Abstract: Some variations provide a process for additive manufacturing of a nanofunctionalized metal alloy, comprising: providing a nanofunctionalized metal precursor containing metals and grain-refining nanoparticles; exposing a first amount of the nanofunctionalized metal precursor to an energy source for melting the precursor, thereby generating a first melt layer; solidifying the first melt layer, thereby generating a first solid layer; and repeating many times to generate a plurality of solid layers in an additive-manufacturing build direction. The additively manufactured, nanofunctionalized metal alloy has a microstructure with equiaxed grains.

Abstract: Some variations provide a process for additive manufacturing of a nanofunctionalized metal alloy, comprising: providing a nanofunctionalized metal precursor containing metals and grain-refining nanoparticles; exposing a first amount of the nanofunctionalized metal precursor to an energy source for melting the precursor, thereby generating a first melt layer; solidifying the first melt layer, thereby generating a first solid layer; and repeating many times to generate a plurality of solid layers in an additive-manufacturing build direction. The additively manufactured, nanofunctionalized metal alloy has a microstructure with equiaxed grains.

Abstract: Some variations provide a method of making an additively manufactured single-crystal metallic component, comprising: providing a feedstock comprising a first metal or metal alloy; providing a build plate comprising a single crystal of a second metal or metal alloy; exposing the feedstock to an energy source for melting the feedstock, generating a melt layer on the build plate; and solidifying the melt layer, generating a solid layer (on the build plate) of a metal component. The solid layer is also a single crystal of the first metal or metal alloy. The method may be repeated many times to build the part. Some variations provide a single-crystal metallic component comprising a plurality of solid layers in an additive-manufacturing build direction, wherein the plurality of solid layers forms a single crystal of a metal or metal alloy with a continuous crystallographic texture. The crystal orientation may vary along the additive-manufacturing build direction.

Abstract: Some variations provide a leading-edge heat pipe comprising: (a) an envelope fabricated from a shell material, wherein the envelope includes at least one edge with a radius of curvature of less than 3 mm, and wherein the envelope includes, or is in thermal communication with, at least one heat-rejection surface; (b) a porous wick fabricated from a ceramic or metallic wick material, wherein the porous wick is configured within a first portion of the interior cavity, wherein at least a portion of the porous wick is adjacent to the inner surface, and wherein the porous wick has a bimodal pore distribution comprising an average capillary-pore size from 0.2 microns to 200 microns and an average high-flow pore size from 100 microns to 2 millimeters (the average high-flow pore size is greater than the average capillary-pore size); and (c) a phase-change heat-transfer material contained within the porous wick.

Abstract: Some variations provide a method of making an additively manufactured single-crystal metallic component, comprising: providing a feedstock comprising a first metal or metal alloy; providing a build plate comprising a single crystal of a second metal or metal alloy; exposing the feedstock to an energy source for melting the feedstock, generating a melt layer on the build plate; and solidifying the melt layer, generating a solid layer (on the build plate) of a metal component. The solid layer is also a single crystal of the first metal or metal alloy. The method may be repeated many times to build the part. Some variations provide a single-crystal metallic component comprising a plurality of solid layers in an additive-manufacturing build direction, wherein the plurality of solid layers forms a single crystal of a metal or metal alloy with a continuous crystallographic texture. The crystal orientation may vary along the additive-manufacturing build direction.

Abstract: A method of repairing a sandwich structure includes: removing a damaged portion of a core and a damaged portion of a first facesheet to form an open volume; filling the open volume with an ultraviolet-curable photomonomer; partially curing the ultraviolet-curable photomonomer to form a plurality of photopolymer waveguides by utilizing ultraviolet light; and arranging a replacement facesheet on the damaged portion of the first facesheet and over the photopolymer waveguides.

Abstract: Some variations provide a composition for additive manufacturing (3D printing) of metals, comprising: from 10 vol % to 70 vol % of a photocurable liquid resin; from 10 vol % to 70 vol % of metal or metal alloy particles, optionally configured with a photoreflective surface; and from 0.01 vol % to 10 vol % of a photoinitiator. Other variations provide a composition for additive manufacturing of metals, comprising: from 1 vol % to 70 vol % of a photocurable liquid resin; from 0.1 vol % to 98 vol % of an organometallic compound containing a first metal; from 1 vol % to 70 vol % of metal or metal alloy particles containing a second metal (which may be the same as or different than the first metal); and from 0.01 vol % to 10 vol % of a photoinitiator. Many examples of metals, photocurable resins, organometallic compounds, photoinitiators, and optional additives are disclosed, and methods of making and using the composition are described.

Abstract: A phononic composite material providing structural strength and blocking the propagation of elastic waves over a frequency range referred to as the bandgap. In one embodiment, the phononic composite material consists of a plurality of periodic units, each of which includes a central fiber, a relatively soft interface layer surrounding the fiber, and a matrix layer surrounding the interface layer. The properties of the interface layer may be adjusted, e.g., by adjusting the temperature of the phononic composite material, to transition from a state with a bandgap to a state lacking a bandgap.

Abstract: Some variations provide a leading-edge heat pipe comprising: (a) an envelope fabricated from a shell material, wherein the envelope includes at least one edge with a radius of curvature of less than 3 mm, and wherein the envelope includes, or is in thermal communication with, at least one heat-rejection surface; (b) a porous wick fabricated from a ceramic or metallic wick material, wherein the porous wick is configured within a first portion of the interior cavity, wherein at least a portion of the porous wick is adjacent to the inner surface, and wherein the porous wick has a bimodal pore distribution comprising an average capillary-pore size from 0.2 microns to 200 microns and an average high-flow pore size from 100 microns to 2 millimeters (the average high-flow pore size is greater than the average capillary-pore size); and (c) a phase-change heat-transfer material contained within the porous wick.

Abstract: Disclosed herein are surface-functionalized powders which alter the solidification of the melted powders. Some variations provide a powdered material comprising a plurality of particles fabricated from a first material, wherein each of the particles has a particle surface area that is continuously or intermittently surface-functionalized with nanoparticles and/or microparticles selected to control solidification of the powdered material from a liquid state to a solid state. Other variations provide a method of controlling solidification of a powdered material, comprising melting at least a portion of the powdered material to a liquid state, and semi-passively controlling solidification of the powdered material from the liquid state to a solid state. Several techniques for semi-passive control are described in detail.

Abstract: Disclosed herein are surface-functionalized powders which alter the solidification of the melted powders. Some variations provide a powdered material comprising a plurality of particles fabricated from a first material, wherein each of the particles has a particle surface area that is continuously or intermittently surface-functionalized with nanoparticles and/or microparticles selected to control solidification of the powdered material from a liquid state to a solid state. Other variations provide a method of controlling solidification of a powdered material, comprising melting at least a portion of the powdered material to a liquid state, and semi-passively controlling solidification of the powdered material from the liquid state to a solid state. Several techniques for semi-passive control are described in detail.

Abstract: A method of forming a sandwich structure including at least partially filling an open volume of an open cellular core with a sacrificial mold material, consolidating the sacrificial mold material to form a sacrificial mold, laying up a composite facesheet on each of at least two surfaces of the open cellular core, co-curing the composite facesheets by applying a consolidation temperature and a compaction pressure to the composite facesheets to form the sandwich structure, and removing the sacrificial mold. The compaction pressure is greater than a compressive strength of the open cellular core and less than a combined compressive strength of the open cellular core and the sacrificial mold.

Abstract: Infrared-transparent and damage-resistant polymer optics with LWIR and/or MWIR transparency are provided. Some variations provide an optic containing at least 50 wt % of an infrared-transparent polymer, wherein the infrared-transparent polymer has a carbon-free polymer backbone, wherein the optic is characterized by at least 80% average transmission of radiation over a wavenumber band with cumulative wavenumber width of at least 1000 cm?1 contained within wavelengths from 3.1 ?m to 5 ?m and/or from 8.1 ?m to 12 ?m, and wherein the average transmission is defined as the percentage ratio of radiation intensity through an optic thickness of 25 microns divided by incident radiation intensity. Many polymer compositions and pendant groups are disclosed for use in the polymer optics.

Abstract: A method of forming a sandwich structure including at least partially filling an open volume of an open cellular core with a sacrificial mold material, consolidating the sacrificial mold material to form a sacrificial mold, laying up a composite facesheet on each of at least two surfaces of the open cellular core, co-curing the composite facesheets by applying a consolidation temperature and a compaction pressure to the composite facesheets to form the sandwich structure, and removing the sacrificial mold. The compaction pressure is greater than a compressive strength of the open cellular core and less than a combined compressive strength of the open cellular core and the sacrificial mold.

Abstract: A method of manufacturing a sandwich structure having an open cellular core and a fluid-tight seal surrounding the core includes coupling a mold to a first facesheet to define a reservoir. The method also includes irradiating a volume of photo-monomer in the reservoir with a series of vertical collimated light beams to form a cured, solid polymer border extending around a periphery of the first facesheet. The method also includes irradiating a remaining volume of photo-monomer in the reservoir with a series of collimated light beams to form an ordered three-dimensional polymer microstructure core defined by a plurality of interconnected polymer optical waveguides coupled to the first facesheet and surrounded by the cured, solid polymer border. The method further includes coupling a second facesheet to the ordered three-dimensional microstructure core and the cured, solid polymer border to form the sandwich structure.

Abstract: A system for fabricating composite parts efficiently. Pre-impregnated (prepreg) composite material is drawn as a sheet from a roll and fed by advancement rollers into a stamping and molding station in which a piece of the prepreg material is cut, on a mold, from the sheet. Pressure is applied to cause the prepreg material to conform to a surface of the mold, and the prepreg is cured with ultraviolet light. Additional layers of prepreg may be cut and cured on any layers that have already been cured on the mold. The complete part may be removed from the mold with ejector pins. Scrap prepreg may be recycled in a recycling station that separates reinforcing fiber from uncured resin.

Abstract: A method of repairing a sandwich structure includes: removing a damaged portion of a core and a damaged portion of a first facesheet to form an open volume; filling the open volume with an ultraviolet-curable photomonomer; partially curing the ultraviolet-curable photomonomer to form a plurality of photopolymer waveguides by utilizing ultraviolet light; and arranging a replacement facesheet on the damaged portion of the first facesheet and over the photopolymer waveguides.

Abstract: Some variations provide a process for additive manufacturing of a nanofunctionalized metal alloy, comprising: providing a nanofunctionalized metal precursor containing metals and grain-refining nanoparticles; exposing a first amount of the nanofunctionalized metal precursor to an energy source for melting the precursor, thereby generating a first melt layer; solidifying the first melt layer, thereby generating a first solid layer; and repeating many times to generate a plurality of solid layers in an additive-manufacturing build direction. The additively manufactured, nanofunctionalized metal alloy has a microstructure with equiaxed grains.

Abstract: Some variations provide a process for additive manufacturing of a nanofunctionalized metal alloy, comprising: providing a nanofunctionalized metal precursor containing metals and grain-refining nanoparticles; exposing a first amount of the nanofunctionalized metal precursor to an energy source for melting the precursor, thereby generating a first melt layer; solidifying the first melt layer, thereby generating a first solid layer; and repeating many times to generate a plurality of solid layers in an additive-manufacturing build direction. The additively manufactured, nanofunctionalized metal alloy has a microstructure with equiaxed grains.

Abstract: An aperture system for a bottom-up stereolithography device including a reservoir having a lower opening, an aperture including a flexible membrane positioned within the reservoir and covering the lower opening, and a boundary seal positioned around a periphery of the flexible membrane, the boundary seal including one or more boundary seal components and immobilizing the periphery of the flexible membrane against the reservoir. The flexible membrane is formed of a material having a low affinity for a liquid resin used in the stereolithography device as well as cured photopolymer resin parts produced by the device. In addition, the flexible membrane is able to deform as the cured resin part is pulled away from the aperture, thus enabling lower energy mixed mode adhesive failure to occur at the interface between the cured resin and the aperture and reducing the chance of cohesive damage to the cured photopolymer part.