The present application relates to a preparation method of neodymium iron boron products and the neodymium iron boron product prepared by using the same. The preparation method of neodymium iron boron products includes the following steps: Step S1: preparing blank magnet; Step S2: obtaining preprocessed sheets; Step S3: surface treating; Step S4: heavy rare earth coating; Step S5: stacking: stacking a plurality of preprocessed sheets to give stacked magnets; and Step S6: grain boundary diffusion: successively subjecting the stacked magnets to a primary heat treatment for 2-40 min, a secondary heat treatment at 700-1000° C. for 4-40 h, and then tempering at 450-700° C., in which the primary heat treatment is induction heat treatment or electric spark sintering.

The present application relates to a preparation method of neodymium iron boron products and the neodymium iron boron product prepared by using the same. The preparation method of neodymium iron boron products includes the following steps: Step S1: preparing blank magnet; Step S2: obtaining preprocessed sheets; Step S3: surface treating; Step S4: heavy rare earth coating; Step S5: stacking: stacking a plurality of preprocessed sheets to give stacked magnets; and Step S6: grain boundary diffusion: successively subjecting the stacked magnets to a primary heat treatment for 2-40 min, a secondary heat treatment at 700-1000° C. for 4-40 h, and then tempering at 450-700° C., in which the primary heat treatment is induction heat treatment or electric spark sintering.

Provided is a magnet including a yoke portion that contains a soft magnetic material, and a magnet portion that is formed on a main surface of the yoke portion and contains a hard magnetic material. An interface of the magnet portion and the yoke portion has an uneven shape.

A sintered R.sub.2M.sub.17 magnet is provided that comprises at least 70 Vol % of a Sm.sub.2M.sub.17 phase, wherein R is at least one of the group consisting of Ce, La, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm,

Yt, Lu and Y, and M comprises Co, Fe, Cu and Zr. In an area of the R.sub.2M.sub.17 sintered magnet of 200 by 200 μm viewed in a Kerr micrograph, an areal proportion of demagnetised regions after application of an internal opposing field of 1200 kA/m is less than 5% or less than 2%.

A sintered R.sub.2M.sub.17 magnet is provided that comprises at least 70 Vol % of a Sm.sub.2M.sub.17 phase, wherein R is at least one of the group consisting of Ce, La, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm,

Yt, Lu and Y, and M comprises Co, Fe, Cu and Zr. In an area of the R.sub.2M.sub.17 sintered magnet of 200 by 200 μm viewed in a Kerr micrograph, an areal proportion of demagnetised regions after application of an internal opposing field of 1200 kA/m is less than 5% or less than 2%.

An alloy having a formula Fe.sub.aCo.sub.bNi.sub.cCu.sub.dM.sub.eSi.sub.fB.sub.gX.sub.h is provided. M is at least one of V, Nb, Ta, Ti, Mo, W, Zr, Cr, Mn and Hf; a, b, c, d, e, f, g are in at. %; X denotes impurities and optional elements P, Ge and C; and a, b, c, d, e, f, g, h satisfy the following:
0≤b≤4,
0≤c<4,
0.5≤d≤2,
2.5≤e≤3.5,
14.5≤f≤16,
6≤g≤7,
h<0.5, and
1≤(b+c)≤4.5, where a+b+c+d+e+f+g=100. The alloy has a nanocrystalline microstructure, a saturation magnetostriction of |λ.sub.s|≤1 ppm, a hysteresis loop with a central linear part, and a permeability (μ) of 10,000 to 15,000.

An alloy having a formula Fe.sub.aCo.sub.bNi.sub.cCu.sub.dM.sub.eSi.sub.fB.sub.gX.sub.h is provided. M is at least one of V, Nb, Ta, Ti, Mo, W, Zr, Cr, Mn and Hf; a, b, c, d, e, f, g are in at. %; X denotes impurities and optional elements P, Ge and C; and a, b, c, d, e, f, g, h satisfy the following:
0≤b≤4,
0≤c<4,
0.5≤d≤2,
2.5≤e≤3.5,
14.5≤f≤16,
6≤g≤7,
h<0.5, and
1≤(b+c)≤4.5, where a+b+c+d+e+f+g=100. The alloy has a nanocrystalline microstructure, a saturation magnetostriction of |λ.sub.s|≤1 ppm, a hysteresis loop with a central linear part, and a permeability (μ) of 10,000 to 15,000.

A sintered R.sub.2M.sub.17 magnet is provided that comprises at least 70 Vol % of a Sm.sub.2M.sub.17 phase, wherein R is at least one of the group consisting of Ce, La, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yt, Lu and Y, and M comprises Co, Fe, Cu and Zr. In an area of the R.sub.2M.sub.17 sintered magnet of 200 by 200 μm viewed in a Kerr micrograph, an areal proportion of demagnetised regions after application of an internal opposing field of 1200 kA/m is less than 5% or less than 2%.

A sintered R.sub.2M.sub.17 magnet is provided that comprises at least 70 Vol % of a Sm.sub.2M.sub.17 phase, wherein R is at least one of the group consisting of Ce, La, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yt, Lu and Y, and M comprises Co, Fe, Cu and Zr. In an area of the R.sub.2M.sub.17 sintered magnet of 200 by 200 μm viewed in a Kerr micrograph, an areal proportion of demagnetised regions after application of an internal opposing field of 1200 kA/m is less than 5% or less than 2%.

HAMR media with a magnetic recording layer having a reduced Curie temperature and methods of fabricating the HAMR media are provided. One such HAMR medium includes a substrate, a heat sink layer on the substrate, an interlayer on the heat sink layer, and a multi-layer magnetic recording layer on the interlayer. In such case, the multi-layer magnetic recording layer includes a first magnetic recording layer including an alloy selected from FePtX and CoPtX, where X is a material selected from the group consisting of Cu, Ni, and combinations thereof, a second magnetic recording layer on the first magnetic recording layer and having at least one material different from the materials of the first magnetic recording layer, and a third magnetic recording layer on the second magnetic recording layer and having at least one material different from the materials of the first magnetic recording layer.