Abstract: In an example of a method for three-dimensional printing, a first amount of a binding agent is selectively applied, based on a 3D object model, to individual build material layers of a particulate build material including metal particles to forming an intermediate structure. The binding agent and/or a void-formation agent is selectively applied, based on the 3D object model, to at least one interior layer of the individual build material layers so that a total amount of the binding agent, the void-formation agent, or both the binding agent and the void-formation agent in the at least one of the individual build material layers is greater than the first amount. This patterns an area that is to contain voids. The intermediate structure is heated to form a 3D structure including a void-containing breakable connection.

Abstract: An example of a method for making a build material composition for three-dimensional (3D) printing includes freezing a dispersion of flow additive nanoparticles in a liquid to form a frozen liquid containing the flow additive nanoparticles. The frozen liquid containing the flow additive nanoparticles is lyophilized to form flow additive agglomerates having a porous, fractal structure. The flow additive agglomerates are mixed with a host metal. The flow additive nanoparticles have an average flow additive particle size ranging from about 1 to about 3 orders of magnitude smaller than an average host metal particle size of the host metal.

Abstract: A three-dimensional printing kit can include a binder fluid and a particulate build material. The particulate build material can include metal particles in an amount from about 95 wt % to about 99.995 wt % and carbon black particles in an amount from about 0.005 wt % to about 2 wt %, wherein weight percentages are based on a total weight of the particulate build material.

Abstract: In a three-dimensional printing method example, a liquid functional agent is selectively applied. The liquid functional agent includes an alloying agent. A metallic build material is applied. The liquid functional agent is selectively applied before the metallic build material, after the metallic build material, or both before and after the metallic build material. The liquid functional agent patterns the metallic build material to form a composite layer. At least some of the metallic build material is exposed to energy to melt the at least some of the metallic build material to form a layer. Upon contact or after energy exposure, the alloying agent and the build material alter a composition of the composite layer.

Abstract: An example of a method for making a build material composition for three-dimensional (3D) printing includes freezing a dispersion of flow additive nanoparticles in a liquid to form a frozen liquid containing the flow additive nanoparticles. The frozen liquid containing the flow additive nanoparticles is lyophilized to form flow additive agglomerates having a porous, fractal structure. The flow additive agglomerates are mixed with a host metal. The flow additive nanoparticles have an average flow additive particle size ranging from about 1 to about 3 orders of magnitude smaller than an average host metal particle size of the host metal.

Abstract: In a three-dimensional printing method example, a liquid functional agent is selectively applied. The liquid functional agent includes an alloying agent. A metallic build material is applied. The liquid functional agent is selectively applied before the metallic build material, after the metallic build material, or both before and after the metallic build material. The liquid functional agent patterns the metallic build material to form a composite layer. At least some of the metallic build material is exposed to energy to melt the at least some of the metallic build material to form a layer. Upon contact or after energy exposure, the alloying agent and the build material alter a composition of the composite layer.

Abstract: An example of a method, for three-dimensional (3D) printing, includes applying a build material and patterning at least a portion of the build material. The patterning includes selectively applying a wetting amount of a binder fluid on the at least the portion of the build material and subsequently selectively applying a remaining amount of the binder fluid on the at least the portion of the build material. An area density in grams per meter square meter (gsm) of the wetting amount ranges from about 2 times less to about 30 times less than area density in gsm of the remaining amount.

Abstract: An apparatus is disclosed to create a breakaway junction for 3D printed parts. Powder is spread along a target zone, such as a build bed. A liquid functional agent is selectively dispensed upon the powder to form a 3D object, a supporting part, and the breakaway junction between them.

Abstract: An example of a composition includes a host metal present in an amount ranging from about 95.00 weight percent to about 99.99 weight percent, based on a total weight of the composition. A flow additive is present in an amount ranging from about 0.01 weight percent to about 5.00 weight percent, based on the total weight of the composition. The flow additive consists of a metal containing compound that is reducible to an elemental metal in a reducing environment at a reducing temperature less than or equal to a sintering temperature of the host metal. The elemental metal is capable of being incorporated into a bulk metal phase of the host metal in a final metal object. The composition is spreadable, having a Hausner Ratio less than 1.25.

Abstract: In an example of a method for three-dimensional (3D) printing, build material layers are patterned to form an intermediate structure. During patterning, a binding agent is selectively applied to define a patterned intermediate part. Also during patterning, i) the binding agent and a separate agent including a gas precursor are, or ii) a combined agent including a binder and the gas precursor is, selectively applied to define a build material support structure adjacent to at least a portion of the patterned intermediate part. The intermediate structure is heated to a temperature that activates the gas precursor to create gas pockets in the build material support structure.

Abstract: In a three-dimensional (3D) printing method example, a metallic build material is applied. A binder fluid is selectively applied on at least a portion of the metallic build material. The binder fluid includes a liquid vehicle and polymer particles dispersed in the liquid vehicle. The application of the metallic build material and the selective application of the binder fluid are repeated to create a patterned green part. The patterned green part is heated to at about a melting point of the polymer particles to activate the binder fluid and create a cured green part. The cured green part is heated to a thermal decomposition temperature of the polymer particles to create an at least substantially polymer-free gray part. The at least substantially polymer-free gray part is heated to a sintering temperature to form a metallic part.

Abstract: An apparatus is disclosed to create a breakaway junction for 3D printed parts. Powder is spread along a target zone, such as a build bed. A liquid functional agent is selectively dispensed upon the powder to form a 3D object, a supporting part, and the breakaway junction between them.

Abstract: A three-dimensional printing system can include a particulate build material including metal particles. The three-dimensional printing system can include a binding agent applicator fluidly coupled or coupleable to a binding agent. The three-dimensional printing system can include a suppression agent applicator fluidly coupled or coupleable to a melting point suppression agent, the melting point suppression agent including a dispersion of melting point suppression particles. The three-dimensional printing system can include a hardware controller to generate a command to direct the binding agent applicator to iteratively apply the binding agent to the particulate build material to form individually patterned object layers of a green body object, and direct the suppression agent applicator to iteratively apply the melting point suppression agent to a discrete location of the individually patterned object layers. The discrete location can include a discrete surface region of the green body object.

Abstract: In a three-dimensional (3D) printing method example, a metallic build material is applied. A binder fluid is selectively applied on at least a portion of the metallic build material. The binder fluid includes a liquid vehicle and polymer particles dispersed in the liquid vehicle. The application of the metallic build material and the selective application of the binder fluid are repeated to create a patterned green part. The patterned green part is heated to at about a melting point of the polymer particles to activate the binder fluid and create a cured green part. The cured green part is heated to a thermal decomposition temperature of the polymer particles to create an at least substantially polymer-free gray part. The at least substantially polymer-free gray part is heated to a sintering temperature to form a metallic part.

Abstract: In a three-dimensional printing method example, a liquid functional agent is selectively applied. The liquid functional agent includes i) an energy source material or ii) an energy sink material. A metallic or ceramic build material is applied. The liquid functional agent is selectively applied any of before the metallic or ceramic build material, after the metallic or ceramic build material, or both before and after the metallic or ceramic build material. The liquid functional agent patterns the metallic or ceramic build material to form a composite layer. At least some of the metallic or ceramic build material is exposed to energy. A reaction involving i) the energy source material or ii) the energy sink material is initiated to alter a thermal condition of the composite layer.

Abstract: In one example, a processor readable medium having instructions thereon that when executed cause an additive manufacturing machine to vary operating characteristics of a fusing laser beam at multiple different voxel locations in a layer of build material according to an energy dosage to be applied at each voxel location in an object slice, including multiple different energy dosages for corresponding multiple different voxel locations in the slice.

Abstract: Described herein are kits, methods, and systems for printing metal three-dimensional objects. In an example, described is a multi-fluid kit for three-dimensional printing comprising: a first fluid comprising a first liquid vehicle comprising metal or metal precursor particles; and a second fluid comprising a second liquid vehicle comprising latex polymer particles dispersed therein, wherein the latex polymer particles have an average particle size of from about 10 nm to about 300 nm, and wherein the metal or metal precursor particles comprise metal nanoparticles, metal oxide nanoparticles, metal oxide nanoparticles and a reducing agent, or combinations thereof.

Abstract: Described herein are kits, methods, and systems for printing metal three-dimensional objects. In an example, described is a kit for three-dimensional printing comprising: powdered metal build material; and a binding fluid comprising a liquid vehicle, metal or metal precursor particles, and latex polymer particles dispersed in the liquid vehicle, wherein the latex polymer particles have an average particle size of from about 10 nm to about 300 nm, and wherein the metal or metal precursor particles comprise metal nanoparticles, metal oxide nanoparticles, metal oxide nanoparticles and a reducing agent, or combinations thereof.

Abstract: In one example, a processor readable medium having instructions thereon that when executed cause an additive manufacturing machine to vary operating characteristics of a fusing laser beam at multiple different voxel locations in a layer of build material according to an energy dosage to be applied at each voxel location in an object slice, including multiple different energy dosages for corresponding multiple different voxel locations in the slice.

Abstract: In an example of a method for three-dimensional (3D) printing, metallic build material layers are patterned to form an intermediate structure. During patterning, a binding agent is selectively applied to define: a build material support structure and a patterned intermediate part. Also during patterning, i) the binding agent and a separate agent including an etch sensitizer or ii) a combined agent including a binder and the etch sensitizer are selectively applied to define a patterned etchable connection between at least a portion of the build material support structure and at least a portion patterned intermediate part. The intermediate structure is heated.