Metal matrix composite
What is Metal?
Metals are substances that have three major things in common. First, they can conduct electricity and heat. Metals can also be shaped. Some are hammered into flat sheets or can be pulled into wires. Finally, metals are often lustrous — which means shiny — when they are polished.
What is Metal matrix composite?
Metal matrix composites (MMCs) comprise of a continuous matrix of metallic alloys together with ceramic reinforcements, or metallic phases (Clyne and Withers, 1995). They offer a wide range of opportunities in various applications such as automobile, power train, aerospace, consumer electronics, packaging, and sports due to improved mechanical properties, wear resistance, creep resistance, damping characteristics, and reduced thermal expansion characteristics (Sijpkes and Vergouwen, 2004; Kainer, 2006; Barrett, 2017) (Fig. 1).
Fig. 1 (a) Turbofan made using MMC and (b) Structural component in F16 Falcon landing gear made using SiC mono fibers reinforced Ti MMC.
Fig. 2 Shows some of the commonly used matrix materials which include aluminum, copper, magnesium, titanium, nickel, steel whose properties are listed in Table 1.
While MMCs based on aluminum, magnesium, and titanium alloys are the excellent candidates for lightweight structures in automotive, aerospace, and defense applications (Adebisi et al., 2011; Jayalakshmi and Gupta, 2015), MMCs based on steel, nickel, and copper alloys are highly recommended for tooling, heavy industries, and electronic packaging, respectively. In general, the reinforcement phases are hard and strong, and they are known to exhibit good thermal stability and Young’s modulus. Hence, the inclusion of reinforcements can improve the performance of matrix material (Ashby, 2005; Callister and Rethwisch, 2007). Some of the commonly used reinforcements are shown in Figure and their properties are listed in Table 2.
Based on the size and shape, reinforcements can be broadly classified into continuous and discontinuous reinforcement forms (Chawla and Chawla, 2004). The most common continuous reinforcement are the carbon or ceramic fibers. As these fibers are brittle and flaw sensitive, they are often provided protective coatings to avoid any unwanted chemical reactions and to improve the bonding/ wetting characteristics. The fiber reinforcements are also known to exhibit size effects (i.e., the strength of these fibers decreases as the length increases), and they can be further classified into long or short fibers. Similarly, discontinuous reinforcement includes ceramic and metallic particulates in the size range from few nanometers to few hundred micrometers which are known to develop MMCs with isotropic properties (Chawla and Chawla, 2004; Kainer, 2006).
Classification of Metal Matrix Composites
Based on the type of reinforcement, MMCs are classified into (1) fiber reinforced MMCs, (2) particle reinforced MMCs, and (3) multilayered laminates (Fig. 3). The fiber composites can be further classified as continuous and discontinuous fiber reinforced composites.
by DOI:10.1016/B978-0-12-803581-8.00001-1
- In book: Reference Module in Materials Science and Materials Engineering
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