R-FE-B-based sintered magnet with low B content and preparation method therefor
Disclosed are an R—Fe—B-based sintered magnet with a low B content and a preparation method therefor. The sintered magnet comprises the following components: 28.5 wt %-31.5 wt % of R, 0.86 wt %-0.94 wt % of B, 0.2 wt %-1 wt % of Co, 0.2 wt %-0.45 wt % of Cu, 0.3 wt %-0.5 wt % of Ga, 0.02 wt %-0.2 wt % of Ti, and 61 wt %-69.5 wt % of Fe. The sintered magnet has an R 6 -T 13−δ M 1+δ series phase accounting for 75% or more of the total volume of grain boundaries. The present invention selects optimal content ranges of R, B, Co, Cu, Ga, and Ti, and forms an R 6 -T 13−δ M 1+δ series phase of a special composition and increases its volume fraction in grain boundary phases, so as to acquire higher Hcj and SQ values.
1. An R—Fe—B-based sintered magnet with a low B content, containing an R 2 Fe 14 B-type main phase, the R being at least one rare earth element comprising Nd, wherein:
the R—Fe—B-based sintered magnet comprises the following components:
28.5 wt %-31.5 wt % of R,
0.86 wt %-0.94 wt % of B,
0.2 wt %-1 wt % of Co,
0.2 wt %-0.45 wt % of Cu,
0.3 wt %-0.5 wt % of Ga,
0.02 wt %-0.2 wt % of Ti, and
61 wt %-69.5 wt % of Fe,
the content of each of Dy, Tb, Gd, or Ho in R is 1 wt % or below, and
the R—Fe—B-based sintered magnet has an R 6 -T 13−δ M 1+δ series phase accounting for 75% or more of a total volume of grain boundaries, wherein T is at least one selected from Fe or Co, M comprises 80 wt % or more of Ga and 20 wt % or below of Cu, and δ is within a range of from −0.14 to 0.04.
2. The R—Fe—B-based sintered magnet with the low B content according to claim 1 , wherein:
the components comprise 5.0 wt % or below of X and inevitable impurities,
X is selected from at least one of a group of elements consisting of Zn, Al, In, Si, Ti, V, Cr, Mn, Ni, Ge, Zr, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, Ta, and W, and
when X comprises at least one of Nb, Zr, or Cr, a total content of Nb, Zr, and Cr is 0.20 wt % or below.
3. The R—Fe—B-based sintered magnet with the low B content according to claim 2 , wherein a balance is Fe.
4. The R—Fe—B-based sintered magnet with the low B content according to claim 2 , wherein:
the inevitable impurities comprise O, and
an O content of the R—Fe—B-based sintered magnet is 0.5 wt % or below.
5. The R—Fe—B-based sintered magnet with the low B content according to claim 1 , wherein the R—Fe—B-based sintered magnet is an R—Fe—B-based sintered magnet having been subjected to heat treatment.
6. The R—Fe—B-based sintered magnet with the low B content according to claim 1 , wherein:
the R—Fe—B-based sintered magnet is prepared according to a method comprising:
preparing a molten raw material component liquid of the R—Fe—B-based sintered magnet at a cooling rate of 10 2 ° C./sec-10 4 ° C./sec into a quenched alloy;
crushing the quenched alloy by alloy hydrogen absorption;
micro-pulverizing the crushed quenched alloy into a fine powder;
acquiring a formed body using a magnetic field forming method or by hot-pressing thermal deformation;
sintering the formed body in a vacuum or inert gas at a temperature of 900° C.-1100° C.; and
performing a heat treatment on the sintered formed body to acquire a product.
7. A method for preparing an R—Fe—B-based sintered magnet with a low B content, containing an R 2 Fe 14 B-type main phase, the R being at least one rare earth element comprising Nd, wherein:
the R—Fe—B-based sintered magnet comprises the following components:
28.5 wt %-31.5 wt % of R,
0.86 wt %-0.94 wt % of B,
0.2 wt %-1 wt % of Co,
0.2 wt %-0.45 wt % of Cu,
0.3 wt %-0.5 wt % of Ga,
0.02 wt %-0.2 wt % of Ti, and
61 wt %-69.5 wt % of Fe,
the content of each of Dy, Tb, Gd, or Ho in R is 1 wt % or below, and
the method comprises:
preparing a molten raw material component liquid of the R—Fe—B-based sintered magnet at a cooling rate of 10 2 ° C./sec-10 4 ° C./sec into an alloy for the R—Fe—B-based sintered magnet;
crushing the alloy by alloy hydrogen absorption;
micro-pulverizing the crushed alloy into a fine powder;
acquiring a formed body using a magnetic field forming method;
sintering the formed body in a vacuum or inert gas at a temperature of 900° C.-1100° C.; and
performing a heat treatment on the sintered formed body to acquire a product.
8. The R—Fe—B-based sintered magnet with the low B content according to claim 2 , wherein:
the R—Fe—B-based sintered magnet is prepared according to a method comprising:
preparing a molten raw material component liquid of the R—Fe—B-based sintered magnet at a cooling rate of 10 2 ° C./sec-10 4 ° C./sec into a quenched alloy;
crushing the quenched alloy by alloy hydrogen absorption;
micro-pulverizing the crushed quenched alloy into a fine powder;
acquiring a formed body using a magnetic field forming method or by hot-pressing thermal deformation;
sintering the formed body in a vacuum or inert gas at a temperature of 900° C.-1100° C.; and
performing a heat treatment on the sintered formed body to acquire a product.