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2013 | Book

Introduction to Metal Matrix Composites

Fabrication and Recycling

Author: Yoshinori Nishida

Publisher: Springer Japan

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About this book

This book is the first of its kind to deal with fabrication processes of metal matrix composites (MMCs) theoretically, experimentally, systematically, and instructively. The theoretical bases of fabrication processes and recycling processes of MMCs are established in this volume. Most other books in the field are concerned with the mechanics of properties, which is not easy for readers to grasp, and they introduce fabrication processes only as techniques without theoretical discussion. Because this book provides a clear image of the fabrication processes of MMCs without using complicated mathematics, readers can use production theory to create new composites. Also, fundamental concepts of recycling of MMCs are given in this book for the first time so as to meet the demands for solving environmental problems. This work originally was published in Japanese and has attained a high reputation among Japanese professors and researchers in the field. 

Table of Contents

Frontmatter
Chapter 1. Introduction
Abstract
Metal matrix composites are discussed fundamentally from the micro- and macroscopic viewpoints. A composite consists of matrix material and dispersoids such as fibers or particles. These constituent materials have their own microstructure, properties and shapes, even in the composite. These materials contact one another at their interfaces. The microscopic structure of the composite is quite different from the structures of alloys and intermetallic compounds, which are atomic-level mixtures. The fundamentals needed to understand interfaces within composites, including the formation energies of interfaces and surfaces, wettability, and contact angles are discussed in this chapter. The classification of composites is described, and the characteristic features of metal matrix composites are compared to those of other composites. Images of typical commercial metal matrix composite products are also shown in this chapter. Darcy’s law is introduced, because it is needed to understand the phenomena which occur during the fabrication of metal matrix composites.
Yoshinori Nishida
Chapter 2. Fabrication Processes for Composites
Abstract
Many processes have been developed for the fabrication of metal matrix composites from constituent materials. These fabrication processes are classified into four categories: solid state fabrication technique, liquid state fabrication technique, gas state fabrication technique and in situ processing. Recent developments in the major processes are introduced and their characteristic features are described. Common phenomena of these processes are discussed in fundamental terms to obtain a systematic understanding of fabrication processes. Each fabrication process is then discussed from the viewpoint of energy consumption. The most important aspect of composite fabrication is making interfaces with good bonding between the matrix metal and the reinforcements, without degradation by chemical reaction. Usually, the reinforcement/matrix interface is formed by conversion from mechanical energy to interface energy. These important points are discussed in more detail in this chapter.
Yoshinori Nishida
Chapter 3. Fabrication by Squeeze Casting
Abstract
The history of squeeze casting as a fabrication process for MMCs is briefly described in this chapter. Squeeze casting is one of the liquid state fabrication techniques. We can learn essentials of the fabrication of composites from studying squeeze casting, because, during squeeze casting, mechanical energy is converted into interface energy at the reinforcement/matrix interface. This energy conversion is economical and efficient and means that composites can be fabricated with minimum energy using squeeze casting. In this chapter, the threshold pressure equation for infiltration into preforms is introduced, and the infiltration energy, effect of preform preheat temperature, and microscopic phenomena occurring during infiltration of molten metal are discussed theoretically.
Yoshinori Nishida
Chapter 4. Theory of Pressure Infiltration
Abstract
In this chapter, the theory of pressure infiltration into preforms, which has been developed for squeeze casting, is discussed and compared with experimental results. The infiltration theory is based on Darcy’s law, which was introduced in Chap.​ 1. It allows us to predict most aspects of pressure infiltration: the start point of preform deformation, the distribution of preform compression, preform breakage, infiltration stop mechanism, infiltration stop point and the influence of preheat temperature of the preform. In addition, the theory enables us to easily determine suitable pressure infiltration conditions for the development of new MMCs. The characteristic features of the pressure infiltration process are also summarized in this chapter.
Yoshinori Nishida
Chapter 5. Centrifugal Casting of Metal Matrix Composites
Abstract
There are three major types of centrifugal casting used for the infiltration of molten metal into fibrous preforms. In this chapter, the infiltration of molten metal into fibrous preforms using centrifugal force is discussed theoretically and the predictions of the theory are compared with experimental results. We discuss the rotational speed necessary for infiltration to start, the pressure distribution in the preforms, the velocity of the infiltration front and other important parameters. When the volume fraction of fibers is not high, the pressure necessary for the infiltration of molten metal is low. This process is suitable for fabricating products which are symmetrical around a rotational axis, and uses simple and economical casting equipment. In addition to discussion of fibrous preforms, centrifugal casting of molten metal including ceramic particles is also discussed, focusing on the theory of the behavior of a ceramic particle in molten metal in the centrifugal force field.
Yoshinori Nishida
Chapter 6. Properties of Composites
Abstract
In this chapter the mechanical and physical properties of metal matrix composites are discussed. Mechanical properties such as strength and elastic modulus depend on the shape and properties of the reinforcements, their distribution and volume fraction and the bonding strength at the reinforcement/matrix interface, as well as the properties of the matrix itself. Basic ideas and proposed models are introduced to understand the mechanical properties. Some physical properties such as specific heat and density are determined by the intrinsic properties of reinforcements and the matrix. However, other properties, such as thermal expansion coefficient, depend on the distribution, volume fraction, shape and state of the reinforcements. Some proposed models for physical properties are also introduced.
Yoshinori Nishida
Chapter 7. Superplasticity of Composites
Abstract
The superplasticity of metal matrix composites is introduced along with production methods for superplastic composites. Composites are strengthened by particles or fibers and usually have poor ductility, so superplastic composites (which were discovered in 1984) are definitely unusual. Superplasticity in MMCs occurs at high strain rates and at high temperatures near the solidus line of the matrix alloys. The strain rate is 100–1,000 times faster than that required to produce superplasticity in alloys. In this chapter, the mechanism of superplasticity is discussed using constitutive equations, where the shapes of the reinforcements are limited to particles or short, fine fibers. Equal channel angular pressing is introduced as one production method for superplastic MMCs.
Yoshinori Nishida
Chapter 8. Materials for the Fabrication of Composites
Abstract
Properties of the major reinforcement materials used for metal matrix composites are introduced in this chapter and their characteristic features are discussed and compared. The properties of a composite are partly determined by the properties of each constituent material, because each constituent retains its own microstructure and properties within the composite. Production methods for reinforcements are briefly described, along with their influence on the properties of the reinforcements including their compatibility with matrix metal. Reinforcements may be particles or fibers, including whiskers, nanofibers and nanotubes. They are made from ceramics or carbon. Carbon fibers with high thermal conductivity are introduced, because they are likely to be useful in carbon/metal composite heat sink materials.
Yoshinori Nishida
Chapter 9. Recycling of Composites
Abstract
The fundamental ideas for the recycling of metal matrix composites are introduced in this chapter. The state of reinforcements in the composite is discussed from a free energy viewpoint. Reinforcements are stable within the composite. However, it is shown thermodynamically that if we change the energy at the reinforcement/matrix metal interface, we can separate the reinforcements from the matrix. Reinforcements can be separated by either mechanical or chemical methods; the theoretical basis for both types of methods is discussed, and experimental examples are presented. Reinforcements can be screened or separated from the molten matrix metal using pressure (an example of a mechanical method). Some molten salts with low surface energy can be very effective at separating reinforcements from molten matrix metal. They do this by replacing the molten matrix metal at the interface (an example of a chemical method). The entropy increase upon addition of particles is also discussed, and the interface entropy is calculated. Finally, one approach for assessing the viability and value of a metal matrix composite is proposed.
Yoshinori Nishida
Backmatter
Metadata
Title
Introduction to Metal Matrix Composites
Author
Yoshinori Nishida
Copyright Year
2013
Publisher
Springer Japan
Electronic ISBN
978-4-431-54237-7
Print ISBN
978-4-431-54236-0
DOI
https://doi.org/10.1007/978-4-431-54237-7

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