A permanent magnet is expressed by a composition formula: R.sub.pFe.sub.qM.sub.rCu.sub.sCo.sub.100-p-q-r-s. The magnet includes a crystal grain having a main phase including a TbCu.sub.7 crystal phase, and a volume ratio of the TbCu.sub.7 crystal phase to the main phase is 95% or more.

A permanent magnet is expressed by a composition formula: R.sub.pFe.sub.qM.sub.rCu.sub.sCo.sub.100-p-q-r-s. The magnet includes a crystal grain having a main phase including a TbCu.sub.7 crystal phase, and a volume ratio of the TbCu.sub.7 crystal phase to the main phase is 95% or more.

Disclosed is a method of manufacturing a rare earth permanent magnet with substantially improved magnetic property. The method comprises: preparing a magnet master alloy by melting an R-T-B based alloy; pulverizing the magnet master alloy to provide a magnet powder; pressurizing the magnet powder as applying magnetic field to the magnet powder under an inert atmosphere to form a magnet molded body; sintering the magnet molded body under a vacuum atmosphere to obtain a sintered magnet molded body having oxygen content of about 0.1 wt % or less based on the total weight of the sintered magnet molded body; and treating the sintered magnet molded body with Dy and Tb.

An RFeB system sintered magnet which does not contain a heavy rare-earth element R.sup.H (Dy, Tb and Ho) in a practically effective amount and yet is suited for applications in which the magnet undergoes a temperature increase during its use. The RFeB system sintered magnet contains at least one element selected from the group consisting of Nd and Pr as a rare-earth element R in addition to Fe and B while containing none of Dy, Tb and Ho, the magnet having a temperature characteristic value t.sub.(100-23) which satisfies −0.58<t.sub.(100-23)<0, where t.sub.(100-23) is defined by the following equation:

[00001]$t_{\left(100-23\right)}=\frac{H_{\mathrm{cj}}\left(100\right)-H_{\mathrm{cj}}\left(23\right)}{\left(100-23\right)\times H_{\mathrm{cj}}\left(23\right)}\times 100$

using H.sub.cj(23) which is the value of the coercivity at a temperature of 23° C. and H.sub.cj(100) which is the value of the coercivity at a temperature of 100° C.

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 μm or more and 2.8 μm 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 μm or more and 2.8 μm 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 main phase grains composed of R.sub.2T.sub.14B type compound. R is a rare earth element. T is iron group element(s) essentially including Fe or Fe and Co. B is boron. An average grain size of the main phase grains is 0.8 μm to 2.8 μm. The R-T-B based permanent magnet contains at least C and Ga in addition to R, T, and B. B is contained at 0.71 mass % to 0.86 mass %. C is contained at 0.13 mass % to 0.34 mass %. Ga is contained at 0.40 mass % to 1.80 mass %. A formula (1) of 0.14≦[C]/([B]+[C])≦0.30 is satisfied, where [B] is a B content represented by atom %, and [C] is a C content represented by atom %.

An R-T-B based permanent magnet includes main phase grains composed of R.sub.2T.sub.14B type compound. R is a rare earth element. T is iron group element(s) essentially including Fe or Fe and Co. B is boron. An average grain size of the main phase grains is 0.8 μm to 2.8 μm. The R-T-B based permanent magnet contains at least C and Ga in addition to R, T, and B. B is contained at 0.71 mass % to 0.86 mass %. C is contained at 0.13 mass % to 0.34 mass %. Ga is contained at 0.40 mass % to 1.80 mass %. A formula (1) of 0.14≦[C]/([B]+[C])≦0.30 is satisfied, where [B] is a B content represented by atom %, and [C] is a C content represented by atom %.

An R-T-B based permanent magnet includes main phase grains composed of R.sub.2T.sub.14B type compound. R is a rare earth element. T is iron group element(s) essentially including Fe or Fe and Co. B is boron. An average grain size of the main phase grains is 0.8 μm or more and 2.8 μm or less. The R-T-B based permanent magnet contains at least C and Zr in addition to R, T, and B. B is contained at 0.75 mass % or more and 0.88 mass % or less. Zr is contained at 0.65 mass % or more and 5.00 mass % or less. A formula (1) of 5.0≦[B]+[C]−[Zr]≦5.6 is satisfied, where [B] is a B content represented by atom %, [C] is a C content represented by atom %, and [Zr] is a Zr content represented by atom %.

An R-T-B based permanent magnet includes main phase grains composed of R.sub.2T.sub.14B type compound. R is a rare earth element. T is iron group element(s) essentially including Fe or Fe and Co. B is boron. The magnet contains at least C, Ga, and M selected from Zr, Ti, and Nb in addition to R, T, and B. B is contained at 0.71 mass % to 0.88 mass %. C is contained at 0.15 mass % to 0.34 mass %. Ga is contained at 0.40 mass % to 1.40 mass %. M is contained at 0.25 mass % to 2.50 mass %. A formula (1) of 0.14≦[C]/([B]+[C])≦0.30 and a formula (2) of 5.0≦[B]+[C]−[M]≦5.6 are satisfied, where [B], [C], and [M] are respectively a content of B, C, and M by atom %.