JPS63273302A - Rare earth permanent magnet - Google Patents

Abstract

PURPOSE:To obtain the magnetic characteristics equivalent to or better than those of Sm-Co magnets by composing the title magnet of a four-component alloy of specified R-Ti-M-Fe. CONSTITUTION:A rare earth permanent magnet of a composition given by the formular is used. R in the formular represents rare earth elements including Y, and M represents one or two or more kinds of elements among B, C, Al, Si, P, Ga, Sn, S and N. In terms of weight percentage, (x) is 12-30%, (y) is 4-10%, (z) is 0.1-8% and (a) is 55-85%. By using a permanent magnet of such a composition, the stabilization of tetragonal compounds is attained and the magnetic characteristics equivalent to or better than those of Sm-Co magnets can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Use) The present invention relates to a rare earth permanent magnet with excellent magnetic properties useful as a material for various electrical and electronic devices.

(Prior art and its problems) Rare earth permanent magnets that are well-known and mass-produced include:
There are Sm-Co magnets, which do not contain Cu11
5 magnet and a two-phase separation type 2/17 magnet containing Cu.

The former 115 magnet has a maximum energy product (BH) wax of 16 to 20 MG-Oe, and the latter 2/171 inch stone has a (BH) Illax of 30 MG-Oa and is used as a high-performance magnet for speakers, motors, measuring instruments, etc. used in

Since Sm-Co magnets use expensive Sm and Co metals, the main development issue is to increase the proportion of replacing Co with Fe as much as possible from the viewpoint of cost. However, even with the 2/17 En stone currently being mass-produced, the CO content is 20 at%.
Replacement is at best.

On the other hand, since 115 magnets do not contain any solid solution of Fe, 2/17142 magnets are becoming the mainstream for mass production.

The recently developed Nd-Fe-B ternary magnet is Sm-C
It is attracting a lot of attention because it has higher characteristics than O-based magnets and uses Nd and Fe, which are abundant in resources, as the main raw materials. However, this NdEu stone is very susceptible to rust and requires some kind of coating, but a method suitable for mass production has not yet been found, and this point has been a bottleneck that has prevented it from being widely used.

On the other hand, as R-Fe-based binary compounds, RFe2, RFe
,,R2Fe,,compounds are well known, but these have a curri point (Tc) of 1. It is not suitable as a magnet material because either the saturation magnetization (4πMs) or the magnetic anisotropy constant (Ku) is low.

Despite these circumstances, Croat et al.
The binary system of e was quenched by the quenched ribbon method, the metastable phase was quenched, and it was magnetized (Appl, Phys, Lett.

37, 1096.1981), also Cadieu
etc. are SmFe3 and (SmTi) by sputtering method.
It was shown that thin films of Fe5 can be created (J, App
l, Phys.

Vol, 55.2811.1984). However, this is also a metastable phase created by sputtering and was thought to not exist in the bulk. They report that these thin films are hexagonal. This type of magnet has low properties because it is isotropic, and its stability is questionable because it is based on a metastable phase.
The development of inexpensive magnets was desired.

(Structure of the Invention) The present invention aims to provide a rare earth magnet that does not use the expensive CO gold metal and has magnetic properties equivalent to or better than Sm-Co magnets, and the gist thereof is expressed by the formula RX Ti, M, Fea (in the formula, R is a rare earth element containing Y, M is B, C.

One or more of AI, Si, P, Ga, Ge, Sn, S, H, X is 12 to 30% in weight percentage, y
is 4 to 10%, Z is 0.1 to 8%, and a is 55 to 85%).

To explain this in detail below, the permanent magnet of the present invention is made of a quaternary alloy of R-Ti-M-Fe.
is 1fffi or 2f of rare earth elements including Y! ! Above, M is B, C, AI, Si, P, and Ga.

One or more of Ge, Sn, S, and N.

The present inventors have already discovered that there is an intermetallic compound in the ternary system R-Ti-Fe that has a tetragonal structure with a stoichiometric ratio close to 1:1:10 and can be magnetized, and has filed a patent application. (Patent application Sho 6l-84723). Below, this ternary compound is defined as ii, -
This is called the to phase. However, since it is difficult to obtain a single phase on the light rare earth side (for example, La, Ce, Pr, Nd), it was necessary to form a homogeneous 1-1-10 phase by solution treatment of the ingot. The present inventors conducted various studies on this point, and found that by introducing the M element, a single structure (1-1 = 10 phases) could be realized in the as-cast state even with light rare earths, eliminating the need for solution treatment, and magnetic properties. It was also found that the above also had a positive effect.

When determining the alloy composition, for example, choose Nd as R, choose B as M, and create NdTiFe+aB2 (z-0
, 5) were created. as-cas at that time
Thermomagnetic curves of Nd and Ti ingots.

A comparison with that of an F e +o as-cast ingot is shown in FIG. As can be seen from this figure, the introduction of B element stabilizes the 1-1-10 phase.

As a result of further investigation, we found that there are elements other than element B that stabilize the 1-1-10 phase, and we also found that the introduction of element M brings about an increase in saturation magnetization even on the heavy rare earth side after Sm. It is something.

Examples of R include La, Ce, Pr, and Nd.

Sm, Eu, Gd, Td, Dy,
Ho, Er.

Rare earth elements such as Tm, Yb, and Lu, and Y may be used, and one or a mixture of two or more of these may be used.

Light rare earth elements are more preferred as magnets. The reason for this is that the saturation magnetization decreases when heavy rare earth elements are used. M elements include B, C, AI,
Si, P, Ga, Ge.

One or more of Sn, S, and N are used. It is thought that the M element is present as an interstitial element in the lattice, so B, C, and AI.

Light elements such as St are more effective.

If R is outside the above range, the tetragonal structure will not be stable, and if it is less than 12%, the coercive force (iHc) will decrease significantly, and if it is more than 30%, the saturation magnetization (4πMs) will decrease significantly, so it must be within the above range. is necessary. Further, when Ti and M are outside the above range, the tetragonal structure is not stable, and especially when 2 is 8% or more, the proportion of tetragonal crystals decreases, so the above range is necessary. Especially when the M element is other than the above, N
The above range is necessary because it is difficult to form a tetragonal single phase on the light rare earth side before d, and especially when it is 8% or more, the saturation magnetization is greatly reduced. The saturation magnetization increases with the introduction of the M element, which is thought to be due to the effect of increasing the distance between Fe atoms, which are responsible for magnetism.

The rare earth permanent magnet according to the present invention can be obtained by melting, casting, pulverizing, forming in a magnetic field, and heat-sintering a composition made of the above-mentioned elements using a powder metallurgy method.

As mentioned above, the rare earth permanent magnet according to the present invention is a magnet mainly composed of a compound phase with a stable tetragonal crystal structure due to Ti and M, so it is one Curie point higher than the binary Sm2Felt compound, and is saturated. The magnetization also shows a significant increase and high magnetic properties can be obtained. In addition, since it is possible to make an anisotropic magnet using the powder sintering method, it is possible to obtain a magnet that is equivalent to or better than Sm-Co magnets, and with less Coff.
1 magnet, it is extremely advantageous as an industrial material.

Furthermore, in addition to these constituent elements, Nb is added to increase the coercive force.
, V, Mo, W, Mn, Ta, Ni.

It is also effective to add transition metals such as Cu and Zn.

When manufacturing Nd-Fe-B magnets by powder metallurgy, rapid oxidation of the fine powder causes a significant deterioration in the mechanical properties of the magnets. Furthermore, the surface of the sintered body is also very susceptible to rust and will not withstand it unless it is coated with an appropriate coating. However, although the rare earth magnet of the present invention is a magnet mainly composed of Fe, it has high corrosion resistance and can be used without any special coating. Naturally, the corrosion resistance can be further improved by coating with resin coating (spray, weight coating), plating (electrolytic, electroless), or PVD (steaming, sputtering, ion blating).

In addition, a ribbon with high coercive force can be obtained by the quenched ribbon method, so it can be crushed to make an isotropic plastic magnet, or an anisotropic sintered body can be crushed to make an anisotropic plastic magnet. You can.

(Effects of the Invention) According to the present invention, by adding a predetermined amount of Ti-M to the R-Fe system, stabilization of tetragonal compounds, which was unknown until now, can be achieved, and Sm- A rare earth permanent magnet that does not contain CO and has high electrical properties can be obtained instead of a Co-based magnet.

(Example 1) After weighing Sm, Ti, B, and Fe metals each having a purity of 99.9% in the proportions shown in Table 1, they were melted in a high-frequency melting furnace, and the molten metal was poured into a copper mold to form four ingots ( No. 1 to 4) were created. In this N2 gas, the particles were pulverized by a jet mill to an average particle size of 2 to 10 μm. The obtained fine powder was oriented in a magnetic field of 15 kOe by a powder sintering method, and then press-molded using a hydraulic press at a pressure of 1.5 t/cm 2 . This molded body was sintered in Ar gas at 1000 to 1200°C for 1 hour, then further treated at 400 to 900°C for 1 hour, and rapidly cooled.

The magnetic properties of the anisotropic sintered bodies N091-3 after the heat treatment were measured and are shown in Table 1 together with the properties of the SmTfFe ternary magnet for comparison.

(Example 2) Nd, Sm, Ti, C, and Sn, each with a purity of 99.9%.

Al and Fe were weighed in the proportions shown in Table 2, and anisotropic sintered bodies (Nos. 4 to 8) were manufactured under the same conditions as in Example 1. Magnetic properties of each anisotropic sintered body When the characteristics were measured, the results shown in Table 2 were obtained.From these results, it can be seen that according to the present invention, a practically sufficient coercive force can be obtained.

[Brief explanation of the drawing]

Figure 1 shows N d Ti Fe + oBo, s ingot and NdTi Fe. It is a graph which shows the thermomagnetic curve of an ingot. patent 6

Claims (1)

[Claims] 1. Formula R_xTi_yM_zFe_a (wherein R is a rare earth element containing Y, M is B, C, Al, S
i, P, Ga, Ge, Sn, S, and N, and x is 12 to 30% and y is 4 to 1 in weight percentage.
0%, z is 0.1 to 8%, and a is 55 to 85%).