JP3313386B2 - Giant magnetostrictive alloy and magneto-mechanical mutation conversion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a giant magnetostrictive alloy used for a magneto-mechanical displacement conversion device and the like, and more particularly to a giant magnetostrictive alloy having an improved Curie temperature.

[0002]

2. Description of the Related Art When an external magnetic field is applied to a magnetic material, a displacement control actuator,
There are magnetostrictive vibrators, magnetostrictive sensors, magnetostrictive filters, ultrasonic delay lines, and the like. Conventionally, Ni-based alloys, Fe-Co alloys, ferrites and the like have been used.

[0003] In recent years, with the advance of measurement engineering and the development of the field of precision machinery, development of a displacement drive unit indispensable for micro displacement control on the order of microns has been required. A magneto-mechanical conversion device using a magnetostrictive alloy as one of the driving mechanisms of the displacement driving unit is effective. However, in the conventional magnetostrictive alloy, the absolute amount of displacement is not sufficient, and as a material for a precision displacement control drive unit on the order of microns, it cannot be satisfied from the viewpoint of not only the absolute drive displacement but also the precision control.

In response to such demands, rare earth-transition metal based magnetostrictive alloys have attracted attention as high magnetostrictive materials and have been studied. (Japanese Patent Publication No. 61-33892, U.S. Pat.
378258)

However, such a magnetostrictive alloy does not have a sufficiently high Curie temperature. For example, rare earth-iron alloys have low magnetostriction characteristics in a low temperature range, and rare earth-cobalt alloys are difficult to use in a high temperature environment. A magnetostrictive material having excellent magnetostrictive properties in a wide temperature range has not been obtained.

[0006]

As described above, the conventional rare earth-transition metal based magnetostrictive alloy has a problem that the Curie temperature is not sufficiently high and good magnetostrictive characteristics cannot be obtained in a wide temperature range. The present invention has been made in consideration of the above points, and has as its object to provide a giant magnetostrictive alloy having a high Curie temperature and excellent magnetostrictive characteristics.

[0007]

Super magnetostrictive alloy according to the present invention SUMMARY OF] <br/> the general formula expressed in _{atomic%: R x T 100-xy} M y (R is Y
At least one of the rare earth elements including, T is Fe,
At least one element of Co, M is an N element, 20
≦ x ≦ 60, 0 <y ≦ 30). In the giant magnetostrictive alloy according to the present invention, the main phase
Is the Laves phase, and N is an interstitial element in the lattice of the main phase.
It is permissible to have been intruded. The magneto-mechanical mutation conversion device according to the present invention includes the above-described super magnetostriction coupling.
It is characterized by having gold.

The rare earth element (R) containing Y is as follows:
Y, La, Ce, Pr, Nb, Pm, Sm, Eu, C
d, Tb, Dy, Ho, Er, Tm, Yb, Lu are used, and at least one of them is Pr, N
d, Sm, Tb, Dy, Ho, Er, TbDy, TbH
o, TbPr, SmYb, TbDyHo, TbDyP
r, TbPrHo is preferred.

As at least one element (T) of Fe and Co, Fe and / or Co is used. It is possible to substitute a part of this with other transition elements such as Ni and Mn. However, if it is excessively substituted, the Curie temperature will decrease. is there. X in the above general formula is less than 20 or 6
If it exceeds 0, the main phase decreases, and the magnetostriction characteristics deteriorate. More preferred x is in the range of 25 to 40.

The giant magnetostrictive alloy is generally composed of a Laves phase, which is a main phase having magnetostrictive properties, and a grain boundary.
The element is a so-called immersion element that penetrates into the lattice of the main phase,
It modulates the band structure of the transition element, and in particular, increases the magnetic polarization of d electrons and enhances the exchange interaction between d electron spins, thereby improving the Curie temperature of the giant magnetostrictive alloy.
This effect can be obtained by adding a very small amount of M element.
This becomes significant when y in the above general formula is 3 or more. On the other hand, as the content increases, solid solution in the main phase becomes difficult and precipitates at the grain boundaries, but when present at the grain boundaries, the resistivity increases and the frequency characteristics are improved. However, when it exceeds 30, the magnetostriction is deteriorated due to the excessive existence at the grain boundary. More preferred y is in the range of 10-25.
Note that hydrogen, oxygen, phosphorus, and the like are similar interstitial elements, and the inclusion of up to a similar amount is allowable. A method for producing a giant magnetostrictive alloy in which M in the general formula is N will be described below.

First, a predetermined atomic ratio of the R element and Fe, C
At least one element of o is prepared and dissolved by high frequency induction melting or the like. Subsequently, after the ingot is subjected to cutting or the like to obtain a sample having a desired shape, crystal controlled dissolution in nitrogen or a gaseous compound containing nitrogen,
For example, floating zone melting and Bridgman melting are performed. The pressure of the nitrogen or the gas containing nitrogen is 0.01 a
It may be performed at tm to 10 atm, and the crystal growth rate is desirably 0.1 mm / hr to 300 mm / hr. As the nitrogen or the gas containing nitrogen, for example, nitrogen, ammonia gas, and cyan gas are preferable.

The single crystal or unidirectionally solidified material obtained by such a method is one that has penetrated into its crystal lattice. Such a nitrogen compound is usually obtained by heat-treating a powdery sample in a nitrogen atmosphere. In this case, it is very difficult to produce a bulky sample, particularly a unidirectionally solidified material or a single crystal. On the other hand, in the above-described method, during the crystal controlled melting, for example, the floating zone melting, Bridgman melting, the molten metal involves nitrogen contained in the atmosphere,
Nitrogen is homogeneously incorporated in the alloy, and an alloy containing nitrogen even in the unidirectionally solidified material or single crystal can be obtained.

[0013]

The giant magnetostrictive alloy according to the present invention has a general formula represented by atomic%: RxT100-x-yMy (R is at least one of rare earth elements including Y, and T is at least one of Fe and Co). Seed element, M is N element, 20 ≦ x ≦ 60, 0 <y ≦
30), it has a high Curie temperature and excellent magnetostriction characteristics.

That is , in a giant magnetostrictive alloy in which M in the above general formula is nitrogen (N) , the nitrogen acts on the magnetic anisotropy of the rare earth-iron Laves type compound and also acts on the crystal structure thereof. The coercive force can be reduced without deteriorating the characteristics and other magnetic characteristics.

[0015]

Embodiments of the present invention will be described below. Reference example 1

An alloy having a composition as shown in Table 1 was prepared by arc melting, and then subjected to a homogenizing heat treatment at 900 ° C. for one week.
× 5 mm, test pieces (No. 1 to No. 1) having the composition shown in Table 1 below.
7). Here, No. 6, 7 are conventional B or C
Is not included, and is manufactured as a comparative example.

The magnetostriction value and the Curie temperature of each test piece produced by the above method were measured. The results are shown in Table 1 below. The magnetostriction value and Curie temperature were evaluated as follows. The magnetostriction characteristics were measured using a coercive gauge, and the magnetic field was generated by an opposing magnetic pole type electromagnet.
Evaluation was performed in a kOe applied magnetic field. In addition, the magnetostriction value is No. 6
Are normalized and the magnetostriction value of 1 is displayed. The Curie temperature was determined from the temperature characteristics of magnetization.

[0018]

[Table 1]

As is clear from Table 1, the test pieces (Nos. 1 to 5) made of the giant magnetostrictive alloy of Reference Example 1 have a higher Curie temperature than those of Comparative Examples (Nos. 6 and 7). It can also be seen that the magnetostriction value is larger than that of the comparative example.

Further, N, which is the giant magnetostrictive alloy of Reference Example 1 , is used.
o. No. 1 which is the giant magnetostrictive alloy of the comparative example A rod-shaped sample having a diameter of 10 mm and a length of 30 mm was prepared for No. 6, and the frequency characteristics of the displacement were evaluated. As the magnetic field applying means,
A sinusoidal alternating current was passed through the air-core coil, and the frequency was varied with a constant current. The amount of displacement is measured without contact using an optical displacement meter,
It was standardized by the displacement at 10 Hz. The result is shown in FIG.

As is apparent from FIG. 1, the giant magnetostrictive alloy of Reference Example 1 has a smaller change in the amount of displacement with respect to the frequency than that of the comparative example, and a good amount of displacement can be obtained even in a high frequency region. Example 1

An alloy having the composition shown in Table 2 below was prepared by arc melting, crushed to a particle size of 100 μm or less, and heat-treated at 500 ° C. × 1 hour in a nitrogen atmosphere of 1 atm. 1200 ℃ × 2 in nitrogen atmosphere
Specimen (N at 15 atomic%)
o. 8 to 12). The magnetostriction value and Curie temperature of the test pieces (Nos. 8 to 12) thus prepared were referred to.
It was determined in the same manner as in Example 1. The results are shown in Table 2 below.

[0023]

[Table 2] As is clear from Table 2, the test pieces (Nos. 8 to 12) made of the giant magnetostrictive alloy of the present invention can obtain the same effects as in Reference Example 1 described above. Example 2

Tb, Dy, Sm, Ho, Pr, Er, F
e, Co, Mn, Al, Zr, Ni, B, and P were blended so as to have the compositions shown in Table 3 below, and subjected to high frequency induction melting using an alumina crucible in an argon atmosphere to obtain 9 Various alloys were prepared. Subsequently, a sample having a diameter of 6 mm and a length of 50 mm was cut out from each of the above alloys.
Floating zone dissolution in nitrogen atmosphere at atmospheric pressure, growth rate 10μ
The test was performed under the conditions of m / sec.

The coercive force of the obtained samples (Nos. 1 to 9) was measured using a vibrating sample magnetometer. Further, a test piece similar to that of Example 1 was taken out from the sample,
The magnetostriction value and the Curie temperature were determined in the same manner as in Example 1. The results are shown in Table 3 below. Table 3
Indicates the coercive force of each alloy before the floating zone melting was performed in a nitrogen atmosphere.

[0026]

[Table 3]

As is clear from Table 3, the test pieces (Nos. 1 to 9) made of the giant magnetostrictive alloy of the present invention were 10 to 20 pieces.
It can be seen that Oe has a low coercive force, a high Curie temperature, and a large magnetostriction value.

Further, in Table 3 above, No. 1 of the present invention and the alloy of the present invention which had the composition of No. 1 and were obtained by melting in a floating zone in a nitrogen atmosphere. 4 mm in diameter and 10 mm in length from an alloy (comparative example) before melting in a floating zone in a nitrogen atmosphere having a composition of 1
A rod-shaped sample having a thickness of 1 mm was prepared, assembled into a magnetostrictive actuator, and the micro-displacement characteristics were evaluated. The actuator includes an air core coil as a magnetic field generating means, a permanent magnet for applying a DC bias, a spiral water cooling pipe for temperature management, a yoke, and a stay. In the measurement, a control current was supplied to the air-core coil, and a minute displacement at that time was measured. During the measurement, cooling water controlled at a constant temperature was supplied from a thermostat to keep the temperature constant. FIG. 2 shows a change in the displacement by the rod-shaped sample of the present invention, and FIG. 3 shows a change in the displacement by the rod-shaped sample of the comparative example. As is clear from FIGS. 2 and 3, the sample of the present invention can obtain a displacement characteristic with extremely small hysteresis compared to the sample of the comparative example.

[0029]

As described above, according to the present invention, a giant magnetostrictive alloy having a high Curie temperature and excellent magnetostrictive properties can be provided. In particular, according to the giant magnetostrictive alloy in which M in the above general formula is nitrogen (N), the nitrogen acts on the magnetic anisotropy of the rare earth-iron Laves type compound and also acts on the crystal structure thereof. The coercive force can be reduced without deteriorating other magnetic characteristics.

[Brief description of the drawings]

FIG. No. 1 and No. 1
FIG. 6 is a diagram showing frequency characteristics of a sample 6 (Comparative Example).

FIG. FIG. 2 is a diagram showing a micro-displacement characteristic of a rod-shaped sample of an alloy (the present invention) obtained by melting a floating zone in a nitrogen atmosphere and having a composition of No. 1;

FIG. FIG. 2 is a diagram showing a micro-displacement characteristic of a rod-shaped sample of an alloy (comparative example) having a composition of No. 1 and before floating zone melting in a nitrogen atmosphere.

Continuation of the front page (72) Inventor Masashi Sabashi 1 Toshiba Research Institute, Komukai, Kawasaki City, Kanagawa Prefecture (56) References JP-A-3-281757 (JP, A) JP-A-58- 3294 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22C 38/00-38/60 C22C 19/03 C22C 19/07 C22C 28/00

Claims (3)

(57) [Claims] 1. A general formula represented by atomic%: R _x T _100-xy M
_y (R is at least one of rare earth elements including Y,
T is at least one element of Fe and Co, and M is N
Element, 20 ≦ x ≦ 60, 0 <y ≦ 30). 2. The method according to claim 1, wherein the main phase is a Laves phase, and N is an interstitial element.
Characterized by being penetrated into the lattice of the main phase
The giant magnetostrictive alloy according to claim 1. 3. A super magnetostrictive alloy according to claim 1 or 2.
A magneto-mechanical mutation conversion device characterized by the above-mentioned.