In one embodiment, a permanent magnet has a composition expressed by a composition formula: RN.sub.x(Cr.sub.pSi.sub.qM.sub.1-p-q).sub.z (R is at least one element selected from Y and rare-earth elements, M is at least one element selected from Fe and Co, and x, p, q, and z are atomic ratios satisfying 0.5≦x≦2.0, 0.005≦p≦0.2, 0.005≦q≦0.2, and 4≦z≦13, respectively). The permanent magnet has a density of 6.5 g/cm.sup.3 or more and satisfies the relationship of I(110)/{I(110)+I(303)}≦0.05, in which I(303) represents a diffraction peak intensity from a (303) plane of a Th.sub.2Zn.sub.17 phase obtained through powder X-ray diffraction of the permanent magnet, and I(110) represents a diffraction peak intensity from a (110) plane of an α-Fe phase obtained through the powder X-ray diffraction.

A permanent magnet of an embodiment includes a sintered compact, the sintered compact including: a composition expressed by R.sub.pFe.sub.qM.sub.rCu.sub.sCo.sub.100-p-q-r-s, (R is at least one element selected from rare earth elements, M is at least one element selected from Zr, Ti, and Hf, 10.5≦p≦12.5 atomic %, 24≦q≦40 atomic %, 0.88≦r≦4.5 atomic %, and 3.5≦s≦10.7 atomic %); and a structure having crystal grains each composed of a main phase including a Th.sub.2Zn.sub.17 crystal phase, and a crystal grain boundary of the crystal grains. An average crystal grain diameter of the crystal grains is 50 μm or more and 100 μm or less, and a ratio of the crystal grains having a crystal grain diameter of 50 μm or more is 75% or more.

A permanent magnet expressed by a composition formula: R.sub.pFe.sub.qM.sub.rCu.sub.tCo.sub.100-p-q-r-t. The magnet comprises: a metal structure including a main phase having a Th.sub.2Zn.sub.17 crystal phase and a grain boundary phase. The main phase includes a cell phase having the Th.sub.2Zn.sub.17 crystal phase, a Cu-rich phase having a Cu concentration higher than the cell phase, and a plurality of M-rich platelet phases extending in a direction intersecting with a c-axis of the Th.sub.2Zn.sub.17 crystal phase in a section including the c-axis and having a M element concentration higher than the cell phase. In the section, the cell phase has a 200 nm diameter or more, and a gap between the M-rich platelet phases is 80 nm or less.

A permanent magnet expressed by a composition formula: R.sub.pFe.sub.qM.sub.rCu.sub.tCo.sub.100-p-q-r-t. The magnet comprises: a metal structure including a main phase having a Th.sub.2Zn.sub.17 crystal phase and a grain boundary phase. The main phase includes a cell phase having the Th.sub.2Zn.sub.17 crystal phase, a Cu-rich phase having a Cu concentration higher than the cell phase, and a plurality of M-rich platelet phases extending in a direction intersecting with a c-axis of the Th.sub.2Zn.sub.17 crystal phase in a section including the c-axis and having a M element concentration higher than the cell phase. In the section, the cell phase has a 200 nm diameter or more, and a gap between the M-rich platelet phases is 80 nm or less.

The present invention relates to a Ce-containing sintered rare earth permanent magnet with high toughness and high coercivity and a method of preparing the magnet, belonging to the technical field of rare earth permanent magnetic materials. The magnet is prepared by steps of raw material batching, strip casting, hydrogen decrepitation and jet milling, powder orientating and forming, sintering and heat treatment. The materials of the permanent magnet comprise the main phase alloy powders and the Ce added phase alloy powders, wherein the Ce added phase alloy is a magnetic phase or a non-magnetic liquid-phase alloy; and the Ce added phase alloy accounts for 5% to 30% of the total weight of the permanent magnet, and the remainder is the main phase alloy. During the jet milling stage, a certain concentration of oxygen is added into the inert gas, so that the final magnet has an oxygen content of 1500 to 2500 ppm. The Ce-containing dual-alloy magnet prepared in accordance with the present invention has high coercivity, and the intrinsic coercivity (H.sub.cj) is up to 17 to 28.73 kOe. The magnet of the present invention has good fracture toughness which is increased by 10% to 30% as compared with the conventional Nd—Fe—B sintered magnet. The magnet of the present invention can meet needs of high-end applications such as wind power generation, new energy vehicles, and the like, and greatly expands the application fields of Ce-containing magnets.

This invention provides a regenerator material having a high specific heat, particularly in the temperature range of 10 to 25K, and a regenerator and a refrigerator comprising the regenerator material. The present invention specifically provides an HoCu-based regenerator material represented by general formula (1): HoCu.sub.2-xM.sub.x (1), wherein x is 0<x≤1, and M is at least one member selected from the group consisting of Al and transition metal elements (excluding Cu), as well as a regenerator and a refrigerator comprising the regenerator material.

This invention provides a regenerator material having a high specific heat, particularly in the temperature range of 10 to 25K, and a regenerator and a refrigerator comprising the regenerator material. The present invention specifically provides an HoCu-based regenerator material represented by general formula (1): HoCu.sub.2-xM.sub.x (1), wherein x is 0<x≤1, and M is at least one member selected from the group consisting of Al and transition metal elements (excluding Cu), as well as a regenerator and a refrigerator comprising the regenerator material.

A method for producing a powdered starting material, which is provided for production of rare earth magnets, including the following steps: pulverizing an alloy, including at least one rare earth metal, wherein a powdered intermediate product is formed from the alloy including at least one rare earth metal, and carrying out at least one classification aimed at particle size and/or density for the powdered intermediate product, wherein a fraction of the powdered intermediate product, which is formed by means of the at least one classification, for fabrication of rare earth magnets. Furthermore, at least one dynamic classifier is provided, implementing at least one classification directed at particle size and/or density for the powdered intermediate product and thereby separates the fraction from the powdered intermediate product, which forms the starting material provided for manufacturing rare earth magnets.

A bi-material permanent magnet for an electric machine includes a core including a first magnetic material and a shell portion located on the core and made of a second magnetic material. The first magnetic material comprises a magnet material with an energy less than 20 Mega Gauss Oersteds (MGOe). The second magnetic material comprises a magnet material with an energy greater than 30 MGOe.

A two-step diffusion method for preparing high-performance dual-main-phase sintered mischmetal-iron-boron magnet belongs to the preparing technical field of rare earth permanent magnet materials. The compositions of the two main phase alloys are RE-Fe—B (RE is Nd or Pr) and (Nd, MM)-Fe—B (MM is mischmetal), respectively. First, PrHoFe strip-casting alloy is used as a diffusion source. Next, a PrHo-rich layer is uniformly coated on the surface of (Nd, MM)-Fe—B hydrogen decrepitation powders. The higher anisotropic fields of Pr.sub.2Fe.sub.14B and Ho.sub.2Fe.sub.14B are used to improve the coercivity. Then, the ZrCu strip-casting alloy is used as a diffusion source. A Zr-rich layer is uniformly coated on the surface of the powders after the first-step diffusion, which prevents the growth of the MM-rich main phase grains during the sintering process and the inter-diffusion between the two main phases, thus obtaining high coercivity.