A hot-deformed magnet is obtained by quenching and solidifying a melt of an alloy containing a rare earth element (RE), Fe, and B as main components by a super quenching method using a rotating roll; preparing an alloy powder in an amorphous structure state or an amorphous-microcrystalline mixed structure state; subjecting the alloy powder to a rapid heat treatment in a falling-type heating furnace so as to obtain a raw material powder; hot-forming the raw material powder so as to densify the raw material powder to near true density and form a hot-formed compact; and subjecting the hot-formed compact to uniaxial hot plastic working to orient crystals.

To provide a rare earth magnet ensuring excellent magnetic anisotropy while reducing the amount of Nd, etc., and a manufacturing method thereof. A rare earth magnet comprising a crystal grain having an overall composition of (R2.sub.(1-x)R1.sub.x).sub.yFe.sub.100-y-w-z-vCo.sub.wB.sub.zTM.sub.v (wherein R2 is at least one of Nd, Pr, Dy and Tb, R1 is an alloy of at least one or two or more of Ce, La, Gd, Y and Sc, TM is at least one of Ga, Al, Cu, Au, Ag, Zn, In and Mn, 0<x<1, y=12 to 20, z=5.6 to 6.5, w=0 to 8, and v=0 to 2), wherein the average grain size of the crystal grain is 1,000 nm or less, the crystal grain consists of a core and an outer shell, the core has a composition of R1 that is richer than R2, and the outer shell has a composition of R2 that is richer than R1.

To provide a rare earth magnet ensuring excellent magnetic anisotropy while reducing the amount of Nd, etc., and a manufacturing method thereof. A rare earth magnet comprising a crystal grain having an overall composition of (R2.sub.(1-x)R1.sub.x).sub.yFe.sub.100-y-w-z-vCo.sub.wB.sub.zTM.sub.v (wherein R2 is at least one of Nd, Pr, Dy and Tb, R1 is an alloy of at least one or two or more of Ce, La, Gd, Y and Sc, TM is at least one of Ga, Al, Cu, Au, Ag, Zn, In and Mn, 0<x<1, y=12 to 20, z=5.6 to 6.5, w=0 to 8, and v=0 to 2), wherein the average grain size of the crystal grain is 1,000 nm or less, the crystal grain consists of a core and an outer shell, the core has a composition of R1 that is richer than R2, and the outer shell has a composition of R2 that is richer than R1.

A permanent magnet includes R and T (R essentially includes Sm one or more of rare earth elements in addition to Sm, and T essentially includes Fe, or Fe and Co, one or more of transition metal elements in addition to Fe, or Fe and Co). A composition ratio of R in the permanent magnet is 20 at % or more and 40 at % or less. A remaining part is substantially only T, or only T and C. T amount is more than 1.5 times of R amount and less than 4.0 times of the R amount. Main phase grains included in the permanent magnet have an Nd5Fe17 type crystal structure. An average crystal grain size of the main phase grains of the permanent magnet is greater than 1 m. A number ratio of main phase grains having a crystal grain size of less than 0.4 m is less than 20%.

A permanent magnet includes R and T (R essentially includes Sm one or more of rare earth elements in addition to Sm, and T essentially includes Fe, or Fe and Co, one or more of transition metal elements in addition to Fe, or Fe and Co). A composition ratio of R in the permanent magnet is 20 at % or more and 40 at % or less. A remaining part is substantially only T, or only T and C. T amount is more than 1.5 times of R amount and less than 4.0 times of the R amount. Main phase grains included in the permanent magnet have an Nd5Fe17 type crystal structure. An average crystal grain size of the main phase grains of the permanent magnet is greater than 1 m. A number ratio of main phase grains having a crystal grain size of less than 0.4 m is less than 20%.

Provided is a plurality of flaky magnetic metal particles of embodiments, each flaky magnetic metal particle having a flat surface having either or both of a plurality of concavities and a plurality of convexities, the concavities or convexities being arranged in a first direction and each having a width of 0.1 m or more, a length of 1 m or more, and an aspect ratio of 2 or higher; and a magnetic metal phase containing at least one primary element selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni). The flaky magnetic metal particles have an average thickness of between 10 nm and 100 m inclusive, and the average value of the ratio of the average length within the flat surface with respect to the thickness is between 5 and 10,000 inclusive.

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 grain boundary phases. The sintered magnet 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 grain boundary phases. The sintered magnet exhibits a coercivity of at least 10 kOe despite a low or nil content of Dy, Tb and Ho.

A negative electrode active material which has a ternary alloy composition represented by SiSn-M (M is one or two or more transition metal elements) and has a microstructure which has a first phase (silicide phase) having a silicide of a transition metal as a main component and a second phase partially containing Sn and having amorphous or low crystalline silicon as a main component, and further has partially a plurality of independent first phases and partially a eutectic structure of the first phase and the second phase is used for an electric device. The negative electrode active material improves cycle durability of an electric device such as a lithium ion secondary battery.

A negative electrode active material which has a ternary alloy composition represented by SiSn-M (M is one or two or more transition metal elements) and has a microstructure which has a first phase (silicide phase) having a silicide of a transition metal as a main component and a second phase partially containing Sn and having amorphous or low crystalline silicon as a main component, and further has partially a plurality of independent first phases and partially a eutectic structure of the first phase and the second phase is used for an electric device. The negative electrode active material improves cycle durability of an electric device such as a lithium ion secondary battery.