A mechanical properties microprobe is an exciting concept. A system with the ability to evaluate the mechanical response of a sample with submicron spacial resolution would have an extremely wide range of applications. Recent developments in hardware and understanding have placed this goal within our grasp.

In 1971, J.J.Gilman wrote the following in his article, “Hardness—A Strength Microprobe”:

“Hardness measurements are at once among the most maligned and the most magnificent of physical measurements. Maligned because they are often misinterpreted by the uninitiated, and magnificent because they are so efficient in generating information for the skilled practitioner. They can quickly yield quantitative information about the elastic, anelastic, plastic, viscous, and fracture properties of a great variety of both isotropic and anisotropic solids. The tools that are used are simple and the sample sizes that are needed are typically small, sometimes submicroscopic. This makes it unnecessary to have large specimens in order to measure strength properties and makes it possible to measure the properties of various microscopic particles within the matrix phase of a polyphase metal, mineral, or ceramic material. This is why hardness may be considered to be a strength microprobe.”

These statements are worth repeating for two reasons. First, they point out the largely untapped potential for microin-dentation tests to improve our understanding of the mechanical properties of materials. Second, it is the first mention of hardness tests in the context of a strength microprobe. In this article the more general term of microindentation tests will be used, since hardness is only one of many properties that can be measured with such tests. In addition, the term mechanical properties microprobe (MPM) will be used rather than strength microprobe-again, to note the wide variety of properties that can be measured.

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.

At the beginning of my career, I encountered a book that Professor Von Hippel edited. In the Preface to that book he wrote the following: “Many foresee that science and industry are building a Tower of Babel and thai this undertaking will be halted as in Biblical times: the laborers, more and more specialized, will finally cease to understand each other. The editor, for one, does not share this is gloomy conviction. On the contrary, as our knowledge grows, old boundaries vanish and the view expands to broader horizons. However, people accustomed to boundaries in certain places tend still to respect them after their actual disappearance. To make them feel at home with their new neighbors is a driving motive of this book and its companion volume.”

The Materials Research Society, being dedicated to interdisciplinariness, has shared Prof. Von Hippel's optimism, and I hope that in this lecture I can give you a small inkling of how interdisciplinary our current research is and how many different fields it touches.

The work that I am going to discuss resulted from the rapid solidification study of aluminum transition metal alloys. One day more than three years ago. Prof. Shechtman, who is the hero of this investigation, came into my office with an electron diffraction picture with ten spots arrayed about the central spots (Figure 1).

Al the plenary session held December 4, 1985 during the annual MRS Fall Meeting in Boston, Dr. Gerold Yonas was the keynote speaker. He was introduced to the packed ballroom by 1985 MRS President Elton N. Kauftnann.

Kaufmann: To introduce our plenary address this evening, I would like to make a few remarks on the context in which it is being presented. Iam sure you are all aware that materials research, as most fields of science, is a field where it is rare indeed that one can cleanly separate the technical aspects of a program from the social, economic, and political aspects. This evening's topic is certainly no exception. It involves the U.S. government's Strategic Defense Initiative, or SDI for short. It has broad technical and political implications and has raised highly contentious issues of both technical feasibility and political appropriateness. It is in every source of news available today. This evening we want to focus on those technical aspects of SDI which involve materials and which should therefore be of interest to this audience.

Recently, in Space Business News, John McTague, Acting Director of OSTP (Office of Science and Technology Policy), indicated that “the technology of Swords and the technology of Plowshares have much in common.” Of course the degree of commonality between the Swords and the Plowshares becomes greateras one goes to more fundamental research. In the same article Gerold Yonas indicated that “several aspects of SDI are likely to have enormous implications in the private sector with spinoffs directed into every part of the economy.” In addition to the technical materials aspect of the program those larger issues will certainly impact our lives. In that spirit we want to make this presentation so you can evaluate the program with a maximum amount of information. Of course, because this is a publicly controversial issue, I need to stress that the Society is not endorsing one particular view or another. But, we are strongly advocating the wide dissemination of information on a topic such as this.

The application of Inertial Confinement Fusion to power production requires the development of a high-yield fusion capsule. Theoretical design calculations suggest that a single shell capsule with a uniformly distributed deuterium-tritium (DT) fuel layer on the inside surface could give the desired high-gain performance when directly driven with 0.35 μm laser light. This design requires operation at cryogenic temperatures necessary to condense DT (20-30 K) and a means of levitating the fuel layer inside the capsule. On e recently suggested method for making this capsule is to use a rigid foam matrix to support the condensed DT in a spherical shell configuration. For such a capsule to be successfully fielded, a number of critical materials problems must be solved.

In 1958 Rudolph L. Mössbauer reported his discovery of a simple, practical way of observing nuclear gamma ray resonance. One of the remarkable features of the discovery was the high precision with which energy changes can be measured: energy resolutions of one part to 1011 −1013 are possible. With this high resolution capability it is possible to measure hyperfine interactions between the nucleus of an atom and its electronic environment. These interactions affect the line shape which can be described by several experimental Mössbauer parameters. The three primary parameters are the isomer shift (δ), the quadrupole splitting (Δ), and the magnetic hyperfine interaction.

The isomer shift, determined by the position of the centroid of a set of lines in a spectrum, is proportional to the electron density at the nucleus. Since only s electrons have a probability of being at the nucleus, it is possible to obtain electronic structure information such as oxidation state and population of certain molecular orbitals.

The quadrupole splitting results when the electron environment surrounding the Mössbauer nucleus is not spherical in its charge distribution. Specifically, Δ is proportional to the imbalance in electron density between the axial and equatorial directions. When this hyperfine interaction is present, there is a quadrupole splitting; i.e., a single spectra line will split into two or more lines.

The modeling of solidification processes is a broad field covering many different types of activities. On one level, technical aspects of casting processes are investigated by computer simulations. The modeling is then a tool for the designer and the calculations may even be integrated with a CAD/CAM system. A more fundamental level may consider how the microstructure develops during solidification and how it can be controlled. This article gives a brief historical survey of the modeling of solidification processes.

A well-known rule of thumb, often given in textbooks, states that the solidification time for a simple casting is proportional to its squared volume-to-area ratio. This rule is named after Chovrinov, who verified it experimentally in 1940. The mathematical treatment of solidification, however, has a much older tradition started more than 100 year s earlier in 1831 when Lamé and Clapeyron analyzed the growth of a solid crust generated by cooling a liquid. Their analysis showed that the thickness of the solid is proportional to the square root of time, which is also the essence of Chovrinov's rule. Their basic idea was that the solidification rate was controlled by the removal of latent heat. That idea may seem quite obvious to us, but a necessary pre-equisite for it is the concept of heat as quantifiable and transportable. Actually, Fourier had made his mathematical analysis of heat propagation only 20 years earlier and had won the prize of the French Academy of Sciences in 1811 for his contribution.