A method for obtaining a lead-free or low lead content brass billet subjects a mixture of lead-free or low lead content brass chips and graphite powder to extrusion, either direct or inverted. The method obtains lead-free or low lead content brass billets.

Described herein are compositions, methods, and systems for printing metal three-dimensional objects. In an example, described is a composition for three-dimensional printing comprising: a metal powder build material, wherein the metal powder build material has an average particle size of from about 10 μm to about 250 μm; and a binder fluid comprising: an aqueous liquid vehicle, and latex polymer particles dispersed in the aqueous liquid vehicle, wherein the latex polymer particles have an average particle size of from about 10 nm to about 300 nm.

Described herein are compositions, methods, and systems for printing metal three-dimensional objects. In an example, described is a composition for three-dimensional printing comprising: a metal powder build material, wherein the metal powder build material has an average particle size of from about 10 μm to about 250 μm; and a binder fluid comprising: an aqueous liquid vehicle, and latex polymer particles dispersed in the aqueous liquid vehicle, wherein the latex polymer particles have an average particle size of from about 10 nm to about 300 nm.

A method for real-time surface imperfection detection for additive manufacturing and 3-D printing parts is provided. The method includes directing a first light radiation using one or more illumination sources, wherein the first light radiation illuminates a target area of a part being manufactured in a uniform chromatic light such that the target area appears to have a substantially uniform monochromatic color; capturing a current image of a second light radiation that is scattered or reflected by the target area using one or more feedback cameras; and analyzing the current image of the second light radiation using at least one of the one or more feedback camera with a previously acquired image to determine whether a surface imperfection exists or does not exist.

A method for real-time surface imperfection detection for additive manufacturing and 3-D printing parts is provided. The method includes directing a first light radiation using one or more illumination sources, wherein the first light radiation illuminates a target area of a part being manufactured in a uniform chromatic light such that the target area appears to have a substantially uniform monochromatic color; capturing a current image of a second light radiation that is scattered or reflected by the target area using one or more feedback cameras; and analyzing the current image of the second light radiation using at least one of the one or more feedback camera with a previously acquired image to determine whether a surface imperfection exists or does not exist.

A method may comprise: placing a probe in a molten metal melt comprising a thixotropic metal alloy; injecting a gas into the molten metal melt to form a saturated slurry, the saturated slurry being at a temperature above a liquidus temperature of the thixotropic metal alloy after injecting the gas; removing the probe from the molten metal melt; and depositing the molten metal melt through an extruder of an additive manufacturing system.

A method comprising the steps of: distributing a titanium alloy or pure titanium powder layer on a work table inside a vacuum chamber, directing at least one electron beam from at least one electron beam source over the work table causing the powder layer to fuse in selected locations, distributing a second powder layer on the work table of a titanium alloy or pure titanium inside the build chamber, directing the at least one electron beam over the work table causing the second powder layer to fuse in selected locations, and releasing a predefined concentration of the gas from the metal powder into the vacuum chamber when at least one of heating or fusing the metal powder layer, wherein at least one gas comprising hydrogen is absorbed into or chemically bonded to the titanium or titanium alloy powder to a concentration of 0.01-0.5% by weight of the hydrogen.

A method comprising the steps of: distributing a titanium alloy or pure titanium powder layer on a work table inside a vacuum chamber, directing at least one electron beam from at least one electron beam source over the work table causing the powder layer to fuse in selected locations, distributing a second powder layer on the work table of a titanium alloy or pure titanium inside the build chamber, directing the at least one electron beam over the work table causing the second powder layer to fuse in selected locations, and releasing a predefined concentration of the gas from the metal powder into the vacuum chamber when at least one of heating or fusing the metal powder layer, wherein at least one gas comprising hydrogen is absorbed into or chemically bonded to the titanium or titanium alloy powder to a concentration of 0.01-0.5% by weight of the hydrogen.

A method for forming a three-dimensional article through successive fusion of parts of a metal powder bed is provided, comprising the steps of: distributing a first metal powder layer on a work table inside a build chamber, directing at least one high energy beam from at least one high energy beam source over the work table causing the first metal powder layer to fuse in selected locations, distributing a second metal powder layer on the work table, directing at least one high energy beam over the work table causing the second metal powder layer to fuse in selected locations, introducing a first supplementary gas into the build chamber, which first supplementary gas comprising hydrogen, is capable of reacting chemically with or being absorbed by a finished three-dimensional article, and releasing a predefined concentration of the gas which had reacted chemically with or being absorbed by the finished three dimensional article.

A method for forming a three-dimensional article through successive fusion of parts of a metal powder bed is provided, comprising the steps of: distributing a first metal powder layer on a work table inside a build chamber, directing at least one high energy beam from at least one high energy beam source over the work table causing the first metal powder layer to fuse in selected locations, distributing a second metal powder layer on the work table, directing at least one high energy beam over the work table causing the second metal powder layer to fuse in selected locations, introducing a first supplementary gas into the build chamber, which first supplementary gas comprising hydrogen, is capable of reacting chemically with or being absorbed by a finished three-dimensional article, and releasing a predefined concentration of the gas which had reacted chemically with or being absorbed by the finished three dimensional article.