A method for producing fine copper particles includes producing fine copper particles having a coating film containing cuprous oxide on a surface by heating copper or a copper compound in a reducing flame formed by a burner. The fine copper particles are produced by adjusting a mixing ratio between a combustible gas and a combustion supporting gas which form the reducing flame such that a volume ratio of CO/CO.sub.2 is in a range of 1.5 to 2.4.

A powder production method includes providing at least one elongated member including a ductile material; providing a rotating or vibrating cutter configured to repeatedly cut an end of the at least one elongated member to produce particles; and advancing the at least one elongated member or the cutter towards the other of the at least one elongated member or the cutter to cut the particles from the at least one elongated member to produce a powder comprising a plurality of the particles. The particles produced by the method can have a diameter ranging from about 10 μm to about 200 μm.

A powder production method includes providing at least one elongated member including a ductile material; providing a rotating or vibrating cutter configured to repeatedly cut an end of the at least one elongated member to produce particles; and advancing the at least one elongated member or the cutter towards the other of the at least one elongated member or the cutter to cut the particles from the at least one elongated member to produce a powder comprising a plurality of the particles. The particles produced by the method can have a diameter ranging from about 10 μm to about 200 μm.

In an example of a three-dimensional (3D) printing method, a metallic build material is applied. A patterning fluid, including a metal salt, is selectively applied on at least a portion of the metallic build material. Prior to an application of additional build material, the metallic build material is exposed to light irradiation to cause the metal salt to reach a thermal decomposition temperature and thermally decompose to a metal. During the exposing, the metallic build material is maintained below a sintering temperature of the metallic build material.

In an example of a three-dimensional (3D) printing method, a metallic build material is applied. A patterning fluid, including a metal salt, is selectively applied on at least a portion of the metallic build material. Prior to an application of additional build material, the metallic build material is exposed to light irradiation to cause the metal salt to reach a thermal decomposition temperature and thermally decompose to a metal. During the exposing, the metallic build material is maintained below a sintering temperature of the metallic build material.

A droplet comprises a core including an alloy comprising a majority of a first metallic element and a minority of a second element, wherein the core is in a liquid state below a solidus temperature of the alloy. A shell is arranged to enclose the core and includes an exterior surface comprising a majority of the second element and a minority of the first metallic element, wherein the shell is in a solid state below the solidus temperature of the alloy. The alloy can comprise a solder material that can be used to form solder connections below a solidus temperature of the alloy.

An additive manufacturing apparatus and corresponding method for building an object by layerwise consolidation of material, where the apparatus includes a build enclosure containing a build support for supporting the object during the build, a material source for providing material to selected locations for consolidation, a radiation device for generating and directing radiation to consolidate the material at the selected locations and an acoustic sensing system. The acoustic sensing system may be arranged to detect acoustic signals generated in the build enclosure by consolidation of the material with the radiation. The acoustic sensing system may be a passive acoustic sensing system arranged to detect acoustic signals generated in the build enclosure that are indicative of at least one condition of the building process and/or the object.

An additive manufacturing apparatus and corresponding method for building an object by layerwise consolidation of material, where the apparatus includes a build enclosure containing a build support for supporting the object during the build, a material source for providing material to selected locations for consolidation, a radiation device for generating and directing radiation to consolidate the material at the selected locations and an acoustic sensing system. The acoustic sensing system may be arranged to detect acoustic signals generated in the build enclosure by consolidation of the material with the radiation. The acoustic sensing system may be a passive acoustic sensing system arranged to detect acoustic signals generated in the build enclosure that are indicative of at least one condition of the building process and/or the object.

A powder cleaning system can include a fluidized bed reactor configured to retain powder and fluidize the powder to remove adsorbate and/or other contaminants from the powder, and one or more gas sources configured to be in selective fluid communication with the fluidized bed reactor via at least one inlet line to selectively provide an inlet flow having one or more gases to the fluidized bed reactor to fluidize the powder with the one or more gases within the fluidized bed reactor. The system can include at least one outlet line in fluid communication with the fluidized bed reactor and configured to allow removal of outlet flow which comprises the adsorbate and/or other contaminants from the fluidized bed reactor.

A method, product, apparatus, and article of manufacture for the application of the Composite Based Additive Manufacturing (CBAM) method to produce objects in metal, and in metal fiber hybrids or composites. The approach has many advantages, including the ability to produce more complex geometries than conventional methods such as milling and casting, improved material properties, higher production rates and the elimination of complex fixturing, complex tool paths and tool changes and, for casting, the need for patterns and tools. The approach works by slicing a 3D model, selectively printing a fluid onto a sheet of substrate material for each layer based on the model, flooding onto the substrate a powdered metal to which the fluid adheres in printed areas, clamping and aligning a stack of coated sheets, heating the stacked sheets to melt the powdered metal and fuse the layers of substrate, and removing excess powder and unfused substrate.