A neodymium-iron-boron permanent magnet, a preparation method and use thereof are disclosed. The neodymium-iron-boron permanent magnet has a composition represented by formula I: [mHR(1−m) (Pr.sub.25Nd.sub.75)].sub.x(Fe.sub.100-a-b-c-dM.sub.aGa.sub.bIn.sub.cSn.sub.d).sub.100-x-yB.sub.y formula I; where a is 0.995-3.493, b is 0.114-0.375, c is 0.028-0.125, d is 0.022-0.100; x is 29.05-30.94, y is 0.866-1.000; m is 0.02-0.05; HR is Dy and/or Tb; M is at least one selected from the group consisting of Co, Cu, Ti, Al, Nb, Zr, Ni, W and Mo.

Disclosed is a method for preparing a high-flatness metal foil suitable for making a metal mask, and the method comprises the following steps: forming a raw metal coarse foil; rolling the raw metal coarse foil at least once into a high-flatness metal foil; performing, by a heat treatment device, heat treatment processing on the precisely rolled metal foil according to a preset temperature and a preset time; using a tension leveler to perform tension leveling on the rolled and heat-treated metal foil; and obtaining a high-flatness metal foil after completion of the tension leveling and forming a rolled metal foil in a continuous forming process. The resulting metal foil has high flatness and low residual stress, which improves quality and performance of the metal foil and is suitable for the fabrication of fine metal masks.

Disclosed is a method for preparing a high-flatness metal foil suitable for making a metal mask, and the method comprises the following steps: forming a raw metal coarse foil; rolling the raw metal coarse foil at least once into a high-flatness metal foil; performing, by a heat treatment device, heat treatment processing on the precisely rolled metal foil according to a preset temperature and a preset time; using a tension leveler to perform tension leveling on the rolled and heat-treated metal foil; and obtaining a high-flatness metal foil after completion of the tension leveling and forming a rolled metal foil in a continuous forming process. The resulting metal foil has high flatness and low residual stress, which improves quality and performance of the metal foil and is suitable for the fabrication of fine metal masks.

A permanent magnet in which demagnetization adjustment can be easily performed and a method for manufacturing the same are provided. The permanent magnet contains 22 to 28 mass % of a rare-earth element R, 12 to 23 mass % of Fe, 3 to 9 mass % of Cu, 1 to 4 mass % of Zr, and a remainder consisting of Co and unavoidable impurities, in which, in a demagnetization curve in which the horizontal axis indicates a demagnetization field (kOe) and the vertical axis indicates the total amount of magnetic flux (×10.sup.−5 WbT) in the permanent magnet, the slope of an approximate straight line in demagnetization field ranges from 0 to −11 kOe is 1.2 or smaller.

A permanent magnet in which demagnetization adjustment can be easily performed and a method for manufacturing the same are provided. The permanent magnet contains 22 to 28 mass % of a rare-earth element R, 12 to 23 mass % of Fe, 3 to 9 mass % of Cu, 1 to 4 mass % of Zr, and a remainder consisting of Co and unavoidable impurities, in which, in a demagnetization curve in which the horizontal axis indicates a demagnetization field (kOe) and the vertical axis indicates the total amount of magnetic flux (×10.sup.−5 WbT) in the permanent magnet, the slope of an approximate straight line in demagnetization field ranges from 0 to −11 kOe is 1.2 or smaller.

This application provides Fe—Mn—Al—C lightweight steel, including: Fe, wherein a weight percentage of the Fe is greater than or equal to 50.4 wt %; Mn, wherein a weight percentage of the Mn is 25-35 wt %; Al, wherein a weight percentage of the Al is 6-12 wt %; C, wherein a weight percentage of the C is 0.8-2.0 wt %; and O, wherein a weight percentage of the O is 0.005-0.6 wt %. This application further provides a terminal to which the Fe—Mn—Al—C lightweight steel is applied, a production method for the Fe—Mn—Al—C lightweight steel, a steel mechanical part, and an electronic device. The lightweight steel in this application has low density, high strength, and high elongation.

A rotary compressor has a combined vane-roller structure that may ensure improved productivity and reliability through control of mechanical properties. The rotary compressor includes a coupling groove which is disposed at one side of an outer circumferential surface of the roller, which has a circular arc shape from an outer diameter of the roller towards an inner diameter of the roller, and which is configured to couple a vane and the roller, and includes a ferrosoferric oxide (Fe.sub.3O.sub.4) film on a surface of the coupling groove. A manufacturing method of the rotary compressor is also described.

An iron-based sintered alloy material having, at the surface of the material, a hardened layer exhibiting a martensite phase containing a solid solution of nitrogen in a supersaturated state. The iron-based sintered alloy material may contain at least one of chromium, copper, molybdenum, manganese and nickel. A production method for the iron-based sintered alloy material includes: subjecting an iron-based sintered alloy substrate containing carbon to a nitriding treatment by heating the substrate to a nitriding temperature of at least 590° C. in an atmosphere containing ammonia, and then performing quenching by rapidly cooling the substrate.

An iron-based sintered alloy material having, at the surface of the material, a hardened layer exhibiting a martensite phase containing a solid solution of nitrogen in a supersaturated state. The iron-based sintered alloy material may contain at least one of chromium, copper, molybdenum, manganese and nickel. A production method for the iron-based sintered alloy material includes: subjecting an iron-based sintered alloy substrate containing carbon to a nitriding treatment by heating the substrate to a nitriding temperature of at least 590° C. in an atmosphere containing ammonia, and then performing quenching by rapidly cooling the substrate.

Provided is an Fe-based nanocrystalline alloy powder. The Fe-based nanocrystalline alloy powder has a chemical composition, excluding inevitable impurities, represented by a composition formula of Fe.sub.aSi.sub.bB.sub.cP.sub.dCu.sub.eM.sub.f, where the M in the composition formula is at least one element selected from the group consisting of Nb, Mo, Zr, Ta, W, Hf, Ti, V, Cr, Mn, C, Al, S, O, and N, 79 at %≤a≤84.5 at %, 0 at %≤b<6 at %, 0 at %<c≤10 at %, 4 at %<d≤11 at %, 0.2 at %≤e≤0.53 at %, 0 at %≤f≤4 at %, a+b+c+d+e+f=100 at %, a degree of crystallinity is more than 10% by volume, and an Fe crystallite diameter of the Fe-based nanocrystalline alloy powder is 50 nm or less.