JP2848643B2 - Giant magnetostrictive alloy and actuator for micro displacement control - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a giant magnetostrictive alloy having a large magnetostriction and suitable for a magnetostrictive element used for a magneto-mechanical displacement conversion device or the like.

(Prior art) When an external magnetic field is applied to a magnetic material, the magnetic material is deformed.
There are magnetostrictive sensors, magnetostrictive filters, ultrasonic delay lines, and the like. Conventionally, Ni-based alloys, Fe-Co alloys, ferrites and the like have been used.

In recent years, with the advance of measurement engineering and the development of the field of precision machinery, it is necessary to develop a displacement drive unit that cannot be controlled for micro displacement on the order of microns. A magneto-mechanical conversion device using a magnetostrictive alloy as one of the driving mechanisms of the displacement driving unit is effective. However, with conventional magnetostrictive alloys,
The absolute amount of displacement was not sufficient, and as a material for a precision displacement control drive unit on the order of microns, it was not satisfactory not only in terms of absolute drive displacement but also in terms of precision control.

As a result of research conducted by the present inventors to solve such problems, a Dy-Tb-Fe-Mn Laves-type intermetallic compound having a saturation magnetostriction (λ _s ) of more than 1000 × 10 ⁻⁶ is obtained. It was found to be obtained (Japanese Patent Publication No. 61-33892).

(Problems to be Solved by the Invention) As shown in JP-B-61-33892, practically, it is required to exhibit a large magnetostriction at a low magnetic field of about several kOe. However, the material disclosed in JP-B-61-33892 is still insufficient, and a higher-performance magnetostrictive material is desired.

The present invention has been made in view of such problems, and has as its object to provide a giant magnetostrictive alloy exhibiting large magnetostriction in a low magnetic field.

[Structure of the Invention] (Means for Solving the Problems and Action) As a result of the present inventors pursuing further improvement of the properties of the R-Fe-Mn-based giant magnetostrictive alloy, the following findings were obtained.

Since the giant magnetostrictive alloy of the present invention contains Mn, the magnetic anisotropy of rare earth atoms is changed, and excellent magnetostriction characteristics can be obtained not only in a high magnetic field but also in a low magnetic field. However, in the case of the R-Fe-Mn-based giant magnetostrictive alloy, the solidification process in the Mn-based Laves-type composition is complicated as shown in FIG. It has been found that it is difficult to control the <111> crystal axis and the like, and as a result, there is a case where the improvement in characteristics is prevented.

Therefore, the inventors found that the solidification process in Laves-type composition
The inclusion of simple Ga or the like (see FIG. 2) compared to the Mn-based alloy provides a Laves phase giant magnetostrictive alloy with good crystallinity, and the magnetostrictive properties of the R-Fe-Mn-based giant magnetostrictive alloy are improved. They found it to improve.

The present invention generally expressed in terms of atomic ratio formula _{R (Fe 1-yz Mn y} M z) w proviso R: at least one rare earth element M: Mg, Al, Ga, Ru, Rh, Pd, Ag, Cd, In , Sn, Sb, Os, Ir, P
At least one selected from t, Au, Hg, Tl and Pb is a giant magnetostrictive alloy characterized by the following: 0.005 ≦ y ≦ 0.5 0.005 ≦ z ≦ 0.2 1.5 ≦ w ≦ 2.5.

Rare earth elements are La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, E
r, Tm, Yb, Lu, and one or more combinations selected from these are Pr, Nd, Sm, Tb, Dy, Ho, Er, Tm, TbDy, TbHo, Tb
A combination of Pr, SmYb, TbDyHo, TbDyPr, and TbPrHo is preferred.

 Preferably, 1.7 <w <2 0.01 ≦ z <0.15 0.01 <y <0.2.

If y is less than 0.005, the effect of Mn on the anisotropy of rare earth atoms is reduced, and if y is more than 0.6, the Curie temperature is reduced, and the magnetostriction is deteriorated. z is 0.005
If it is smaller, the solidification process is changed, and the effect of improving crystallinity is reduced. If it exceeds 0.2, the amount of magnetostriction is reduced, and the magnetostriction characteristics are deteriorated. If w is outside the above range, the Laves phase that should be the main phase decreases, and the magnetostriction characteristics deteriorate.

It is also possible to partially replace Fe with a T element (Co, Ni). However, if the substitution amount is too large, the Curie temperature is lowered, and the magnetic properties are lowered.
_{When 1−x} Tx), x ≦ 0.5 is the limit.

Furthermore, when the alloy of the present invention has a specific orientation of cubic, for example, <100
The preferred orientation in the>, <110>, and <111> directions further improves the magnetostrictive characteristics in those directions. The magnetostrictive properties are further improved by subjecting the preferentially oriented alloy to a heat treatment in a magnetic field to align the axis of easy magnetization in a specific direction.

(Example) An example of the present invention will be described below.

Example 1 The composition shown in Table 1 was prepared by an arc melting method using an isotropic polycrystal,
After making it as a unidirectional solid and sintered body in which the crystal is oriented in a specific direction of cubic, it is subjected to homogenization treatment at 900 ° C × 1 week,
A test piece of 10 mm × 10 mm × 5 mm was formed by cutting. The magnetostriction characteristics were evaluated at room temperature using a strain gauge and a magnetic field generated by a facing magnetic pole type magnet under a 2 kOe applied magnetic field. Each magnetostriction is expressed by the value normalized by the magnetostriction amount of DyFe _2.

As is evident from Table 1, the alloy of the present invention has improved magnetostriction characteristics in a low magnetic field, and in particular, an alloy in which crystals are oriented in a specific cubic direction is excellent.

Example 2 The alloys shown in Table 2 were prepared by the method described in Example 1, and each were subjected to a heat treatment in a magnetic field under the conditions shown in the table. The magnetostriction characteristics were evaluated in the same manner as in Example 1.

As is evident from Table 2, the properties are further improved by performing the heat treatment in a magnetic field to give the easy axis of magnetization in a specific direction.

[Effects of the Invention] As described above, the giant magnetostrictive alloy of the present invention has extremely excellent magnetostrictive properties as compared with the properties of conventional magnetostrictive materials, and is sufficient as a practical material. Particularly, it has extremely excellent characteristics as a constituent material of a micro displacement control drive unit, a vibrator for generating strong ultrasonic waves, a sensor, and the like.

[Brief description of the drawings]

 FIG. 1 is a phase diagram of Dy-Mn, and FIG. 2 is a phase diagram of Dy-Ga.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C22C 28 / 00,38 / 00-38/60

Claims (2)

(57) [Claims] 1. A general expressed in atomic ratio formula _{R ((Fe 1-x T} x) 1-yz Mn y M z) w proviso R: at least one rare earth element T: at least one of Co and Ni M: At least one selected from Mg, Al, Ga, Ru, Rh, Pd, Ag, Os, Ir, Pt and Au 0 ≦ x ≦ 0.5 0.005 ≦ y ≦ 0.5 0.005 ≦ z ≦ 0.2 1.5 ≦ w ≦ 2.5 A giant magnetostrictive alloy, characterized in that: 2. A drive unit for controlling minute displacement, wherein the giant magnetostrictive alloy according to claim 1 is used.