For the reinforcement of metal-matrix composites, four general classes of materials are commercially available: oxide fibers based primarily on alumina and alumina silica systems, nonoxide systems based on silicon carbide, boron fibers, and carbon fibers. This article discusses the key aspects of the aluminum oxide fibers, silicon carbide fibers, boron fibers, and carbon fibers. The commercial fibers for reinforcement of metal-matrix composites are presented in a table. A tabulation of coating schemes for silicon carbide monofilament fibers is also provided.

This article focuses on the sample preparation methods for titanium honeycomb composites, boron fiber composites, and titanium/polymeric composite hybrids. These include mounting, sectioning, grinding, and polishing. The article also provides information on the sample preparation of unstaged and staged prepreg materials for optical analysis.

This article begins with a review of the purposes of mechanical characterization tests and the general considerations related to the mechanical properties of anisotropic systems, specimen fabrication, equipment and fixturing, environmental conditioning, and analysis of test results. It provides information on the specimen preparation, instrumentation, and procedures for various mechanical test methods of fiber-reinforced composites. These include the compression test, flexure test, shear test, open hole tension test, and compression after impact test. The article describes three distinct fracture modes, namely, crack opening mode, shearing mode, and tearing mode. It presents an overview of fatigue testing and fatigue damage mechanisms of composite materials and reviews the types of mechanical measurements that can be made during the course of testing to assess fatigue damage. The article concludes with a discussion on the split-Hopkinson pressure bar test.

One of the key attributes of continuous fiber-reinforced ceramic composites (CFCCs) is their ability to undergo inelastic straining upon mechanical loading. This article reviews the mechanics of inelastic deformation and fracture of CFCCs, as needed for the development of damage-tolerant failure prediction methodologies for use in engineering design. It outlines a general framework for the description of fracture in structural materials in the presence of notches and cracks. The article describes the common classes of fracture behavior of CFCCs and presents the constitutive laws needed to describe crack-tip inelasticity. It demonstrates the effects of inelasticity on crack-tip stress fields and addresses the environmental degradation effects on damage tolerance.

This article addresses the types, properties, forms, and applications of fibers that are available for use in fiber-reinforced polymeric matrix composites, including glass, graphite, carbon, aramid, boron, silicon carbide, ceramic, continuous oxide and discontinuous oxide fibers. It describes the functions, types, and chemical composition of fiber sizing agents. The article discusses the styles, properties, applications, and weaving methods of unidirectional, two-directional and multidirectionally reinforced fabrics. The article also reviews the use of prepreg resins in aerospace and lower performance applications.

This article focuses on the production methods, properties, and applications of two main types of commercially available continuous-length ceramic fibers, namely, oxide fibers based on the alumina-silica system and on alpha-alumina, and nonoxide fibers based primarily on beta-phase silicon carbide. It provides a discussion on factors that are considered in understanding thermostructural capability of ceramic fiber for high-temperature ceramic-matrix composites (CMC) applications. The article tabulates other commercial oxide and nonoxide fiber types for CMC reinforcement.

Fiber-matrix adhesion is a variable to be optimized in order to get the best properties and performance in composite materials. This article schematically illustrates fiber matrix interphase for composite materials. It discusses thermodynamics of interphase in terms of surface energy, contact angle, work of adhesion, solid surface energy, and wetting and wicking. The article describes the change in interphase depending on the reinforcing fiber such as glass fiber, polymeric fiber, and carbon fiber. It discusses fiber-matrix adhesion measurements by direct methods, indirect methods, and composite laminate tests. The effects of interphase on fiber-matrix adhesion are also discussed. The article concludes with a discussion on interphase and fiber-matrix adhesion effects on composite mechanical properties, such as composite on-axis properties, composite off-axis properties, and composite fracture properties.

Reinforcing fibers are a key component of polymer-matrix composites (PMCs), ceramic-matrix composites (CMCs), and metal-matrix composites (MMCs). This article discusses the mechanical and nonmechanical properties of these composites. It presents an overview of PMC, CMC, and MMC reinforcing fibers. The article describes cost-considered value-in-use of the ultimate-use temperature of selected fibers in three fiber categories: metal fibers or wires, oxide ceramic fibers, and non-oxide ceramic fibers.

This article discusses the types, properties, and uses of continuous-fiber-reinforced composites, including glass, carbon, aramid, boron, continuous silicon carbide, and aluminum oxide fiber composites. While polyester and vinyl ester resins are the most used matrix materials for commercial applications, epoxy resins, bismaleimide resins, polyimide resins, and thermoplastic resins are used for aerospace applications. The article addresses design considerations as well as product forms and fabrication processes.

The principal superhard materials are found as phases in the boron-carbon-nitrogen-silicon family of elements. Of these, the superhard materials of commercial interest include silicon nitride (Si3N4), silicon carbide (SiC), boron carbide (B4C), diamond, and cubic boron nitride (CBN). This Article describes the synthesis of diamond and cubic boron nitride (CBN) for transforming a crystal structure from a soft hexagonal form to a hard cubic form. Polycrystalline diamond (PCD) or polycrystalline CBN (PCBN) are produced by sintering (or binding) many individual crystals of diamond or CBN together to produce a larger polycrystalline mass. The Article also provides useful information on the physical properties of diamond, CBN, and sintered polycrystalline diamond. Further, the Article describes superabrasive grains that are commercially available in a range of sizes, shapes, and qualities. Diamond or CBN grains can be used as loose abrasives, as bonded abrasives in grinding wheels and hones, and as bonded abrasives in single-point applications such as turning tools, dressers, and scribes. Finally, the Article provides a short note on the applications of ultrahard cutting tool materials of sintered PCD or PCBN.

This article is a compilation of tables containing property data for major reinforcement materials, including high-modulus fibers, carbon fibers, graphite fibers, glass fibers, ceramic short fibers and whiskers. Data are provided for physical, mechanical, chemical, thermal and electrical properties of these materials. Maximum service temperatures of whisker reinforcements also are provided.

Metal-matrix composites (MMCs) are a class of materials with potential for a wide variety of structural and thermal applications. This article discusses the mechanical properties of MMCs, namely aluminum-matrix composites, titanium-matrix composites, magnesium-matrix composites, copper-matrix composites, superalloy-matrix composites, and intermetallic-matrix composites. It describes the processing methods of discontinuous aluminum MMCs which include casting processes, liquid-metal infiltration, spray deposition and powder metallurgy. The article provides useful information on aluminum MMC designation system and also describes the types of continuous fiber aluminum MMCs, including aluminum/boron MMC, aluminum/silicon carbide MMC, aluminum/graphite MMC, and aluminum/alumina MMC.

This article discusses the types, oxide composition, as well as mechanical and physical properties of general-purpose and special-purpose glass fibers. It describes the glass melting and fiber forming processes and provides information on important commercial products such as continuous roving, woven roving, fiberglass mat, chopped strand, and textile yarns.

Carbon-carbon composites (CCCs) are introduced in fields that require their high specific strength and stiffness, in combination with their thermoshock resistance, chemical resistance, and fracture toughness, especially at high temperatures. The use of CCCs has expanded as the price of carbon fibers has dropped and their mechanical properties have increased. This article begins with an overview of the carbon conversion processes, fiber properties and microstructures, and interfacial bonding and environmental interaction of carbon fibers, followed by a detailed discussion on the various techniques available for processing CCCs for specific applications, including preform fabrication (fiber weaving), densification, application of protective coatings, and joining. The article closes with a description of the mechanical and physical properties and applications of CCCs. The main applications of CCCs, in terms of money and mass, are in the military, space, and aircraft industries.

Boriding is a thermochemical diffusion-based surface-hardening process that can be applied to a wide variety of ferrous, nonferrous, and cermet materials. It is performed on metal components as a solution for extending the life of metal parts that wear out too quickly in applications involving severe wear. This article presents a variety of methods and media used for boriding of ferrous materials, and explains their advantages, limitations, and applications. These methods include pack cementation boriding, gas boriding, plasma boriding, electroless salt bath boriding, electrolytic salt bath boriding, and fluidized-bed boriding. The article briefly describes the chemical vapor deposition process, which has emerged to be dominant among metal-boride deposition processes.

This article illustrates the polymer matrices used for composite materials. It describes the use of prepeg materials in manufacturing high-performance composites. The article discusses the various infusion processes for the development of fiber-reinforced composites, namely, resin transfer molding, vacuum-assisted resin transfer molding, and resin film infusion. It explains the composite- and matrix-toughening methods for fiber-reinforced composites, such as dispersed-phase toughening and interlayer toughening. The article concludes with information on optical microscopy, which provides an insight into the micro- and macrostructure of fiber-reinforced composites.

In general, metal-matrix composites (MMCs) are classified into three broad categories: continuous fiber-reinforced composites, discontinuous or short fiber-reinforced composites, and particle-reinforced composites. This article focuses on stir casting and melt infiltration as the two main methods of MMC solidification processing. It describes the MCC casting methods, such as sand and permanent mold casting, centrifugal casting, compocasting, and high-pressure die casting. The article discusses the MMC infiltration processes in terms of pressure infiltration casting and liquid metal infiltration. It reviews the powder metallurgy processing of aluminum MMCs and deformation processing of discontinuously reinforced aluminum composites. The article concludes with a discussion on the processing of fiber-reinforced aluminum.

Metal-matrix composites (MMCs) are a class of materials with a wide variety of structural, wear, and thermal management applications. This article discusses primary processing methods that are used to manufacture discontinuous aluminum MMCs, namely, high-pressure die casting, pressure infiltration casting, liquid metal infiltration, spray deposition, and powder metallurgy methods. It describes the processing of continuous fiber-reinforced aluminum, discontinuously, reinforced titanium, and continuous fiber-reinforced titanium. The article concludes with information on work done to develop magnesium, copper, and superalloy MMCs.

This article begins with a discussion on fiber-reinforced composite materials and describes the generic behavior and structure/property relationships of composites. The article summarizes lamina properties and presents equations that help in calculation of lamina properties. Composite laminates are constructed from lamina with uniaxial fiber orientation and frequently from textile fabrics as well. The article describes the characteristics of symmetric in-plane and through-thickness laminates; asymmetric in-plane and symmetric through-thickness laminates; asymmetric laminates; and curved laminates. It provides information on controlled thermal expansion composites, metal-matrix composites, and ceramic-matrix composites as well as their properties. The article addresses the consideration of variance and scaling. It illustrates the types of bonded joints and concludes with a discussion on design for manufacturing.

A unidirectional fiber composite (UDC) consists of aligned continuous fibers that are embedded in a matrix. This article describes a variety of analytical methods that are used to determine the various physical properties of the UDC. The properties include elasticity, thermal expansion coefficients, moisture swelling coefficients, static and dynamic viscoelastic properties, conductivity, and moisture diffusivity.