Chapter 30 - Metallic Composite Materials

Abstract

This chapter provides a summary of the main factors that are responsible for the thermo-mechanical characteristics of metal matrix composites (MMCs). Because the production of material with suitable microstructure is central to any attempt to optimize such characteristics, this is preceded by an outline of the processing methods developed for MMCs. MMCs can offer various attractive combinations of properties. However, their commercial usage has been limited by difficulties in finding technically and economically attractive methods of preparing material and components with appropriate microstructural characteristics. Research on processing of MMCs has, therefore, assumed considerable importance. A particular aim is often to ensure that the reinforcement is homogeneously distributed because this tends to improve the fracture characteristics. One of the attractions of MMCs is centered on their high temperature properties. The presence of ceramic reinforcement in metals can certainly improve their strength at elevated temperature. The changes induced in thermal expansion characteristics are also of interest. A study of thermal expansion is instructive because it highlights the importance of the stresses that result from differential thermal expansion between the two constituents. These strongly affect the deformation characteristics, as well as the expansion behavior.