JP3200137B2 - Giant magnetostrictive alloy - 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 exhibiting a large magnetostrictive property even in a low magnetic field.

[0002]

2. Description of the Related Art Since a magnetic substance is deformed by magnetostriction when a magnetic field is applied from the outside, the following magneto-mechanical displacement conversion device (hereinafter referred to as "device") has been developed by applying this magnetostriction. In other words, in the field of vibration, it can be applied to speakers, sonars, parts feeders, ultrasonic delay lines, ultrasonic processing machines, vibration isolation / vibration prevention mechanisms for motors, etc. in magnetostrictive transducers, and in precision positioning mechanisms as displacement control actuators in machine applications. It can be applied to valve control valves, mechanical switches, micro pumps, printer heads, etc. Further, it can be used as a magnetostrictive sensor for a pressure sensor, a knock sensor, a sound pressure sensor, and the like, and is a very industrially useful material for application to a surface acoustic wave application element.

[0003] The magnetostrictive materials used in these devices have conventionally been Ni-based alloys, Fe-Co alloys,
Although such a ferrite-based material has been known, much better (saturation magnetostriction lambda _s is 1000 × 10 ^-6 or higher) in the absolute amount of magnetostriction than these magnetostrictive materials recently (magnetostriction) rare earth - Laves ferrous Type intermetallic compound (general formula AB
No. ₂ , an alloy phase having a crystal structure of MgCu ₂ (cubic system, showing magnetostriction) was reported (JP-B-61-33).
No. 892).

[0004]

However, in practice, it is necessary to show a large magnetostriction even in a low magnetic field of several kOe. However, such a low magnetic field is still unsatisfactory, including the rare earth-iron alloy. A magnetostrictive alloy having a magnetostrictive amount to be developed has not been developed.

The present invention has been made in view of the above circumstances, and has as its object to provide a giant magnetostrictive alloy exhibiting a large amount of magnetostriction (magnetostrictive characteristics) even in a low magnetic field.

[0006]

In order to solve the above-mentioned problems, the present invention provides, as a first invention, a general formula Tb
_{x R y Dy 1-xy (} Fe 1-z Mn z) w (R is Y, L
at least one rare earth element selected from the group consisting of a, Ce, Pr, Nd and Sm, x + y <1,0.00
5 ≦ y ≦ 0.9, 0.005 ≦ z ≦ 0.5, 1.5 ≦ w
≦ 2.5) is provided.

The present invention provides, as a second invention, a compound represented by the general formula REFe _p (where RE is at least one kind of rare earth element;
5 ≦ p ≦ 2.5) and a giant magnetostrictive alloy grown in the <110> plane index.

Furthermore the present invention comprises at least one a third aspect, the general formula _{RE (Fe 1-qr Mn q} M r) s (RE is at least one rare earth element, M is selected from the group consisting of Al and Ga Metal element of 0.005 ≦ q ≦
0.5, 0.005 ≦ r ≦ 0.2, 1.90 ≦ s ≦ 2.
The present invention also provides a giant magnetostrictive alloy represented by 10), wherein the content of the 1-3 phase that is a different phase is 5% by volume or less.

The first invention according to the present invention, Tb _x R _y Dy
_{In 1-xy} (Fe _1-z Mn _z ) _w , Tb and Dy belong to the lanthanum series and, unlike 3d transition elements such as Fe and Ni, have extremely large crystal magnetic anisotropy due to the strong orbital angular momentum of 4f electrons. And a group exhibiting large magnetostriction characteristics. The R element is an element such as Pr which can be obtained relatively inexpensively. However, when the R element partially replaces the expensive Tb and Dy, the magnetic anisotropy of both rare earth atoms changes and the low magnetic field magnetostriction characteristic is reduced. Is improved.

[0010] Fe forms a Laves-type intermetallic compound (Laves phase) with rare earth elements such as Tb, Dy and R elements, and exhibits remarkable magnetostriction characteristics. Also F
When Mn is contained in addition to e, the magnetic anisotropy of the rare earth atom changes, and the Laves-type intermetallic compound exhibits excellent magnetic properties not only in a high magnetic field but also in a low magnetic field.

The giant magnetostrictive alloy according to the first invention has a T
b, R, Dy, Fe and Mn are x, y, z and w
Where Dy is indispensable and x + y <
Let it be 1. Note that Tb is effective for magnetostriction characteristics, and preferably, x ≧ 0.05. When x exceeds 0.5, the magnetic anisotropy energy of the alloy may be increased and the magnetostrictive properties may be reduced. Therefore, x ≦ 0.5 is preferable.
When y is less than 0.005, the influence of the R atom on the above-described magnetic anisotropy is insufficient, and when y exceeds 0.5, the Laves phase responsible for the magnetostrictive property decreases and the 1-3 phase which is a different phase is formed. (An alloy phase having a crystal structure in which the atomic ratio of rare earth to iron is 1: 3,
Magnetostriction is very small), etc., and both cause deterioration of magnetostriction characteristics.

On the other hand, if z is less than 0.005, the influence of Mn on the above-mentioned magnetic anisotropy becomes insufficient, and on the other hand, the value of 0.
If it exceeds 5, the Curie temperature lowers, and both of them cause deterioration of magnetostriction characteristics. Further, w is less than 1.5 or 2.
If it exceeds 5, the Laves phase that should be the main phase decreases, and the magnetostriction characteristics deteriorate.

Incidentally, in order to improve the corrosion resistance of the giant magnetostrictive alloy, a part of Fe can be replaced with a T element (Co, Ni). However, if the substitution amount is too large, the Curie temperature decreases and the magnetostriction characteristics deteriorate, so that Fe _1-a
When considered as T _a is, a ≦ 0.5 is the limit.

Further, in this giant magnetostrictive alloy, part of Mn is changed to the element M ′ (M ′) in order to improve material strength, saturation magnetostriction and corrosion resistance.
g, Al, Ga, Ru, Rh, Pd, Ag, Cd, I
n, Sn, Sb, Os, Ir, Pt, Au, Hg, Tl
And Pb). But this M '
Element also, when considered as _{Fe 1-z-z1 Mn z} M 'z1 to deteriorate magnetostriction and very substitution amount is large, Z1 ≦
0.2 is the limit.

The giant magnetostrictive alloy according to the first invention has a specific orientation of <110> and <11> which are cubic.
1> If the crystal is preferentially oriented in one of the directions (the crystal axes are aligned), the magnetostriction characteristics in this direction are larger than those in other directions.

Next, in the second invention according to the present invention, a giant magnetostrictive alloy REFe forming a Laves-type intermetallic compound of a rare earth element (RE) and iron for the above-described reason.
_{For p} (1.5 ≦ p ≦ 2.5), the crystal orientation is set to <11
0> direction.

That is, the present inventors have found that this rare earth-iron based giant magnetostrictive alloy is easy to grow in the <110> direction in both single crystal and polycrystal. Therefore, when the device is formed into a rod shape, for example, in the form of a rod, a flooding zone method (a method of gradually molding the entire molded product while moving a heated portion of the molded product during heat molding) or a thermal gradient is applied. In the casting or the like, if the growth is performed in the <110> direction, the manufacturing time is shortened (for example, in the case of the floating zone method, the number of repetitions of the pass for sequentially heating from one end to the other end of the rod is greatly increased. Can be reduced.).

Then, the giant magnetostrictive alloy REFe _p (1.5
≦ p ≦ 2.5), the magnetostriction is high even in a low magnetic field.
When the atomic ratio p is less than 1.5, the rare earth excess phase increases, and when it exceeds 2.5, the Laves phase decreases, and both have poor magnetostrictive characteristics.

By the way, the giant magnetostrictive alloy according to the second aspect of the present invention has an RE (Fe _{1 -cM} n _c ) _p (1.5 ≦ p ≦ 2.
(5, 0.005 ≦ c ≦ 0.5), substitution of Fe by Mn by the atomic ratio c can promote preferential growth of the crystal in the <110> direction. Note that the atomic ratio c is
If it is less than 0.005, this effect cannot be obtained. On the other hand, if it exceeds 0.5, the Curie temperature lowers and the magnetostriction characteristics deteriorate.

Further, the giant magnetostrictive alloy according to the second invention also has the same element T (C) as the giant magnetostrictive alloy according to the first invention.
o, Ni) and M 'element (Mg, Al, Ga, Ru, R
h, Pd, Ag, Cd, In, Sn, Sb, Os, I
When r, Pt, Au, Hg, Tl and Pb) are included in the same amount as in the first invention, the same effect can be obtained.

Further, when the axis of easy magnetization and the crystal axis are aligned, excellent magnetostriction characteristics can be obtained particularly at a low magnetic field.
Therefore, it is preferable to grow in the <110> direction with the <110> easy axis. When the crystal is grown in the <110> direction, the crystal grows in a plate shape. However, if the plate surfaces are aligned in the same direction, the <111> perpendicular to the <110> direction is formed.
It can be aligned in any direction. Therefore, an alloy piece in the <111> direction can be obtained from the alloy grown in the <110> direction. In this case, the axis of easy magnetization is preferably in the <111> direction in terms of magnetostriction characteristics.

Finally, the RE of the third invention according to the present invention
_{(Fe 1-qr Mn q M} r) s (0.005 ≦ q ≦ 0.
5,0.005 ≦ r ≦ 0.2, 1.90 ≦ s ≦ 2.1
0) The giant magnetostrictive alloy has the same rare earth-iron Laves phase as described above due to the atomic ratio s. However, since this giant magnetostrictive alloy first substituted a part of Fe with Mn, the Laves-type intermetallic compound Prevents the inevitable precipitation of 1-3 phases (5% by volume or less), which is unavoidable when forming, and is used immediately without performing homogenizing treatment (elimination of heterogeneous phase / segregation) for a long time after molding. it can. And M element (C, Mg, Al,
At least one of Si, Ca, Zr, Y, Ga and B)
Has the effect of preferentially precipitating the 1-2 phase,
n function. Note that the above-mentioned M 'element can be contained in the same atomic ratio range as the M element.

The atomic ratio q is 1 if it is less than 0.005.
The effect of suppressing the precipitation of the -3 phase cannot be obtained. On the other hand, if it exceeds 0.5, the Curie temperature decreases and the magnetostriction characteristics deteriorate. If the atomic ratio r is less than 0.005, the effect of the element M cannot be obtained, and if it exceeds 0.2, the magnetostriction decreases.

When the atomic ratio s is less than 1.9, M
Even if n is not present, there is almost no precipitation of the 1-3 phase, but the rare earth excess phase increases. On the other hand, if it exceeds 2.1, 1
The effect of suppressing -3 phase precipitation cannot be obtained.

The giant magnetostrictive alloy according to the third invention also has the same element T (C) as the giant magnetostrictive alloy according to the first and second inventions.
The same effect can be obtained by including the same substitution amount of (o, Ni). Further, it is possible to contain the above-mentioned M 'element such as a white metal element as long as the characteristics are not impaired. And the giant magnetostrictive alloy according to the third invention also has a specific orientation of cubic <110> like the giant magnetostrictive alloy according to the first invention.
If it is preferentially oriented in one of the <111> directions and the <111> direction (the crystal axes are aligned), the magnetostriction in this direction is larger than in other directions.

When this alloy was used as a master alloy during crystal growth, it was found that unidirectional solidification for aligning the crystal orientation in one direction and production of a single crystal could be easily performed.

[0027]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Examples 1 to 17> Examples 1 to 17 having the compositions according to the first invention of the present invention shown in Table 1 below and Comparative Examples 1 to 5 having the conventional rare earth-iron composition were used. Test pieces of 10 mm × 10 mm × 5 mm were formed from the magnetostrictive alloy. That is, as shown in Table 1, Examples 1 to 7, 15
The alloys of Examples 8 to 11 and Comparative Examples 1 to 5 were prepared by an arc melting method in a water-cooled copper boat in an argon atmosphere, and the alloys of Examples 8 to 11 were prepared by the unidirectional solidification method. A directionally solidified body is obtained, and for the alloys of Examples 12 to 14, the polycrystalline powder is sintered by applying a magnetic field to obtain a sintered body, and further subjected to a homogenization treatment at 900 ° C. for one week. Then, these alloy ingots, unidirectionally solidified bodies, and sintered bodies were individually cut to obtain test pieces having the above dimensions.

With respect to this test piece, a low magnetic field of 2 kOe was applied by a facing magnetic pole type electromagnet at room temperature, the amount of magnetostriction (magnetostriction characteristic) was measured by a strain gauge, and further normalized by the amount of magnetostriction of DyFe ₂ . The results are shown in Table 1.

[0030]

[Table 1]

As is clear from the table, the giant magnetostrictive alloy of the present embodiment has a much larger magnetostriction in a low magnetic field than the conventional rare earth-iron based magnetostrictive alloy (standardized magnetostrictive characteristics are 1 to 5). Characteristics (standardized magnetostriction characteristics are 8 to 18). And, among the giant magnetostrictive alloys of the present example, the unidirectionally solidified bodies (Examples 8 to 11) showed particularly large magnetostrictive characteristics.

<Examples 18 to 31> After preparing each composition shown in Table 2 below, Example 18 according to the second invention of the present invention was prepared.
For 〜31, the cubic <11
Unidirectional solids in which crystals were oriented in the <0> direction or in the <111> direction were obtained, and in Comparative Examples 6 to 9, magnetostrictive alloy pieces with random crystal orientations were obtained. Then, test pieces of 10 mm × 10 mm × 5 mm were formed by cutting.

With respect to this test piece, a low magnetic field of 2 kOe was applied in the orientation direction at room temperature by a facing magnetic pole type electromagnet, and the amount of magnetostriction (magnetostriction characteristics) was measured by a strain gauge.
Normalized by the magnetostriction of the Fe _2. The results are shown in Table 2.

Here, the <110> orientation means, for example,

Px = I ₂₂₀ / I ₃₁₁ ≧ 1 (I ₂₂₀ : <220> X-ray diffraction intensity, I ₃₁₁ : <311
> X-ray diffraction intensity).

Similarly, the <111> orientation

## EQU2 ## It is defined that Px = I ₂₂₂ / I ₃₁₁ ≧ 1.

[0036]

[Table 2]

As is clear from the table, the giant magnetostrictive alloy of the present embodiment shows that the conventional rare earth-
It shows much higher magnetostriction characteristics (standardized magnetostriction characteristics are 17-22 to -14 to -17) than iron-based magnetostrictive alloys (standardized magnetostriction characteristics are 1 to 8).

FIG. 1 shows the crystal orientation of the giant magnetostrictive alloy of Example 28 by X-ray diffraction. The giant magnetostrictive alloy of this example having a high low-field magnetostrictive property is certainly <1.
It can be seen that they are oriented in the 10> direction (observed as <220> and <440>, which are even multiples of <110>).

<Examples 32 to 36> After the respective compositions shown in Table 3 below were prepared, Example 32 according to the third invention of the present invention was carried out.
About 36 and Comparative Examples 10-14, after obtaining an alloy ingot by arc melting, 1
A test piece of 0 mm × 10 mm × 5 mm was formed.

With respect to this test piece, a low magnetic field of 2 kOe was applied by a facing magnetic pole type electromagnet at room temperature, the amount of magnetostriction (magnetostriction characteristic) was measured by a strain gauge, and the value was normalized by the amount of magnetostriction of DyFe ₂ . Table 3 also shows the results.

[0041]

[Table 3]

As is clear from the table, the giant magnetostrictive alloy of the present embodiment shows that the conventional rare earth-
Magnetostrictive properties significantly larger than iron-based magnetostrictive alloys (standardized magnetostrictive properties are 1 to 8) (standardized magnetostrictive properties are 10 to 18)
Is shown. And, the giant magnetostrictive alloy of the present embodiment is 1-
The content of the three phases is ○ (almost 0) or △ (1 to 5% by volume), which is overwhelmingly smaller than × (exceeding 5% by volume) in Comparative Examples 10 to 15. Therefore, the giant magnetostrictive alloy of this example does not require equipment for homogenization except for the 1-3 phase as a heterophase having a very small magnetostriction property, and can be used immediately after production without taking time for homogenization. .

FIGS. 2 and 3 show SEM (voltage 25
3 is a photomicrograph of a metallographic structure of Example 32 according to the third invention of the present invention and a metal structure of Comparative Example 11 taken at kV). The giant magnetostrictive alloy of Example 32 of FIG. It can be confirmed that many of the acicular 1-3 phases found in the magnetostrictive alloy of Example 11 do not exist.

[0044]

As described above, according to the giant magnetostrictive alloy of the present invention, the alloys according to the first, second and third inventions all show good magnetostriction characteristics in a low magnetic field, and Has the advantage that the material is economical, the second invention is easy to manufacture, and the third invention does not require a homogenization treatment.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction pattern diagram of a giant magnetostrictive alloy according to Example 28 of the present invention.

FIG. 2 is a micrograph showing a metal structure of a giant magnetostrictive alloy according to Example 32 of the present invention.

FIG. 3 is a micrograph showing the metal structure of the magnetostrictive alloy of Comparative Example 11.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masashi Sabashi 1 Toshiba, Komukai Toshiba-cho, Saisaki-ku, Kawasaki City, Kanagawa Prefecture (56) References JP-A-5-43992 (JP, A) JP-A-3-115540 (JP, A) JP-A-2-170942 (JP, A) JP-A-64-73050 (JP, A) JP-A-4-362159 (JP, A) JP-A-3-37182 (JP) JP-A-1-130221 (JP, A) JP-A-59-158574 (JP, A) JP-A-2-1455753 (JP, A) JP-A-55-134150 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C22C 38/00 C22C 38/04 H01L 41/20

Claims (3)

(57) [Claims] 1. The general formula Tb _x R _y Dy _1-xy (Fe _1-z
Mn _z ) _w (R is Y, La, Ce, Pr, Nd and S
at least one rare earth element selected from the group consisting of m, x + y <1,0.005 ≦ y ≦ 0.9,0.005
≦ z ≦ 0.5, 1.5 ≦ w ≦ 2.5). 2. A giant magnetostrictive alloy represented by a general formula REFe _p (RE is at least one rare earth element, 1.5 ≦ p ≦ 2.5) and grown in a plane index <110> direction. 3. A general formula _{RE (Fe 1-qr Mn q} M r) s
(RE is at least one rare earth element, M is C, Mg,
At least one metal element selected from the group consisting of Al, Si, Ca, Zr, Y, Ga and B, 0.005 ≦ q ≦
0.5, 0.005 ≦ r ≦ 0.2, 1.90 ≦ s ≦ 2.
A giant magnetostrictive alloy represented by 10), wherein the content of the 1-3 phase, which is a different phase, is 5% by volume or less.