The concept of functionally graded materials (FGMs) introduced a class of highly engineered structures tailored to specific properties, resulting of compositional changes in used materials. The necessity to bring into practice new materials appears crucial with, for instance, space vehicles: on the surface side the skin plates should have very good heat-resistance, on the inside, however, – high mechanical qualities (e.g. toughness) were needed. The problem was successfully solved in Japan in the mid of 1980s by manufacturing specific composite: metallic matrix and ceramic particles with graded distribution of these particles. That solution is close with ingenious structural systems in some plants, e.g. bamboo. After 20 years of intensive research and practical applications, the field of FGMs is still in development and a precise definition of that new class of materials is till now not accepted. Modeling of FGMs is recognized as indispensable step in designing at the microstructural level to meet specific requirements of an intended application. Many production technologies were proved to be useful for practical adoption.
The authors of the book discuss two important topics concerning activities within the field of FGMs. One of them is dealing with practical methods used in graded materials technology to control the composition and microstructure. A considerable number of problems belong to the field of FGMs manufacturing and a rich source of motivation stimulates in some cases application of new specific fabrication techniques. The book brings condensed but valuable information about main solidification and sintering techniques, which can be used for appropriate manufacturing solutions.
Second part of the book gives theoretical approach to the mathematical modeling and design of FGMs: appendixes A, B, C and D are presenting the authors’ novel research results. The authors deserve congratulations for a very compressed but useful information source.
D.h.c., Ph.D., D.Sc.
Warsaw University of Technology
Chairman of Composite Section
Polish Academy of Sciences
Functionally graded materials, their characterization, properties and production methods are a new rapidly developing field of materials science. From the most informative and widely acceptable opinion, functionally graded materials are characterized by gradual space changes in their composition, structure and, as a result, in their properties. Usually, they are composites in the common sense, but graded structures can be obtained also in traditional, monolithic materials on the basis of a variety of microstructures formed during some kind of material processing. These materials do not contain well distinguished boundaries or interfaces between their different regions as in the case of conventional composite materials. Because of this, such materials posses good chances of reducing mechanical and thermal stress concentration in many structural elements, which can be developed for specific applications. The structure is not simply inhomogeneous, but this inheterogeneity is usually in one direction, typical for the entire volume of a material. The development of instruments for micro- and macrostructure design in functionally graded materials is a challenge for modern industry. On this path, mathematical modeling and numerical simulation are extremely helpful tools for design and investigation of functionally graded materials, which, in fact, are typical representatives of knowledge-based multiphase materials.
The aim of this book is to provide a comprehensive overview of the basic production techniques for manufacturing functionally graded materials, with attention paid to the methods for quantitative estimation of the main structure parameters and properties of these materials. A concise description of experimental methods and type analysis of some specific structures obtained are presented. In order to provide an easily-readable text, general mathematical models and specific tools for management of graded structures in metal matrix composites are presented separately in appendixes. The movement of particles during gravity and centrifugal casting is widely discussed in Appendix A and Appendix B, respectively. Basic equations, which describe solid particle movement in the case of Lorenz force application in graded structure production techniques, are given in Appendix C. A comprehensive model of physical phenomena in gasar technology can be found in Appendix D.
It is our hope that this book provides valuable information for all colleagues who interested in the field of functionally graded structures and materials, and who need a compact informative overview of recent experimental and theoretical activity in this area.
This book has been published as one of the results of Commissioned Research Project PBZ/KBN/114/T08/2004 “Innovative materials and processes in foundry industry” sponsored by the Polish Ministry of Science and Education (Task II.2.4. The study of technology of graded metal-ceramic products by advanced casting techniques, including use of external pressure).
We would like to thank Bentham Science Publishers, particularly Director Mahmood Alam and Manager Bushra Siddiqui for their very kind support and efforts.
Jerzy J. Sobczak
Foundry Research Institute
Ludmil B. Drenchev
Institute of Metal Science
List of Contributors
Professor Jerzy J. Sobczak Ph.D.
Associate Professor Ludmil B. Drenchev Ph.D.