Technology innovation in aluminum products

In 2001, the aluminum industry continues to benefit from technical innovations made in alloy development, product-manufacturing technologies, and processing equipment over the last century. This paper examines the top ten alloy, product, and process developments that have shaped the industry’s production methods and markets. The interrelationships among the alloy development, process innovations, and markets are highlighted. Omitted are details about patent literature or the inception of many technologies; the major criterion for placement on the list was impact on the total industry. Editor’s Note: A hypertext-enhanced version of this article can be found at www.tms.org/pubs/journals/JOM/0002/Sanders-0002.html. For more information, contact R.E. Sanders, Jr., Alcoa Inc., 100 Technical Drive, Alcoa Center, Pennsylvania 15069; (724) 337-2478; fax (724) 337-2044; e-mail robert.sanders@alcoa.com.     

The status of utah coal in global resources

Coal resources have had a historical effect on the development of Utah and a far-reaching influence in the western expansion of the United States. Although Utah’s production is just more than two percent of the total national production, the resource quality is higher than most other coal fields in the United States. Coal production surpassed 25 million tons in 1995 and has increased in recent years. In this article, the specific properties of Utah’s various coal fields are discussed in terms of marketability, mining difficulty, and transport to markets. The broad spectrum of Utah’s coal production—past, present, and potential future growth—is reviewed through distribution and coal usage data spanning a ten-year period. Editor’s Note: Although JOM style dictates the use of metric units of measurement, this article retains U.S. customary units to conveniently reflect the commodities standards employed in the coal industry. F.R. Jahanbani earned his M.S. in business management at Brigham Young University in 1967. He is currently a senior energy specialist at the Department of Natural Resources, State of Utah.     

The structure and mechanical behavior of ice

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. Editor’s Note: A hypertext-enhanced version of this paper can be found on JOM’s web site at www.tms.org/pubs/journals/JOM/9902/Schulson-9902.html. Author’s Note: The Ice Research Laboratory at Dartmouth College was founded by the author in 1983 through a development grant from Mobil Corporation. It was expanded in 1984 through an Army Research Office-URIP, expanded again in 1986 through an Office of Naval Research-URI, and expanded again in 1994 through a second Army Research Office-URIP. The IRL is a materials research facility housed within cold rooms. The laboratory currently consists of ten separate cold rooms, some capable of reaching below −40°C. Situated within are facilities for growing and characterizing ice of different kinds, preparing test specimens, and measuring mechanical and electrical properties. For more information, contact E.M. Schulson, Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755; (603) 646-2888; fax (603) 646-3856; e-mail erland.schulson@dartmouth.edu     

New applications for tantalum and tantalum alloys

High-strength tantalum alloy usage has been limited since the cancellation of the manned space-power program in 1969. Yet, because of its unique combination of mechanical properties, fabricability, and high melting temperature, certain tantalum alloys are still used in applications where no other material is suitable, primarily for applications in the electronics industry. For more information, contact R.W. Buckman, Jr., Refractory Metals Technology, P.O. Box 10055, Pittsburgh, Pennsylvania 15236; (412) 653-0940; fax (412) 653-0940; e-mail rmtbuckman@juno.com. Author’s Note: All compositions are in weight percent unless otherwise indicated.     

Calculating phase diagrams using <Emphasis Type="Italic">PANDAT</Emphasis> and panengine

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. Author’s Note: Trial versions of PANDAT and PanEngine may be downloaded at www.computherm.com. Editor’s Note: A related article, “Our Experience in Teaching Thermodynamics at the University of Wisconsin, Madison,” by Y. Austin Chang and W.A. Oates, is available on-line only at www.tms.org/pubs/journals/JOM/0312/Chang/Chang-0312.html. For more information, contact S.-L. Chen, Compu-Therm LLC, 437 South Yellowstone Drive, Madison, Wisconsin 53719, USA; chen@chorus.net.     

The strength properties of iron aluminides

For the development of Fe−Al alloys as structural materials, a deep understanding of slip and deformation properties is necessary. In particular, since mechanical properties of the iron aluminides are affected by excess vacancy strengthening as well as the positive-temperature dependence of yield stress, controlling these strength features is essential. In this article, the strength properties of iron aluminides are reviewed. Author’s Note: All compositions are provided in mole percent. Kyosuke Yoshimi earned his Ph.D. in materials science and engineering at Tohoku University in 1997. He is currently a research associate at Tohoku University. Shuji Hanada earned his Ph.D. in materials science and engineering at Tohoku University. He is currently a professor at Tohoku University. Dr. Hanada is also a member of TMS.     

The non-destructive and nano-microstructural characterization of thermal-barrier coatings

The durability of thermal barrier coatings (TBCs) plays an important role in the service reliability and maintainability of hot-section components in advanced turbine engines for aerospace and utility applications. Photostimulated luminescence spectroscopy (PSLS) and electrochemical impedance spectroscopy (EIS) are being concurrently developed as complimentary nondestructive evaluation (NDE) techniques for quality control and liferemain assessment of TBCs. This paper discusses recent achievements in understanding the residual stress, phase constituents, and electrochemical resistance (or capacitance) of TBC constituents—with an emphasis on the thermally grown oxide. Results from NDE by PSLS and EIS are correlated to the nano- and microstructural development of TBCs. Authors’ Note: More information on the authors’ research and education activities can be obtained from mmae.ucf.edu/∼ysohn and me.udel.edu/karlsson. For more information, contact Y.H. Sohn, University of Central Florida, Advanced Materials Processing and Analysis Center (AMPAC) and Department of Mechanical, Materials and Aerospace Engineering, Orlando, FL 32816-2455, USA; (407) 882-1181; fax (407) 882-1462; e-mail ysohn@mail.ucf.edu, and A.M. Karlsson, Department of Mechanical Engineering, University of Delaware, Newark, DE 19716-3140; (302) 831-6437; fax (302) 831-3619; e-mail karlsson@mde.udel.edu.     

Simultaneous ultrasonic evaluation with differentiation of stress and texture

An ultrasonic method for either independent or simultaneous determination of stress and texture is discussed. Quantitative differentiation between stress and texture during simultaneous measurements can be made. The method is useful for unidirectionally rolled, extruded, or cast material, and the validity of the method has been experimentally verified by extensive tests on rolled materials. Electromagnetic acoustic transducers (EMAT’s) have been used, and these allow measurements during processing. In principle the method is applicable to non-conducting materials if piezoelectric or ferroelectric transducers are used, but since they are contracting and EMAT’s are noncontacting, the constraints are more severe.     

Alloy design strategies for promoting protective oxide-scale formation

This article discusses general strategies for designing alloys to form protective oxide scales. Approaches based on classical alloyoxidation theories work reasonably well for single-phase alloys. However, high-temperature alloy development has been and will increasingly be based on multiphase microstructures in order to achieve many of the needed, but usually opposing properties, such as high-temperature strength and room-temperature toughness. No theoretical-based, well-defined strategies exist for the design of oxidation-resistant multiphase alloys. Still, key factors are beginning to emerge, which can provide guidance for promoting the formation of protective scales on multiphase alloys and for taking advantage of some unique mechanisms that are operative in multiphase alloys but not in single-phase alloys. Editor’s Note: Compositions are given in weight percent unless otherwise noted. Formoreinformation, contactM.P. Brady, Metals and Ceramics Division, Oak Ridge National Laboratory, OakRidge, Tennessee37831-6115; (423) 574-5153; fax (423) 574-7659; e-mail bradymp@oml.gov.     

Analyzing and characterizing the steel used at frank lloyd wright’s fallingwater

Conclusions When Frank Lloyd Wright designed Fallingwater, he must not have specified a steel grade or condition that varied from common production available. Yet, it is notable that the Bessemer steel reinforcing bar had not deteriorated during service in the concrete terrace. Also, the open-hearth hatch steel performed well, as severe corrosion occurred only at the concrete-bar interface while the remainder of the flat bar, also exposed above the Bear Run stream for 68 years, showed only pitting corrosion. Fallingwater has timeless interest as an architectural achievement, and some of the steel used to produce this landmark was made using techniques whose time has passed. Editor’s Note: A hypertext-enhanced version of this article can be found at www.tms.org/pubs/journals/JOM/0303/Dean0303.html. Author’s note: The units are both metric and U.S. customary, as the publications and the steel sections referred to used U.S. customary units. For more information, contact Louise Dean, Westmoreland Mechanical Testing & Research, PO Box 388, Youngstown, PA. 15696-0388; (724) 537-3131; e-mail louise@stargate.net.     

Understanding the unique properties of SPD-induced microstructures

Refining microstructure by severe plastic deformation to a nanometer range changes fundamental properties, such as the Curie and Debye temperatures, and engineering properties of pragmatic significance, such as strength and ductility. These enhancements originate in the combination of very small grain sizes coupled with specific defect structures. Ongoing research is rapidly advancing the understanding of severe plastic deformation-induced microstructures, leading toward the commercialization of these materials. For more information, contact T.C. Lowe, Los Alamos National Laboratory, Materials Science and Technology Division, MD G754, Los Alamos, New Mexico 87545; (505) 665-1131; fax (505) 665-4584; e-mail tlowe@lanl.gov. Authors’ Note: All compositions are given in weight per cent.     

Estimating U.S. uranium reserves

This article presents information on the Energy Information Administration’s (U.S. Department of Energy) annual estimates of U.S. uranium reserves. Encompassed is information for year-end 1997’s uranium reserves, which were estimated by employing numerous resources. Author’s Note: In this article, uranium reserves are discussed for the $30, $50, and $100 per pound forward-cost categories. Forward costs are determined based on anticipated future operating and capital expenditures incurred in the recovery of uranium ore materials. Reserves are cumulative; the quantity at a given level includes all reserves at lower costs. Thus, reserves for the $50 per pound category include the $30 per pound totals, and the $100 per pound category includes totals from the other two categories. Uranium reserves that could be recovered as a by-product of phosphate and copper mining are not included. (Sources for the data presented here are: the EIA, Office of Coal, Nuclear, Electric and Alternate Fuels, based on industry conferences, DOE Grand Junction Projects Office data files, and EIA form EIA-858, Uranium Industry Annual Survey 1997.) Luther L. Smith earned his B.A. in geology at the University of North Carolina at Chapel Hill in 1962. He is currently a geologist with the Energy Information Administration, U.S. Department of Energy.     

Preparation and processing of rare earth chalcogenides

Rare earth chalcogenides are initially prepared by a direct combination of the pure rare earth metal and the pure chalogen element with or without a catalyst. The use of iodine (10 to 100 mg) as a fluxing agent (catalyst), especially to prepare heavy lanthanide chalcogenides, greatly speeds up the formation of the rare earth chalcogenide. The resultant powders are consolidated by melting, pressure assisted sintering (PAS), or pressure assisted reaction sintering (PARS) to obtain near theoretical density solids. Mechanical alloying is a useful technique for preparing ternary alloys. In addition, mechanical alloying and mechanical milling can be used to form metastable allotropic forms of the yttrium and heavy lanthanide sulfides. Chemical analysis techniques are also described because it is strongly recommended that samples prepared by melting should have their chemical compositions verified because of chalogen losses in the melting step. TMS symposium on “Solidification and Powder Processing of Rare Earth Based Materials”, ASM/TMS Materials Week, Cincinnati, OH, 6–10 Oct, 1996.     

The mechanical properties of in-situ composites

Because in-situ composites offer such a wide selection of reinforcement types, size, and volume fractions, understanding the mechanisms controlling mechanical properties will allow more intelligent decisions to be made when tailoring a composite system for a specific application. This article provides an overview of the mechanical properties of discontinuously reinforced metal-ceramic and intermetallic-ceramic composites produced by in-situ techniques. Systems for which the mechanisms controlling mechanical properties are known are emphasized. Editor’s Note: A hypertext-enhanced version of this article can be found at http://www.tms.org/pubs/journals/JOM/9708/Aikin-9708.html. Robert M. Aikin, Jr., earned his Ph.D. in metallurgical engineering at Michigan, Technological University in 1987. He is currently an associate professor at Case Western Reserve University. Dr. Aikin is also a member of TMS.     

Modeling composition/processing/property relationships in a cold-rolled aluminum alloy

Two semi-empirical models have been developed that allow the yield strength and tensile strength of 3105 aluminum alloy sheet, cold rolled to various H1x tempers, to be predicted with reasonable accuracy directly from the ingot composition. Expansion of these models also enables the calculation of the percent cold reductions required to produce tensile properties specified for these tempers also from the ingot composition. Author’s Note: All compositions are given in weight percent. For more information, contact I.J. Polmear, Monash University, Department of Materials Engineering, Wellington Road, Clayton, Victoria 3165, Australia; fax 011-61-3-9905-4940; e-mail val.palmer@eng.monash.edu.au.     

A cantilever beam method for evaluating Young’s modulus and Poisson’s ratio of thermal spray coatings

Young’s modulus and Poisson’s ratio for thermal spray coatings are needed to evaluate properties and characteristics of thermal spray coatings such as residual stresses, fracture toughness, and fatigue crack growth rates. It is difficult to evaluate Young’s modulus and Poisson’s ratio of thermal spray coatings be-cause coatings are usually thin and attached to a thicker and much stiffer substrate. Under loading, the substrate restricts the coating from deforming. Since coatings are used while bonded to a substrate, it is desirable to have a procedure to evaluate Young’s modulus and Poisson’s ratio in situ. The cantilever beam method to evaluate the Young’s modulus and Poisson’s ratio of thermal spray coat-ings is presented. The method uses strain gages located on the coating and substrate surfaces. A series of increasing loads is applied to the end of the cantilever beam. The moment at the gaged section is calcu-lated. Using a laminated plate bending theory, the Young’s modulus and Poisson’s ratio are inferred based on a least squares fit of the equilibrium equations. The method is verified by comparing predicted values of Young’s modulus and Poisson’s ratio with reference values from a three-dimensional finite ele-ment analysis of the thermal spray coated cantilever beam. The sensitivity of the method is examined with respect to the accuracy of measured quantities such as strain gage readings, specimen dimensions, ap-plied bending moment, and substrate mechanical properties. The method is applied to evaluate the Young’s modulus and Poisson’s ratio of four thermal spray coatings of industrial importance.     

Will the titanium golf club be tomorrow’s mashy niblick?

In the sporting goods industry, the application of game-improving advanced materials has resulted in titanium golfclubs attaining near-mythical status. These improvements have not come cheaply, however, and titanium clubs are losing ground to creative designs that employ combinations of lower cost materials. As a result, unless the cost of titanium can be lowered, the metal will see its share of the market become significantly reduced by the judicious use of lower-cost materials. For more information, contact F.H. Froes, Institute for Materials and Advanced Processes, University of Idaho, Moscow, Idaho 83844; (208) 885-7989; fax (208) 88504009; e-mail imap@uidaho.edu. Author’s Note: Do not expect good club design and advanced materials to cure all golfing woes. They can help, but they are not a panacea for a bad swing and/or lack of strength. For these problems, see your local, friendly Professional Golfers’ Association professional.     

Mechanical Properties and Microstructure of VPS and HVOF CoNiCrAlY Coatings

In this study, high velocity oxy-fuel (HVOF) and vacuum plasma spraying (VPS) coatings were sprayed using a Praxair (CO-210-24) CoNiCrAlY powder. Free-standing coatings underwent vacuum annealing at different temperatures for times of up to 840 h. Feedstock powder, and as-sprayed and annealed coatings, were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction (XRD). The hardness and Young’s modulus of the as-sprayed and the annealed HVOF and VPS coatings were measured, including the determination of Young’s moduli of the individual phases via nanoindentation and measurements of Young’s moduli of coatings at temperatures up to 500 °C. The Eshelby inclusion model was employed to investigate the effect of microstructure on the coatings’ mechanical properties. The sensitivity of the mechanical properties to microstructural details was confirmed. Young’s modulus was constant up to ~200 °C, and then decreased with increasing measurement temperature. The annealing process increased Young’s modulus because of a combination of decreased porosity and β volume fraction. Oxide stringers in the HVOF coating maintained its higher hardness than the VPS coating, even after annealing.     

Designing DRA composites for high creep strength

Metal-matrix composites with discontinuous reinforcement are attractive for high-temperature applications because of their creep strength. An additional benefit is the ease of fabrication through a number of processing routes. The magnitude of creep strengthening depends on the chemistry, size, and volume fraction of the reinforcement phase. By using a dislocation-creep-mechanism map, it is possible to predict the level of creep strengthening in discontinuously reinforced aluminum-matrix composites. Editor’s Note: All compositions are given in volume percent unless otherwise indicated. For more information, contact R.S. Mishra, Department of Metallurgical Engineering, University of Missouri, 1870 Miner Circle, Rolla, Missouri 65409; (573) 341-6361; fax (573) 341-6934; e-mail rsmishra@umr.edu.