JPS63216307A - Alloy powder for magnet - Google Patents

Abstract

PURPOSE:To offer low-cost and high-performance alloy powder for a magnet, composed of a rare-earth element, iron and boron, which can be used for sintering and for resin bonding by a method wherein the alloy powder which has been finely pulverized by a gas atomizing method are classified and they are then annealed while their heat-treatment condition is changed according to the range of their particle size. CONSTITUTION:Alloy powder for a magnet by this invention are composed of 8-30 atomic % of R (R contains at least more than one rare-earth element including Y), 2-28 atomic % of B, less than 50 atomic % of Co and less than 16 atomic % of Al; their remaining part is composed of Fe. Because the alloy powder is produced by using a gas atomizing method, their particle sizes are distributed widely. The powder of a big particle size whose particles are constituted by a crystal phase and where an amorphous phase is hardly detected are annealed at a high temperature and for long hours such as at 1000 deg.C and for 24 hours so that their coercive force can be increased. The powder of a small particle size which contains the amporphous phase are annealed at a low temperature and for short hours such as at 700 deg.C and for 10 minutes so that their high coercive force can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an alloy powder tail for magnets based on a rare earth-iron-boron compound.

[Conventional technology]

Conventionally, alloy powders used in the production of rare earth-iron-boron magnets include those prepared by crushing alloy ingots for sintering as shown in Japanese Patent Publication No. 61-34242, or those shown in Japanese Patent Application Laid-Open No. 59-64739. The conductive band obtained by the melt spinning method was pulverized, and the JP-A-6
Powders obtained by gas atomization such as those shown in O-j7905 are well known. Next known.

[Problem that the invention seeks to solve]

1. However, the above-mentioned conventional rare earth-iron-poron alloy powder for magnets has the following drawbacks. First, an alloy ingot is crushed and the resulting powder is effective for use in sintered magnets; the magnetic force in the powder state is IK.
It is about Og and cannot be used as powder for resin bonded magnets. In addition, when using the melt spinning method, it is possible to obtain bt powder that is effective for both sintered magnets and resin bonded magnets.
This powder is essentially isotropic, and its maximum energy product is about 10 MGOg (resin pound magnet), so it cannot be said that the performance advantages of rare earth-iron-boron magnets are fully utilized, and compared to the atomization method. This requires an extra step of grinding. Although the powder is obtained by the atomization method, when this powder is simply heat treated, the performance obtained as a resin pound magnet is worse than that obtained by the melt spinning method (+(BH)WLZ = 5 MG Oe), and the performance is high. In order to improve the performance, a pulverization process is still required, resulting in high costs, a risk of oxidation, and problems with processing times.

The alloy for magnets according to the present invention solves these problems, and its purpose is to create a rare earth-iron alloy that is low cost, has high performance, and can be used for both sintering and resin ponds. The purpose of the present invention is to provide alloy powder for boron-based magnets.

[Tth method to solve the problem]

The alloy powder for magnets of the present invention has 8 to 30 atoms of R (at least one kind of rare earth element including R and Y).

Melting an alloy consisting of 2 to 28 atoms of B (poron), 50 atoms or less of Co (cobalt), 15 atoms or less of a (aluminum), the balance hZ 'Fe (iron) and other impurities unavoidable in manufacturing, It is characterized in that the nine alloy powder is made into fine particles by gas atomization, classified, and annealed by changing the heat treatment conditions depending on the particle size range.

The reasons for limiting the composition of the alloy powder for magnets according to the present invention will be explained below. Rare earth elements include Y and La.

Oe, P'r, Nd, Sm, Bu',
Gd, Tb, Dy, Ho, Hr, T
m.

yb and Lu are listed as candidates, and one or a combination of two or more of these may be used. The highest magnetic performance is obtained with Nd and Pr, so it is practical to use Nd.
, pr, yd -pr gold alloy Nd-Pr-0g gold alloy is used. Main phase R47g of R-Fe-B magnet
, 4B. Therefore, if the Rh"-8 atoms are less than 8 atoms, the above compound will no longer be formed, and it will become a cubic crystal structure with the same structure as α-iron, making it impossible to obtain high magnetic properties. -When the force R exceeds 30 atoms, The amount of non-magnetic Rrich phase increases, and the magnetic properties deteriorate significantly.

B is an essential element for forming R, Fe, and B phases, and when it is less than two atoms, it forms a rhombohedral R-Fe system groove structure.
High coercive force cannot be expected. If you go beyond the 7t2B atomic group, B
Rich's non-magnetic phase increases and the residual magnetic flux density decreases significantly, so it is desirable that it be lower than that. boCo is effective in raising the Curie point of a water-based magnet, and the temperature characteristics of the magnet are also improved accordingly. . Basically KeCobaR
2Fe,, the 7g site of phase B was replaced with R, (PaCo
)1. As the added g hz increases, an rrav g s phase called R (FeOo) is formed, resulting in a decrease in coercive force. For this reason, the appropriate amount to add is 50w and h to the baby.

kl was developed by Zhang Maocai et al.
ocas, MaDoging, :Jiang
Xturing and Liu EJhigiang
.

proceeding of the Bth
International Works opo
n Rare-F,arth Magtutts (1
985) P, 541) has the effect of increasing coercive force.

However, since At is a non-magnetic element, as the amount of At is increased, the residual magnetic flux density decreases5, so it is desirable to add up to 15 atoms.

Since the alloy powder for magnets of the present invention is produced using a gas atomization method, the powder has a wide particle size distribution. The cooling rate/l'' differs depending on the particle size, and the fine structure of the powder changes accordingly. A high coercive force can also be obtained by heat treatment in the casting method.Therefore, for powders with large particle sizes where each particle is composed of a crystalline phase and almost no amorphous phase can be seen, it is possible to obtain a high coercive force by heat treatment at 1000℃ for 24 hours. To increase the coercive force, apply annealing at a high temperature for a long time such as to obtain a high coercive force.In this case, it is important not to completely crystallize the amorphous phase.
This is the point of high operating magnetic force, so you must be careful.

As mentioned above, the high coercive force alloy powder that has been heat-treated according to particle size is also mixed and used as alloy powder for resin bonded magnets, but due to the problem of magnet formability, the largest particle Since a diameter of about 200 μm is required, the particle diameter h″-20 is required as a condition for gas atomization.
It is desirable that the thickness be down to about 0 μm. Since the alloy powder for sintered magnets is required to have a small particle size, the conditions for 7 totomization must be adjusted so that the powder has a small particle size.

〔Example〕

The following is a detailed description of the present invention based on examples.

(Example 1) First, an alloy of a desired composition is melted by high frequency in an atmosphere,
By performing supersonic gas atomization using Ar gas, 20
A spherical powder of 0 μm or less was produced. This powder was classified into two types, 40 μm or more and 40 μm or less, using an air classifier.
For powders larger than 0 μm.

Annealing at 1000°C for 24 hours, and for powders smaller than 40 μm, annealing at 700°C for 10 minutes in Ar
Mix again and add 2.5 wtc4 Evo Chishi resin.
After mixing and molding in a 15KOg magnetic field,
A resin pound magnet was made by firing at C and its magnetic performance was measured.

Table 1 shows the compositions of various alloy powders for magnets produced by the above steps. At this time, ]'l'e, CO, and α are 9
Purity of 99% or higher, B is 7-engineered roboron alloy (16.32% B, 0.15% A1..0.68% F)
! ? :, 0.1240, balance Fe), rare earth metal and 12. In this case, we used one with a purity of 95% (the impurities were mainly other rare earth metals).

Table 2 shows the magnetic performance at 9 o'clock when the powder with the specific composition shown in Table 1 was resin-bonded by the method described above. The HA field effect appeared differently from that of amorphous powder, and clearly high magnetic performance was obtained.

Table 1 Table 2 (Samples/% 23 and 24 are cases where powders with the composition of sample 417.21 were heat-treated for 1 c 1000' c x 24 hours without distinguishing the particle size) (Example 2) Table 1 Of the compositions shown, 42.10.17.21
The various types of powder were coarsely pulverized to 80 mesh under using a stamp mill, and then subjected to ball milling for 4 hours to obtain a fine powder with an average particle size of 4 μm. This fine powder was oriented in Takai, molded at a pressure of 2t/cm'', and 11(jO
Sintering was carried out in Af for 2 hours at 700°C.
Aging treatment was performed for 1 hour. The magnetic performance of the sintered magnet thus obtained is shown in Table 3.

Table 3 [Effects of the Invention] As described above, according to the present invention, it is possible to improve the magnetic properties of the powder by subjecting the gas atomized powder to specific heat treatment according to the particle size. When using HZ, the magnetic performance hZ has the effect of clearly increasing compared to that of conventional simple heat-treated amorphous powder. Even when used in sintered magnets, its magnetic performance is sufficiently high, and it is industrially useful as a powder for magnet alloys that can be used for both resin ponds and sintering at low cost.

that's all

Claims (1)

[Claims] (1) R (R is at least one kind of rare earth element including Y) 8 to 30 atom%, B (boron) 2 to 28 atom%, C
o (cobalt) 50 atomic% or less, Al (aluminum)
An alloy consisting of 15 atomic % or less, the balance being Fe (iron) and other impurities unavoidable in manufacturing, is melted, the alloy powder is made into fine particles by gas atomization, and the alloy powder is classified, and the heat treatment conditions are changed depending on the particle size range. An alloy powder for magnets that is characterized by being annealed.