bluuebunny/crossref_metadata_2025_split huggingface dataset:
Applications of Atom Probe Microanalysis in Materials Science
Authors: Miller M.K. , Smith G.D.W. 
Published: August 2016

The atom probe field ion microscope is the most powerful and direct method for the analysis of materials at the atomic level. Since analyses are performed by collecting atoms one at a time from a small volume, it is possible to conduct fundamental characterization of materials at this level. The atom probe technique is applicable to a wide range of materials since its only restriction is that the material under analysis must possess at least some limited electrical conductance. Therefore, since its introduction in 1968, the atom probe field ion microscope has been used in many diverse applications in most branches of materials science. Many of the applications have exploited its high spatial resolution capabilities to perform microstructural characterizations of features such as grain boundaries and other interfaces and ultrafine scale precipitation that are not possible with other microanaly tical techniques. This article briefly outlines some of the capabilities and applications of the atom probe. The details of the atom probe technique are described elsewhere.The power of the atom probe may be demonstrated by its ability to see and identify a single atom, which is particularly useful in characterizing solute segregation to grain boundaries or other interfaces. An example of a brightly-imaging solute atom at a grain boundary in a nickel aluminide is shown in Figure 1. In order to conclusively determine its identity, its image is aligned with the probe aperture in the center of the imaging screen and then the selected atom is carefully removed by field evaporation and analyzed in the time-of-flight mass spectrometer. This and many other bright spots in this material were shown to be boron atoms. This example also illustrates the light element analytical capability of the atom probe. In fact, the atom probe may to used to analyze all elements in the periodic table and has had applications ranging from characterizing the distribution of implanted hydrogen to phase transformations in uranium alloys.
Up Close: Laboratoire de Recherche des Musées de France: Materials Science in the Service of Art History
Authors: Bernard Maurice , Dupouy Jean-Michel 
Published: August 2016

Until the 18th century, the word “art” meant the product of the artisan (not the artist) and, by extension, also meant the product itself. Objects manufactured by craftsmen had, first of all, a useful function, although they might also have had a symbolic or aesthetic meaning. The concept of aesthetics is actually much older, considering the antiquity of Rome and Greece. And in Egypt, 3,500 years ago, at Saqqara, the first stone pyramid was engraved by scribes expressing their admiration for it.These artisans were famous for the quality of their work, for their genius in mastering their knowledge. One is reminded of Phidias in Athens, Michelangelo and Julius II, or Leonardo da Vinci and Francois the 1st.However, the social status of such artists was probably not very different from the status of other exceptional artisans in fields such as jewelry, metallurgy, clothing, music, etc. “Ĺart pour l'art,” a tenet which ignored the function of the object, arose only during the last century. In other words, almost all objects or artifacts in museums were originally devised and built to achieve a very specific and useful function.
Materials Engineering Problems in Crystal Growth and Epitaxy of Cuprate Superconductors
Authors: Scheel Hans J. 
Published: August 2016

The discovery of superconductivity in yttrium barium cuprate above the boiling point of liquid nitrogen by Wu et al. initiated a race in the search for higher critical temperatures (Tc) which was singular in the history of science. Since the ceramic superconducting pellets could be prepared nearly overnight and superconductivity easily demonstrated with liquid nitrogen and a levitating magnet, a great deal of effort went into garnering funds for a “new technological era.” High Tc superconductivity (HTSC) was expected to have applications in many areas of our life, be it for energy transport and high-power generators, transformers, current limiters, or for ultrafast computers and communication technology, or in medicine for NMR tomography and for SQUIDs in magnetic encephalography. Large-scale uses were also foreseen, such as levitation for trains, magnetohydrodynamic propulsion in ships, and applications for fusion reactors. Thousands of physicists and engineers searched for new materials with high Tc, and explored thin-film preparation by physical vapor deposition. In the early phase only a few scientists recognized that materials engineering problems would greatly hinder the development of applications of the cuprate superconductors. Most early efforts on HTSC went toward physical investigations of samples (crystals, layers, sheets, wires, etc.) which due to their complexity could not be reproducibly prepared, and which were not adequately characterized (see the section on Characterization). The Bi-, Tl-, and Hg-containing cuprates with Tc up to 135 K, for example, were found empirically, not by physical understanding of the HTSC phenomenon. Applications of HTSC have been limited to very specific areas, but a concerted effort should reveal opportunities for the materials research and superconductivity communities. Significant applications could be developedwhich in the long run would also benefit fundamental physical investigations of the HTSC phenomenon.
Graphitic Nanoparticles
Authors: Ugarte D. 
Published: August 2016

Pure carbon materials, graphite and diamond, possess a wide array of interesting physical properties, and so attract a large spectra of interests and applications. Carbon microparticles (carbon black) and carbon fibers are widely used in practical applications including common materials (paints, inks, polymers, etc.) and high-performance composite materials.Carbon displays a remarkably rich and complex chemical behavior (three different possible hybridizations: sp1, sp2, and sp3). In particular, the covalent carboncarbon bond is one of the strongest in nature, and induces a high melting temperature (> 4000°C). The phase changes associated with unusually high temperatures and pressures as revealed in the carbon phase diagram, and the fact that the solid sublimates at low pressures before melting, lead to many experimental difficulties in the study of high-temperature properties of carbon materials. Experiments must therefore rely on transient melting, for example, laser vaporization or arc-discharge heating. This explains why fullerenes and related graphitic structures have only recently been discovered.From a fundamental point of view, the discovery of fullerenes has introduced new ideas about how carbon atoms bond. The curvature and closure of graphitic surfaces has become a standard concept in carbon chemistry, and recently a wide range of structures formed by curved graphitic networks has been observed. A surprising aspect of fullerene research is that these novel graphitic structures were found in well-known experiments, and that they had been overlooked for so many years.This article will describe recent progress in the generation and physical characterization of graphitic nanoparticles, or multishell fullerenes. The lack of an efficient method for producing, as well as a method for purifying these particles makes it difficult to characterize them and to develop possible applications.
Synroc: A Suitable Waste Form for Actinides
Authors: Vance E.R. 
Published: August 2016

Synroc, a ceramic made from a reactive mixture of Al, Ba, Ca, Ti, and Zr oxides, is proving to be a suitable and effective medium for immobilizing nuclear wastes.Synroc-C, a titanate-based ceramic variant, was initially developed in 1978 by Ringwood et al. for immobilizing high-level nuclear waste (HLW) from nuclear power reactor fuel reprocessing. HLW is essentially a solution of radioactive fission products, actinides, and process contaminants in ~3 mol/L nitric acid. The developers of Synroc-C aimed to immobilize radioactive waste ions by incorporating them in a ceramic. They accomplished this by mixing the HLW solution (liquid waste) with a ceramic precursor, then forming the ceramic by drying, calcining, and hot-pressing the mixture in a metal container for two hours at 1200°C/20 MPa. The result, Synroc-C, is composed of hol-landite, zirconolite, perovskite, and rutile, together with a few percent of minor phases and metal alloys. The Synroc-C precursor has the following composition (wt%): Al203(5.4); BaO(5.6); CaO(11); TiO2(71.4); and ZrO2(6.6). Since 1984, it has been prepared by hydrolyzing a mixture of Al, Ti, and Zr alkoxides with an aqueous slurry of Ba and Ca hydroxide. The abundances of the phases, and the radionuclides contained in them in dilute solid solution, are identified in Table I.
FGMs High-Heat-Flux Environments: Cost/Performance Issues
Authors: Lannutti John J. 
Published: August 2016

This article focuses exclusively on the application of functionally gradient materials (FGMs) as structural components in high-heat-flux environments. Preliminary data suggest that FGMs can equal or surpass the properties of fiber-reinforced composites (FRCs) in these applications at a fraction of the material costs. An optimistic value of $1 per foot for 100-μm-diameter Saphikon alumina fiber yields a per-pound cost of $48,000. In contrast, a costly alumina powder used for FGMs might be in the range of .$20 per pound. While many counter-arguments can be advanced, this price differential cannot be easily overcome.One relative difficulty with FGMs is their inherent compositional flexibility which, ironically, is normally considered an advantage. Determination of the optimum material combination for a given application should precede any effort directed toward determining the “best” processing route. This combination will then specify the processing technique. This would “short circuit” the expensive learning curve historically associated with FRCs.“Processing for processing's sake” is no longer a viable option in today's composite research market. Without necessary advances in the predictive modeling of structure, composition (and, concurrently, cost) and behavior, FGMs may remain an “on-the-horizon” advanced composite.
FGM Fabrication by Combustion Synthesis
Authors: Stangle Gregory C. , Miyamoto Yoshinari 
Published: August 2016

FGMs have been fabricated using the combustion synthesis (or self-propagating high-temperature synthesis (SHS)) process by exploiting a rapid and exothermic chemical reaction, in order to synthesize some (or all) of the constituents in an FGM to simultaneously increase its density. The thermal energy required to drive the process is derived from this internal, chemical source, rather than from an external and usually expensive source (e.g., a furnace). The combustion synthesis process is a powder-based process that has been used to synthesize over 300 compounds, and is particularly useful in preparing materials such as highly refractory ceramics and high-temperature intermetallics that are difficult to prepare by other synthesis methods. In addition, the process can be used to prepare ceramic-metal and ceramic-intermetallic composite materials. As a result, only slight modifications of the combustion synthesis are required to prepare functionally gradient materials from these same combinations of materials.Sample preparation begins by the creation of a series of mixtures from the powders that will react to form the constituent materials of the FGM sample. Each of these mixtures contains a slightly different percentage of reactants, so that each mixture will yield its own (predetermined) volume fraction of each of its constituents, following the combustion synthesis process. Prior to the combustion step, the samples are assembled by stacking layers of each of the reactant powder mixtures in appropriate amounts, in such a way that the multilayered powder mixture will faithfully produce the composition gradient that is required in the resultant FGM.
Optimization of Mechanical Properties in SiC Control of the Microstructure
Authors: Krstic V.D. 
Published: August 2016

The optimization of mechanical properties through microstructural design in metallurgical industries has been used successfully for many years. In comparison, the microstructural design in ceramics has been less successful, mainly due to the complexity and difficulties associated with low diffusivity (in their monolithic form) and to the ability to be sintered at elevated temperatures. For years, many structural ceramics could not be sintered to high densities (>95% of their theoretical density) without large quantities of sintering aids. A typical example is silicon carbide (SiC), which has a unique combination of properties, such as: high hardness and wear resistance, considerable strength at high temperatures, and excellent thermal conductivity, but, due to a high level of covalent bonding and consequently low diffusion rates, it cannot be sintered to high density (without the addition of sintering aids) even at temperatures approaching 3000°C.Since the first successful sintering of SiC with small additions of boron and carbon in the early 1970s, remarkable progress has been made in developing a wide range of properties for the microstructure, including fracture toughness from 3–4 MPa m½ to 12–14 MPa m½ four-point-bending strength from 300 MPa to over 900 MPa, and thermal conductivity from 60 to 260 W/m K.4This article presents the most recent developments in SiC ceramics, emphasizing optimization of mechanical properties through microstructure control. The discussion is limited to β-phase SiC pressureless sintering, using oxide additives.
Thermodynamic Calculations as the Basis for CVD Production of Silicide Coatings
Authors: Bernard Claude , Pons Michel , Blanquet Elisabeth , Madar Roland 
Published: August 2016

The exponential increase in computing power realized over the past three decades has required devices of ever-decreasing dimensions. With these reductions in feature size, each generation of circuit technology creates a new set of materials-science challenges, as exemplified by the use of silicide-based diffusion barriers.The use of transition-metal silicides in the semiconductor industry began in the early 1980s with (in retrospect) fairly thick films, simple compositions, and minimal microstructural requirements. The implementation of thin-film binary silicides in integrated circuit (IC) applications required the development of appropriate modeling techniques to select the deposited metal, its gaseous precursor, and the Silicon precursor. These vectors were used to define experimental conditions to yield desired films. Chemical-vapor-deposition (CVD) experiments were simulated and CVD phase diagrams were used to describe the changing film properties with different thermodynamic conditions.In the early 1990s, research began to focus on CVD of ternary Systems (Ta-Si-N, Ti-Si-N). Modeling these complex Systems required optimization of the thermodynamic data and careful evaluation of the ternary phase diagrams.Current-generation materials are deposited in extremely thin layers (ULSI, or ultralarge-scale integration), composed of multiple elements from a variety of gas sources, an d have tailored micro-structures. As described in this article, early thermodynamic modeis helped develop deposition techniques for early-generation silicides. As the technological requirements increased, the modeling method s evolved in parallel, yielding continued insight into the relevant processes. Current work on CVD modeling couples thermodynamic calculations with heat and mass transfer. Incorporating both kinetic and thermodynamic effects, these methods provide a more realistic description of the CVD reactor.
Computer Applications in the Development of Steels
Authors: Sundman Bo , Ågren John 
Published: August 2016

Despite the fact that thermodynamic calculations, strictly speaking, apply only to equilibrium, they may of ten be used in nonequilibrium situations. If one or several of the stable phases are suppressed in the calculations, we have a metastable equilibrium, which is often of practical interest. For example, one may calculate the driving force available to form the more stable phases and model nucleation.Thermodynamic calculations may be performed stepwise to predict microseg-regation during solidification by a Scheil-type calculation (no diffusion in the solid State, infinite diffusion in the liquid, and equilibrium at the interface). In such a calculation, no information other than the thermodynamic properties of the System is used.A more ambitious approach is to com-bine the thermodynamic calculations with kinetic modeis (e.g., diffusion calculations) and thereby predict the rate of reactions. This approach is extremely powerful and may be used to simulate a wide range of different phenomena, including precipitation, homogenization, and diffusional interactionsbetween Substrate and coating.It is usually assumed that thermodynamic equilibrium holds locally at the migrating phase interface between two phases, and the rate of transformation is calculated at each instant by solving a set of flux-balance equations. The fluxes are obtained from a numerical Solution of the multicomponent diffusion equations (see Reference 3).
Corrosion Science
Authors: Newman R.C. , Sieradzki K. 
Published: August 2016

Corrosion is a branch of materials research that is, by its nature, “schmutzy” (dirty). It has a reputation as an unglamorous subject and certainly suffers from an image problem in the materials community: the guest editors would like to have a dollar for every time we sat down and discussed “How can we make corrosion sound positive?” Solving corrosion problems requires an understanding of corrosion mechanisms, and corrosion mechanisms are infinitely subtle and interesting. Corrosion processes can often encompass concepts from a variety of disciplines, including thermodynamics, surface science, electrochemistry, physical metallurgy, and solid-state and statistical physics. While corrosion of metals is the subject of this issue of MRS Bulletin, ceramics, polymers, and geological materials are all greatly affected by corrosion.Corrosion of metals is an electrochemical process, composed of anodic (metal oxidation) and cathodic (reduction) reactions occurring on a surface. The rates of these reactions are measured as current densities (in units of A m−2). On a single piece of metal, the anodic and cathodic current densities can vary arbitrarily from point to point, as long as the total anodic and cathodic currents are equal. This variation, which is associated with local differences in pH, surface composition, or defects in a surface film, leads to various localized phenomena, such as pitting and stress-corrosion cracking, and also to intriguing oscillatory dynamics.
Advances in Lithium and Nickel-Metal Hydride Battery Performance
Authors: Oman Henry 
Published: August 2016

Traditional batteries stored energy in thick plates made from heavy metals like lead, nickel, and zinc. They delivered from 15 to 20 Wh/kg. Lighter-weight lithium anodes were used in some military batteries. Then came the need for lightweight batteries for powering cellular telephones and laptop computers. Lithiumion batteries were developed, and the worldwide demand, just for use in laptop computers, has grown to 150 million units per year.The need to reduce air pollution in downtown areas has created a market for battery-powered electric vehicles. Clara Ford chose to drive an electric car, even though her husband, Henry Ford, was making gasoline-powered cars. However, the cost of replacing worn-out leadacid batteries soon ended the electric-car age of the early 1900s. The need for lightweight, long-life batteries for zero-emission cars has produced unprecedented investments in battery technology. The lithium-battery technology used in laptop-computer batteries did not support the requirements of high power and long life for the charge/discharge cycling needed in electric cars. An executive of a lithium-battery manufacturer was asked what he was doing about the cycle life of his batteries. His answer: “The life of a laptop computer is nine months. Then a newer model makes it obsolete. We meet this requirement!”
Materials Research at Alcoa
Authors: Jarrett Noel 
Published: August 2016

The competitive forces that have dominated the aluminum industry over the last decade are similar to those in many other industries. New international competitors, driven primarily by their ability to compete with long-standing U.S. producers on the basis of cost and quality, have made significant inroads into virtually all aluminum markets.As more emerging nations, driven by the need to create jobs and hard currency rather than profits, entered the primary metal business and exported their output, ingot prices fell. Eventually, ingot became a commodity traded in the international marketplace, with metal prices no longer related to production costs.While these structural changes in the worldwide aluminum industry are of great concern (particularly in the United States), by no means do they signal the light metal's demise in the materials marketplace. What they have done, however, is to provide the impetus for the development and pursuit of economic and technical strategies designed to ensure long-term, profitable growth.By the beginning of the 21st century, most monolithic metals will be firmly entrenched as commodities. This will solidify emerging nations as key producers, based upon their access to raw materials, less costly labor and energy resources, and subsidized capital. The ability of companies like Alcoa to compete in this commodity marketplace will be based upon their ability to reduce manufacturing costs and provide technically-based product differentiation, primarily via quality control, through new and improved processing technologies.
Up Close: Northwestern University Materials Research Center
Authors: Carr Stephen H. 
Published: August 2016

The Materials Research Center at Northwestern University is an interdisciplinary center that supports theoretical and applied research on experimental advanced materials. Conceived during the post-Sputnik era, it is now in its 26th year.The Center, housed in the university's Technological Institute, was one of the first three centers funded at selected universities by the federal government in 1960. The federal government, through the National Science Foundation, now supplies $2.4 million annually toward the Center's budget, and Northwestern University supplements this amount. Approximately one third of the money is used for a central pool of essential equipment, and the other two thirds is granted to professors for direct support of their research. Large amounts of time on supercomputers are also awarded to the Materials Research Center from the National Science Foundation and other sources.The Center's role enables it to provide partial support for Northwestern University faculty working at the frontiers of materials research and to purchase expensive, sophisticated equipment. All members of the Center are Northwestern University investigators in the departments of materials science and engineering, chemical engineering, electrical engineering, chemistry, or physics. The Materials Research Center is a major agent in fostering cross-departmental research efforts, thereby assuring that materials research at Northwestern University includes carefully chosen groups of faculty in physics, chemistry, and various engineering departments.