An example of a kit for three-dimensional (3D) printing includes a host metal and fumed flow additive aggregates to be mixed with the host metal. The fumed flow additive aggregates include flow additive nanoparticles and partially fused necks between at least some of the flow additive nanoparticles. Each of the flow additive nanoparticles 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.

An example of a composition includes a host metal present in an amount of at least about 90 wt % based on a total weight of the composition. A flow additive is also present in an amount of less than about 10 wt % based on the total weight of the composition. The flow additive consists of an organic particle having crosslinked polymer chains, a glass transition temperature (T.sub.g) of at least 90° C., and a primary particle diameter of 100 nm or less.

An example of a composition includes a host metal present in an amount of at least about 90 wt % based on a total weight of the composition. A flow additive is also present in an amount of less than about 10 wt % based on the total weight of the composition. The flow additive consists of an organic particle having crosslinked polymer chains, a glass transition temperature (T.sub.g) of at least 90° C., and a primary particle diameter of 100 nm or less.

An additive manufacturing method of manufacturing a product by laminating metal includes: laminating the metal so as to form a half-finished product of the product and a support; and spraying dry ice pellets having a particle shape to the support, after the laminating.

An additive manufacturing method of manufacturing a product by laminating metal includes: laminating the metal so as to form a half-finished product of the product and a support; and spraying dry ice pellets having a particle shape to the support, after the laminating.

Some variations provide a system for producing a functionalized powder, comprising: an agitated pressure vessel; first particles and second particles contained within the agitated pressure vessel; a fluid contained within the agitated pressure vessel; an exhaust line for releasing the fluid from the agitated pressure vessel; and a means for recovering a functionalized powder containing the second particles disposed onto surfaces of the first particles. A preferred fluid is carbon dioxide in liquefied or supercritical form. The carbon dioxide may be initially loaded into the pressure vessel as solid carbon dioxide. The pressure vessel may be batch or continuous and is operated under reaction conditions to functionalize the first particles with the second particles, thereby producing a functionalized powder, such as nanofunctionalized metal particles in which nanoparticles act as grain refiners for a component ultimately produced from the nanofunctionalized metal particles. Methods for making the functionalized powder are also disclosed.

A method includes acquiring particles doped with at least one analyte and forming a monolithic reference material. The method includes forming includes using the analyte-doped particles as feedstock particles in an additive manufacturing process. A product includes a monolithic reference material formed of Stober particles doped with a trace element. A method includes acquiring particles doped with platinum group elements (PGEs). The method includes forming a monolithic reference material using the PGE-doped particles as feedstock particles in an additive manufacturing process.

A method includes acquiring particles doped with at least one analyte and forming a monolithic reference material. The method includes forming includes using the analyte-doped particles as feedstock particles in an additive manufacturing process. A product includes a monolithic reference material formed of Stober particles doped with a trace element. A method includes acquiring particles doped with platinum group elements (PGEs). The method includes forming a monolithic reference material using the PGE-doped particles as feedstock particles in an additive manufacturing process.

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 m to about 250 m; 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 tantalum-titanium alloy powder that is highly spherical is described. The alloy powder can be useful in additive manufacturing and other uses. Methods to make the alloy powder are further described as well as methods to utilize the alloy powder in additive manufacturing processes. Resulting products and articles using the alloy powder are further described.