A metal powder producing apparatus includes a molten metal supply unit, a cylinder body, and a cooling liquid introduction unit. The molten metal supply unit discharges a molten metal. The cylinder body is capable of being formed with a layer of a cooling liquid for cooling the molten metal on an inner circumference surface of the cylinder body. The cooling liquid introduction unit supplies the cooling liquid to an upper inside of the cylinder body. The inner circumference surface of the upper inside of the cylinder body has a substantially elliptical shape.

A method for producing a water-atomized metal powder, comprising applying water to a molten metal stream, dividing the molten metal stream into a metal powder, and cooling the metal powder, wherein the metal powder is further subjected to secondary cooling with cooling capacity having a minimum heat flux point (MHF point) higher than the surface temperature of the metal powder in addition to the cooling and the secondary cooling is performed from a temperature range where the temperature of the metal powder after the cooling is not lower than the cooling start temperature necessary for amorphization nor higher than the minimum heat flux point (MHF point).

A method of producing iron powder by a water atomization process may include preparing a molten metal in a tundish, discharging the molten metal in a free-falling manner by opening an orifice formed on a bottom of the tundish, and producing iron powder by spraying water onto the free-falling molten metal using a pair of water spraying nozzles, an angle formed by the water spraying nozzles being at least 45.

A magnesium-based alloy powder is made of a magnesium-based alloy that contains 0.2 mass % to 5 mass % of calcium, wherein the magnesium-based alloy powder has an average particle diameter of 100 m to 1,500 m, wherein the magnesium-based alloy powder has a particle average aspect ratio of 0.5 to 1, wherein the magnesium-based alloy powder has an apparent density of 0.2 g/cm.sup.3 to 1.2 g/cm.sup.3, and wherein the mean value of hardness variation index values obtained by dividing the difference of the maximum value and the minimum value of micro Vickers hardnesses taken at 10 measurement points in a particle cross section by the maximum value is 0.3 or less.

A water-atomized metal powder is produced by dividing a molten metal stream into a metal powder by making injection water having a liquid temperature of 10 C. or less and an injection pressure of 5 MPa or more impinge on the molten metal stream and cooling the metal powder. Cooling with injection water having a liquid temperature of 10 C. or less and an injection pressure of 5 MPa or more enables can be performed not in the film boiling region but in the transition boiling region from the beginning of cooling. A gas-atomized metal powder may also be produced by dividing a molten metal stream into a metal powder by making an inert gas impinge on the molten metal stream and cooling the metal powder with injection water having a liquid temperature of 10 C. or less and an injection pressure of 5 MPa or more.

An alloy represented by the formula (Mn.sub.xAl.sub.y)C.sub.z, the alloy being aluminum (Al), manganese (Mn), and carbon (C), and optionally unavoidable impurities; wherein x=56.0 to 59.0 y=41.0 to 44.0 x+y=100, and z=1.5 to 2.4. The alloy is highly suitable for forming the and phase in high purity and high microstructural homogeneity. A method for processing an alloy of formula (Mn.sub.xAl.sub.y)C.sub.z, wherein x=52.0 to 59.0, y=41.0 to 48.0, x+y=100, and z=0.1 to 3.0, the process including providing the raw materials of the alloy, melting the raw materials, and forming particles of the alloy by gas atomization of the molten alloy.

An alloy represented by the formula (Mn.sub.xAl.sub.y)C.sub.z, the alloy being aluminum (Al), manganese (Mn), and carbon (C), and optionally unavoidable impurities; wherein x=56.0 to 59.0 y=41.0 to 44.0 x+y=100, and z=1.5 to 2.4. The alloy is highly suitable for forming the and phase in high purity and high microstructural homogeneity. A method for processing an alloy of formula (Mn.sub.xAl.sub.y)C.sub.z, wherein x=52.0 to 59.0, y=41.0 to 48.0, x+y=100, and z=0.1 to 3.0, the process including providing the raw materials of the alloy, melting the raw materials, and forming particles of the alloy by gas atomization of the molten alloy.

A magnetic core including a magnetic powder. A total area ratio of particles of the magnetic powder in a cross section of the magnetic core is 75% or more and 90% or less. An average circularity of large size particles is 0.70 or more when the large size particles are particles extracted from the particles of the magnetic powder in the cross section of the magnetic core in the order of size from the largest size until a cumulative area ratio of the extracted particles reaches a smallest area ratio exceeding 20% of the total area ratio of the particles of the magnetic powder.