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.

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.

Powder metallurgy, in particular production of tungsten monocarbide spherical powders, which is a major component of metalloceramic hard alloys used for manufacture of tools, drill bits, steel alloying, wear-resistant coating cladding at elements operating in intensive wear conditions. The method includes melting of the starting material, and melt atomization with forming of spherical powder. As starting material a tungsten monocarbide grit is used. Melting and atomization of the material is implemented by continuous filling of grit into a rotating crucible of a centrifugal atomization device under an inert atmosphere and melting it by a plasma arc. After that an annealing of the obtained powder is made at a temperature of 1200-1400 C. during a time necessary for W.sub.2C breakup with subsequent cooling of the powder in a furnace. And, the production of tungsten monocarbide spherical powder with WC content of more than 70%.

A gas atomization nozzle includes a through-hole formed along a center line; a nozzle portion configured of a Laval nozzle which is disposed around the center line and provided to be inclined at a predetermined angle toward the center line; and swirling motion imparting means for imparting a swirling flow around the center line to gas which is injected from the nozzle portion. The nozzle portion is formed in a ring shape which is continuous around the center line, and the swirling motion imparting means is configured as a fin provided in the nozzle portion to impart a swirling flow.

A gas atomization nozzle includes a through-hole formed along a center line; a nozzle portion configured of a Laval nozzle which is disposed around the center line and provided to be inclined at a predetermined angle toward the center line; and swirling motion imparting means for imparting a swirling flow around the center line to gas which is injected from the nozzle portion. The nozzle portion is formed in a ring shape which is continuous around the center line, and the swirling motion imparting means is configured as a fin provided in the nozzle portion to impart a swirling flow.

Embodiments of a method for producing powder mixtures having uniform dispersion of ceramic particles within larger superalloy particles are provided, as are embodiments of superalloy powder mixtures. In one embodiment, the method includes producing an initial powder mixture comprising ceramic particles mixed with superalloy mother particles having an average diameter larger than the average diameter of the ceramic particles. The initial powder mixture is formed into a consumable solid body. At least a portion of the consumable solid body is gradually melted, while the consumable solid body is rotated at a rate of speed sufficient to cast-off a uniformly dispersed powder mixture in which the ceramic particles are embedded within the superalloy mother particles.

Embodiments of a method for producing powder mixtures having uniform dispersion of ceramic particles within larger superalloy particles are provided, as are embodiments of superalloy powder mixtures. In one embodiment, the method includes producing an initial powder mixture comprising ceramic particles mixed with superalloy mother particles having an average diameter larger than the average diameter of the ceramic particles. The initial powder mixture is formed into a consumable solid body. At least a portion of the consumable solid body is gradually melted, while the consumable solid body is rotated at a rate of speed sufficient to cast-off a uniformly dispersed powder mixture in which the ceramic particles are embedded within the superalloy mother particles.

Embodiments of a method for producing powder mixtures having uniform dispersion of ceramic particles within larger superalloy particles are provided, as are embodiments of superalloy powder mixtures. In one embodiment, the method includes producing an initial powder mixture comprising ceramic particles mixed with superalloy mother particles having an average diameter larger than the average diameter of the ceramic particles. The initial powder mixture is formed into a consumable solid body. At least a portion of the consumable solid body is gradually melted, while the consumable solid body is rotated at a rate of speed sufficient to cast-off a uniformly dispersed powder mixture in which the ceramic particles are embedded within the superalloy mother particles.

Provided is a group of rare-earth regenerator material particles having an average particle size of 0.01 to 3 mm, wherein the proportion of particles having a ratio of a long diameter to a short diameter of 2 or less is 90% or more by number, and the proportion of particles having a depressed portion having a length of 1/10 to of a circumferential length on a particle surface is 30% or more by number. By forming the depressed portion on the surface of the regenerator material particles, it is possible to increase permeability of an operating medium gas and a contact surface area with the operating medium gas.

Provided is a group of rare-earth regenerator material particles having an average particle size of 0.01 to 3 mm, wherein the proportion of particles having a ratio of a long diameter to a short diameter of 2 or less is 90% or more by number, and the proportion of particles having a depressed portion having a length of 1/10 to of a circumferential length on a particle surface is 30% or more by number. By forming the depressed portion on the surface of the regenerator material particles, it is possible to increase permeability of an operating medium gas and a contact surface area with the operating medium gas.