The importance of the structural stability of intermetallics with regard to their mechanical properties is illustrated with two case studies. First, the importance of structural and thermal defects for the strength of (weakly ordered) FeAl and (strongly ordered) NiAl is shown. Several inconsistencies and unresolved issues in the present understanding of point defects in FeAl are addressed. Since point defects alone may not explain the mechanical differences between these two materials, the role of dislocations is considered as well. It is shown that the differences in the atomic bonding of FeAl and NiAl, which deter-mine the active slip systems, are likely to influence the compositional dependence of the strength of these two intermetallics. Second, the class of the trialuminides is reviewed with emphasis on Al3Ti. In addition to stabilizing a cubic crystal structure, the ratio of K/G, where K is the bulk modulus and G the shear modulus, needs to be increased in order to achieve extensive plastic deformation at room temperature. It is not clear, at the present time, to what extent macroalloying of trialuminides can achieve this goal, although promising results have been reported for Al3Ti containing relatively high concentrations (14 at. %) of chromium.

This book is dedicated to the fundamental physical aspects of stability, the influence of structural defects on the properties and structural phase transformations of BCC alloys. The authors present patterns that occur in the structural-phase states of functional alloys with low stability or instability under thermal cycling effects. Structural-phase transformations and the physical laws governing the influence of the thermomechanical effect on the properties of alloys are examined to advance development of technological processes for processing functional materials. Features: Studies the correlation between structural phase states and changes in the physico-mechanical properties of intermetallic compounds Explores the influence of thermomechanical cycling on the properties of functional alloys Details low-stability pretransition states in alloys

Derived from the highly acclaimed series Materials Science and Technology, this book covers the properties as well as the present and emerging applications of intermetallics. Mechanical characteristics, microstructure as well as the environmental influence on intermetallics are treated in depth. In addition, the prospects and risks inherent in materials development as well as typical applications of intermetallics are critically assessed. It is the author's aim to provide the basis for understanding the physical mechanisms, which influence the properties of the materials and ultimately their areas of application. Materials covered include: Titanium Aluminides and Related Phases * Nickel Aluminides and Related Phases * Iron Aluminides and Related Phases * Cu-Base Phases * A15 Phases * Laves Phases * Rare-Earth Compound * Beryllides * Silicides Intermetallics is a valuable source of information for researchers and graduate students working in materials science, metallurgy, condensed-matter physics, and engineering.

The fascinating world of intermetallics is largely unexplored. There are many exciting physical properties and important technological applications of intermetallics, from magnetism to superconductivity. The main focus of this book is on the statistics, topology and geometry of crystal structures and structure types of intermetallic phases. The underlying physics, in particular chemical bonding, is discussed whenever it helps understand the stability of structures and the origin of their physical properties. The authors' approach, based on the statistical analysis of more than twenty thousand intermetallic compounds in the data base Pearson's Crystal Data, uncovers important structural relationships and illustrates the relative simplicity of most of the general structural building principles. It also shows that a large variety of actual structures can be related to a rather small number of aristotypes. The text aims to be readable and beneficial in one way or another to everyone interested in intermetallic phases, from graduate students to experts in solid state chemistry and physics, and materials science. For that purpose it avoids the use of enigmatic abstract terminology for the classification of structures. Instead, it focuses on the statistical analysis of crystal structures and structure types in order to draw together a larger overview of intermetallics, and indicate the gaps in it - areas still to be explored, and potential sources of worthwhile research. The text should be read as a reference guide to the incredibly rich world of intermetallic phases.

Ordered intermetallics constitute a unique class of metallic materials which may be developed as new-generation materials for structural use at high temperatures in hostile environments. At present, there is a worldwide interest in intermetallics, and extensive efforts have been devoted to intermetallic research and development in the U.S., Japan, European countries, and other nations. As a result, significant advances have been made in all areas of intermetallic research. This NATO Advanced Workshop on ordered intermetallics (1) reviews the recent progress, and (2) assesses the future direction of intermetallic research in the areas of electronic structure and phase stability, deformation and fracture, and high-temperature properties. The book is divided into six parts: (1) Electronic Structure and Phase Stability; (2) Deformation and Dislocation Structures; (3) Ductility and Fracture; (4) Kinetic Processes and Creep Behavior; (5) Research Programs and Highlights; and (6) Assessment of Current Research and Recommendation for Future Work. The first four parts review the recent advances in the three focus areas. The fifth part provides highlights of the intermetallic research under major programs and in different institutes and countries. The last part provides a forum for the discussion of research areas for future studies.

Intermetallic compounds are usually brittle with high melting points. Their properties are often found among ceramic and metallic materials. In most cases, their hot corrosion resistance and simultaneously hardness are important. One of the main applications of intermetallic compounds is for superalloy turbine blades in which they show appropriate high-temperature-related properties. This book collects new developments about intermetallic compounds and their recent usages.