A waste magnet regeneration method includes the following steps. First, waste magnets and auxiliary alloys are provided, pre-treat the waste magnets, hydrogen decrepitating and sieving the waste magnets and the auxiliary alloys to form main alloy powders and auxiliary alloy powders. The main alloy powders and the auxiliary alloy powders are mixed in a predetermined ratio to form a mixture, and then the mixture is subjected to the jet mill pulverization, magnetic field alignment compacting, sintering and aging treatment to obtain a regenerated magnet.

Polymer magnet composites including NdFeB in a polycarbonate (PC) binder matrix are processed using processes including batch mixing and twin screw extrusion. One method includes adding PC to a compartment of a batch mixer and mixing the PC while the compartment is at a temperature greater than a flow temperature of the PC, to form a mixed PC material. The method also includes adding a NdFeB magnetic material to the compartment with the mixed PC material in four batches while the compartment is at the temperature greater than the flow temperature of the PC to form a mixed PC and NdFeB magnetic material, wherein each batch is mixed in the compartment for 1 to 3 minutes before the next batch is added. In addition, a total mixing time is 6 to 12 minutes, and the compartment includes an inert atmosphere. Other embodiments are described and claimed.

Polymer magnet composites including NdFeB in a polycarbonate (PC) binder matrix are processed using processes including batch mixing and twin screw extrusion. One method includes adding PC to a compartment of a batch mixer and mixing the PC while the compartment is at a temperature greater than a flow temperature of the PC, to form a mixed PC material. The method also includes adding a NdFeB magnetic material to the compartment with the mixed PC material in four batches while the compartment is at the temperature greater than the flow temperature of the PC to form a mixed PC and NdFeB magnetic material, wherein each batch is mixed in the compartment for 1 to 3 minutes before the next batch is added. In addition, a total mixing time is 6 to 12 minutes, and the compartment includes an inert atmosphere. Other embodiments are described and claimed.

Disclosed are a cerium magnet with diffused grain boundaries containing REFe2 and a preparation method therefor, wherein an original cerium magnet contains a 2-14-1 main phase, a REFe2 phase and a rare earth-rich phase, and the REFe 2 phase is a CeFe2 phase or a (Ce,RE′)Fe2 phase. The RE″ element in a rare earth diffusion source is diffused into the original cerium magnet by means of a grain boundary diffusion treatment at the melting point of the REFe2 phase, and same is then cooled directly or cooled after a tempering treatment to room temperature to obtain a final cerium magnet. The final cerium magnet contains a new 2-14-1 main phase, a new enhanced REFe2 phase and a new rare earth-rich phase, wherein the new 2-14-1 main phase is a (Ce,RE″)2Fe14B or (Ce,RE′,RE″)2Fe14B main phase, and the new enhanced REFe2 phase is a (CeRE″)Fe2 phase or a (Ce,RE′,RE″)Fe2 phase, wherein RE′ and RE″ are one or more of La, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y. The cerium magnet improves the diffusion efficiency of the element RE″ in the diffusion source, and substantially improve the coercivity thereof.

The invention relates to high entropy alloy of rare earth elements (RE-HEAs) including at least four and up to twelve elements selected form rare earth elements R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10, R.sub.11, R.sub.12, which rare earth elements R.sub.1 to R.sub.12 each represents one of elements 57 to 60, 62 to 70, 39 and 40 of the periodic system and to high entropy alloy of transition elements (TM-HEAs) including at least 3 and up to 12 elements selected from transitional elements TM.sub.1, TM.sub.2, TM.sub.3, TM.sub.4, TM.sub.5, TM.sub.6, TM.sub.7, TM.sub.8, TM.sub.9, TM.sub.10, TM.sub.11, TM.sub.12, which transitional elements TM.sub.1 to TM.sub.12 each represent at least one of elements 21 to 30, 41 to 48 and 72 to 79 of the periodic system. Such RE-HEAs and/or TM-HEAs can be used as building blocks in magnetic high entropy composite alloys, e.g. of the type (RE-HEAs).sub.x(TM-HEAs).sub.yT.sub.z, for the manufacture of magnetic devices and permanent magnets.

The present invention provides a rare earth sintered magnet which contains R (R represents one or more rare earth elements essentially including Nd), T (T represents one or more iron group elements essentially including Fe), B, M.sup.1 (M.sup.1 represents one or more elements selected from among Al, Si, Cr, Mn, Cu, Zn, Ga, Ge, Mo, Sn, W, Pb and Bi) and M.sup.2 (M.sup.2 represents one or more elements selected from among Ti, V, Zr, Nb, Hf and Ta), while comprising an R.sub.2T.sub.14B phase as the main phase. This rare earth sintered magnet is characterized in that: the M.sup.1 is in an amount of from 0.5% by atom to 2% by atom; if (R), (T), (M.sup.2) and (B) are the respective atomic percentages of the above-described R, T, M.sup.2 and B, the relational expression (1) ((T)/14)+(M.sup.2)≤(B)≤((R)/2)+((M.sup.2)/2) is satisfied; and from 0.1% by volume to 10% by volume of all grain boundary phases in the magnet is composed of an R.sub.6T.sub.13M.sup.1 phase. This rare earth sintered magnet is able to achieve excellent magnetic characteristics including a good balance between high Br and high H.sub.cJ.

The present invention relates to an alloy with formula of RE-M-B—Fe as defined herein and oxygen content less than 0.9 wt %, wherein said RE is in the range of 29.0 weight % to 33.0 weight %; M is in the range of 0.25 weight % to 1.0 weight %; B is in the range of 0.8 weight % to 1.1 weight %; and Fe makes up the balance. The present invention also relates to a method for preparing a RE-M-Fe—B magnetic powder, as defined herein comprising the steps of: (a) melt spinning a RE-M-Fe—B alloy composition to obtain a melt-spun powder; (b) pressing the melt-spun powder of step (a) to obtain a compact body; (c) hot deforming the compact body of step (b) to obtain a die-upset magnet; (d) crushing the die-upset magnet of step (c) to obtain a powder; (e) milling and sieving the powder of step (d); and (f) passivating the powder of step (e) to obtain a magnetic powder; wherein: each of steps (d) to (f) is performed under a low oxygen environment and transfer between each of steps (d) to (f) is a sealed transfer; and wherein the oxygen content of the low oxygen environment and during each sealed transfer is below 0.5 weight %.

Provided is an R—Fe—B-based sintered magnet which has a composition comprising R (wherein R represents at least one element selected from rare earth elements, and essentially contains Nd), B, M (wherein M represents at least one element selected from Si, Al, Mn, Ni, Co, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb and Bi), X (wherein X represents at least one element selected from Ti, Zr, Hf, Nb, V and Ta) and C, with a remainder comprising Fe, O and unavoidable impurities, and has a main phase comprising R.sub.2Fe.sub.14B and a grain boundary phase comprising an R—C phase having a higher R concentration and a higher C concentration than those in the main phase, the R—Fe—B-based sintered magnet being characterized in that the area ratio of the R—C phase in a cross section of the magnet is more than 0% and 0.5% or less.

The purpose of the present invention is to achieve both high residual flux density and high coercivity, which are conventionally mutually exclusive characteristics, in an R—Fe—B sintered magnet. The present invention provides an R—Fe—B sintered magnet characterized by having a composition which contains R (R is one or more elements selected from among the rare-earth elements but must be Nd), B. X (X is one or more elements selected from among Ti, Zr, Hf, Nb, V, and Ta), and C, with the remainder comprising Fe, O, other arbitrary elements, and unavoidable impurities. The R—Fe—B sintered magnet is also characterized by satisfying relational expression (1), where [B], [C], [X], and [O] are the atomic percentages of B, C, X, and O, respectively.

0.86×([B]+[C]−2×[X])−4.9<[O]<0.86×([B]+[C]−2×[X])−4.6   (1).

The purpose of the present invention is to achieve both high residual flux density and high coercivity, which are conventionally mutually exclusive characteristics, in an R—Fe—B sintered magnet. The present invention provides an R—Fe—B sintered magnet characterized by having a composition which contains R (R is one or more elements selected from among the rare-earth elements but must be Nd), B. X (X is one or more elements selected from among Ti, Zr, Hf, Nb, V, and Ta), and C, with the remainder comprising Fe, O, other arbitrary elements, and unavoidable impurities. The R—Fe—B sintered magnet is also characterized by satisfying relational expression (1), where [B], [C], [X], and [O] are the atomic percentages of B, C, X, and O, respectively.

0.86×([B]+[C]−2×[X])−4.9<[O]<0.86×([B]+[C]−2×[X])−4.6   (1).