This article focuses on the directed-energy deposition (DED) additive manufacturing (AM) technique of biomedical alloys. First, it provides an overview of the DED process. This is followed by a section describing the design and development of the multiphysics computational modeling of the layer-by-layer fusion-based DED process. A brief overview of the primary governing equations, boundary conditions, and numerical methods prescribed for modeling laser-based metal AM is then presented. Next, the article discusses fundamental concepts related to laser surface melting and laser-assisted bioceramic coatings/composites on implant surfaces, with particular examples related to biomedical magnesium and titanium alloys. It then provides a review of the processes involved in DED of biomedical stainless steels, Co-Cr-Mo alloys, and biomedical titanium alloys. Further, the article covers novel applications of DED for titanium-base biomedical implants. It concludes with a section on the forecast of DED in biomedical applications.

Magnesium-matrix composites (MgMCs) are very promising as structural materials because of their low density, high specific strength, and excellent castability. This article provides information on the characteristics, mechanical properties, and applications of magnesium alloys and composites. It discusses the microstructures used for the most common magnesium alloys used in metal-matrix composites, namely, magnesium-aluminum, magnesium-rare earth and magnesium-lithium alloys. The article focuses on the most common methods of heat treatment, including solution heat treatment, precipitation strengthening or aging, and annealing, applied to these alloys. Finally, it describes the microstructural aspects and precipitate-matrix relationships of MgMCs as well as the heat treatment methods for MgMCs.

This article describes the different types of precipitation and transformation processes and their effects that can occur during heat treatment of various nonferrous alloys. The nonferrous alloys are aluminum alloys, copper alloys, magnesium alloys, nickel alloys, titanium alloys, cobalt alloys, zinc alloys, and heat treatable silver alloys, gold alloys, lead alloys, and tin alloys. It also provides a detailed discussion on the effects due to precipitation and transformation processes in these non-ferrous alloys.

Magnesium alloys are used predominantly for high-pressure die-cast applications in which the use of a deliberate heat treatment is uncommon. This article provides information on the heat treatment designations for magnesium alloys. It describes the effects of grain size on magnesium alloys and the relationship between hardness and mechanical properties of the alloys. The article discusses the effects of elements such as aluminum, zinc, manganese, rare earths, and yttrium, on precipitation hardening. It describes the types of heat treatment for magnesium alloys, including annealing, stress relieving, solution treating and aging, and reheat treating. The article also discusses the preventive measures for the common problems encountered in heat treating magnesium alloys; and the evaluation of the effectiveness of heat treating procedures. In addition, it presents the processing steps involved in the heat treatment of magnesium alloys and in the prevention and control of magnesium fires.

This article focuses on the temperature requirements of typical nonferrous metals and their alloys of commercial importance. These include aluminum, copper, magnesium, and titanium. The article describes the thermoelectricity, photoelectricity, and capacity of aluminum alloys. In addition, it provides information on the electrical properties of copper and its alloys. The article also lists typical physical and mechanical properties of aluminum alloys at ambient temperature.

This article presents a table that lists the linear thermal expansion of selected metals and alloys. These include aluminum, copper, iron, lead, magnesium, nickel, tin, titanium, and zinc and their alloys. Thermal expansion is presented for specific temperature ranges.

This article contains a table that lists the thermal conductivity of selected metals and alloys near room temperature. These include aluminum and aluminum alloys; copper and copper alloys; iron and iron alloys; lead and lead alloys; magnesium and magnesium alloys; nickel and nickel alloys; tin and tin alloys; titanium and titanium alloys; zinc and zinc alloys; and pure metals.

This article reviews the solubilities of the common gases present in ferrous metals, such as cast irons, and nonferrous metals, such as aluminum, copper, magnesium, and their alloys. The kinetics of the relevant reactions, reactions during solidification, and possible methods of control or removal of the dissolved gases are discussed. The most common method for removing hydrogen from aluminum, copper, and magnesium is inert gas flushing. The article provides information on techniques to overcome gas porosity in ferrous and nonferrous metals.

This article provides an overview of exogenous and indigenous inclusions. It discusses the general concepts of phase diagrams, thermochemical relationships, and reaction rates, along with their practical significance. The article describes the most common techniques for controlling the occurrence of inclusions in any cast metal. It presents a discussion on the inclusions in ferrous and nonferrous alloys, including steels, cast irons, aluminum alloys, copper alloys, and magnesium alloys.

This article focuses on the variety of alloys, furnaces, and associated melting equipment as well as the casting methods available for manufacturing magnesium castings. These methods include sand casting, permanent mold casting, die casting, thixomolding, and direct chill casting. The article discusses the flux process and fluxless process for the melting and pouring of magnesium alloys. It describes the advantages and disadvantages of green sand molding and tabulates typical compositions and properties of magnesium molding sands. The article provides information on the machining characteristics of magnesium and the applications of magnesium alloys.

Sheet forming comprises deformation processes in which a metal blank is shaped by tools or dies, primarily under the action of tensile stresses. This article discusses the classification of sheet-forming processes for obtaining desired dimensional features. It describes different process-related developments, namely, superplastic forming of aluminum, forming of tailor-welded blanks, rubber-pad forming, and high-velocity metal forming. The article explains cost-effective approaches of evaluating tooling designs prior to the manufacture of expensive steel dies and dieless forming techniques such as thermal forming and peen forming. It provides information on the application of advanced high-strength steels, magnesium alloys, and various ultrafine-grain materials for superplastic sheet forming. The article concludes with information on the development and application of simulation, design, and control of sheet-forming processes.

This article discusses the advantages and limitations of drop hammer forming and presents the key factors for determining a process plan. It describes the characteristics of hammers and presents information on tool materials. It explains the use of lubricants and preparation of blanks for forming. The article also details the drop hammer forming process of steels, aluminum alloys, magnesium alloys, and titanium alloys.

In terms of forming, magnesium alloys are much more workable at elevated temperatures due to their hexagonal crystal structures. This article describes the deformation mechanisms of magnesium and provides information on the hot and cold forming processes of magnesium alloys and the lubricants used in the processes. It discusses the various forming processes of magnesium alloys. These include press-brake forming, deep drawing, manual and power spinning, rubber-pad forming, stretch forming, drop hammer forming, and precision forging.

This article discusses the forging processes and equipment and forging practice associated with the forging of magnesium alloys. It describes the workability of magnesium alloys. The article concludes with a discussion on the inspection of magnesium alloy forgings.

This article begins with a discussion on the environmental factors that induce corrosion in magnesium alloys. It reviews the factors that determine the severity of different forms of localized corrosion, namely, galvanic corrosion, corrosion fatigue, and stress-corrosion. The article discusses corrosion protection in magnesium assemblies and the protective coating systems used in corrosion protection practices. Protection schemes for specific applications and the production of novel magnesium alloys with improved corrosion resistance are also reviewed. The article concludes with a discussion on the corrosion of bulk vapor-deposited alloys and magnesium-matrix composites.

Magnesium and its alloys are among the most difficult metals to prepare for metallographic examination. This article describes specimen preparation processes, including sectioning, mounting, grinding, and polishing. It discusses macro and microexamination techniques as well as related etching processes, including macroetching and color etching based on polarized light enhancement. The article concludes with an overview of the effects of alloying elements, including aluminum, beryllium, calcium, copper, iron, lithium, manganese, rare earth metals, silicon, silver, strontium, thorium, tin, zinc, and zirconium.

Most alloys are susceptible to intergranular corrosion, also known as intergranular attack (IGA), when exposed to specific environments. This article reviews the theory and application of acceptance tests for detecting the susceptibility of stainless steels and nickel-base alloys to IGA. It describes the most serious forms of structure-dependent corrosion, such as stress-corrosion cracking and exfoliation, in aluminum alloys including strain-Hardened 5xxx (Al-Mg) alloys and heat treated high-strength alloys. The article concludes with information on the evaluation tests for other alloys such as magnesium alloys and zinc die casting alloys.

This article begins with a discussion on the corrosion characteristics of unalloyed magnesium and two major magnesium alloy systems. It shows the effects of iron and 13 other elements on the saltwater corrosion performance of magnesium in binary alloys with increasing levels of the individual elements. The article illustrates the effect of increasing iron, nickel, and copper contamination on the standard ASTM B 117 salt-spray performance of the die-cast AZ91 test specimens as compared to the range of performance observed for cold-rolled steel and die-cast aluminum alloy 380 samples. It discusses the effect of heat treating and cold working on the corrosion rates of the die-cast AZ91 alloy. The article concludes with a description on the causes of corrosion failures in magnesium alloys.

This article commences with a discussion on the characteristics of stress-corrosion cracking (SCC) and describes crack initiation and propagation during SCC. It reviews the various mechanisms of SCC and addresses electrochemical and stress-sorption theories. The article explains the SCC, which occurs due to welding, metalworking process, and stress concentration, including options for investigation and corrective measures. It describes the sources of stresses in service and the effect of composition and metal structure on the susceptibility of SCC. The article provides information on specific ions and substances, service environments, and preservice environments responsible for SCC. It details the analysis of SCC failures, which include on-site examination, sampling, observation of fracture surface characteristics, macroscopic examination, microscopic examination, chemical analysis, metallographic analysis, and simulated-service tests. It provides case studies for the analysis of SCC service failures and their occurrence in steels, stainless steels, and commercial alloys of aluminum, copper, magnesium, and titanium.