr-1V-0.8Mo (Ti-5111) is a near-alpha titanium alloy of intermediate strength, excellent toughness, and room temperature creep resistance designed in a U.S. Navy-sponsored titanium alloy development program for structural submarine applications.
Abstract: Titanium offers virtually unsurpassed resistance to crevice, pitting, and stress-corrosion cracking in seawater environments. Ti-5Al-1Sn-1Zr-1V-0.8Mo (Ti-5111) is a near-alpha titanium alloy of intermediate strength, excellent toughness, and roomtemperature creep resistance designed in a U.S. Navy-sponsored titanium alloy development program for structural submarine applications. Ti-5111’s desirable mechanical properties and excellent corrosion resistance render this titanium alloy an ideal fastener material from both a technical and economic perspective.
TL;DR: The preferred form of arsenic for disposal is as a basic ferric arsenate, FeAsO4·xFe(OH)3, which can be readily produced by coprecipitation with iron in a high-density sludge process as discussed by the authors.
Abstract: Arsenic is often present in a variety of forms in sulfide mineral deposits and can become a soluble constituent of mine drainage due to oxidation reactions taking place in mine workings and waste deposits. Its removal from solution must be carried out to meet water-quality discharge criteria, and it must be fixed in a solid form that is environmentally stable. The preferred form of arsenic for disposal is as a basic ferric arsenate, FeAsO4·xFe(OH)3, which can be readily produced by coprecipitation with iron in a high-density sludge process. High-density sludge plants are simple to operate and can be designed to meet stringent water-quality specifications and produce stable sludges over long periods of continuous operation.
TL;DR: In this paper, a hydro-pyrometallurgical method was used to recover metal values from spent dry battery cells, and the results revealed that metallic parts, carbon rods, and paper were safely recovered; pure NH4Cl, MnO2, and ZnCl2 salts were obtained.
Abstract: A hydro-pyrometallurgical method was used to recover metal values from spent dry battery cells. Water-soluble ingredients were filtered, and solid residue was sorted by magnetic separation and water flotation. Parameters affecting the recovery efficiency were also studied. Results revealed that metallic parts, carbon rods, and paper were safely recovered; pure NH4Cl, MnO2, and ZnCl2 salts were obtained. Maximum recovery efficiencies reached 93 percent for manganese and 99.5 percent for zinc and NH4.
TL;DR: At the Kennecott Utah copper smelter in Magna, Utah, bleed streams from the refinery tankhouse and precious-metals plant are combined with smelters weak acid and electrostatic precipitator dust to produce leach solutions containing copper and impurities.
Abstract: At the Kennecott Utah copper smelter in Magna, Utah, bleed streams from the refinery tankhouse and precious-metals plant are combined with smelter weak acid and electrostatic precipitator dust to produce leach solutions containing copper and impurities. Copper and arsenic are precipitated from the solutions as sulfides in a two-stage continuous process that enables excess arsenic to be removed from the circuit and routed to hazardous waste disposal as a highly concentrated material.
TL;DR: In this article, material issues and the characterization of low-k materials for integration into advanced interconnects are discussed and the properties of these materials are discussed in relation to structure-property relationships.
Abstract: Materials with low dielectric constants are being developed to replace silicon dioxide as interlevel dielectrics. This paper discusses material issues and the characterization of low-k materials for integration into advanced interconnects. Measurement techniques for the characterization of low-k films are discussed, and the results for several classes of low-k materials are presented. The properties of these materials are discussed in relation to structure-property relationships.