JPH0827545A - Giant magnetostrictive material and manufacturing method thereof - Google Patents

Abstract

PURPOSE:To produce a material giving a huge magnetic strain even if an applying magnetic field is small by suppressing deterioration in the saturation value of magnetic strains and simultaneously regulating the grain size. CONSTITUTION:This material is a one having a compositional formula of (FexTb1-yDyy)100-zMz(M denotes Si/Al, and the atomic ratio of each element in the compsn. satisfies 1.8<=x<=2.2, 0<y<=0.7 and 1<=z<=5 and furthermore having a structure of fine crystalline grains of <=20nm diameter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a giant magnetostrictive material and a method for producing the same, and more particularly to a giant magnetostrictive material having excellent characteristics in a low magnetic field region and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally used magnetostrictive materials are
Ni is used as a metal, Fe-Co-V is used as an alloy, and NiCu.Co ferrite is used as a ferrite. However, since the magnetostriction of these conventional materials is very small at about 10 ^-6 to 10 ^-5 , it is greatly limited in application. Was there. However, in recent years, Fe ₂ Tb and Fe ₂ which are iron-rare earth intermetallic compounds have been used.
At room temperature, Sm alloy is about 20 times 10 ^-3 that of conventional materials.
A compound has been discovered that produces a table magnetostriction. Magnetic properties required for applying a giant magnetostrictive material to a microdevice, an actuator, etc. include, of course, a large magnetostriction value, easy magnetization, and a small coercive force. The above alloys have a large magnetocrystalline anisotropy and thus are hard to be magnetized, and are not suitable for practical use except for being used as a single crystal or a directionally solidified material. As means for reducing the crystal magnetic anisotropy, a method of amorphizing an alloy and a method of combining compounds having different positive and negative signs of magnetic anisotropy constant, for example, Fe ₂ Tb and Fe ₂
There is a method of combining Dy. In the former method, magnetic anisotropy is greatly reduced, but magnetostriction is also greatly reduced. (IEEE, Trans, MAG-
10 (1974), 807. ). On the other hand, according to the latter method, the amount of increase in magnetostriction in the low magnetic field region is significantly larger than that in the Fe ₂ Tb alloy. (For example, AECl
ark, Ferromagnetic Material
ls, Ed. by E. P Whohfarth, V
ol. 1, North-Holland, Amster
dam, (1980), p. 531) In addition to this, as a means for reducing the magnetic anisotropy, there is a method of refining crystal grains. This method is used as a means for reducing magnetostriction in a soft magnetic alloy. Recently, Fe-Tb-M system (M: Si, Al) having a large magnetic anisotropy, Fe
In the -Tb-B system and the Fe-Tb-Dy-B system, a method of reducing the magnetic anisotropy by refining crystal grains has been reported (Sci. Rep. RITU A39.
(1994) pp. 147-153. , The Japan Society for Applied Magnetics 17, 267-270 (1993): Spring Meeting of the Japan Institute of Metals (1993). 154).

[0003]

According to the above reported example, in the sample of the composition formula (Fe ₂ Tb _0.5 Dy _0.5 ) _100-X B _X , the addition element B is added by 7 atomic% or more. It is said that an amorphous material can be obtained. However, addition of B not only reduces the saturation value of magnetostriction but also B element is very expensive, so that it was not practical from the viewpoint of production cost. This Fe-Tb-Dy alloy has a problem that the saturation value of magnetostriction becomes smaller as the ratio of Dy becomes larger than that of the Fe-Tb alloy. Further, the composition (atomic ratio) of Fe ₂ Tb _0.27 Dy _0.73 that has the minimum magnetic anisotropy at room temperature is Fe ₂ Tb ([11
1]) and Fe ₂ Dy ([100]), which are solid binary alloys, tend to cause spin rearrangement due to temperature changes, and have a problem that the magnetostrictive characteristics become unstable. The present invention selects relatively inexpensive Si or Al as the additional element M in the Fe-Tb-Dy system having a large magnetic anisotropy, and selects the additional element M (at least one element of Si or Al). Provided are a material that suppresses a decrease in a saturation value of magnetostriction by reducing a ratio of an additive amount and Dy, and at the same time, exhibits a large magnetostriction even when an applied magnetic field is small by a control of a crystal grain size, and a manufacturing method thereof. The purpose is to

[0004]

The gist of the present invention is as follows. (1) having a composition formula (Fe _x Tb _1-y Dy _y ) _100-Z M _Z ,
In the composition formula, at least one selected from M: Si and Al, and the atomic ratio of each element in the composition satisfies the following three formulas, and 1.8 ≦ x ≦ 2.20 <y ≤0.7 1 ≤z≤5 Further, a giant magnetostrictive material having a structure composed of fine crystal grains having a diameter of 20 nm or less. (2) Fe-Tb-Dy-M for obtaining the target composition formula
(However, M is one or more selected from Si and Al)
An amorphous alloy or an alloy containing fine crystals produced by a liquid quenching method in which a system raw material metal or alloy is melted in an argon atmosphere and is injected through a nozzle onto a rotating roll surface to rapidly solidify A method of manufacturing a giant magnetostrictive material, characterized by performing a heat treatment at a temperature near a crystallization temperature Tx. (3) In the above (2), a fine crystal grain structure having a diameter of 20 nm or less is directly generated without passing through an amorphous material by controlling the peripheral speed of a rotary roll for injecting a quenching speed by the liquid quenching method. A method for producing the giant magnetostrictive material described. (4) The heat treatment temperature is 40 ° C /
The production of the giant magnetostrictive material according to (2) or (3) above, which is best performed at the crystallization temperature Tx measured in min, and at least at a temperature in the range of -50 ° C to + 50 ° C centered on Tx. Method.

The present invention will be described in detail below. The alloy composition of the present invention is based on iron (Fe) and contains terbium (T).
b), dysprosium (Dy) and additional element M. The ratio of Fe to Tb and Dy is Fe ₂
Since the compound of R (R: Tb and Dy) exhibits the maximum magnetostriction, 1.8 ≦ Fe / (Tb + Dy) ≦
It is preferably set to 2.2. When the atomic ratio of Fe / (Tb + Dy) is less than 1.8 or more than 2.2, the magnetostriction becomes small, so the atomic ratio of 1.8 or more and 2.2 or less is preferable. In the above composition formula, the ratio of Dy is 0.7 <
In the y region, spin rearrangement is likely to occur due to temperature change, and the magnetostriction characteristic becomes unstable. Also, the magnetostriction becomes small. Therefore, the substitution amount y of Dy is 0 <y ≦ 0.
7 is preferable.

The additional element M is at least one element selected from Si or Al and is added to obtain an amorphous alloy. In addition, the additional element M
Is also necessary for controlling the crystal grain size of the Fe ₂ R (R: Tb and Dy) compound to be 20 nm or less. On the other hand, when the cooling rate is controlled to directly crystallize without obtaining the amorphous substance, the additional element M also has a function of controlling the crystal grains to have a diameter of 20 nm or less. If the crystal grains become coarser than the diameter of 20 nm, they become magnetic anisotropy to increase the coercive force and deteriorate the characteristics of magnetostriction in the low magnetic field region. Therefore, in practice, it is necessary to control the crystal grain size to 20 nm or less. The magnetostriction was measured by a three-terminal capacitance method, the coercive force was measured by VSM, and the crystal grain size was measured by a transmission electron microscope.

If the addition amount of the additional element M is less than 1 atom%, it is difficult to produce an amorphous alloy or an alloy containing fine crystals, and if it is added in excess of 5 atom%, the magnetostriction value becomes large. Therefore, it is preferable that the content be 1 atomic% or more and 5 atomic% or less. Therefore, it is limited to 1 ≦ z ≦ 5. The heat treatment temperature is -50 ° C. to + 50 ° C. with respect to the crystallization temperature Tx measured at a temperature rise temperature of 40 deg / min of the quenched body, and particularly, the heat treatment is performed at the crystallization temperature Tx. It was found that the best characteristics were obtained. Heat treatment temperature is 1
The time is from 0 minutes to 10 hours. If the heat treatment temperature is too low, a crystalline alloy cannot be obtained, and if the heat treatment temperature is too high, the crystal grains become coarse and the magnetostrictive properties deteriorate.
The heat treatment atmosphere may be either in vacuum or in an inert gas.

[0008]

The present invention will be described in more detail with reference to the following examples.

Example 1 In an argon atmosphere, a single roll liquid quenching method was used to obtain a width of 1 mm at a roll peripheral speed of 32 m / sec.
Composition formula (Fe ₂ Tb _0.5 Dy _0.5 ) _97.5 S with a thickness of 20 μm
An amorphous ribbon having an atomic ratio of i _2.5 was prepared. FIG.
In addition, an amorphous sample, a sample heat-treated at 493 ° C., which is 70 ° C. lower than the crystallization temperature Tx = 563 ° C., a sample heat-treated at crystallization temperature Tx = 563 ° C., and 633 ° C. 70 ° C. higher than the crystallization temperature. The change of the magnetostriction with respect to the applied magnetic field of the sample heat-treated at. An increase in magnetostriction due to crystallization was confirmed in the heat-treated sample. In particular, in the sample heat-treated at the crystallization temperature Tx, a rapid increase in magnetostriction was observed at 30 to 50 kA / m on the low magnetic field side, and 627 × 1 even at an applied magnetic field of 240 kA / m.
A magnetostriction value of / 10 ⁶ was obtained. As a result of observing the structure with a transmission electron microscope, it was found to be composed of fine crystal grain aggregates having a diameter of 10 to 20 nm. However, if the heat treatment temperature is higher than the crystallization temperature, the crystal grains become coarse,
The magnetostriction characteristic in the low magnetic field region deteriorates. On the other hand, if the heat treatment temperature is too lower than the crystallization temperature, crystallization does not proceed,
Cannot get large magnetostriction.

Table 1 shows the values of magnetostriction and coercive force in the low magnetic field region due to the difference in heat treatment temperature.

[Table 1] A magnetostrictive material having excellent magnetostrictive characteristics in a low magnetic field region was obtained in a sample heat-treated at a temperature of 513 to 613 ° C. In particular, the sample heat-treated at the crystallization temperature Tx = 563 ° C. had the lowest coercive force and the excellent magnetostriction characteristic. Also, Tx = 563 ° C. to −70 ° C. 493
It was found that the samples heat-treated at 633 ° C. of + 70 ° C. and + 70 ° C. had significantly higher coercive force and were inferior in magnetostriction characteristics than the samples heat-treated at 513 ° C. of −50 ° C. and 613 ° C. of + 50 ° C., respectively. Therefore, it was found that it is best to perform the heat treatment at the crystallization temperature Tx, and the heat treatment should be performed at a temperature in the range of -50 ° C to + 50 ° C centering on Tx.

[0010]

[Examples 2 to 9] Width of 1 m at a peripheral speed of the roll of 32 m / sec by a single roll liquid quenching method in an argon atmosphere.
m, composition formula (Fe ₂ Tb _1-y Dy _y ) _{100-z with} a thickness of 20 μm
A ribbon containing an amorphous or fine crystal having an atomic ratio of M _z was prepared. It should be noted that when z = 2.5 atomic%, the composition of y = 0.7 contains a small amount of fine crystals in the amorphous structure, and as the ratio of Dy increases, the amorphous structure becomes amorphous. It becomes difficult to obtain an organization. Also, no significant difference was observed in the amorphous forming ability in the case of using either Si or Al as the additive element. Tables 2 to 5 show the applied magnetic fields 50 and 10 respectively.
The value of magnetostriction of the sample heat-treated at the crystallization temperature Tx at 0,240 (kA / m) is shown.

[0011]

[Table 2]

[0012]

[Table 3]

[0013]

[Table 4]

[0014]

[Table 5]

The materials of the examples in Tables 2 to 5 and y =
Regarding the composition of 0, the crystal grains are controlled to have a diameter of 20 nm or less, and the crystal grains of the reference example are not controlled F
Compared to e ₂ Tb, a significant increase in magnetostriction is observed at an applied magnetic field region of ~100kA / m. From the results of Examples 2 to 9, the magnetostriction at 240 kA / m tends to decrease with an increase in the substitution amount of Dy regardless of whether the additive element is Si or Al. However, in the applied magnetic field in the low magnetic field region, it exhibits excellent magnetostriction characteristics comparable to the amorphous material of the reference example. Moreover, also in the samples of Examples 2 to 9, as in Example 1, the heat treatment was performed at −50 ° C. to + with respect to the crystallization temperature Tx.
It was carried out at a temperature in the range of 50 ° C., but excellent characteristics were obtained although the characteristics were slightly inferior to those obtained by heat treatment at the crystallization temperature.

If the addition amount of the additional element M is less than 1 atomic%, it becomes difficult to obtain a ribbon containing amorphous or fine crystals, and it becomes impossible to uniformly control the crystal grains to 20 nm or less. Therefore, the magnetostriction characteristic in the low magnetic field region is deteriorated. However, even if the addition amount of the additional element M is less than 1 atom%, by further increasing the cooling rate,
It is believed possible to produce amorphous alloys or alloys containing fine crystals.

[0017]

[Embodiment 10] A composition formula (Fe ₂ Tb) having a width of 1 mm and a thickness of 20 μm under the condition that the peripheral speed of the roll was controlled to 10 to 21 m / sec by a single roll liquid quenching method in an argon atmosphere.
A quenched ribbon having an atomic ratio of _0.75 Dy _0.25 ) _97.5 Si _2.5 was prepared. The quenched ribbon produced at a quenching speed of 21 m / sec of the peripheral speed of the roll contains a fine grain structure of 10 nm or less in the amorphous phase. On the other hand, the thin ribbons produced at the peripheral speeds of 16 m / sec and 21 m / sec are both crystalline, and the crystal structure tends to become coarse due to the decrease in the peripheral speed. However, it was confirmed that fine crystals having a diameter of 20 nm or less are generated by performing the peripheral speed at 10 m / sec or more. Table 6 shows an example of the change in magnetostriction value due to the difference in roll peripheral speed when the applied magnetic field strength is 50, 100, and 240 kA / m, respectively.

[0018]

[Table 6]

Compared with the same composition as in Example 2, the magnetostriction at an applied magnetic field of 50 kA / m is 10 to 15 m / s.
In the peripheral speed condition of ec, although slightly inferior, 100,
At an applied magnetic field of 240 kA / m, the magnetostriction value was almost the same. In addition, the peripheral speed of the roll is 21 m / se
In the case of c, the magnetostriction under an applied magnetic field of 50 kA / m was remarkably excellent. Furthermore, the peripheral speed of the roll is 32 m /
When it is set to sec, it becomes amorphous and the magnetostriction is reduced. From this result, it is possible to obtain an arbitrary magnetostriction characteristic by controlling the quenching condition.
A material having excellent magnetostrictive properties can be obtained as in the case of
In the same manner as in Examples 1 to 9, the addition amount of the additional element M is 1 atomic%.
If it is less than the range, the crystal grains cannot be controlled to have a diameter of 20 nm or less, and the magnetostriction characteristic in the low magnetic field region is deteriorated. However, even if the addition amount of the additional element M is less than 1 atomic%, if the crystal grain can be controlled to have a diameter of 20 nm or less by further increasing the cooling rate, a material having a larger magnetostriction value will be obtained. The quenching method of the above embodiment is not limited to the single roll method.

[0020]

The giant magnetostrictive material according to the present invention is F
An e-Tb-Dy-M (where M is one or more elements selected from Si-Al) alloy, and has a composition formula (F
e _x Tb _1-y Dy _y ) _100-z M _z , and the atomic ratio of each element of the composition satisfies the following three formulas: 1.8 ≦ x ≦ 2.2 0 <y ≦ 0.7 1 ≦ z ≦ 5 Further, it is an alloy having a composition composed of fine crystal grains having a diameter of 20 nm or less. Therefore, the manufacturing method is to melt the raw material metal or alloy in an argon atmosphere and inject it onto a rotating roll surface through a nozzle to rapidly cool it. It is produced by producing an alloy containing the alloy and subjecting it to a heat treatment at a crystallization temperature Tx of the alloy or in the vicinity thereof at a temperature range of −50 ° C. ≦ Tx ≦ + 50 ° C. 10 ^-3 times as many magnetostrictive materials,
Since it has a small magnetic anisotropy, is easily magnetized, has a small coercive force, and has a large amount of magnetostriction even when the applied magnetic field is small, it has excellent magnetic characteristics applicable to microdevices, actuators and the like.

[Brief description of drawings]

FIG. 1 is a diagram showing a change in magnetostriction with respect to different applied magnetic fields when an amorphous alloy of an example according to the present invention is heat-treated at various temperatures around a crystallization temperature.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Akihisa Inoue Kawauchi Muzen, Aoba-ku, Sendai-shi, Miyagi 11-806 (72) Inventor Ken Masumoto 3-8-22, Uesugi, Aoba-ku, Sendai-shi, Miyagi

Claims (4)

[Claims] 1. A composition formula (Fe _x Tb _1-y Dy _y ) _100-Z M _Z
And in the composition formula, M: one or more selected from Si and Al, and
The atomic ratio of each element of the composition satisfies the following three formulas, and 1.8 ≤ x ≤ 2.2 0 <y ≤ 0.7 1 ≤ z ≤ 5 Further, it has a structure composed of fine crystal grains with a diameter of 20 nm or less. A giant magnetostrictive material characterized in that 2. Fe-Tb-D for obtaining a target composition formula
y-M (where M is at least one selected from Si and Al) -based raw material metal or alloy is melted in an argon atmosphere and injected through a nozzle onto a rotating roll surface for rapid solidification. A method for producing a giant magnetostrictive material, characterized in that an amorphous alloy or an alloy containing fine crystals produced by a liquid quenching method is heat-treated at a temperature near the crystallization temperature Tx of the alloy. 3. A fine crystal grain structure having a diameter of 20 nm or less is directly generated without passing through an amorphous material by controlling the peripheral speed of a rotary roll for injecting a quenching speed by the liquid quenching method. A method for manufacturing a giant magnetostrictive material according to. 4. The heat treatment temperature is best performed at a crystallization temperature Tx measured at a temperature rise temperature of the quenching body of 40 ° C./min, and at least -50 ° C. to +50 centering on Tx.
The method for producing a giant magnetostrictive material according to claim 2 or 3, which is performed at a temperature in the range of ° C.