JPS62297448A - Composite material for niti series functional alloy - Google Patents

Abstract

PURPOSE:To provide a uniform composition and uniform characteristics by uniformly arranging plural Ti filaments and Ni filaments and bringing them into close contact with each other by mechanical bonding. CONSTITUTION:Plural Ti filaments 2 and Ni filaments 3 are uniformly arranged and the adjacent filaments 2, 3 are integrated by mechanical bonding to obtain a composite material 1 for an NiTi series functional alloy consisting of 40-60atom% Ni and the balance Ti. The composite material 1 is composed of composite wires 4 each formed by twisting Ti filaments 2 and Ni filaments 3 together. The filaments 2, 3 have <=0.01mm<2> cross-sectional area.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Technical Field] The present invention relates to a composite material for NiTi-based functional alloys, such as shape memory alloys, superelastic alloys, and anti-vibration alloys.

[Conventional technology]

Since it was discovered that NiTi alloys with a certain composition ratio have various functions such as shape memory effect, B-elastic behavior, and anti-vibration effect, they have been used in a wide range of applications, and compared to the conventional It has been mainly manufactured using the following methods.

One method is to hot or cold process an ingot obtained by melting a predetermined amount of T1 and Ni, and in some cases heat treat it to produce a product with a predetermined size. This is the way to get it.

Another method is to mix a predetermined amount of Ti powder and N1 powder and obtain an integral NiT1 alloy by heat treatment and diffusion.

However, these methods leave many problems that must be solved when considering the quality and economic efficiency of the NiT1 alloy.

That is, in the former melting method, (1) Generally, Ti material has a property of being easily oxidized, and in this melting method, the Ti material is further melted, so that the Ti material is not oxidized. N
The absolute amount of TI that can be alloyed with the i material is insufficient, making it difficult to obtain an alloy having a desired composition ratio.

(2) Furthermore, during the melting process, oxygen, carbon, and other gaseous impurities are often mixed in.
As shown in FIG. 6, a large number of black dot-shaped oxides are present inside.

Such inconveniences have various adverse effects on the characteristics of the product.

For example, even if the N1 composition in a shape memory alloy is changed by only 0.1 at%, the transformation point of the resulting product will change significantly by several degrees, and the operating temperature will change accordingly. Fluctuations in the composition ratio due to this pose a major problem.

(3) Also, when processing NiT1 alloy, which is difficult to process, the degree of processing per diameter reduction cannot be set too thick, and as a result, when obtaining a thin wire of about 1 crane in size, requires many steps, and therefore has low productivity and is expensive.

(4) Furthermore, this method, which uses melting equipment, is not suitable for small-scale production.

On the other hand, in the latter powder metallurgy method, the powder generally has a large surface area, and an oxide layer is generated on the surface of the Ti powder in particular.
Since this is accompanied by the formation of oxides that become TI and Ni2O after diffusion, there is a problem that the transformation point is abnormally lowered, and furthermore, the remaining internal pores reduce the strength and life.

Furthermore, in Japanese Patent Application Laid-open No. 59-116340, Ti material and N
It has been proposed to pressure-bond the i-material and heat them to obtain a NiTi phase, but since the diffusion rate is generally very slow, it is difficult to produce large-diameter products. For example, to obtain a wire material with a diameter of about 0.3 to 1.5 mm, which is in relatively high demand for shape memory alloys, a long diffusion process of over 100 hours is required. Therefore, this method cannot be called practical after all.

(Objective of the invention) In view of the current situation, the present invention is based on uniformly dispersing Ti wire material and N1 wire material that are controlled to have a predetermined composition ratio, directly any size N
It was born from the idea of obtaining an iTi-based alloy, and its purpose was to obtain an iTi-based alloy that was highly productive, homogeneous, and inexpensive.
The purpose of the present invention is to provide a composite material that can be suitably used in the production of T-based functional alloys.

[Disclosure of the invention]

A composite material for a NiTi-based functional alloy controlled to contain at least 48 to 60 at% of Ni and TI, the composite material having a plurality of Ti filaments therein, This is a composite material of a NiTl-based functional alloy, characterized in that these are uniformly dispersed, and the adjacent wire materials are integrated by mechanical bonding to each other.

An embodiment of the composite material of the present invention will be described below based on the drawings.

Figure 1 shows a plurality of Ti films whose composition ratio has been controlled in advance.
The filament material 2 and the Ni filament material 3 are uniformly dispersed in the cross section and are mechanically connected to form a single filament composite material 1. Also second
As an example of improving the uniform dispersibility of the Ti wire material 2 and the Ni wire material 3, the figure shows a composite wire in which the respective wire materials 2 and 3 are twisted together to have a predetermined composition ratio. Each composite material 1 formed using a plurality of bodies 4 is shown.

The Ti wire material 2 and Ni wire material 3 used in the present invention are:
They are formed of pure metal wire materials of pure Ti material and pure Ni material, respectively. , and if necessary, in order to improve various properties such as transformation point, mechanical properties, processing type, etc. of the final product, for example, Cu, V% MOSCr, A1 is added to the T1 base material or N1 base material.
Other elements such as 1Fe can also be contained. However, its content is desirably about 5 at% or less of the total composite.

The final use of the composite material 1 of the present invention is, for example, as a functional alloy such as a shape memory alloy or a superelastic alloy.
Since the i-phase is basically used, the thickness and number of the Ti wire material 2 and the Ni wire material 3 are determined in advance so that the composition of the composite material 1 contains at least 48 to 60 at% of N1 and Ti. The combination is adjusted.

Furthermore, these Ti wire materials 2 and Ni wire materials 3 do not necessarily have to be of the same thickness, but may have different wire diameters, and their cross sections may be circular, polygonal, or even polygonal. may have an irregular shape.

Further, the thickness and number of the internal Ti wire material 2 and Ni wire material 3 may be set freely depending on the finished dimensions of the final product, etc., and generally, for example, 0. 0
It is preferable to include a larger number (for example, 100 or more, preferably 1000 or more) of fine fibrous filaments having a cross-sectional area of 1 mm or less, and by forming in this way, the final This greatly shortens the time required for Ti and Ni diffusion treatment, and improves the surface condition and homogeneity of the product.

Furthermore, when using a twisted composite wire body 4 as shown in FIG. 2, the composite wire body 4 is already twisted in such a manner that the atomic weight composition ratio is already controlled to a predetermined composition ratio. Therefore, no matter how it is distributed, the composite material 1
The uniformity of the composition ratio inside is sufficiently maintained.

Further, suppose that an attempt is made to obtain a NiT1 alloy with a stoichiometric Ti:Ni atomic weight composition ratio of 1:1, and both the Ti wire material 2 and the Ni wire material 3 inside the composite wire body 4 are If the wire diameters are approximately the same, the ratio of wires must be controlled in advance by a method such as setting it to a ratio of 3:2.Of course, even if the wire diameters are different, calculations and adjustments must be made to match it. Needless to say.

In this case, the number of each of the wire materials constituting the composite wire body 4 and the number of twists may be freely selected and practiced, but from the viewpoint of uniformity of composition distribution, for example, A small number of books, about 2 to 10, is desirable.

Furthermore, in the present invention, a plurality of such composite wires can be further twisted together to form a single thicker composite wire 4, or these can be directly made into the composite material 1.

Therefore, in the latter case, the composite wire body 4 is oriented along the longitudinal direction of the composite material 1, as shown in FIG.

In the composite material 1 of the present invention, in its cross section, the T1 wire material 2 and the Ni wire material 3 are extremely uniformly dispersed, and the adjacent Ti wire material 2 and Ni wire material are both A composite material 1 that is mechanically bonded and integrated at the interface between
is formed.

In this specification, "mechanical bonding" is defined as "a bond obtained by mechanical pressure bonding means such as wire drawing, rolling, press working, etc., and which is capable of forming the composite material in that state alone." ``a state of being connected to a certain degree''.

Moreover, the cross-sectional shape of the Ti wire material 2 and the Ni wire material 3 has an irregular shape with fine irregularities on the outer periphery, as shown in FIG. 3, for example.

This shape is created when the composite material is manufactured by applying sufficient pressure (force) from the cross-sectional direction to make the internal filaments finer and to eliminate the pores between them.

In the present invention, such fine irregularities are also utilized, which is effective in increasing the bonding strength of adjacent wire members and forming a stronger integrated product.

Such a state can also be understood from FIG. 3, which is also an enlarged view of the AA' cross section of FIG. 1.

Of course, in the present invention, other types than those described above may be used.

Further, in the present invention, for example, a plurality of N1 wire members 2 or T
It also includes a portion where the i-line members 3 partially contact each other. In this case, it may be difficult to distinguish the boundaries between Ni wire materials, but they can be recognized by using special chemicals (11 food methods).

Moreover, the composite material 1 of the present invention can be applied in various ways. For example, as shown in FIG. 4, in addition to the Ti wire material 2 and the N1 wire material 3, the third element is It is also possible to use these in combination as 6, and the shape and dimensions of the composite material 1 can also be set arbitrarily.

Examples thereof include, for example, wire rods, plate materials, square timbers, other blank articles, and various non-circular articles.

In order to obtain the composite material 1 of the present invention, as disclosed in Japanese Patent Application No. 60-260844 previously proposed by the applicant, it is necessary to use a tubular material made of an inexpensive and easily workable material such as iron, copper, or Monel alloy. A predetermined amount of Ni wire material 2 and Ti wire material 3 are inserted into the matrix material, and processed at a processing rate of, for example, about 50% or more (preferably cold working) to reduce their fine diameter. Along with this, the internal Ti wire material 2 and Ni wire material 3 are also made almost equally fine, internal voids are removed, and each wire material is mechanically bonded.

Note that the composite material 1 of the present invention can be obtained by removing the matrix material by mechanical means, chemical means, etc. after processing.

Especially in this case, the fact that the above processing (diameter reduction processing) is performed at a high processing rate means that the wire rod (especially TI
It is advantageous to reduce the influence of the oxidized layer that has been generated on the surface of the wire (wire rod), and to obtain a product (functional alloy) with properties close to the target.

Further, in order to manufacture a desired functional alloy using such a composite material 1, the Ti and N
An alloy of NiTi phase in which i and i are diffused can be obtained.

However, due to diffusion, compared to the undiffused state,
Since it has the disadvantage of extremely low workability, it is preferable to process it directly to near the final dimensions and shape, and then perform a diffusion treatment as a final treatment.

Furthermore, although it is desired that the diffusion treatment be carried out sufficiently, according to an experiment conducted by the inventor of the present application, the heating temperature was 90°C.
It was found that the diffusion rate at 0° C. produced a 40 μm thick NiTi phase after 2 hours of treatment, and 70 μm thick NiTi phase after 10 hours of treatment. Therefore, it has been found that if each of the above-mentioned wire materials is refined to a diameter of about 70 μm, a uniform NiTi phase alloy can be obtained by a diffusion treatment of about 5 hours.

Next, examples of the present invention will be described.

[Example-1] Composite wire material (internal wire material) made by burning TI wire material with a diameter of 0.18 mm and Ni wire material with a diameter of 0.2 mm at a ratio of 2:1. 500 pieces (including 3 pieces) were each bundled in parallel and inserted into a mild steel pipe-shaped matrix with an outer diameter of 12 m and a wall thickness of 1 piece.

Next, this material was subjected to cold wire drawing at a total processing rate of 99.8%, and after being processed into a long wire with an overall diameter of 0.6 mm,
The exterior matrix material was removed by a mechanical method to obtain a composite material of the present invention.

As a result of adjusting the obtained composite material, the cross-sectional area of each of the filaments was refined to a fiber strip of approximately 2 × 10'ms2, which correlated with the processing rate, and the composition ratio was also different from the state of the material. It was found that the composite material contained 49.8 at% of Ni, which was hardly changed.

Furthermore, even when this composite material was tightly bent with pliers, no cracks were observed on its surface, and it was found that further processing was necessary.゛[Example-2] The composite material obtained in Example-1 was heat-treated in vacuum at 1000°C for 10 hours to form an N1 composite material in which Ni and Ti were sufficiently diffused.
．． A Ti alloy was obtained.

When the NiT1 alloy thus obtained was bent and heated by hand, it was found that it had a shape memory function that allowed it to recover to its original state.

Table 1 shows the measurement results of the characteristic values of this alloy.

Table 1 [Example-3] A total of 160 composites of 80 composites with an N1 composition of 49.8 at% obtained in Example-1 and 80 composites with an N1 composition of 54 at% treated in the same manner. The materials were dispersed appropriately and inserted into the aforementioned mild steel vibrator. This material was further reduced in outer diameter 11j using a wire drawing machine, and then the sheathing material was removed. As a result, it was found that the material had a sufficient integrity.

Then, heat treatment was further performed at a temperature of 900° C. for 20 hours to obtain a NiTi alloy with an N1 composition ratio of 52 at % and a residual amount of T1.

[Example-4] A Ti material with a diameter of 1 fl and a Ni material of approximately the same size were made with an inner dimension of 30 mm.
fl square pipes (made of mild steel) arranged alternately on the shore, totaling 100
In addition to packing 0 pieces, the rolling reduction rate is 99.998%.
A strip product was obtained by cold rolling.

The processing was repeated several times.

Further, as a result of observing the cross-section of the sample using a microscope, it was found that each of the above-mentioned materials had been refined to a cross-sectional area of 8×IQ=mt2, and that countless irregularities were observed on the outer periphery of each of the internal materials. After removing the exterior material, hold the composite material with pliers and
An 80° right angle repeated bending test was conducted, and it was found that the welding was sufficiently pressure-welded.

[Example-5] 100 straight piltm Ti wire materials and 1fl diameter N
By appropriately dispersing 65 single wire materials and further 100 Cu wire materials with a diameter of 0.2 fl, one composite wire material in which a total of 265 wire materials are twisted together is obtained, and this composite wire material Fifty pieces were inserted into the exterior material of a mild steel pipe with a length of 1 m, cold worked at a working rate of 98%, and further subjected to a diffusion treatment at 900 to 1000°C.

Note that the exterior material was removed in advance before the heat treatment.

As a result, NiT with a composition of 43%Ti-54%Ni-3%Cu (reduction%) and a hysteresis of 4°C was obtained.
An i-based alloy was obtained.

〔Effect of the invention〕

As mentioned above, the composite material of the present invention is made by uniformly dispersing the T1 wire material and the Ni wire material, which are controlled in advance to have a predetermined composition ratio, and bringing them into sufficient contact by mechanical bonding. As a result, variations in composition within the alloy can be greatly suppressed and products with uniform characteristics can be obtained.

Moreover, in the composite material, each of the above-mentioned materials constituting it is hardly diffused, and moreover, the Ni material and the Ti material are hardly diffused.
Since the material is soft, it is possible to set an extremely high processing rate compared to conventional processing of NiT1 alloy.

In addition, since each wire material can be made finer to the point of fiber, it is also possible to shorten the diffusion time, and the shape and dimensions of the resulting alloy can be freely set. For example, the final dimensions can be directly adjusted. products can also be obtained.

Furthermore, since the composite material of the present invention can be formed without any steps such as melting, the oxidation of the Ti material and the generation of oxides due to gas impurities, etc. are extremely difficult, as shown in Figure 7. It is possible to obtain very clean tissue with very little hysteresis.

Furthermore, in the present invention, it is possible to obtain a NiTi-based functional alloy with arbitrary characteristics by arbitrarily selecting a plurality of composite materials with different composition ratios of N1 and Ti and further combining them. 1. Its applicability is extremely high.

[Brief explanation of the drawing]

FIG. 1 is an enlarged perspective view schematically showing one embodiment of the present invention, FIG. 2 is an enlarged perspective view schematically showing another embodiment,
Fig. 3 is an enlarged sectional view showing the composition of the composite material, Fig. 4 is a schematic enlarged perspective view showing another example, and Fig. 5.6 shows the metal structure of the N1T1 alloy obtained by the conventional melting method. photograph,
FIG. 7 is a photograph of the metal structure of the NiTi-based functional alloy composite material of the present invention in a state where it has been subjected to a diffusion treatment. 1-Composite material, 2-Ti wire material, 3.-N1 wire material, 4-.-Composite wire material. Patent applicant Japan Seisen Co., Ltd. Agent Patent attorney Tadashi Naemura Figure 1 Figure 2 Figure 3

Claims (7)

[Claims] (1) A composite material for a NiTi-based functional alloy containing 48 to 60 at% Ni and at least Ti, the composite material having a composite Ti wire material and a Ni wire material inside. What is claimed is: 1. A composite material for a NiTi-based functional alloy, characterized in that the above-mentioned wire materials are uniformly dispersed, and the adjacent wire materials are integrated by mechanical bonding to each other. (2) The composite material according to claim 1, wherein the composite material includes at least one composite wire body formed by twisting a Ti wire material and a Ni wire material. (3) The Ti wire material and the Ni wire material are each 0.01
Claim 2 having a cross-sectional area of mm^2 or less
Composite material as described in section. (4) The composite material according to claim 3, wherein the Ti wire material and/or the Ni wire material have an irregular cross-sectional shape. (5) The composite material according to claim 4, wherein the Ti wire material and the Ni wire material have fine irregularities formed on their outer surfaces. (6) The composite material according to claim 1, wherein the composite material includes a filament material made fine by diameter reduction processing. (7) The composite material contains 5 at% or less of Cu, V, Mo,
The composite material according to claim 1, which contains one or more third elements selected from Cr, Al, and Fe.