JPH0375340A - Supermagnetstriction alloy - Google Patents

Abstract

PURPOSE:To offer the supermagnetstriction alloy by which high magnetstriction can be obtd. in a low magnetic field and having reduced change in magnetstriction value to the variation in temp. by forming it from the compsn. constituted, as a main phase, of Laves-type intermetallic compounds constituted of prescribed atomic ratios of Dy, Tb, Fe and Mn and one or both of Co and Ni. CONSTITUTION:The above supermagnetstriction alloy is formed by regulating Laves-type intermetallic compounds constituted of the compsn. expressed by inequality (shown in table 1) as a main phase. Figure shows the properties of temp.-magnetstriction amt. in a supermagnetstriction alloy of which Co and/or Ni is added to Dy-Tb-Fe-Mn. Then, as cleared from the same figure, the magnetstriction amt. is nearly be changed in the range from -100 to +100 deg.C when the above Co and/or Ni is added. However, the magnetstriction amt. is drastically changed in the case of comparative example free from the addition of Co and/or Ni. Furthermore, the magnetstriction alloy has excellent mechanical characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a giant magnetostrictive alloy that has large magnetostriction and is suitable for use in magnetostrictive elements used in magneto-mechanical displacement conversion devices and the like.

(Prior art) Applications of magnetostriction, which is a repellent strain produced by applying an external magnetic field to a magnetic material, include magnetostrictive filters, magnetostrictive sensors, ultrasonic delay lines,
There are magnetostrictive vibrators, etc. Conventionally, Ni-based alloys, Fe-Co alloys, ferrites, etc. have been used.

In recent years, with advances in measurement engineering and development in the field of precision machinery, there has been a need to develop a displacement drive unit that is indispensable for minute displacement control on the micron order. A magneto-mechanical conversion device using a magnetostrictive material is effective as one of the drive mechanisms for this displacement drive section. However, with conventional magnetostrictive materials, the absolute amount of displacement is not sufficient, and as a material for a drive part for precision displacement control on the micron order, they are not satisfactory not only in terms of absolute drive displacement amount but also in terms of precision control.

As a result of the research carried out by the present inventors to solve these problems, a Dy-Tb-Fe-Mn-based Laves-type intermetallic compound with a saturation magnetostriction (λS) exceeding 1000 x 10'''6 was discovered. I found that it can be obtained (Tokuko Sho 61-3)
No. 3892).

(Problems to be Solved by the Invention) As shown in Japanese Patent Publication No. 33892/1983, in practice, it is required to exhibit large magnetostriction in a low magnetic field of several koe and to have high toughness. There is.

However, the material disclosed in Japanese Patent Publication No. 61-33892 is still insufficient, and a magnetostrictive material with higher performance is desired.

Furthermore, when generating minute displacements, a problem is the change in magnetostrictive characteristics within the operating temperature range. If such temperature characteristics are not good, the amount of displacement will be temperature dependent, which will pose a serious problem in practice.

The present invention was made in consideration of such problems, and
The object of the present invention is to provide a giant magnetostrictive alloy that can obtain large magnetostriction in a low magnetic field, reduce changes in magnetostriction value due to temperature changes, and have excellent mechanical properties.

[Structure of the Invention] (Means and Effects for Solving the Problems) The present invention is characterized in that the main phase is a Laves-type intermetallic compound having a composition of Dy14Tb, (Fe, -x-yMnzXy)z in terms of particle ratio. It is a giant magnetostrictive alloy with the following characteristics.

The present inventors previously developed a Dy-Tb-Fe-Mn quaternary alloy with excellent magnetostriction (Patent No. 1370488).
issue). The present invention improves the temperature characteristics of the alloy without degrading its magnetostrictive characteristics.

FIG. 1 shows the temperature-magnetostriction characteristics of a giant magnetostrictive alloy in which Go and Ni are added to Dy-Tb-Fe-Mn. The figure also shows a comparative example without the addition of Go or Ni.
As is clear from the figure, the amount of magnetostriction of the addition of Go and Ni according to the present invention hardly changes between -100 and +100°C. On the other hand, in the case of the comparative example, there is a large change.

In the above formula, V indicates the amount of X (Co, Ni), but 0.
A remarkable effect of improving temperature characteristics can be obtained between 0.05 and 0.1. If the value of V is too large, the magnetostrictive properties will deteriorate, and addition of the X component has the effect of compensating for the decrease in the Curie temperature due to the addition of Mn, but if the value of V is too small, the effect of addition will not be noticeable.

Good magnetostrictive properties are obtained when a, which represents the ratio of Dy and Tb, is 0.2 to 0.9, but Dy-Tb- which is the basic component of the present invention
For the four elements Fa-Mn, a peak of magnetostriction value is observed in the region of a≧0.35. Therefore, preferably a=0.35~
It is 0.9. Figure 2 shows the results of investigating the relationship between the composition of rare earth metals and magnetostrictive properties.The zero alloy set is DYx-aTb.
a (Feo, sMno, asXo, oi) x, s C
However, X = Co1. As for the evaluation method of magnetostriction characteristics, the magnetostriction value on the vertical axis in Figure 6, which was obtained by applying a magnetic field of up to 10 kOe using the strain gauge method, is 2 kOe (low input power) considering the practicality of low magnetic field drive (low input power). D y is the magnetostriction value of each composition alloy when a magnetic field of Kloersted
From the same figure, which shows the relative value normalized by the magnetostriction value of Fe under the same conditions, it can be seen that a peak is observed in the region where a≧0.35 is exceeded.

The value indicating the amount of Mn is O,OS~0.4. If it is too large, the Curie temperature will drop, causing a practical problem, and if it is too small, toughness and workability will decrease.

2 indicates the ratio of rare earth metals to transition metals, and Z>2.
1, a different phase (rare earth: transition metal = 1 = 3, etc.) is generated, which deteriorates the magnetostrictive properties. In addition, at Z) 1.95, the proportion of Laves type intermetallic compounds in the alloy volume is almost 100.
%, the rare earth metal phase rich in ductility disappears, the toughness decreases, the material becomes difficult to process, and the magnetostrictive properties also decrease, so it is preferably mini 1.95. On the other hand, Z<1.4
In this case, the proportion of the Laves-type intermetallic compound in the alloy volume is less than 50%, and the magnetostriction properties decrease significantly.For example, at Z=2, the magnetostriction constant when 100% Laves-type intermetallic compound is 100. In this case, when Z<1.4, the magnetostriction constant is 30 to 50, and the deterioration of the magnetostrictive properties is significant, so it cannot be used as a practical material.

In the present invention, the rare earth elements are basically Dy-Tb, but La, Ce, etc. are used as long as the characteristics of the present invention are not impaired.
, Pr, Nd, Pa, Sm, Eu, Gd,
Ho.

Other rare earth elements such as Er, Tag, Yb, Lu, and Y may be added. The upper limit of the amount added is about 50 at% of the total amount of oy-'rb.

In the rare earth iron-based giant magnetostrictive alloy of the present invention, the main alloy (addition)
The elements iron and manganese form a Laves-type intermetallic compound with terbium and dysprosium, which provides good workability and toughness, and also significantly improves magnetostriction properties in the temperature range above room temperature, resulting in satisfactory properties. It is something.

Improvements in workability and toughness are achieved by selecting iron and manganese as transition metals constituting the Laves-type intermetallic compound. Furthermore, as a means to further improve workability and toughness, Laves-type intermetallic compounds (A
B2) The method is to improve the fracture toughness value by dispersing the highly ductile rare earth metal α phase (R) (Fig. 3). However, in this case, when compounds other than Laves-type intermetallic compounds are formed, magnetostriction occurs. Because the characteristics deteriorate significantly,
Based on the thermal equilibrium phase diagram, it is limited to the above rare earth metal/transition metal systems.

Further, the alloy of the present invention may be a polycrystalline body such as a cast body or a sintered body, or may be one whose crystallinity is controlled using a method such as crystal orientation by unidirectional solidification or a floating zone melt method.
The <111> direction is the axis of the amount of magnetostriction, and control in this direction can be expected to be effective.

(Example) After creating the alloy shown in Table 1 by arc melting,
A sample subjected to homogenization treatment at ℃×1veak was cut into a test piece of 101 m x 10 mm x 5 mm thick.

The magnetostrictive properties were evaluated at room temperature using a coercive gauge, the magnetic field was generated by an electromagnet with opposing magnetic poles, and an applied magnetic field of 2 kOe was evaluated.

Changes in the temperature characteristics of the amount of magnetostriction were conducted using the above evaluation method while changing the temperature of the sample.

The temperature characteristics of magnetostriction were obtained by normalizing the amount of change from -100°C to +100°C by the magnetostriction value at room temperature, and are shown in Table 1.

For the comparative evaluation of toughness, a drop test on a steel floor plate was adopted, in which test pieces of the same shape (same weight) were dropped naturally from a position of 3 m to examine the presence or absence of fracture. At this time, 10 test pieces of the same composition were subjected to a drop test, and when none of the test pieces were broken, it was marked as Δ when even 0.1 of the test pieces were broken, and when all of them were broken, it was marked as ×.

Further, the alloy composition was identified as a two-phase state or a single-phase state using an optical microscope and EDX.

As is clear from the examples shown in Table 1 below, the rare earth/iron giant magnetostrictive alloy according to the present invention has an extremely large magnetostriction property in a low magnetic field, and has a Laves-type intermetallic compound phase and a rare earth This is because it has a two-phase alloy structure enhanced by the metal α phase.

It was confirmed that toughness was also significantly improved.

For comparison, the characteristics of Comparative Example 1.2 are also shown in Table 1.

Although Comparative Example 1 shows good magnetostrictive properties, it has low toughness and is brittle.

Comparative Example 2 has good toughness, but the magnetostriction properties deteriorate significantly.

〔Effect of the invention〕

As explained above, the rare earth-iron giant magnetostrictive alloy of the present invention has extremely superior magnetostrictive properties compared to the properties of conventional magnetostrictive materials, and has good temperature stability and toughness of magnetostriction, which is essential for practical materials. It satisfies the following factors and has extremely excellent properties as a constituent material of the drive unit 1 for controlling minute displacements on the micron order, vibrators for generating strong ultrasonic waves, sensors, etc.

[Brief explanation of drawings]

FIG. 1 is a characteristic diagram showing temperature changes in the amount of magnetostriction, FIG. 2 is a diagram showing the relationship between magnetostriction characteristics and composition ratio, and FIG. 3 is a configuration diagram of a two-phase alloy structure.

Claims (1)

[Claims] Dy_1_-_aTb_a(Fe_1_-_x_-_y
Mn_xX_y)_z However, 0.2≦a≦0.9 0.05≦x≦0.4 0.05≦y≦0.1 1.4≦z≦2.1 x; Composition of at least one of Co and Ni A giant magnetostrictive alloy characterized by having a Laves-type intermetallic compound as its main phase.