A method for fabricating a piston with a layering device via an additive manufacturing process is provided. The method may include forming a first layer of the piston on a substrate with a layering device, forming a second layer of the piston adjacent the first layer with the layering device, and binding the first layer with the second layer. The first layer of the piston may include a first material, and the second layer of the piston may include the first material and a second material.

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. Other variations provide an additively manufactured, nanofunctionalized metal alloy comprising metals selected from aluminum, iron, nickel, copper, titanium, magnesium, zinc, silicon, lithium, silver, chromium, manganese, vanadium, bismuth, gallium, or lead; and grain-refining nanoparticles selected from zirconium, tantalum, niobium, titanium, or oxides, nitrides, hydrides, carbides, or borides thereof, wherein the additively manufactured, nanofunctionalized metal alloy has a microstructure with equiaxed grains.

A piston ring is made from a copper-beryllium alloy. This material permits the top compression ring of a piston to be moved closer to the piston crown, reducing crevice volume and reducing the tendency for pre-ignition. Ignition timing advance can be realized by installing the rings and letting the ECU advance the timing as the sensors allow, increasing efficiency. Also, shorter pistons and longer connecting rods are possible. The shorter pistons reduces the reciprocated mass in the engine and the longer connecting rods reduce the frictional loss caused by radial forces pushing the piston against the liner. Both reducing volume and tendency for pre-ignition increase engine efficiency.

Provided is a composite for a wear-resistant ring having excellent heat conductivity. In the composite for a wear-resistant ring, an iron-based sintered compact for a wear-resistant ring having a composition that contains, by mass, C of 0.4 to 1.5% and Cu of 20 to 40%, and having a structure in which pores exist continuously at a porosity of 15 to 50% in terms of volume fraction, and in which a matrix is pearlite, and in which a free Cu phase or further dispersion particles are dispersed in the matrix, is insert-cast in an aluminum alloy, and has the pores impregnated with the aluminum alloy.

Provided is a composite for a wear-resistant ring having excellent heat conductivity. In the composite for a wear-resistant ring, an iron-based sintered compact for a wear-resistant ring having a composition that contains, by mass, C of 0.4 to 1.5% and Cu of 20 to 40%, and having a structure in which pores exist continuously at a porosity of 15 to 50% in terms of volume fraction, and in which a matrix is pearlite, and in which a free Cu phase or further dispersion particles are dispersed in the matrix, is insert-cast in an aluminum alloy, and has the pores impregnated with the aluminum alloy.

An iron alloy powder consists of, when the entirety thereof is assumed to be 100 mass %, Cr: 2.5 mass % to 3.5 mass %, Mo: 0.4 mass % to 0.6 mass %, and Fe and inevitable impurities as the balance, a mixed powder consisting of 15 mass % to 40 mass % of the iron alloy powder, 1.2 mass % to 1.8 mass % of a copper powder, 0.5 mass % to 1.0 mass % of a graphite powder, and a pure iron powder as the balance when the entire mixed powder is assumed to be 100 mass % is compacted into a compact, and the compact is sintered while transforming a structure derived from the pure iron powder into a structure in which a ferritic structure and a pearlitic structure are mixed and transforming a structure derived from the iron alloy powder into a martensitic structure.

An iron alloy powder consists of, when the entirety thereof is assumed to be 100 mass %, Cr: 2.5 mass % to 3.5 mass %, Mo: 0.4 mass % to 0.6 mass %, and Fe and inevitable impurities as the balance, a mixed powder consisting of 15 mass % to 40 mass % of the iron alloy powder, 1.2 mass % to 1.8 mass % of a copper powder, 0.5 mass % to 1.0 mass % of a graphite powder, and a pure iron powder as the balance when the entire mixed powder is assumed to be 100 mass % is compacted into a compact, and the compact is sintered while transforming a structure derived from the pure iron powder into a structure in which a ferritic structure and a pearlitic structure are mixed and transforming a structure derived from the iron alloy powder into a martensitic structure.

A thermal spray powder is provided for use in a thermal spray technique, such as flame spraying, plasma spraying, cold spraying, and high velocity oxygen fuel spraying (HVOF). The thermal spray powder is formed by water or gas atomization and comprises 3.0 to 7.0 wt. % carbon, 10.0 to 25.0 wt. % chromium, 1.0 to 5.0 wt. % tungsten, 3.5 to 7.0 wt. % vanadium, 1.0 to 5.0 wt. % molybdenum, not greater than 0.5 wt. % oxygen, and at least 40.0 wt. % iron, based on the total weight of the thermal spray powder. The thermal spray powder can be applied to a metal body, such as a piston or piston ring, to form a coating. The thermal spray powder can also provide a spray-formed part.

A thermal spray powder is provided for use in a thermal spray technique, such as flame spraying, plasma spraying, cold spraying, and high velocity oxygen fuel spraying (HVOF). The thermal spray powder is formed by water or gas atomization and comprises 3.0 to 7.0 wt. % carbon, 10.0 to 25.0 wt. % chromium, 1.0 to 5.0 wt. % tungsten, 3.5 to 7.0 wt. % vanadium, 1.0 to 5.0 wt. % molybdenum, not greater than 0.5 wt. % oxygen, and at least 40.0 wt. % iron, based on the total weight of the thermal spray powder. The thermal spray powder can be applied to a metal body, such as a piston or piston ring, to form a coating. The thermal spray powder can also provide a spray-formed part.

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. Other variations provide an additively manufactured, nanofunctionalized metal alloy comprising metals selected from aluminum, iron, nickel, copper, titanium, magnesium, zinc, silicon, lithium, silver, chromium, manganese, vanadium, bismuth, gallium, or lead; and grain-refining nanoparticles selected from zirconium, tantalum, niobium, titanium, or oxides, nitrides, hydrides, carbides, or borides thereof, wherein the additively manufactured, nanofunctionalized metal alloy has a microstructure with equiaxed grains.