JPS63166941A - Ni-ti functional material and its production - Google Patents

Abstract

PURPOSE:To manufacture an Ni-Ti functional material improved in functional characteristics, by bundling plural Ni-Ti bar bodies and excess materials consisting of Ni bar or Ti bar and by applying size reduction working and diffusion heat treatment to the resulting composite material. CONSTITUTION:A Ti material 5 is coated with Ni material 6 by plating, etc., to be formed into an Ni-Ti bar body 7 of the prescribed composition. Plural pieces of the above Ni-Ti bar bodies 7 and prescribed amounts of excess materials 8 consisting of Ni bar and/or Ti bar are bundled and, by means of a sheath material 10 such as soft-steel pipe, etc., formed into a composite material 9 having, in part, nonuniform-composition parts in its cross section. Subsequently, the above composite material 9 is subjected to high-degree size reduction working of >=about 50% draft by means of wire drawing, rolling, etc. Then, after the sheath material 10 is removed, diffusion heat treatment working is applied to the composite material 9. In this way, the above Ni-Ti bar bodies 7 are diffused to be formed into a base phase 2 of NiTi phase and, in this base phase 2, secondary phases 3 containing Ti2Ni phase and/or TiNi3 phase stretched uniformly from one end 1A to the other end 1B are formed from the excess materials 8, so that functional material 1 can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an Nt-Ti based functional material that can be suitably used as a shape memory alloy, a superelastic alloy, a vibration damping alloy, etc., and a method for manufacturing the same.

[Prior art]

Since it was discovered that Ni-74 alloy with a certain composition ratio has new functions such as shape memory effect, superelasticity, and pseudoelastic behavior, extensive research and development including application development has been carried out. There is.

These various functions mainly utilize the metal compound phase of NL-Ti phase created by the equivalent atomic ratio of Ni and Ti, and have conventionally been produced by the following method.

(1) One method is to use a predetermined amount of Ni:! : It is a melting method in which a product of a predetermined size is obtained by hot and cold processing and heat treatment on an ingot obtained by melting Ti, (2) and others. For example, this method uses a predetermined amount of Ti powder and Nt lead powder and mixes them, as disclosed in "Metal J September 1984 issue P34-37 "Production of TiNi-based memory alloy using powder alloy". This is an application of the so-called powder method in which an integrated Ni-Ti alloy is obtained by heat-treating and diffusing a mixed powder.

[Problem that the invention seeks to solve]

By the way, functional materials generally made of Ni-Ti alloys are
Compared to those made of other compositions (e.g. Cu-Zn system, Cu-Al-Zn system, etc.), it is superior not only in corrosion resistance but also in strength, recovery stress due to heat, recovery rate, and lifespan. Although it is becoming widely used, when considering its practical use, it is difficult to say that the general Ni-Ti alloys obtained by various conventional methods have sufficient properties, and in recent years, the requirements for these functional properties have been As the technology becomes more sophisticated, there is a need to respond to it.

[Purpose of the invention]

In view of the current situation, the present invention specifically combines a second phase containing a TiNis phase and/or a Ti2Ni phase from one end to the other end in a TiNi phase matrix whose composition ratio is controlled to a predetermined composition ratio. The present invention aims to provide a Ni-Ti based functional material (hereinafter referred to as "functional material") which has improved functional properties based on the above-mentioned properties, and to provide a method for producing the same.

[Disclosure of the invention]

An example of the present invention will be described below along with a manufacturing method thereof based on the accompanying drawings.

As shown in FIGS. 1 to 3, the functional material 1 of the present invention has a TiNi phase matrix 2 formed by predetermined Ni and TI, which has a structure extending from one end IA toward the other end IB. The functional material 1 is formed to include two phases 3, and in FIG.
It is finished in a round shape.

In the present invention, the final use of the functional material 1 is for functional alloys such as shape memory alloys, superelastic alloys, pseudoelastic alloys, and anti-vibration alloys, and it mainly contains at least 47 to 60 at% Ni and the balance Ti. Since it is obtained from the Ti1l phase, the parent phase 2 has a composition ratio controlled within the above range and also has the necessary functions.

Furthermore, in view of the necessity as a functional alloy (for example, adjustment of transformation point in the final product, workability, etc.), part of the composition of the matrix 2 is replaced with one or more third elements such as Cu, v+Mo1CrJ1+Co+Fe, etc. However, the amount thereof is at most 5 at% or less.

On the other hand, in this example, the second phase 3 compounded within the TiNi phase mother phase 2 along its longitudinal direction is a Ti+Ni phase or a TiNi phase.
It has a fibrous shape with a fine cross section containing at least an IS phase, and in FIG.

In this example, the second phase 3 is a TiNi three phase or a TiNi three phase or a TiNi three phase in this example.
It is composed of at least a Ji phase, but in this case, when looking in more detail, it is found that, for example, Ti2N
In the case of the i-phase, an intermediate phase 3A, which is a mixture of the two, is present between the i-phase and the parent phase 2. However, these are very intermediate, and can be substantially represented by the TiJi phase and the TiNi phase (symbol 3B). FIG. 2 is a sketch of the AA' cross section of the functional material 1 shown in FIG. 1, enlarged approximately 800 times, and shows its state. Further, reference numeral 3C in the same figure indicates that the surplus material 8 used here remains without being sufficiently diffused.

These 7iNis and TiJi phases are intermetallic compounds created by the compositional relationship between Ni and Ti elements, similar to the TiNi phase, which is the matrix 2, but they are characterized by being extremely hard and having high strength. have.

For example, looking at the TiNis phase mentioned above, its composition is obtained by approximately 75 at% Ni and the balance Ti, and its characteristics are a very hard phase with a Vickers hardness of 400 degrees or more, which is completely different from the general TiNi phase. It's different.

From this perspective, it appears that within the cross section of the second phase 3, the Ti or Ni composition changes gradually from the parent phase 2 toward the center of the second phase 3.

In addition, in this example, the second phase 3 distributed in the functional material 1 can be dispersed approximately evenly in a plurality of pieces with a cross-sectional area of 1000 μd or less, or distributed concentrated in an arbitrary part. , can be arbitrarily adjusted depending on the purpose of use of the functional material 1, and these can be arranged in parallel or in a spiral shape along the longitudinal direction of the functional material 1.

FIG. 3 shows another example of the present invention, in which a plurality of second phases 3 are twisted together in a spiral shape along the inside of the parent phase 2 formed in an irregular shape.

In such a configuration, two or more second phase 3 comrades may be partially combined in an adjacent portion in a certain portion, and may include a second phase that has grown larger.

Although the second phase 3 has mainly been described so far as having a circular cross section, the present invention is not limited thereto, and may be formed in a non-circular shape, such as an irregular shape, a flat shape, or a foil shape. , and when a plurality of them are combined, each size, shape, and dispersion state may be made uniform or non-uniform.

However, in general, it is preferable to provide them uniformly from the viewpoint of productivity and quality characteristics.

Furthermore, the second phase 3 can also have a TiJi phase and a TiNis phase dispersed therein.

As detailed above, compounding the second phase 3 extending along the longitudinal direction inside the matrix 2 causes it to function like a fiber-reinforced composite material, and for this reason, the strength such as recovery stress is reduced. The properties of the required functional materials can be improved, and the shape is not limited to just round wires, but can also be applied to plates, irregularly shaped products, etc.

The functional material 1 having such a novel structure is, for example,
This can be obtained by applying the method disclosed in Japanese Patent Application No. 60-260844, which was previously proposed by the applicant of the present application.

FIG. 4 is an example schematically showing a manufacturing method for obtaining the linear functional material 1 as shown in FIG.
A plurality of (for example, about 10 to 100,000) four filamentous Ti-N stripes 7 each having a predetermined amount of Ni material 6 coated on the surface of a Ti material 5 capable of forming a Ni material, and a Ni material and / or surplus material 8 selected from Ti materials (e.g. 1 to 100
(approximately 0 pieces) are combined and bundled to form a composite material 9 having a compositional non-uniformity portion where the composition ratio of Ni and Ti is partially different in its cross section, and a reduction process is performed on the composite material 9.
Diffusion processing is applied. Note that the code 1 in Figure 4
0 is an exterior material temporarily used to form the composite material 9, and a vibrator made of copper or mild steel can be used.

The Ti-Ni strip 7 used in this method is
In this example, on the surface of the Ti material 5 with a diameter of about 0.05 to 5W,
It is constructed by coating a controlled amount of Ni material 6 with the Ti material 5 by a method such as plating or crafting so that a TiNi material can be formed. Of course, the Ni-
As the Ti strip body 7, a structure obtained by twisting a Ti wire material and a Ni wire material as disclosed in the above-mentioned Japanese Patent Application No. 60-260844 can also be used.
Mechanically bonded composites such as those obtained by "Composite material for NiTi-based functional alloys" No. 38495 or "Composite material for NiTi-based functional alloys" published in Japanese Patent Application No. 142187/1987 may also be used.

Such a Ni-Ti strip 7 has already been adjusted to have a predetermined TiNi composition ratio for each strip 7, thus improving manufacturing efficiency.

On the other hand, as the surplus material 8, a wire material made of Ni and/or Ti and having a diameter of about 0.1 to 10 mm is preferably used.

Further, in the final stage, the surplus material 8 undergoes a diffusion reaction with the Ni-Ti strip 7 or the second phase 3 is formed inside the surplus material 8.
A second phase 3 containing Ti, Ni material or TjNis is formed by a diffusion reaction between the Ni and Ti contained to generate
Since the composition ratio and cross-sectional area of these materials change depending on the diffusion heat treatment conditions, it is desirable that the thickness, number, etc. of the surplus material 8 that can be used be determined in advance together with the heat treatment conditions. . Note that it is generally preferable to set the capacity of the surplus material 8 to be larger than that of each Ni material 6 or Ti material 5 in the Ni-Ti strip 7.

Such a composite material 9 is then subjected to cold or warm reduction processing by wire drawing, rolling, swaging, etc. to reduce its cross-sectional area and to finely form the Ni-Ti strips 7 and surplus materials 8. and eliminate internal gaps.

The processing rate is generally 50% or more, followed by a diffusion heat treatment that allows the Ni material 5 and Ti material 6 inside to diffuse into each other.

At this time, each of the Ni-Ti strips 7 is made of approximately uniform TiN.
The surplus material 8 is heated at a temperature of 700 to 1100° C. for a period of 10 to 100°C so that the surplus material 8 finally forms a second phase 3 extending from -@IA of the functional material 1 toward the other part IB.
Select the conditions according to the usage and purpose from the range of 30 hours.

In particular, the size of the second phase 3 changes mainly depending on the composition ratio relationship between Ni and Ti and the heat treatment conditions, so it is necessary to set the conditions in advance. An example of this condition is explained in the following example. Ru.

[Example-1] As a Ni41 strip that can form a TiNi phase, a pure Ni wire with a diameter of 0.2 mm and a pure Ti wire with a diameter of 0.18 mm were used in combination and twisted together, and the surplus material was Pure Ni materials with a diameter of 0.3 m were each prepared.

Then, by arranging a plurality of these Ni-Ti strips and the surplus material at a ratio of approximately 10:1 so that they are uniformly dispersed within the cross section, a composite material having a partially non-uniform composition ( 10 cranes in diameter), and its outer periphery was covered with an exterior material made of mild steel pipe.

The composite material covered with this exterior material is then subjected to strong processing with a processing rate of 50% or more using a cold wire drawing machine, and then only the exterior material is removed using a mechanical method. Each Ni-
A single wire rod was obtained in which the Ti strip EL and the surplus material were pressed together.

Then, we investigated the composition ratio of Ni and Ti at this time.
The value is almost unchanged from the ratio in the initial twisted state, and from this it can be inferred that both are reduced in diameter at approximately the same rate. At this time, the surplus material was also reduced to about 20 μm or less, and the internal gaps were completely eliminated by the wire drawing process.

For this reason, it is very easy to handle and can be used as is.
Diffusion heat treatment was performed for 15 hours in a vacuum heating furnace at 0° C., and as a result, the Ni—Ti strips produced a uniform TiNi phase by mutual diffusion. However, the surplus material with a relatively large cross-sectional area has not yet completely diffused, and a functional material with a diameter of 0.4 mm in which a fine second phase including three TxNi phases is mixed is obtained. The functional material was made continuous with approximately the same size in the longitudinal direction.

Samples were taken from this material and each transformation temperature was measured using a DSC calorimeter. As a result, it was found that the material was a shape memory alloy with an Af hot water temperature of 80°C.

[Example-2] 2000 Ni-Ti strips having the same configuration as those used in Example-1 were inserted into a mild steel pipe (1 m in length) and wire-drawn with a processing rate of 80% or more. After that, only the exterior material was removed mechanically.

Next, the remaining 100 composite wires and 10 pure Nl wires with a diameter of 0.1 mm as surplus material were each uniformly mixed, for a total of 110 wires, and re-focused in the same mild steel pipe as above for secondary production. After making it into a bundled material, it was further subjected to a wire drawing process of 90% or more to obtain a wire rod with a diameter of 1.2 wm. As a result, each pure Ni &! Each of the jI material and Tii material is in the form of fibers of about 1 to 3 μm, and the surplus material is also 14 μm.
They were each miniaturized to about m.

This greatly shortened the diffusion time, suppressed oxidation of the Ti wire, and greatly contributed to the homogenization of the obtained product.

From this state, as a result of removing the exterior material and performing a diffusion heat treatment at 1000°C for 10 hours, the Af hot water temperature was 80°C, and the surplus material contained a TiNis phase in the parent phase of the TiNi phase. A functional material in which two phases (cross-sectional area: 70 μd) were mixed was obtained.

[Comparative material]

Ni-Ti consisting of a uniform TiNi phase obtained by a dissolution method
The alloy (Ni 41 strips%) was processed to 0.7 wire by cold wire drawing and annealed at 900℃ for 0.5 hours, resulting in a shape memory with an Af hot water temperature of 85℃. Since a wire rod was obtained, this was used as a comparison material.

[Test results-1] The shape memory properties and superelastic properties of these functional materials were investigated. (a) Restoration stress measurement results Set on the test machine with a gauge length of 20 cranes and set it at 5%.
A pre-strain was added and the applied stress at that time was determined.

Once the stress was unloaded, hot air at 100°C was applied, and the recovery stress generated at that time was determined. As shown in Table 1, the functional material of the present invention is more effective than conventional materials. It appears that it has much higher functionality.

Table 1 (b) The annealed materials obtained from thermal fatigue life test examples 1 and 2 and comparative materials were cut into lengths of 5C11, one part was fixed, and the other part was loaded with 20 kg.
One cycle (approximately 10 seconds) of heating at 100°C and cooling at about 20°C with a stress of /man'' applied.
This is repeated alternately, and the displacement f1 changes accordingly.
(elongation) was investigated.

The results are shown in FIG.

[Test Results-2] In order to test the superelastic function of each of the functional materials obtained in Examples 1 and 2 and the comparative example, each sample was once processed at a processing rate of 30% and then heated at 400°C x 0. Heat treatment was performed for .5 hours.

The test method was to heat each sample above its Af temperature, set it on an Instron tensile tester with a gauge length of 20, give it a pre-strain of 5%, and then unload it. From the stress-strain diagram, the stress-induced martensite formation start stress σM and the reverse transformation start stress σR due to unloading were determined, and the superelastic properties of each material were compared.

Table 2 summarizes the results.

Table 2 [Effects of the Invention] As detailed above, the functional material of the present invention has a composite structure in which a second phase extending from one end of the TiNi phase to the other end is mixed into the mother phase of the TiNi phase. This improves general mechanical properties, resulting in materials with higher elongation, for example, with the same tensile strength. Regarding this point, the present inventors have confirmed that, for example, when the tensile strength is 170 kg/m+w'', an improvement of about 1.5 times has been achieved, from 7% to 10%, and it is possible to develop new applications. This is thought to be a factor in development.

It has improved various properties when used for superelasticity and shape memory. For example, in terms of mechanical properties in shape memory, both yield stress and recovery stress are far superior to conventional materials, and it also has resistance to thermal cycle fatigue. Since the product of the present invention has a stable lifespan, it can withstand long-term use.

This tendency is also seen in the case of superelasticity, and it can be seen that it has a great effect.

Therefore, the functional material of the present invention can reduce the material cost because its diameter and dimensions can be reduced, and the manufacturing method does not require large-scale equipment such as melting.
Because it can be obtained easily and in a short time, it is not related to production volume.
The industrial value of the present invention is great, as it is possible to obtain a homogeneous and high-characteristic product without being limited by size or shape.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an example of the functional material of the present invention, Fig. 2 is an enlarged cross-sectional view taken along line A-A', Fig. 3 is a perspective view showing another example of the functional material, and Fig. 4 is the functional material. FIG. 5 is a perspective view showing one manufacturing process, and a diagram showing the results of measuring the characteristics of the functional material. 1-Functional material, 2-.-TiNi phase matrix, 3-.Second phase, 5--Ni material, 6-Ti material, 7--
Ni-Ti strip, 8--surplus material, 9--composite material. Patent applicant Japan Seisen Co., Ltd. Agent
Patent Attorney Tadashi Naemura fJ4 ml Figure 5 Ikuru Bohi (time) March 8, 1986 2. fmei o name ,=,, system functional materials and their manufacturing method 3.1 Relationship with the person who makes the i correction Patent applicant address Higashi-ku, Osaka City [! ! 5-45 name
Representative of Nippon Seisen Co., Ltd. Kazu 1) Kado Hei 4, Agent address: 4-2-26-5 Nishinakajima, Yodoyo-ku, Osaka City, Number of inventions increased by amendment 16.11 Positive object Ha In the margin at the top of the paper, write ``A patent application pursuant to the proviso to Article 38 of the Patent Act,'' and place an item between the title of the invention column and the inventor column, and write ``In the scope of claims.'' The number of described inventions 2 is added.

Claims (3)

[Claims] (1) Ni-T containing at least Ni and Ti
An i-based functional material, the functional material includes Ti stretched from one end to the other end in a matrix consisting of a TiNi phase;
A Ni-Ti-based functional material characterized by containing a second phase including a Ni phase and/or a TiNi_3 phase. (2) The Ni-Ti-based functional material according to claim 1, wherein a plurality of the second phases exist in the cross section of the functional material and are uniformly dispersed. (3) Multiple N controlled to form a TiNi phase
The i-Ti strips and a predetermined amount of surplus material consisting of Ni strips and/or Ti strips are collected to form a composite material having a partial compositional non-uniformity in its cross section, and the composite material By applying size reduction processing and diffusion heat treatment to
A method for producing a Ni-Ti-based functional material, characterized in that a second phase containing an extended Ti_2Ni phase and/or TiNi_3 phase is generated in a TiNi phase matrix formed by the Ni-Ti strips.