JPH0339428A - Manufacture of ni and b-containing rare earths-transition metal series magnet alloy stock - Google Patents

Abstract

PURPOSE:To manufacture the Ni and B-contg. rare earths-transition metal series magnet alloy stock having excellent magnetic characteristics by melting a rare earth elements raw material, transition metallic elements raw material and an Ni-B alloy having specified compsn. and solidifying the melt. CONSTITUTION:A rare earth elements raw material, a transition metallic elements raw material and, as a boron raw material, an Ni-B alloy having the compsn. contg. 45 to 85at% Ni and the balance substantial B are melted and then solidified. In the above alloy, by properly selecting the B raw material, its melting temp. is advantageously reduced to effectively prevent the deterioration of the final magnetic characteristics. In this way, the Ni and B-contg. rare earths-transition metal series magnet alloy stock having excellent coercive force and rectangular hysteresis properties and furthermore having excellent corrosion resistance and temp. characteristics can be obtd.

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention provides an alloy material of a rare earth-transition metal magnet alloy that not only has excellent coercive force and squareness, but also has excellent corrosion resistance and temperature characteristics. This relates to a manufacturing method.

(Prior art) Typical permanent magnet materials currently manufactured include:
Examples include alnico magnets, ferrite magnets, and rare earth magnets. Alnico magnets have a long history and have accounted for most of the magnet material market for a long time, but due to the temporary supply instability of cobalt, which contains a large amount as an ingredient, the price of alnico magnets has soared, and cheap ferrite magnets or Furthermore, with the development of rare earth magnets with higher magnetic properties, demand is decreasing. On the other hand, ferrite magnets are
Because it uses oxide as its main raw material, it is chemically stable and low-cost, so it still occupies the mainstream of magnet materials today, but it has the disadvantage of a small maximum energy product.

Subsequently, Sm--Co magnets appeared that combined the magnetic anisotropy of rare earth ions and the magnetic moment of transition metal elements, significantly updating the conventional maximum energy product.

However, Sm-Co magnets are made of S, which is a scarce resource.
Since the main components are M and Co, the magnet has to be expensive.

Therefore, an effort was made to develop an inexpensive magnetic alloy that did not contain expensive Sa+ or Co and had high magnetic properties.As a result, Banyo et al.
34242 and JP-A-59-132104), and J. J. Croat et al. developed an alloy with high coercive force (JP-A-59-64739) by a liquid quenching method. These are alloys consisting of Nd, Fe, and B, and the maximum energy product of the magnets made by the sintering method is 5I.
This exceeds that of l-Co magnets.

However, Nd-Fe-B magnets are composed of light rare earth elements such as Nd, which has very high activity, and F, which easily rusts.
Since it contains a large amount of e, it has a disadvantage of poor corrosion resistance, resulting in deterioration of magnetic properties and lack of reliability as an industrial material.

In order to overcome the above-mentioned problem, the inventors previously proposed in Japanese Patent Application No. 63-232258 that Fe was replaced with C.

Corrosion resistance rare ±! consisting of composite substitution with and Ni! -Proposed a transition metal diameter magnet alloy.

(Problems to be Solved by the Invention) Conventionally, among raw materials for rare earth magnets containing Fe and B, ferroboron has been used as a B source. Such ferroboron usually contains about 18 to 24 wt% B.
(53 to 62 at% B) is used for magnets.

However, the polides formed in the Fe-B binary system generally have a high melting point <(FeJ; 1389 °C
1Fen; 1540″C, FeBt; 2070
'C) Also, in combination with the high specific resistance of the magnetic alloy during high-frequency melting, the temperature of the molten metal must be raised to 1600°C or higher for melting, and as a result,
There were problems such as the contamination of impurities due to the volatilization of components with high vapor pressure and the reaction with the crucible, and the problem remained that the final magnetic properties, especially the coercive force, deteriorated.

The present invention advantageously solves the above-mentioned problems, and effectively prevents the conventionally concerned deterioration of the final magnetic properties by advantageously reducing the melting temperature through proper selection of B raw materials. It is something.

(Means for Solving the Problems) The inventors have developed a phase diagram (Izvest Akad Nauk SSS) in FIG. 1 for the B-Ni binary alloy.
R-NEORGMATERIALY vol, 3 (1
967) - English translation page 643), the melting point is 15
Apart from B and Ni at 90°C, the polides formed generally have low melting points (BNi; 1065"C1B3N
i4; 995°C, BNiz; 1110°C,
BNis; 1140°C).

This invention was developed after numerous experiments and studies based on the above viewpoint.

That is, this invention uses a rare earth element raw material, a transition metal element raw material, and a boron raw material of Ni: 45 to 85.
Ni-
N consisting of melting B alloy and then solidifying it.
This is a method for manufacturing a rare earth-transition metal magnet alloy material containing i and B.

(Function) The master alloy according to the present invention must have a high boron concentration (approximately 15 at% or more) and a low liquidus temperature (approximately 1,350 at% or more).
(°C or less).

Now, considering the Ni-B binary alloy that satisfies the above conditions, according to the Ni-B binary alloy phase diagram shown in Figure 1 above, when Ni1i is in the range of 45 to 85 at%,
The maximum temperature of the liquidus line is 45a t%Ni-B alloy at 1340°C1-power The lowest temperature is the eutectic composition of BNi and B5Ni 53a t%Ni-B alloy at 900°C
'C.

In this regard, the phase diagram for the Co-B binary alloy is shown in Figure 2 (
Z, Metalkunde 57 (1966) P
, 323), when the Co concentration is 45 to 85a t
% range, the lowest temperature of the liquidus is the eutectic composition (82a
t%Co), and increases to 1460°C as the B concentration increases. As is clear from a comparison with the Fe-B system binary phase diagram shown in Figure 3, the liquidus line in the Co-B system is only about 100°C lower than that in the Fe-B system. It can be seen that there is not much merit in adopting a Co-B based mother alloy.

Therefore, in this invention, a Ni-B alloy is used as the B source, and the Ni content is limited to a range of 45 to 85%.

Now, in the production of rare earth-iron-B magnets, it is required to create a homogeneous alloy in order to improve the magnetic properties, and for this purpose, transition metals such as iron are first melted using high-frequency melting, and then The procedure used was to raise the temperature of the molten metal to over 1,600°C, then melt the ferroboron, and finally, after lowering the temperature of the molten metal to about 1,400°C, the rare earth elements were introduced from the hopper.

As mentioned above, during this series of processes, the molten metal and the crucible material (usually alumina is used) react at high temperatures of over 1,600°C, resulting in impurities being mixed into the raw material and deteriorating the magnetic properties. However, this problem can be solved by using a Ni-B binary alloy as a melting raw material in melting a rare earth magnet alloy containing Ni and B.

(Example) 10 kg each of rare earth-transition metal magnetic alloys having various compositions shown in Table 1 were manufactured in a 20 kHz high frequency melting furnace using an aluminum crucible.

Raw materials include Nd metal, electrolytic iron, electrolytic cobalt, electrolytic Ni, ferrotitanium (50a t%Ti) and 53a
A t%Ni-B master alloy was used.

First, electrolytic iron, electrolytic cobalt, electrolytic Ni, and N are placed in a crucible.
The i-B master alloy and ferrotitanium were added, and the high frequency power was increased to melt them. When the maximum temperature measured with a pyrometer was 1550°C, the molten metal was sufficiently stirred by electromagnetic force. Thereafter, the temperature of the molten metal was lowered to 1400°C, Nd metal was introduced from a hopper, and after confirming that the entire molten metal was uniform by electromagnetic stirring, it was cast into a water-cooled copper mold.

In this casting process, corrosion of the crucible used for melting is extremely small, and the amount of oxygen in the cast alloy is 110%.
It was about 0pp.

Next, the cast alloy was coarsely pulverized with a stamp mill, then finely pulverized with a jet mill to about 1 to 3 μm, pressed into a bottom mold in a magnetic field, and then sintered at 1040'C and oil quenched.

Regarding the rare earth-transition metal magnet alloy thus obtained,
Table 1 also shows the measurement results for the residual magnetic flux density Br, coercive force 11c, and maximum energy product (BH) □8 after pulse magnetization.

In addition, the same table shows the results of examining corrosion resistance under an environment of a temperature of 70° C. and a humidity of 95%, and the weight increase due to oxidation after 1000 hours.

For comparison, an alloy with the same composition was used as ferroboron (B).
: 18aL%) was melted as a raw material, and ferroboron was melted only after the temperature of the molten metal was raised to 1650°C. After casting, the inner surface of the aluminum crucible was examined and found to be severely corroded. When the ingot was analyzed for oxygen, it was found to be 300 ppm. Thereafter, a sintered magnet was manufactured in the same manner as in the example. Table 1 also shows the investigation results regarding its magnetic properties and il corrosion resistance.

As is clear from the same table, when the alloy material according to the present invention was used, the coercive force was 2 kOe superior to that when manufactured by the conventional method.

The reason why the coercive force of the conventional material was inferior is thought to be that oxygen was mixed in during casting, and that the temperature during melting was still low and the distribution of boron in the molten metal was uneven.

(Effects of the Invention) Thus, according to the present invention, a rare earth-transition metal magnet alloy material containing Ni and B can be melted at a lower melting temperature than before, and the magnetic properties of the final product can be improved. Deterioration can be effectively prevented.

[Brief explanation of drawings]

Figure 1 is a binary phase diagram of the Ni-B system, Figure 2 is a Co-B system binary phase diagram, FIG. 3 is a binary phase diagram of the Fe-B system. Figure 1 Nj (weight y) Figure 2 co(ILt%)

Claims (1)

[Claims] 1. A rare earth element raw material, a transition metal element raw material, and a Ni-B alloy containing 45 to 85 at% Ni as a boron raw material, with the remainder having a composition of substantially B are melted and then solidified. A method for producing a rare earth-transition metal magnet alloy material containing Ni and B.