Aluminum fluxing is a step in obtaining clean molten metal by preventing excessive oxide formation, removing nonmetallic inclusions from the melt, and preventing and/or removing oxide buildup on furnace walls. This article discusses the solid fluxes and gas fluxes used in foundries. It reviews the classification of solid fluxes depending on their use and function at the foundry operation. These include cover fluxes, drossing fluxes, cleaning fluxes, and furnace wall cleaner fluxes. The article also examines the operational practices and applications of the flux injection in the foundries. It describes the applications of the aluminum fluxing such as crucible furnaces, transfer ladles, reverberatory furnaces, and holding/casting furnaces.

This article describes eight stages of the atomistic film growth: vaporization of the material, transport of the material to the substrate, condensation and nucleation of the atoms, nuclei growth, interface formation, film growth, changes in structure during the deposition, and postdeposition changes. It also discusses the effects and causes of growth-related properties of films deposited by physical vapor deposition processes, including residual film stress, density, and adhesion.

One impressive example of plane front solidification (PFS) is the industrial production of large silicon single crystals, used mainly as substrates for integrated circuits. This article explores the PFS of a single phase, without taking convection into account. It discusses the solute build-up at the solid-liquid interface forming transients and steady state, the morphological stability/instability and perturbation theory, and rapid solidification effects, including solute trapping and oscillatory instabilities. The article presents a microstructural selection map that presents an overview of interface stability as a function of composition for a given alloy.

Electroslag welding (ESW) and electrogas welding (EGW) are two related procedures that are used to weld thick-section materials in the vertical or near-vertical position between retaining shoes. This article discusses the fundamentals of the electroslag process in terms of heat flow conditions and metal transfer and weld pool morphology. It presents constitutive equations for welding current, voltage, and travel rate for ESW. The article describes the metallurgical and chemical reactions in terms of fusion zone compositional effects, weld metal inclusions, solidification structure, and solid-state transformations. It describes the electroslag process development and the applications of electroslag and electrogas processes. The article concludes with a discussion on weld defects, such as temper embrittlement, hydrogen cracking, and weld distortion.

Electroslag welding (ESW) involves high energy input relative to other welding processes, resulting generally in inferior mechanical properties and specifically in lower toughness of the heat-affected zone. Electrogas welding (EGW) is a method of gas metal or flux cored arc welding, wherein an external gas is supplied to shield the arc, and molding shoes are used to confine the molten weld metal for vertical-position welding. This article describes the fundamentals, temperature relations, consumables, metallurgical and chemical reactions, and process development of ESW. The problems, quality control, and process applications of ESW and EGW are also discussed.

There are a wide variety of furnace types and designs for melting aluminum. This article discusses the various types of furnaces, including gas reverberatory furnaces, crucible furnaces, and induction melting furnaces. It describes the classification of solid fluxes: cover fluxes, drossing fluxes, cleaning fluxes, and furnace wall cleaner fluxes. The article reviews the basic considerations in proper flux selection and fluxing practices. It explains the basic principles of degassing and discusses the degassing of wrought aluminum alloys. The article describes filtration in wrought aluminum production and in shape casting. It also reviews grain refinement in aluminum-silicon casting alloys, aluminum-silicon-copper casting alloys, aluminum-copper casting alloys, aluminum-zinc-magnesium casting alloys, and aluminum-magnesium casting alloys. The article concludes with a discussion on aluminum-silicon modification.

Primary silicon in hypereutectic aluminum-silicon alloys is very hard, not only imparting improved wear resistance but also decreasing tool life during machining. This article discusses the importance of primary silicon refinement and the process of accomplishing primary silicon refinement.

Fluxes are added to the welding environment to improve arc stability, provide a slag, add alloying elements, and refine the weld pool. This article discusses the effect of oxygen, which is an important chemical reagent to control the weld metal composition, microstructure, and properties. It provides information on the inclusions that form as a result of reactions between metallic alloy elements and nonmetallic tramp elements, or by mechanical entrapment of nonmetallic slag or refractory particles. The article reviews the considerations of flux formulation during shielded metal arc welding and flux cored arc welding (FCAW). It describes the types of fluxes used for submerged arc welding and FCAW as well as five essential groups of flux ingredients and their interactions.

Fluxes are added to the welding environment to improve arc stability, to provide a slag, to add alloying elements, and to refine the weld pool. This article describes the effect of oxygen that directly reacts with alloying elements to alter their effective role by reducing hardenability, promoting porosity, and producing inclusions. It proposes basicity index for welding as a measure of expected weld metal cleanliness and mechanical properties. The article discusses alloy modification in terms of slipping and binding agents, slag formation, and slag detachability. It reviews the types of fluxes for different arc welding processes, such as shielded metal arc welding (SMAW), flux-cored arc welding (FCAW), and submerged arc welding (SAW).

This article begins with a list of the factors that influence the properties of physical vapor deposited films. It describes the steps involved in ion plating, namely, surface preparation, nucleation, interface formation, and film growth. The article discusses the factors influencing the properties of ion-plated films. The sources of potential applied on substrate surface, bombarding species, and depositing species are addressed. The article also provides information on the parameters that influence bombardment. It concludes with a discussion on the advantages, limitations, and applications of ion plating.

Penetration-enhanced gas tungsten arc welding (GTAW) processes have been referred to variously as flux tungsten inert gas (TIG), A-TIG, and GTAW with a penetration-enhancing compound. This article provides a discussion on the principles of operation, advantages, disadvantages, procedures, and applications of GTAW. It also includes information on the equipment used and health and safety issues associated with GTAW.

This article begins with a schematic illustration of a eutectic system in which the two components of the system have the same crystal structure. Eutectic systems form when alloying additions cause a lowering of the liquidus lines from both melting points of the pure elements. The article describes the aluminum-silicon eutectic system and the lead-tin eutectic system. It discusses eutectic morphologies in terms of lamellar and fibrous eutectics, regular and irregular eutectics, and the interpretation of eutectic microstructures. The article examines the solidification of a binary alloy of exactly eutectic composition. It concludes with a discussion on terminal solid solutions.

Aluminum alloys are primarily used for nonferrous castings because of their light weight and corrosion resistance. This article discusses at length the melting and metal treatment, structure control, sand casting, permanent mold casting, and die casting of aluminum alloys. It also covers the types and melting and casting practices of copper alloys, zinc alloys, magnesium alloys, titanium alloys, and superalloys, and provides a brief account on the casting technique of metal-matrix composites.

This article discusses the susceptibility of carbon steels to hydrogen-induced cracking, solidification cracking, lamellar tearing, weld metal porosity, and heat-affected zone (HAZ) mechanical property variations. The composition and mechanical properties of selected carbon steels used in arc welding applications are listed in a table. The article presents process selection guidelines for arc welding carbon steels. It provides information on the shielded metal arc welding, gas-metal arc welding, and flux-cored arc welding, gas-tungsten arc and plasma arc welding, submerged arc welding, electrogas welding, electroslag welding, and stud arc welding.

This article presents various equations that are essential for the modeling of both single-phase and multiphase profiles. It includes the fundamental laws of diffusion, along with its equations and solutions. The article provides information on the series of applications that illustrate how various diffusional processes can be modeled.

Metals and ceramics exposed to high-temperature salt solutions are susceptible to a form of corrosion caused by fused salts accumulating on unprotected surfaces. This article examines the electrochemistry of such hot corrosion processes, focusing on sodium sulfate systems generated by the combustion of fossil fuels. It explains how salt chemistry, including acid/base and oxidizing properties, affects corrosion rates and mechanisms. The article also provides information on electrochemical testing and explains how Pourbaix methods, normally associated with aqueous corrosion, can be used to study fused-salt corrosion.

Brazing and soldering are done at temperatures below the solidus temperature of the base material but high enough to melt the filler metal and allow the liquid filler metal to wet the surface and spread into the joint gap by capillary action. This article discusses the common advantages of both brazing and soldering. It describes the brazing and soldering of cast irons, as well as the selection of brazing filler material. The article discusses various brazing methods: torch brazing, induction brazing, salt-bath brazing, and furnace brazing. It concludes with information on the application examples of brazing of cast iron.

Metal transparency and interaction with X-rays have been recognized as obvious candidate principles from which methods for in situ monitoring of solidification processes could be developed. This article describes the use of X-ray imaging-based techniques to investigate interface morphology evolution, solute transport, and various process phenomena at spatiotemporal resolutions. It discusses the three viable imaging techniques made available by synchrotron radiation for the real-time investigation of solidification microstructures in alloys. These include two-dimensional X-ray topography, two-dimensional X-ray radiography, and ultra-fast three-dimensional X-ray tomography.

This article describes the physical principles of brazing with illustrations and details elements of the brazing process. The elements of brazing process include filler-metal flow, base-metal characteristics, filler-metal characteristics, surface preparation, joint design and clearance, temperature and time, rate and source of heating, and protection by an atmosphere or flux. The article explains the different types of brazing processes: manual torch brazing, furnace brazing, induction brazing, dip brazing, resistance brazing, infrared (quartz) brazing, exothermic brazing, electron-beam and laser brazing, microwave brazing, and braze welding.