This article provides an overview of the supply chain for metallic additively manufactured materials, with an emphasis on spherical alloy powders. The article describes powder production processes as well as the various metal alloys that can be produced using powder AM techniques. It also reviews the basic characteristics of powder feedstocks and the management of metallic powders.

Additive manufacturing (AM) techniques include powder-bed fusion (PBF), directed-energy deposition, binder jetting (BJ), extrusion-based desktop, vat photopolymerization, material jetting, and sheet lamination. The development of suitable powders for AM is a challenging task because of critical design parameters including chemical composition, flowability of powders, and melt surface tension. This article explains the fabrication methods of metal and novel alloy powders for medical applications. The development of zirconium alloy powder for laser-PBF is introduced as a case study.

Traditional processing methods for the part production of Co-Cr alloys include casting, powder metallurgy, and metal forming. However, the steps involved during materials processing followed by metal forming and machining are time consuming and fraught with processing variables. Three-dimensional (3D) printing enables rapid evolution in design, personalization, and so on. This article presents a brief description of some common additive manufacturing (AM) processes for the production of cobalt alloy parts, and provides a comparison between AM and conventional processing methods. The discussion is centered on process-microstructure-properties correlation in additively manufactured cobalt alloys and applications of these alloys.

This article is a detailed account of additive manufacturing (AM) processes for copper and copper alloys such as copper-chromium alloys, GRCop, oxide-dispersion-strengthened copper, copper-nickel alloys, copper-tin alloys, copper-zinc alloys, and copper-base shape memory alloys. The AM processes include binder jetting, ultrasonic additive manufacturing, directed-energy deposition, laser powder-bed fusion, and electron beam powder-bed fusion. The article presents a review of the literature and state of the art for copper alloy AM and features data on AM processes and industrial practices, copper alloys used, selected applications, material properties, and where applicable, compares these data and properties to traditionally processed materials. The data presented and the surrounding discussion focus on bulk metallurgical processing of copper components. The discussion covers the composition and performance criteria for copper alloys that have been reported for AM and discusses key differences in process-structure-property relationships compared to conventionally processed material. The article also provides information on feedstock considerations for copper powder handling.

This article covers the current state of materials development of nickel-base superalloys for additive manufacturing (AM) processes and the associated challenges. The discussion focuses on nickel-base superalloy fusion AM processes, providing information on typically encountered cracking mechanisms in AM nickel-base superalloys, such as solid-solution-strengthened nickel-base superalloys and precipitate-strengthened nickel-base superalloys. The mechanisms include solidification cracking, strain-age cracking, liquation cracking, and ductility-dip cracking. The article also provides a short discussion on binder jet AM and powder recyclability.

This article uses metal and alloy powders as examples to briefly discuss how to perform the characterization of powders. It begins by reviewing some of the techniques involved in the sampling of powders to ensure accurate characterization. This is followed by a discussion on the important properties to characterize powders, namely the particle size, surface area, density, porosity, particle hardness, compressibility, green strength, and flowability. For characterization of powders, both individual particles and bulk powders are used to evaluate their physical and chemical properties. The article also discusses the important characteristics and compositions of powder as well as impurities that directly affect powder properties. It ends with a description of the ignition and dust-explosion characteristics of organic and metal powders.

Aluminum powders can be formed into components by several competing technologies, including powder metallurgy (PM), metal injection molding, powder forging, and additive manufacturing. This article explores PM methodologies that are being exploited to manufacture such components. It reviews emerging technologies that promise to offer exciting ways to produce aluminum parts. The article discusses the various steps involved in PM, such as powder production, compaction, sintering, repressing, and heat treatment. It provides information on aluminum production statistics and the wear-resistance applications of PM.

This article provides a summary of the conventional technologies used for titanium powder production. It focuses on the various processes for titanium powder production, namely, Hunter, Kroll, Armstrong, MER, TIRO, FFC-Cambridge, Chinuka, and CSIR processes. Employment of titanium powder significantly improves the synthesis of titanium and its alloys.

Metals and alloy powders are used in welding, hardfacing, brazing, and soldering applications, which include hardface coatings, the manufacturing of welding stick electrodes and flux-cored wires, and additives in brazing pastes or creams. This article reviews these applications and the specific powder properties and characteristics they require.

Direct powder rolling (DPR) is a process by which a suitable powder or mixture of powders is compacted under the opposing forces of a pair of rolling mill rolls to form a continuous green strip that is further densified and strengthened by sintering and rerolling. This article discusses the basic principle, process considerations, and advantages of DRP, and describes the application of this process in the manufacture of powder titanium and titanium alloy components. It further illustrates the complexity of the process and describes the benefits of using DRP in terms of economics and product quality.

The primary market for metal powder is the production of powder metallurgy (PM) parts, which are dominated primarily by iron and copper powders. This article reviews the chemical and pyrotechnics applications of ferrous and nonferrous powders. It describes the characteristics of iron powder used in oxygen scavengers and chemical reactive warmers and heaters. Metal powders used as fuels in solid propellants, pyrotechnic devices, explosives, and similar applications are reviewed. Atomized aluminum, magnesium, tungsten, and zirconium powders are also discussed.

Consolidation of titanium powders at room temperature may be performed by low-cost conventional powder metallurgy processes. This article provides information on various consolidation methods, namely, die pressing, direct powder rolling, and cold isostatic pressing. It also describes the sintering of blended elemental powders, high-strength titanium alloys, and porous material as well as the sintering of titanium powders by microwave heating.

This article discusses the production of aluminum and aluminum alloy powders with emphasis on the gas atomization method and the atomizing nozzle. It illustrates the particle formation mechanism and details the requisites for particle size distribution, control, and morphology. The article presents information on the mean oxide thickness formed on atomized powders. It also describes the mechanical and physical properties of aluminum and aluminum alloy powders, as well as their applications.

This article describes the fundamentals of various techniques used for the production of copper and copper alloy powders. These include atomization (water, air, and gas), oxide reduction, and electrolysis. The article discusses the effects of electrolyte composition and operating conditions on the characteristics of copper and copper alloy powders.

Prealloyed (PA) powder metallurgy is a technique where complex near-net shape titanium aircraft components are fabricated with low buy-to-fly ratios. This article describes the physical principle, mechanism, and simulation and modeling of metal can and hot isostatic pressing (HIP) processes involved in the PA powder metallurgy technique. It discusses the technical problems addressed in shape control and their solutions for understanding the advantages of powder metallurgy HIP.

Superalloys are predominantly nickel-base alloys that are strengthened by solid-solution elements including molybdenum, tungsten, cobalt, and by precipitation of a Ni 3 (Al, Ti) type compound designated as gamma prime and/or a metastable Ni 3 Nb precipitate designated as gamma double prime. This article provides a discussion on the conventional processing, compositions, characteristics, mechanical properties, and applications of powder metallurgy (PM) superalloys. The conventional processing of PM superalloys involves production of spherical prealloyed powder, screening to a suitable maximum particle size, blending the powder to homogenize powder size distribution, loading powder into containers, vacuum outgassing and sealing the containers, and consolidating the powder to full density. PM superalloys include Rene 95, IN-100, LC Astroloy, Udimet 720, N18, ME16, RR1000, Rene 88DT, PA101, MERL 76, AF2-1DA, Inconel 706, AF115, and KM4. The article reviews specialized PM superalloy processes and technical issues in the usage of PM superalloys.

This article focuses on mechanical testing characterization of blended elemental powder metallurgy (PM) titanium alloys and prealloyed PM titanium alloys. It examines the tensile properties, fracture toughness, stress-corrosion threshold resistance, fatigue strength, crack propagation properties, and processing-microstructure-property relationships of these alloys. The article also reviews five considerations for powder process selection.