A high-performance NdFeB permanent magnet including a nitride phase and a production method thereof are provided. A main phase of the NdFeB permanent magnet has a structure of R.sub.2T.sub.14B; a grain boundary phase is distributed around the main phase and contains N, F, Zr, Ga and Cu; a composite phase containing R1, Tb and N exists between the main phase and the grain boundary phase and includes a phase having a structure of (R1, Tb).sub.2T.sub.14(B, N). R represents at least two rare earth elements, and includes Pr and Nd; T represents Fe, Mn, Al and Co; R1 represents at least one rare earth element, and includes at least one of Dy and Tb; the main phase contains Pr, Nd, Fe, Mn, Al, Co and B; and the grain boundary phase further contains at least one of Nb and Ti. Through placing partially B by N, a magnetic performance is increased.

A high-performance NdFeB permanent magnet including a nitride phase and a production method thereof are provided. A main phase of the NdFeB permanent magnet has a structure of R.sub.2T.sub.14B; a grain boundary phase is distributed around the main phase and contains N, F, Zr, Ga and Cu; a composite phase containing R1, Tb and N exists between the main phase and the grain boundary phase and includes a phase having a structure of (R1, Tb).sub.2T.sub.14(B, N). R represents at least two rare earth elements, and includes Pr and Nd; T represents Fe, Mn, Al and Co; R1 represents at least one rare earth element, and includes at least one of Dy and Tb; the main phase contains Pr, Nd, Fe, Mn, Al, Co and B; and the grain boundary phase further contains at least one of Nb and Ti. Through placing partially B by N, a magnetic performance is increased.

An R-T-B based rare earth permanent magnet is expressed by a compositional formula: (R11x(Y1yz Cey Laz)x)aTbBcMd in which R1 is one or more kinds of rare earth element not including Y, Ce and La, T is one or more kinds of transition metal, and includes Fe or Fe and Co as an essential component, M is an element having Ga or Ga and one or more kinds selected from Sn, Bi and Si, and 0.4x0.7, 0.00y+z0.20, 0.16a/b0.28, 0.050c/b0.075 and 0.005d/b0.028. The magnet includes a main phase, including a compound having a R2T14B type tetragonal structure, and a grain boundary phase. D10, D50, D90 of crystal grain diameter according to the main phase crystal grains satisfies the following formula: D504.00 m and (D90D10)/D501.60. A coating rate of the grain boundary is 70.0% or more.

An R-T-B based rare earth permanent magnet is expressed by a compositional formula: (R11x(Y1yz Cey Laz)x)aTbBcMd in which R1 is one or more kinds of rare earth element not including Y, Ce and La, T is one or more kinds of transition metal, and includes Fe or Fe and Co as an essential component, M is an element having Ga or Ga and one or more kinds selected from Sn, Bi and Si, and 0.4x0.7, 0.00y+z0.20, 0.16a/b0.28, 0.050c/b0.075 and 0.005d/b0.028. The magnet includes a main phase, including a compound having a R2T14B type tetragonal structure, and a grain boundary phase. D10, D50, D90 of crystal grain diameter according to the main phase crystal grains satisfies the following formula: D504.00 m and (D90D10)/D501.60. A coating rate of the grain boundary is 70.0% or more.

An R-T-B based permanent magnet includes R-T-B based compounds as main-phase crystal grains. R is a rare earth element. T is iron group element(s) essentially including Fe or Fe and Co. B is boron. A two-grain boundary is contained between the two adjacent main-phase crystal grains. An average grain size of the main-phase crystal grains is 0.9 m or more and 2.8 m or less. A thickness of the two-grain boundary is 5 nm or more and 200 nm or less.

An R-T-B based permanent magnet includes R-T-B based compounds as main-phase crystal grains. R is a rare earth element. T is iron group element(s) essentially including Fe or Fe and Co. B is boron. A two-grain boundary is contained between the two adjacent main-phase crystal grains. An average grain size of the main-phase crystal grains is 0.9 m or more and 2.8 m or less. A thickness of the two-grain boundary is 5 nm or more and 200 nm or less.

The invention provides an RFeB sintered magnet consisting essentially of 12-17 at % of Nd, Pr and R, 0.1-3 at % of M.sub.1, 0.05-0.5 at % of M.sub.2, 4.8+2*m to 5.9+2*m at % of B, and the balance of Fe, containing R.sub.2(Fe,(Co)).sub.14B intermetallic compound as a main phase, and having a core/shell structure that the main phase is covered with a grain boundary phases. The sintered magnet has an average grain size of less than 6 m, a crystal orientation of more than 98%, and a degree of magnetization of more than 96%, and exhibits a coercivity of at least 10 kOe despite a low or nil content of Dy, Tb, and Ho.

The invention provides an RFeB sintered magnet consisting essentially of 12-17 at % of Nd, Pr and R, 0.1-3 at % of M.sub.1, 0.05-0.5 at % of M.sub.2, 4.8+2*m to 5.9+2*m at % of B, and the balance of Fe, containing R.sub.2(Fe,(Co)).sub.14B intermetallic compound as a main phase, and having a core/shell structure that the main phase is covered with a grain boundary phases. The sintered magnet has an average grain size of less than 6 m, a crystal orientation of more than 98%, and a degree of magnetization of more than 96%, and exhibits a coercivity of at least 10 kOe despite a low or nil content of Dy, Tb, and Ho.

The present disclosure is directed at methods of preparing rare earth-based permanent magnets having improved coercivity and remanence, the method comprising one or more steps comprising: (a) homogenizing a first population of particles of a first GBM alloy with a second population of particles of a second core alloy to form a composite alloy preform, the first GBM alloy being substantially represented by the formula: AC.sub.bR.sub.xCo.sub.yCu.sub.dM.sub.z, the second core alloy being substantially represented by the formula G.sub.2Fe.sub.14B, where AC, R, M, G, b, x, y, and z are defined; (b) heating the composite alloy preform particles to form a population of mixed alloy particles; (c) compressing the mixed alloy particles, under a magnetic field of a suitable strength to align the magnetic particles with a common direction of magnetization and inert atmosphere, to form a green body; (d) sintering the green body; and (e) annealing the sintered body. Particular embodiments include magnets comprising neodymium-iron-boron core alloys, including Nd.sub.2Fe.sub.14B.

The present disclosure is directed at methods of preparing rare earth-based permanent magnets having improved coercivity and remanence, the method comprising one or more steps comprising: (a) homogenizing a first population of particles of a first GBM alloy with a second population of particles of a second core alloy to form a composite alloy preform, the first GBM alloy being substantially represented by the formula: AC.sub.bR.sub.xCo.sub.yCu.sub.dM.sub.z, the second core alloy being substantially represented by the formula G.sub.2Fe.sub.14B, where AC, R, M, G, b, x, y, and z are defined; (b) heating the composite alloy preform particles to form a population of mixed alloy particles; (c) compressing the mixed alloy particles, under a magnetic field of a suitable strength to align the magnetic particles with a common direction of magnetization and inert atmosphere, to form a green body; (d) sintering the green body; and (e) annealing the sintered body. Particular embodiments include magnets comprising neodymium-iron-boron core alloys, including Nd.sub.2Fe.sub.14B.