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 the primary processing methods 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.

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.

Metal matrix composites (MMCs) can be synthesized by vapor phase, liquid phase, or solid phase processes. This article emphasizes the liquid phase processing where solid reinforcements are incorporated in the molten metal or alloy melt that is allowed to solidify to form a composite. It illustrates the three broad categories of MMCs depending on the aspect ratio of the reinforcing phase. The categories include continuous fiber-reinforced composites, discontinuous or short fiber-reinforced composites, and particle-reinforced composites. The article discusses the two main classes of solidification processing of composites, namely, stir casting and melt infiltration. It describes the effects of reinforcement present in the liquid alloy on solidification. The article examines the automotive, space, and electronic packaging applications of MMCs. It concludes with information on the development of select cast MMCs.

Ceramic-matrix composites (CMCs) have ability to withstand high temperatures and have superior damage tolerance over monolithic ceramics. This article describes important processing techniques for CMCs: cold pressing, sintering, hot pressing, reaction-bonding, directed oxidation, in situ chemical reaction techniques, sol-gel techniques, pyrolysis, polymer infiltration, self-propagating high-temperature synthesis, and electrophoretic deposition. The advantages and disadvantages of each technique are highlighted to provide a comprehensive understanding of the achievements and challenges that remain in this area.

This article provides information on the infiltration mechanism of carbide structures. It reviews the basic techniques used for metal infiltration, including dip infiltration, contact filtration, gravity feed infiltration, and external-pressure infiltration. The article highlights various applications of contact infiltration in oil, gas, and blast-hole drilling such as fixed-cutter drill bits and diamond-impregnated coring bits. It also discusses the applications of infiltrated carbide material in erosion-resistant cladding.

This article reviews various rapid prototyping (RP) processes such as stereolithography, powder sintering, hot melt extrusion, sheet lamination, solid ground curing, and three-dimensional printing. It discusses the various material prototypes produced by RP technology. The list of materials includes particulate and fiber-reinforced polymers, ceramic-matrix composites, and metal-matrix composites. The article also provides information on freeform-fabrication techniques for composite part lay-up.

The residual porosity in sintered refractory metal ingots is usually eliminated by different densification processes, such as thermomechanical processes. This article focuses on thermomechanical processing of tungsten, molybdenum, and tantalum. It provides an overview of liquid-phase sintering of tungsten heavy alloys and describes the infiltration of tungsten and molybdenum for attaining full density. The article concludes by providing information on hot isostatic pressing of refractory metal alloys to full density.

Iron powders are the most widely used powder metallurgy (P/M) material for structural parts. This article reviews low to medium density iron and low-alloy steel parts produced by the pressing and sintering technology. It explains different powder production methods, including Hoeganaes process, Pyron process, atomization of liquid metal, thermal decomposition and the electrodeposition process for carbonyl and electrolytic iron powders. It describes the types of compaction and sintering, explaining their effects of processing with designations. Further, the article deals with the mechanical and physical properties of ferrous P/M materials, which may depend on certain factors, namely microstructure, porosity, density, infiltration, re-pressing, chemical composition, and heat treatment.

The two most important classes of materials that are manufactured via infiltration methods are copper- and silver-infiltrated refractory metals and refractory carbides, and copper-infiltrated steels. This article focuses on copper-infiltrated steels and discusses the basic requirements for infiltration, which is a technique that is only applicable to material systems that meet certain requirements. It addresses these requirements and describes the conventional (partial) infiltration process of powder metallurgy (PM) steel. The materials used in the process, such as matrix and infiltrant, are discussed. The article also details several criteria used to evaluate the performance of an infiltration process. It concludes with information on alloy steels and fully infiltrated steels.

This article focuses on binder-jetting technologies in additive manufacturing (AM) that produce metal artifacts either directly or indirectly. The intent is to focus on the most strategic and widespread uses of the binder jetting technology and review some of the challenges and opportunities for that technology. The discussion includes a historical overview and covers the major steps involved and the advantages of using the binder jetting process. The major steps of the process covered include printing, curing, de-powdering, and sintering.

This article discusses the solidification of a matrix alloy in cast metal matrix composites (MMCs). It begins with a discussion on the mixing techniques in reinforcement incorporation and wettability of reinforcement. It describes the solidification processes, such as stir mixing and melt infiltration, used in the synthesis of MMCs. The article also considers the fundamentals of the process and presents a computational modeling of particle/solidification front interactions in metal-ceramic systems. The article concludes with information on nanocomposites.

This article provides information on the microstructure of powder metal alloys and the special handling requirements of porous materials. It covers selection, sectioning, mounting, grinding, and polishing, and describes procedures, such as washing, liquid removal, and impregnation, meant to preserve pore structures and keep them open for analysis. The article compares and contrasts the microstructures of nearly 50 powder metal alloys, using them to illustrate the effect of consolidation and compaction methods as well as particle size, composition, and shape. It discusses imaging equipment and techniques and provides data on etchants and etching procedures.