JPS62297437A - Magnetic material having high saturation magnetic moment - Google Patents

Abstract

PURPOSE:To obtain a magnetic material having extremely high magnetic properties, particularly saturation magnetic moment, by constituting the above material of a foil, thin film, or powder of a steel containing respectively prescribed amounts of C, O, and one or more elements among Ti, V, Cr, Mn, Ni, Co, Cu, Al, etc., and also by providing a precipitated phase of Fe16N2 to the inside of the above. CONSTITUTION:The magnetic material is composed of a foil, thin film, or powder of a steel containing, by weight, <=0.02% C, <=0.01% O, and <=10.0% of one or more elements among Ti, V, Cr, Mn, Ni, Co, Cu, Al, Zr, Nb, and Mo and is provided with a precipitated phase of Fe16N2 inside. Further, the above foil usually means a thin steel strip of about 20-500mum thickness, the above thin film means the one as thin as about 1,000-50,000Angstrom , and further the above powder means that of <=300mum grain size, particularly of <=150mum. According to this invention, the magnetic material having extremely high saturation magnetization and further saturation magnetic moment can easily be obtained by effectively precipitating the Fe16N2 phase in an iron matrix.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a magnetic material with an extremely high saturation magnetic moment, and the present invention relates to a magnetic material having an extremely high saturation magnetic moment. By precipitating it, the saturation magnetization and thus the saturation magnetic moment are advantageously improved.

(Conventional technology) The rapid development of the electronics industry in recent years has been greatly influenced by the research and development of magnetic materials.
A good magnetic material with a high saturation magnetic moment is required for magnetic recording, miniaturization of electronic equipment, and increase in information density.

Conventionally, in order to obtain materials with high magnetic moment, attempts have been made to increase the saturation magnetization by alloying iron, but such alloying additive elements are ptJ? 0) Since they are all expensive elements such as PD, they have not been used industrially.

In 1972, Takahashi et al. (Minoru Takahashi: Solid State Physics.

Vol. 7 (1972), 483), (T.,
Kim and M, Takahashr: Appl;
Phys, Lett, Vol. 20 (1972
), 492) and (Minoru Takahashi: Academic Monthly Report, Vol. 1.
24 (1972), 719), 2X10-'
The saturation magnetization value of an iron thin film deposited in a nitrogen atmosphere of ~2×1O−3 Torr is 26,400 to 29,000 Ga.
uss, and the saturation magnetization value of the pure iron thin film is 21500 G.
The results showed very interesting experimental results, showing that it is far more descended from the auss. Crystal structure analysis using electron diffraction revealed that this high saturation magnetization originates from iron nitride of Fe16Nz, which is preferentially formed in the iron thin film.

After that, Mitsuma et al. and Retard (Katsuya Mitsuoka).

Hideki Miyajima, Satoshi Saikaku: Abstracts of the 2nd Japanese Society of Applied Magnetics Academic Conference, (1978) P, 176) (and Satoshi Saikaku: Applied Physics, 53 (1984), 291) Fe, N, Iron Nitride is B, C, T, (Body
Since it has a centered tetragonal structure, it was shown that the magnetization increases due to the elongation of the lattice due to the intrusion of N atoms.

In addition to the above technology, the inventors (Y, Inoku
ti+N, N15hida and N, 0hashi
:Met, Trans16A (1975), 773)
and (Yukio Iro: Bulletin of the Japan Institute of Metals, 15 (197)
5).

101), a (100)-oriented pure iron single crystal is
When treated in a nitriding atmosphere of ammonia and hydrogen gas in the temperature range from 50°C to 500°C, Fe1Jz of about 0.5 to 3 μm is preferentially precipitated near the single crystal sample surface, and Fe,..., IJ. Subway Matrix <to
o>, , □/ <100>. It was shown that it satisfies the following.

The recent series of studies on Fe+Jz have been summarized above, and it is clear that the temperature at which this Fe, N, precipitate is observed is relatively low, 200 to 250°C, and that this F
Even if an attempt is made to extract only e,,N, it has been revealed that with current chemical solvents, the iron nitrides of Fe,,N, dissolve first, making extraction almost impossible.

(Problems to be solved by this invention) This invention elucidates the behavior of Fe+Jz in the base metal matrix,
The purpose of this study is to propose magnetic materials with excellent magnetic properties, especially saturation magnetic moment.

(Means for Solving the Problems) Under these circumstances, the inventors realized that stably precipitating the Fe16Nz iron nitride in the matrix at higher temperatures is an essential condition for improving magnetic properties. Recognizing this, we began a number of trial experiments. As a result, Fe, N2, TitV, Cr, Mn.

10.0 wt% of at least one element among Ni+ Co, Cu, Al t Zr, Nb and 10
(hereinafter simply expressed in %) It has been found that the following iron alloys are stably precipitated in iron alloy ribbons, thin films, or powders, and that the presence of such a Pe+Jg precipitated phase makes it possible to obtain a material with an extremely high saturation magnetic moment. This led to the completion of this invention.

In other words, in the invention, C: 0.02% or less, O: 0
．． 01% or less and Ti, V, Cr, Mn, Ni, C
It is a magnetic material with a high saturation magnetic moment, containing 10% or less of at least one of O, Cu, A It +Zr, Nb, and Mo.

This invention will be specifically explained below based on the experimental results that led to this invention.

C in pure iron (electrolytic iron) in various ranges from 0 to 15%
Various steel ingots containing r were heated to 1250°C, bloomed and rolled into sheet bars, and then hot rolled to 1.8
It was made into a hot-rolled plate with a thickness of mm. After that, while performing warm rolling at 300-500℃, the
.

Cold rolled sheets with various thicknesses of 0.30 mm and 0.10 mm were created. Also, during the cold rolling of these samples, the L direction (
Cold rolling was repeated in the C direction (the same rolling direction as during hot rolling) and in the C direction (direction perpendicular to the direction during hot rolling). Next, after degreasing the surface of the cold-rolled sheet to make the surface clean, it was heated in hydrogen for 8 hours.
After annealing at 00°C for 3 minutes to develop a primary recrystallized structure with a strong (100) orientation, NH, (5
30 to 6 in a nitriding atmosphere of χ) and 82 (95χ) gas
After performing nitriding treatment for 0 minutes, rapid cooling treatment was performed. Thereafter, an aging treatment was performed in a temperature range of 100° C. to 400° C., and then the precipitation state of Fe16Nz iron nitride was observed using a transmission electron microscope (acceleration voltage 200 KV).

Among various plate thicknesses from 1.0 to 0.10 mm, Fe+J
The sample in which z was uniformly precipitated over the thickness of the plate was a sample with a thin plate of 0.10 mm thickness. In this regard, in the case of thick samples of 1.0, 0, and 8 mm, only the vicinity of the surface is nitrided, and even if a subsequent diffusion precipitation treatment is performed, Fe, N, or Fe4. Iron nitrides such as N were formed, and a state in which Fe+ 6N2 and FeaN were simultaneously precipitated was also observed.

From the above experimental results, it was found that a thin plate thickness of 0.1 mm is optimal for tracking the precipitation phenomenon of FeN2.
The results of an investigation into the relationship between the precipitation state and the Cr content using the 0.1 mm plate thickness sample shown in FIG. 1 are shown.

As is clear from FIG. 1, the stable precipitated Crf3 degree of Feb, Nz is 10% or less, preferably 6% or less, and within this range, a large number of Fe1 are present in the matrix.
6N is precipitated, and the precipitation temperature is also 350-400℃.
It was found that the temperature shifted to the high temperature side.

Note that even when Cr was in a small amount of 0.01%, the stable precipitation temperature of Fe16N2 shifted to the high temperature side.

From the above experiments, the optimal precipitation conditions for Fe16N2 are:
Cr content is 0.01-10.0% (especially Cri is 3-10.0%)
F in the range of 6% (precipitated in the high temperature range of 350 °C
It was newly discovered that eIbNz precipitates stably at high temperatures, and that Fe, Nz precipitates uniformly and in large quantities in thin samples. It is also possible to develop a texture in which the matching relationship between Fe16N2 and the matrix takes precedence, that is, a texture in which the (100) plane is strong parallel to the steel plate surface.
This is considered to be an important factor for stable precipitation of z. This is because the crystal structure of Fe, ..., Nz is a B, C, T structure in which N atoms occupy interstitial positions on the Z axis in the interstitial octahedral gaps of Fe atoms, and therefore In particular, the state is markedly distorted. For this reason, Feb.
In order to achieve stable precipitation of N2, it is considered important to achieve a preferential morphology of the texture with the (100) plane that alleviates the strain of Feb bNz by making the steel sheet thinner.

Next, Fe16N in the Fe-Cr joint as described above
We conducted extensive experiments to determine whether the stable precipitation of 2 also exists in other alloy systems. That is, TLνJn+N++
Iron alloys (50 kg ingots) containing Co, 81, Cu, Zr, Nb and MO were prepared, and after blooming, hot rolling (1.4 mm thick) and cold rolling (0.5 mm thick) were made.
, 05mm thick) was applied.

During the cold rolling, rolling was repeated alternately in the L direction (the same direction as the hot rolling) and the C direction (the direction perpendicular to the hot rolling direction). The rolling temperature at this time is 250 to 400
It was warm rolled at ℃. Its a 8o.

After performing primary recrystallization annealing at °C for 30 minutes, the surface was polished to a mirror-like state with a centerline average roughness Ra of 0.05 μm by pickling and electrolytic polishing.

Thereafter, using an IVD (ion implantation) apparatus shown in FIG. 2, an iron nitride phase was formed while N2 ions were implanted into the surface of the steel sheet (ion implantation amount: 8×10 16 ions/cm 2 ). The temperature of the substrate at that time was 250
The temperature was maintained between 300°C and 300°C.

Table 1 shows the saturation magnetization of the sample after N2 ion implantation and the XwA diffraction results of the precipitates in the sample. These iron alloy elements show a high saturation magnetization of 21,800 to 24,900 Gauss (G), and at the same time, The precipitates on the steel plate surface are FeIbN
It was found that z was the main component, and Fe4N was only slightly suppressed.

Table 1 Furthermore, similar experiments were conducted on a ferroalloy containing two or more of the above elements, and the saturation magnetization of the obtained sample was measured and the precipitated phase was subjected to X-ray diffraction, but the results shown in Table 1 were Almost the same results were obtained.

Next, iron and Fe-N with the compositions shown in Table 2 with numbers ■ to ■.
A powder sample of i alloy was heated to NH3 (52) and H8 at 500℃.
After nitriding in a mixed gas with (95χ), the sample was rapidly cooled to room temperature. Table 2 also shows the measurement results of the particle size and saturation magnetization by the torque method of the obtained powder sample which was then annealed at 250° C. for 1 hour.

As is clear from Table 2, the saturation magnetization of the sample (■) is 24
800 G, which is higher than other samples of 20,000 to 21,500 G, is noteworthy.

The reason for the high saturation magnetization of this sample is that the powder contains 4.2% Ni and the particle size of the sample powder is 15%.
This is thought to be due to the extremely small size of 0 μm. By the way, the saturation magnetization of the sample (■) is considerably lower than that of the sample (21,500 G and ■), but the reason for this is that 3.
．． Although it contains 2% Ni, the particle size of the powder is 10%.
Because of the large size of 00 to 300 μm, uniform nitriding is not performed in the powder, and the strain of Fe and J2 (the structure of Fet6Nz has no strain in the X and Y directions, and large strain exists only in the Z axis direction). This is thought to be because it is extremely difficult to precipitate in a state where it can be sufficiently released.

As is clear from the above, in order to achieve stable precipitation of Fe+Jz iron nitride with a high saturation magnetic moment, ■ Ti, V, and C must be added to the material in a range of 10.0% or less.
r, Mn.

Ni, Co, Cu, A j2 , Zr, Nb and Mo
■ Developing a strong set of (100) planes Mi fiti with a good matching relationship between Fet6Nz and the matrix; ■ Forming thin strips or thin films to help release the strain of Fe+, Nz. Alternatively, it has been newly discovered that it is necessary to use fine-grained powder.

Note that the thin strip mentioned here refers to a Φ thin steel strip that is usually about 20 to 500 μm thick, the thin film refers to a very thin steel strip with a particle size of about 1,000 to 50,000, and the powder refers to a thin steel strip with a particle size of 300 μm.
It means a sample with a diameter of 150 μm or less, preferably 150 μm or less.

(for production) Next, we will discuss the reasons for limiting the material components.

Ti, V, Cr, Mn, Ni+Co, Cu, 'Al
, Zr, Nb and phylum. In each case, Fe, ..., Nz are stably precipitated in large amounts in the range of 10.0% or less, so whether these elements are used alone or in combination, the content is 10.0% or less, preferably 0.5 to 0.5%. The content was set to be within a range of 6.0%.

Since C is an element harmful to magnetic properties, it is desirable that the content be as low as possible, but a range of 0.02% or less is acceptable.

0 forms oxides in the steel and causes deterioration of magnetic properties, so it is desirable to reduce it as much as possible, but it is acceptable within a range of 0.01% or less.

There is no problem in containing small amounts of other elements that are inevitably mixed as impurities in ordinary iron alloys, such as B, S, Sb, Sn, and P.

Furthermore, FeIbNz iron nitride precipitated in these iron alloy ribbons, thin films, and powders is usually detected by electron microscopy or X-ray diffraction for ribbons and thin films.
It is determined by the ratio of N precipitates to the matrix, and in the case of powder, it is determined from the height of the main diffraction peak of Fe, N2 by X-ray diffraction, but the amount of precipitated Fe, N2 is 0.
．． It is desirable that the content be about 5% or more (50% or more of the total iron nitride precipitated phase).

(Example) C on charcoal: 0.003 χ, Si: 0.009%, Mn: 0.
06X, Ti 2.6X, P:0.00B! .

Copper ingots containing N: 0.002χ and 0:0.0045χ were heated to 1250°C and subjected to blooming rolling to obtain jidopa, which were then hot rolled to form hot rolled sheets with a thickness of 1.5 mm.

Thereafter, the surface was pickled and then cold rolled. During the cold rolling of this sample, cold rolling was repeated in the L direction and the C direction to produce a cold rolled ribbon with a thickness of 0.05 mm. After degreasing the surface of the ribbon, it was annealed in hydrogen at 800°C for 5 minutes. After that, NH3 (5χ) and N at 500℃
After nitriding in a nitriding atmosphere with 2(95χ) gas, the sample was rapidly cooled to room temperature and then subjected to aging annealing at 300°C for 3 hours. Electron microscopy and X-ray diffraction of the sample thus obtained revealed that it was Fe16N2. A large peak of the precipitated phase was observed, and a small amount of Fe4. Only an N-phase peak was observed. Furthermore, the saturation magnetization measured by the torque method showed an extremely high value of 23,200 G.

Implementation 1 - C: 0.003χ, Co: 4. IZ, Mn: 0.065
χ, P: 0.007Z, S: 0.006Z.

N: 0.040X and O: O,0O13X.

An iron nitride thin film was created by implanting N2 ions by the ion plantation method of N2 ions as schematically shown in FIG. The temperature of the substrate at this time was maintained at 270°C.

When the thin film thus obtained was subjected to X-ray diffraction, it was found that mainly Fe
It turned out to be made up of 16N2. In addition, some FeJ and Fe3N were observed. Moreover, the saturation magnetization measured by the torque method showed an extremely high value of 24,300G.

Futo base owner C: 0. O05χ, Mo: 2.6χ, Mn: 0.06χ
, P: 0.008χ, S: 0.009χ.

Fine powder (particle size 100 μm or less) containing N:0.002χ and 0:0.009χ was heated at 500°C with Nnz (5
After nitriding for 30 minutes in a nitriding atmosphere of χ) and N2 (95χ), it was rapidly cooled to room temperature. Thereafter, aging annealing was performed at 250°C for 1 hour.

The saturation magnetization of the sample thus obtained was measured by the torque method and showed an extremely high value of 23,600G.

Furthermore, when this powder was subjected to X-ray diffraction, it was found that almost all of the powder contained Fe and N2.
Some amount of Fe4N was observed.

(Effect of the invention) Thus, according to this invention, Fe1 is contained in the iron matrix.
By effectively precipitating the bN2 phase, a magnetic material with an extremely high saturation magnetization and thus an extremely high saturation magnetic moment can be easily obtained.

[Brief explanation of the drawing]

Figure 1 shows the precipitation situation of Fe16NZ depending on aging treatment temperature and Cr.
Figure 2 is a schematic diagram showing the procedure for producing iron nitride by the ion implantation method of N2 ions.

Claims (1)

[Claims] 1. C: 0.02wt% or less O: 0.01wt% or less and Ti, V, Cr, Mn, Ni, Co, Cu, Al, Zr
, at least one of Nb and Mo: 10.0wt
% or less, with the remainder being Fe and unavoidable impurities.
A magnetic material with a high saturation magnetic moment characterized by having a precipitated phase of _6N_2.