JP2002105561A - Low thermal expansion alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a low thermal expansion alloy having shape memorizing characteristics and superelasticity and exhibiting excellent low thermal expanding characteristics in a wide temperature range. SOLUTION: Strain is applied to a shape memory alloy in which thermoelastic type martensitic transformation occurs by cold working, and by the control of the total working ratio, the low thermal expansion alloy in which the average thermal expansion coefficient at -150 to 150 deg.C is variable in the range of -10×10-6 to 10×10-6/k can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low thermal expansion alloy having shape memory characteristics and superelasticity and exhibiting excellent low thermal expansion characteristics in a wide temperature range.

[0002]

2. Description of the Related Art Low thermal expansion alloys have been used for structural materials for precision equipment, heat sink materials, lead frame materials, and the like.
It used the Invar effect based on magnetic transformation of NiCo alloy and the like.

However, it has recently been proposed to use a shape memory alloy as a low thermal expansion alloy for a heat sink material.
And JP-A-10-92989. As shape memory alloys, in JP-A-10-17959, CuAlMn-based alloy and Ni
Ti-based alloys are disclosed in JP-A-10-92989, NiTi-based alloys and
CuZnAl-based alloys are listed respectively. This heat sink material is obtained by dispersing a fibrous or particulate shape memory alloy as a low thermal expansion material in a good heat conductive material (copper alloy or the like). The effect is that the good heat conductive material enhances the heat dissipation,
Further, a compressive stress is generated in the shape memory alloy to which the pre-strain has been imparted to such an extent that the superelastic property is not destroyed, so that the thermal expansion coefficient of the entire composite material is reduced. In other words, this is a use method in which the expansion of the entire composite is reduced by applying a strain to the good thermal conductor with the recovery force due to the normal shape memory effect, and does not utilize the low thermal expansion characteristics of the shape memory alloy.

[0004] This is because shape memory alloys such as CuAlMn-based alloys, CuZnAl-based alloys, and NiTi-based alloys exhibit a remarkable shape memory effect accompanying the reverse transformation of thermoelastic martensitic transformation. As for the thermal expansion coefficient, only a change caused by a volume change accompanying the transformation occurs, and -5 × 10
^This is because a low coefficient of thermal expansion such as ^{−6 to} 5 × 10 ⁻⁶ / k cannot be obtained.

Therefore, the above-mentioned shape memory alloy has a wider low thermal expansion temperature range (coefficient of thermal expansion is −5 × 10 ^{−6 to} 5 × 10 5).
^It refers to the difference between the upper limit temperature and the lower limit temperature indicating ^-6 / k. Hereinafter the same)
Or a characteristic in which the coefficient of thermal expansion is variable in a wide temperature range (a temperature range defined by a specific upper limit temperature and a lower limit temperature; the same applies hereinafter). It can be expected to be used as an excellent low thermal expansion alloy in various applications including the above applications (hereinafter, the above-mentioned characteristics in which the thermal expansion coefficient is variable in a wide low thermal expansion temperature range and a wide temperature range are summarized as low thermal expansion characteristics. ).

Accordingly, it is an object of the present invention to provide a low thermal expansion alloy having shape memory characteristics and superelasticity, and exhibiting excellent low thermal expansion characteristics in a wide temperature range.

[0007]

Means for Solving the Problems In view of the above-mentioned problems, as a result of intensive studies, the present inventors have solved the above-mentioned problems by imparting distortion due to cold working to a shape memory alloy that causes thermoelastic martensitic transformation. The present inventor has found out what can be done and arrived at the present invention.

That is, the low thermal expansion alloy of the present invention is obtained by cold working of a shape memory alloy which generates a thermoelastic martensitic transformation, and has an average thermal expansion coefficient of -10 × at -150 to 150 ° C. by controlling the working ratio. It is characterized by being variable between 10 ^{-6 and} 10 × 10 ^-6 / k.

[0009] Further, it can have a low thermal expansion temperature range of 50 ° C or more.

The above-described cold working may be performed in only one direction, or may be performed in a plurality of different directions in the case of rolling or the like.

In the low thermal expansion alloy, the difference between the martensitic transformation start temperature and the martensitic transformation end temperature is preferably 30 ° C. or more.

The thermo-elastic martensitic transformation-induced shape memory alloys include CuAlMn-based alloys, CuZnAl-based alloys and
It is preferable that at least one selected from NiTi-based alloys is used.

In the case of CuAlMn-based alloys and CuZnAl-based alloys, the total working rate by cold working (total working rate when a plurality of stages of cold working are performed) is preferably 0.05 to 20%. In the case of a NiTi-based alloy, the content is preferably 0.05 to 40%.

Further, the low thermal expansion alloy of the present invention may be an alloy having a multiphase structure containing at least 15% by volume or more of a phase which causes the thermoelastic martensitic transformation.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [1] Shape memory alloy causing thermoelastic martensitic transformation The shape memory alloy causing thermoelastic martensitic transformation used in the present invention has a high-temperature β phase (body-centered cubic), An alloy that becomes a martensite phase (monoclinic) at low temperatures and has shape memory properties and superelasticity. As such alloys, Cu-based alloys including CuAlMn-based alloys and CuZnAl-based alloys, Ti-based alloys, Fe-based alloys, Au-based alloys,
Examples thereof include a NiTi-based alloy and a NiAl-based alloy. Among them, a CuAlMn-based alloy, a CuZnAl-based alloy, and a NiTi-based alloy are preferable.

(1) Cu-based alloy (a) CuAlMn-based alloy The preferred composition of the CuAlMn-based alloy is 5 to 11% by mass.
Examples thereof include those containing Al and 5 to 20% by mass of Mn, with the balance being Cu and unavoidable impurities.

If the content of the Al element is less than 5% by mass, CuAlMn
The base alloy cannot form a β single phase, and if it exceeds 11% by mass, the CuAlMn base alloy becomes extremely brittle. The more preferable content of the Al element changes depending on the content of the Mn element.
% By mass.

By containing the Mn element, the composition range in which the β phase can exist is widened toward the low Al side, and the cold workability of the CuAlMn-based alloy is remarkably improved. If the addition amount of the Mn element is less than 5% by mass, satisfactory cold workability cannot be obtained, and a β single phase region cannot be formed. If the amount of the Mn element exceeds 20% by mass, sufficient shape recovery characteristics cannot be obtained. The preferred Mn content is 8 to 14% by mass. As the Mn content increases, the low thermal expansion temperature range shifts to a lower temperature region.

The CuAlMn-based alloy having the above composition is excellent in hot workability and cold workability, can be worked at 90% or more in the cold state, and can be easily formed into a fine wire or the like.

(B) CuZnAl-based alloy The preferred composition of the CuZnAl-based alloy is 4 to 10% by mass.
Examples thereof include those containing Al and 12 to 30% by mass of Zn, with the balance being Cu and unavoidable impurities.

If the content of the Al element is less than 4% by mass, CuZnAl
The base alloy cannot form a β single phase, and if it exceeds 10% by mass, the CuZnAl base alloy becomes extremely brittle. The more preferable content of the Al element changes depending on the content of the Zn element.
% By mass.

By containing the Zn element, the composition range in which the β phase can be present expands to the low Al side, and the cold workability of the CuZnAl-based alloy is remarkably improved. If the amount of the Zn element is less than 12% by mass, satisfactory cold workability cannot be obtained, and a β single phase region cannot be formed. If the amount of the Zn element exceeds 30% by mass, sufficient shape recovery characteristics cannot be obtained. The preferred Zn content is 18 to 26% by mass.

(C) Elements other than the basic composition In addition to the elements of the above basic composition, the Cu-based alloy of the present invention further comprises Ni, Co, Fe, Ti, V, Cr, Si, Nb, Mo, W, Sn , S
b, Mg, P, Be, Zr, B, C, Ag, Zn (in CuAlMn-based alloy), Mn (in CuZnAl-based alloy) and one or more selected from the group consisting of misch metal Can be contained. Among them, Ni and / or Co are particularly preferred. These elements exert the effect of solid solution strengthening while maintaining the cold workability to improve the strength of the Cu-based alloy.
The content of these additional elements is preferably 0.001 to 10% by mass in total, and particularly preferably 0.001 to 5% by mass.
If the total content of these elements exceeds 10% by mass, the martensitic transformation temperature decreases, and the β single phase structure becomes unstable.

Ni, Co, Fe, Sn and Sb are effective elements for strengthening the matrix structure. The preferred contents of Ni and Fe are each 0.001 to 3% by mass. Co also strengthens precipitation by forming CoAl, but when excessive, reduces the toughness of the alloy. The preferred content of Co is 0.001 to 2% by mass. Sn
And the preferable content of Sb is 0.001 to 1% by mass, respectively.

Ti is an element which inhibits alloy properties, N and O
Forms oxides and nitrides. When added in combination with B, boron is formed and contributes to precipitation strengthening.
The preferable content of Ti is 0.001 to 2% by mass.

W, V, Nb, Mo and Zr have the effect of improving hardness and improving wear resistance. Further, since these elements hardly form a solid solution in the alloy matrix, they precipitate as bcc crystals and are effective for precipitation strengthening. The preferred contents of W, V, Nb, Mo and Zr are each 0.001 to 1% by mass.

Cr is an element effective for maintaining abrasion resistance and corrosion resistance. The preferable Cr content is 0.001 to 2% by mass.

Si has the effect of improving corrosion resistance. Si
Is preferably 0.001 to 2% by mass.

Mg is an element that inhibits alloy properties, N and O
Is removed, and S, which is an inhibitory element, is fixed as a sulfide, which is effective in improving hot workability and toughness. However, a large amount of addition causes grain boundary segregation and causes embrittlement. The preferred content of Mg is 0.001 to 0.5% by mass.

P acts as a deoxidizing agent and has an effect of improving toughness. The preferred content of P is 0.01 to 0.5% by mass.

Be has the effect of strengthening the base tissue. Be
Is preferably 0.001 to 1% by mass.

In a CuAlMn-based alloy, Zn has the effect of increasing the shape memory temperature. The preferred content of Zn is 0.00
It is 1 to 5% by mass.

B and C segregate at the grain boundaries and have the effect of strengthening the grain boundaries. The preferred content of B and C is 0.001 each.
0.5% by mass.

Ag has the effect of improving cold workability. The preferred content of Ag is 0.001 to 2% by mass.

The misch metal acts as a deoxidizing agent and has an effect of improving toughness. The preferred content of misch metal is 0.001 to 5% by mass.

(2) NiTi-based alloy The preferred composition of the NiTi-based alloy is 54.0 to 57.1% by mass.
And 42.9 to 46.0% by mass of Ti and other inevitable impurities.

When the Ni content is less than 54.0% by mass or more than 57.1% by mass, there is no shape memory effect. Preferably, the content of Ni is 55.1 to 56.1% by mass.

Part of Ni and / or Ti is V, Cr, Fe, Co, C
By substituting one or more of u and Nb in the range of 0.01 to 5.0% by mass, strength, corrosion resistance, workability and the like can be improved according to various uses. But 0.01
If the amount is less than 5% by mass, the effect is small.

The composition in this case is 50.0 to 57.0 mass% of N
i, 40.0 to 50.0% by mass of Ti, and V, Cr, Fe, Co, Cu, Nb
It is preferable that one or more of the above are contained in an amount of 0.01 to 5.0% by mass.

[2] Manufacturing Method The low thermal expansion alloy of the present invention may be an alloy containing 15% by volume or more of a β phase and an alloy having a multiphase structure including an α phase, an intermetallic compound, a Heusler phase, and the like. The content of the phase is more preferably 50% by volume or more. Particularly preferably, substantially β
It consists of a single phase.

(1) Forming of Alloy An alloy having the composition described in [1] is melt-cast and formed into a desired shape by a forming method such as hot rolling, cold rolling, and pressing.

(2) Solution treatment Next, the solution is heated in the solid solution temperature range to transform the crystal structure into a β single phase. The holding time at the β single phase region temperature may be 0.1 minute or more, but if the holding time exceeds 60 minutes, the effect of oxidation cannot be ignored, so the holding time is preferably 0.1 to 60 minutes. When it is desired to obtain an alloy composed of a β single phase, it is preferable to freeze the β single phase state by rapidly cooling at a rate of 50 ° C./sec or more after the heat treatment. More preferred cooling rate is 200
C / sec or more. The quenching is carried out by putting into a coolant such as water or by forced air cooling. When the cooling rate is less than 50 ° C / sec, α
Precipitation of phases and the like occurs, resulting in an alloy having a multiphase structure.

For a Cu-based alloy, the preferred heating temperature is
The temperature is at least 600 ° C, more preferably 700 to 900 ° C.

In the NiTi-based alloy, a preferable heating temperature is 400 ° C. or higher, more preferably 500 to 900 ° C.

However, when the composition of the CuAlMn-based alloy is 8% by mass or less of the Al element, and when the composition of the CuZnAl-based alloy is 5% by mass or less of the Al element, the heating temperature is set to 400 ° C. or more. If the temperature is lower than 700 ° C., an alloy containing a β phase of 15% by volume or more and having a multiphase structure such as an α phase, an intermetallic compound, and a Heusler phase is obtained.

(3) Aging Treatment Next, it is preferable to perform aging treatment on the Cu-based alloy. When it is desired to obtain an alloy consisting of a β single phase, if the aging treatment temperature is too low, the β phase is unstable, and if left at room temperature, the martensitic transformation temperature may change. Conversely, if the aging temperature is too high, precipitation of the α phase occurs, and the shape memory properties and superelasticity tend to decrease.

The preferred aging temperature for obtaining an alloy consisting of β single phase is 250 ° C. or less, more preferably 100 to 200 ° C.
It is.

The aging time varies depending on the composition of the alloy, but is preferably 1 to 300 minutes, more preferably 5 to 100 minutes. If the aging treatment time is less than 1 minute, a sufficient aging effect cannot be obtained. If the aging treatment time exceeds 300 minutes, precipitation of the α phase occurs, and the low thermal expansion characteristics are reduced.

The alloy composed of the β single phase is a low rigid material having shape memory characteristics and superelasticity. On the other hand, a multi-phase alloy composed of the α phase and other phases is a highly rigid material, but is inferior in shape memory characteristics or superelasticity. However, since the α phase has better workability, a high cold working rate can be realized.

(4) Cold working After the aging treatment, a strong working deformation by cold working or warm working is applied to form permanent deformation such as dislocation together with the martensite phase. Preferably, it is cold working. Permanent strains such as dislocations introduced appropriately by controlling the processing rate (internal stress field)
The transformation width of the austenite reverse transformation and the martensitic transformation can be extended to 30 ° C. or more by utilizing the above. Thereby, the above-mentioned transformation accompanying the temperature change occurs little by little, and the expansion and contraction due to the temperature change are canceled little by little, so that a low thermal expansion characteristic can be obtained in a wide temperature range. Therefore, if the working ratio is too low, the transformation width is small, and consequently the temperature range at which low thermal expansion characteristics can be obtained becomes narrow. Conversely, if the working ratio is too high, the martensitic transformation is hindered and the thermal expansion coefficient becomes large.

The principle by which low thermal expansion characteristics are obtained will be described with reference to FIGS. FIG. 1 shows an example of a change in the coefficient of thermal expansion when the low thermal expansion alloy of the present invention is heated and cooled. M in FIG.
s, Mf, As and Af indicate a martensitic transformation start temperature, a martensitic transformation end temperature, an austenite reverse transformation start temperature and an austenite reverse transformation end temperature, respectively. In this case, the transformation width of the martensitic transformation (Ms-Mf)
Alternatively, it is preferable to perform processing so that the transformation width (Af-As) of the austenite reverse transformation is 30 ° C. or more. FIG. 2 shows an example of the thermal expansion coefficient and the thermal expansion coefficient change when the same low thermal expansion alloy is heated and cooled. In FIG. 2, Ts and Tf are the upper limit temperature and the lower limit temperature of the low thermal expansion temperature range in the cooling process, respectively, and Ts 'and Tf' are the lower limit temperature and the upper limit temperature of the low thermal expansion temperature range in the heating process, respectively. Further, the low thermal expansion temperature width in each process of cooling and heating is defined as a cooling low thermal expansion temperature width ΔT (= Ts−Tf) and a heating low thermal expansion temperature width ΔT ′.
(= Tf′−Ts ′). As described above, by appropriately expanding the transformation width, a wide low thermal expansion temperature width ΔT and ΔT ′ can be obtained.
Is obtained.

However, in the case of a NiTi-based alloy, a low thermal expansion temperature range may be obtained even in a martensite phase region of Mf or less. The reason for this is not clear, but it is conceivable that the remaining austenite phase is transformed little by little even below Mf.

Further, by changing the working ratio, not only the transformation temperature range but also the form of the temperature change-thermal expansion coefficient hysteresis changes as shown in FIG. 3, and accordingly, the form of the temperature change-thermal expansion coefficient hysteresis also changes. -150 to 150 ° C by selecting the alloy composition and / or processing rate as appropriate
, An arbitrary average coefficient of thermal expansion can be selectively obtained between -10 × 10 ^{−6 and} 10 × 10 ⁻⁶ / k.

As the cold working, cold rolling, cold drawing and the like are preferable. The cold working may be performed in only one direction, or may be repeated in different directions.
When one-way processing is performed, since anisotropy occurs, particularly excellent low thermal expansion characteristics can be obtained in the processing direction. It is suitable for a member such as a bar used in a use form in which thermal stress is applied only in one direction. In order to reduce the anisotropy of the low thermal expansion characteristic and obtain the low thermal expansion characteristic in a plurality of directions, it is preferable to process in at least two directions.
In the case of processing in a plurality of different directions, it is preferable that the sum of the processing rates of the processing performed in each direction is a necessary total processing rate. For example, when making a sample with a maximum processing rate of 10% by cross rolling in two directions,
Roll at a processing rate of 5% per direction.

However, since cold working can generally be carried out only at a small working rate, the required working is difficult.
If the processing is not completed in one processing step, it is preferable to perform a plurality of stages of cold working. C in one processing step
0.01-3% for u-base alloy, 0.01-2% for NiTi-base alloy
% Is preferred.

The total processing rate at which excellent low thermal expansion characteristics are obtained is 0.05 to 20% for CuAlMn-based alloy and CuZnAl-based alloy.
Is more preferable, and more preferably 2 to 10%. Also, Ni
For Ti-based alloys, the content is preferably 0.05 to 40%, more preferably 1 to 8%. -150 ~
At 150 ° C., an arbitrary average coefficient of thermal expansion and a wide low thermal expansion temperature range of 50 ° C. or more can be obtained between −10 × 10 ^{−6 and} 10 × 10 ⁻⁶ / k.

The cold working is preferably performed in a temperature range of 0 to 80 ° C.

Further, by cold working, a wire including a plate material,
It can be processed into various forms such as rods and pipes.

When cold rolling is performed in the production of a sheet material, the thickness of the slab before rolling is preferably 0.01 to 10 mm. If the thickness of the slab before rolling is in the above range, the same low thermal expansion characteristics can be obtained at the same processing rate.

[4] Characteristics The low thermal expansion alloy strained as described above exhibits excellent low thermal expansion characteristics as described in the following (1) to (4) as compared with the conventional one.

(1) Adjustment of thermal expansion coefficient By controlling the processing rate and the processing direction, the temperature of -150 to 150 ° C.
-10 × 10 in range ^-6~ 10 × 10^-6any flat between / k
Adjust the thermal expansion coefficient or set a negative thermal expansion coefficient.
It is possible to

(2) Temperature range of low thermal expansion coefficient By controlling the working ratio and alloy composition, a low thermal expansion coefficient of -5 × 10 ^{-6 to} 5 × 10 ^-6 / k can be obtained in a temperature range of 50 ° C. or more. . The higher the content of the β phase in the alloy, the wider the low thermal expansion temperature range.

(3) Temperature range in which low thermal expansion temperature range can be set By controlling the processing rate and alloy composition, it is possible to set a low thermal expansion temperature range of 50 ° C. or more in an arbitrary temperature range of 150 ° C. or less.

(4) Repetitive Characteristics Even if the heating / cooling process is repeated at least 400 times or more, the low thermal expansion characteristics can be maintained.

[0065]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 (1) Preparation of Plate Material A CuAlMn-based alloy having a composition of 81.0% by mass of Cu, 8.7% by mass of Al, and 10.3% by mass of Mn was melted and cast, and cooled at an average of 50 ° C./min. Solidified at a speed to form an ingot having a diameter of 20 mmφ. This ingot was hot-rolled at 800 ° C. to a thickness of 2 mm and then cut to obtain a plate material having a length of 14 mm × a width of 5 mm × a thickness of 2 mm.
The obtained plate was subjected to a solution treatment at 850 ° C. for 15 minutes, then rapidly cooled by being put into ice water, and then subjected to an aging treatment at 150 ° C. for 15 minutes to obtain a plate substantially consisting of β single phase. .

(2) Preparation of Sample by Cold Rolling The obtained sheet material was subjected to cold rolling at 25 ° C. with a total working ratio of 5%, and then cut to obtain a 15 mm long × 5 mm wide × 1.9 mm thick.
Was prepared. Table 1 shows the rolling directions.

(3) Measurement of coefficient of thermal expansion Using a thermal dilatometer (Dilatometer DIL402C manufactured by NETZSCH),
The measurement was performed in a temperature range of 0 to 60 ° C and a cooling rate of 3 ° C / min, and the average coefficient of thermal expansion during the cooling process was examined. Table 1 shows the measurement directions of the thermal expansion coefficient. FIG. 4 shows the results.

Table 1 Cold rolling direction and thermal expansion coefficient measuring direction based on hot rolling direction

As is apparent from FIG. 4, when the longitudinal and width cross rolling was performed, the measurement direction was -10 × 1 in any measurement direction, and in the case of unidirectional rolling, the rolling direction and the measurement direction were the same.
A low thermal expansion coefficient of 0 ^-6 to 10 × 10 ^-6 / k is obtained. In the case of unidirectional rolling, since the anisotropy is generated, a relatively large coefficient of thermal expansion can be obtained when the rolling direction and the measurement direction are different, but it is used in a usage form in which thermal stress is applied only in one direction It can be said that it is suitable for a member such as a rod material. In order to obtain a low coefficient of thermal expansion in a plurality of directions, it is preferable to perform rolling in at least two or more directions.

Example 2 (1) Preparation of Plate Material The plate material was prepared in the same manner as in Example 1.

(2) Preparation of Sample by Cold Rolling The obtained sheet material was subjected to cold rolling in the longitudinal direction while changing the total working ratio between 1% and 8% in the same manner as in Example 1 except that the sample was cold rolled. Was prepared.

(3) Measurement of coefficient of thermal expansion The same procedure as in Example 1 was carried out except that the coefficient of thermal expansion in the heating / cooling process at -100 to 100 ° C. was measured only in the longitudinal direction. 3 ° C / min). Table 2 shows the results of the cooling low thermal expansion temperature width ΔT and the heating low thermal expansion temperature width ΔT ′ (Sample Nos. 1 to 8).

Comparative Example 1 A sheet material was prepared in the same manner as in Example 2 except that cold rolling was not performed, and the thermal expansion coefficient was measured. The results are shown in Table 2 (Sample No. 9).

[0075]

As is clear from Table 2, the CuAl of Example 2
For Mn-based alloys (Sample Nos. 1 to 8), the total processing rate was 1 to 8
In the range of%, ΔT is 100 ° C. or more and ΔT ′ is 90 ° C. or more. Further, in Sample No. 9 of Comparative Example 1 which was not subjected to cold working, ΔT was as narrow as 25 ° C.

Example 3 (1) Preparation of Plate Material The plate material was prepared in the same manner as in Example 1.

(2) Preparation of Sample by Cold Rolling A sample was prepared in the same manner as in Example 1 except that the obtained plate was subjected to cold rolling in the longitudinal direction at a total processing rate of 5%.

(3) Measurement of Thermal Expansion Coefficient The thermal expansion coefficient was measured in the same manner as in Example 1 except that the measurement was performed while changing the longitudinal direction to 0 ° and changing the angle to a predetermined angle up to 90 °. Table 3 shows the results of the average thermal expansion coefficient.

[0080]

As is evident from Table 3, as the angle from the rolling direction increases, the average coefficient of thermal expansion increases and the anisotropy occurs. It can be said that the unidirectional rolling is suitable for producing a member used in a usage form in which thermal stress is applied only in one direction.

Example 4 (1) Preparation of Plate Material 15 mm long × 5 mm wide × 0.92 mm thick and 15 mm long × 5 mm wide ×
The procedure was performed in the same manner as in Example 1 except that a plate material having a thickness of 3.42 mm was produced.

(2) Preparation of Sample by Cold Rolling For each of the obtained sheet materials, a total processing rate of 5% in the longitudinal direction was obtained.
A sample was prepared in the same manner as in Example 1 except that cold rolling was performed.

(3) Measurement of Coefficient of Thermal Expansion The coefficient of thermal expansion was measured in the same manner as in Example 1 except that the measurement was performed only in the longitudinal direction. Table 4 shows the results of the cooling low thermal expansion temperature range.

[0085]

As is clear from Table 4, regardless of the thickness of the sheet material before the cold rolling, the cooling low thermal expansion temperature range of both was 70 ° C.
It can be seen that the influence of the thickness of the sheet material before rolling is small.

Example 5 (1) Preparation of Plate Material The plate material was prepared in the same manner as in Example 1.

(2) Preparation of Sample by Cold Rolling The obtained plate was subjected to cold rolling in the longitudinal direction while changing the total working ratio between 1% and 20% in the same manner as in Example 1 except that the sample was cold rolled. Was prepared.

(3) Measurement of Thermal Expansion Coefficient The thermal expansion coefficient was measured in the longitudinal direction and the width direction as in Example 1. The result is shown in FIG.

As is clear from FIG. 5, the average thermal expansion coefficient at ^-60 to 60 ° C. is controlled to -25 × 10 ⁻⁶ to 15 × 10 by the cold working rate control.
It can be controlled to any value between ^-6 / k and can have a negative average coefficient of thermal expansion.

Example 6 (1) Preparation of a plate material Example 1 was repeated except that a CuAlMn-based alloy having a composition of 78.3 to 82.3% by mass of Cu, 8.7% by mass of Al, and 9.0 to 13.0% by mass of Mn was used. Performed similarly.

(2) Preparation of Sample by Cold Rolling For each of the obtained sheet materials, a total working ratio of 8% in the longitudinal direction was obtained.
A sample was prepared in the same manner as in Example 1 except that cold rolling was performed.

(3) Measurement of Thermal Expansion Coefficient The thermal expansion coefficient was measured in the same manner as in Example 1 except that the measurement was performed only in the longitudinal direction, and the cooling low thermal expansion starting temperature Ts and the cooling low thermal expansion temperature width ΔT were examined. Was. Table 5 shows the results.

[0094]

As is clear from Table 5, by changing the Mn content, the cooling low thermal expansion start temperature Ts can be changed, and the low thermal expansion temperature range can be set to various temperature ranges at 100 ° C. or less. You can see that you can do it.

Example 7 (1) Preparation of a plate material The same operation as in Example 1 was performed except that a CuAlMn-based alloy having a composition of 80.5% by mass of Cu, 8.7% by mass of Al, and 10.8% by mass of Mn was used. .

(2) Preparation of Sample by Cold Rolling A sample was prepared in the same manner as in Example 1 except that the obtained sheet material was subjected to cold rolling at a total working ratio of 8% in the longitudinal direction.

(3) Measurement of Thermal Expansion Coefficient The operation of heating and cooling the obtained sample in the range of -60 to 60 ° C. was repeated 400 times, and the thermal fatigue stability was examined. The thermal expansion coefficient was measured in the same manner as in Example 1 except that the thermal expansion coefficient was measured only in the longitudinal direction. FIG. 6 shows the results.

As is clear from FIG. 6, at least 400
A low coefficient of thermal expansion can be maintained during more than one heating / cooling operation.

Example 8 (1) Preparation of a plate material The same procedure as in Example 1 was carried out except that CuAlMn-based alloys having the respective compositions shown in Table 6 were used.

(2) Preparation of sample by cold rolling A sample was prepared in the same manner as in Example 1 except that the obtained sheet material was subjected to cold rolling in the longitudinal direction at a total working ratio shown in Table 6.

(3) Measurement of Coefficient of Thermal Expansion The coefficient of thermal expansion was measured in the same manner as in Example 1 except that it was measured only in the longitudinal direction, and the cooling low thermal expansion temperature range ΔT was examined. FIG. 7 shows the results.

Table 6 Composition and total processing rate Composition (% by mass) Cu Al Mn V Total processing rate (%) 81.50 8.70 9.80 −4 81.25 8.70 10.05 −6 80.95 8.70 10.30 0.05 7 81.00 8.70 10.30 −8 81.00 8.20 10.80 −8 80.50 8.70 10.80 − 8

As is clear from FIG. 7, by controlling the composition and the total processing rate, it is possible to set a low thermal expansion characteristic having a temperature width of at least 50 ° C. in a wide temperature range of 100 ° C. or less.

Example 9 (1) Preparation of Plate Material A CuZnAl-based alloy having a composition of 71.0% by mass of Cu, 22.0% by mass of Zn, and 7.0% by mass of Al was subjected to a solution treatment at 700 ° C. for 30 minutes. Example 1 except that aging treatment was performed at 150 ° C. for 10 minutes.
In the same manner as described above, a plate material substantially consisting of a β single phase was obtained.

(2) Preparation of Sample by Cold Rolling A sample was prepared in the same manner as in Example 1 except that the obtained plate was subjected to cold rolling at a total working ratio of 7% in the longitudinal direction.

(3) Measurement of coefficient of thermal expansion The same procedure as in Example 1 was carried out except that the obtained sample was measured only in the longitudinal direction. FIG. 8 shows the results.

As apparent from FIG. 8, a low coefficient of thermal expansion of −5 × 10 ^{−6 to} 5 × 10 ⁻⁶ / k was obtained at −30 to 45 ° C.

Example 10 (1) Preparation of Plate Material Using a CuZnAl-based alloy having a composition of 69.0% by mass of Cu, 27.0% by mass of Zn, and 4.0% by mass of Al, a solution treatment was performed at 600 ° C. for 30 minutes. Other than that, it carried out similarly to Example 1. The composition of the obtained sample was such that the α phase and the β phase were each 50% by volume.

(2) Preparation of Sample by Cold Rolling A sample was prepared in the same manner as in Example 1 except that the obtained sheet material was subjected to cold rolling at a total working ratio of 7% in the longitudinal direction.

(3) Measurement of Coefficient of Thermal Expansion The obtained sample was measured in the same manner as in Example 1 except that it was measured only in the longitudinal direction in a temperature range of -100 to 25 ° C.
FIG. 8 shows the results.

As apparent from FIG. 8, a low coefficient of thermal expansion of −5 × 10 ^{−6 to} 5 × 10 ⁻⁶ / k was obtained at −85 to −53 ° C. A low thermal expansion coefficient can be obtained even in a CuZnAl-based alloy containing 50% by volume of the α phase.

Example 11 (1) Preparation of Plate Material NiTi-based alloys having the respective compositions shown in Table 7 were melted in a graphite crucible and solidified at an average cooling rate of 50 ° C./min to obtain a 20 mmφ diameter. Ingot. This ingot is hot-rolled at 800 ° C and then cut to a length of 14 mm.
A plate material having a width of 5 mm and a thickness of 1.7 mm was obtained. 850
After a solution treatment at 60 ° C. for 60 minutes, the mixture was put into ice water and rapidly cooled to obtain a plate material substantially consisting of β single phase.

(2) Preparation of sample by cold rolling A sample was prepared in the same manner as in Example 1 except that the obtained sheet material was subjected to cold rolling in the longitudinal direction. Table 7 shows the total processing rate
Shown in

(3) Measurement of coefficient of thermal expansion The obtained sample was measured in the same manner as in Example 1 except that it was measured only in the longitudinal direction in a temperature range of -120 to 100 ° C. FIG. 9 shows the results of the cooling low thermal expansion temperature width ΔT.

[0116]

As is clear from FIG. 9, the cooling low thermal expansion temperature width ΔT of 60 ° C. or more can be obtained also for the NiTi-based alloy containing Fe or V.

Example 12 (1) Preparation of sheet material A sheet material made of a NiTi alloy having a composition of 55.6% by mass of Ni and 44.4% by mass of Ti and a composition of 54.9% by mass of Ni and 45.1% by mass of Ti was used. Prepared in the same manner as 11.

(2) Preparation of Sample by Cold Rolling The obtained plate was subjected to a total working ratio of 0.5 to 40% in the longitudinal direction.
A sample was produced in the same manner as in Example 1 except that cold rolling was performed while changing the total working ratio between the steps.

(3) Measurement of coefficient of thermal expansion The coefficient of thermal expansion was measured in the same manner as in Example 1 except that it was measured only in the longitudinal direction in a temperature range of -100 to 100 ° C. FIG. 10 shows changes in the average thermal expansion coefficient. As is clear from FIG. 10, the NiTi alloy having the above composition was -60
Average coefficient of thermal expansion at ~ 20 ° C is -10 × 10 ^{-6 to} 6 × 10 ^-6 / k
It is possible to control to any value between. Further, by controlling the total processing rate, the average thermal expansion coefficient can be made substantially zero.

[0121]

As described in detail above, the low thermal expansion alloy of the present invention has good low thermal expansion characteristics. Furthermore, since the low thermal expansion alloy of the present invention also has shape memory properties and superelasticity, it can be used not only for precision electronic components such as heat sink materials and lead frame materials, but also for various uses such as LNG containers.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing a change in temperature between a martensitic transformation start temperature Ms, a martensitic transformation end temperature Mf, an austenite reverse transformation start temperature As and an austenite reverse transformation end temperature Af in a hysteresis model diagram of a temperature change-thermal expansion coefficient of the low thermal expansion alloy of the present invention. Show how to find.

FIG. 2 shows the temperature change of the low thermal expansion alloy of the present invention—the cooling low thermal expansion start temperature Ts, the cooling low thermal expansion end temperature Tf, and the heating low thermal expansion start temperature in a hysteresis model diagram of the thermal expansion coefficient.
How to determine Ts 'and the heating low thermal expansion end temperature Tf' will be described.

FIG. 3 shows a hysteresis model diagram of temperature change-thermal expansion coefficient when the total working ratio is different in the low thermal expansion alloy of the present invention.

FIG. 4 shows the average thermal expansion coefficient when the combination of the rolling direction and the thermal expansion coefficient measurement direction when the sheet material of the CuAlMn-based alloy of Example 1 is rolled at a total processing rate of 5% is changed. It is a graph.

FIG. 5 is a graph showing changes in the average thermal expansion coefficient in the width direction and in the longitudinal direction when the total working ratio in the longitudinal direction of the plate material of the CuAlMn-based alloy of Example 5 is changed.

FIG. 6 shows the average thermal expansion when the heating / cooling process at -60 to 60 ° C. is repeated for a sample obtained by subjecting the CuAlMn-based alloy plate material of Example 7 to rolling processing at a total processing rate of 8% in the longitudinal direction. It is a graph which shows the change of a coefficient.

FIG. 7 is a graph showing a change in a low thermal expansion temperature range at each total working rate of CuAlMn-based alloys having various compositions in Example 8.

FIG. 8 is a graph showing the low thermal expansion temperature range of the CuZnAl-based alloys of Examples 9 and 10.

9 is a graph showing low thermal expansion temperature ranges of NiTi-based alloys having various compositions of Example 11. FIG.

FIG. 10 is a graph showing a change in average thermal expansion coefficient with respect to a change in total working rate of the NiTi alloy of Example 12.

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Claims (11)

[Claims] 1. An average thermal expansion coefficient at −150 to 150 ° C. of −10 × 10 ⁻⁶ obtained by controlling cold working of a shape memory alloy that causes thermoelastic martensitic transformation.
A low thermal expansion alloy characterized by being variable between 10 × 10 ⁻⁶ / k. 2. The low thermal expansion alloy according to claim 1, wherein the temperature range in which the coefficient of thermal expansion is −5 × 10 ^{−6 to} 5 × 10 ⁻⁶ / k is 50 ° C. or more. Expansion alloy. 3. The low thermal expansion alloy according to claim 1, wherein the cold working is performed only in one direction. 4. The low thermal expansion alloy according to claim 1, wherein the cold working is performed in a plurality of different directions. 5. The low thermal expansion alloy according to claim 1, wherein a difference between a martensitic transformation start temperature and a martensitic transformation end temperature is 30 ° C. or more. 6. The low thermal expansion alloy according to claim 1, wherein the shape memory alloy that causes the thermoelastic martensitic transformation is a CuAlMn-based alloy. 7. The low thermal expansion alloy according to claim 1, wherein the shape memory alloy that causes the thermoelastic martensitic transformation is a CuZnAl-based alloy. 8. The low thermal expansion alloy according to claim 1, wherein the shape memory alloy that causes the thermoelastic martensitic transformation is a NiTi-based alloy. 9. The low thermal expansion alloy according to claim 6, wherein a total working ratio of the cold working is 0.05 to 20%. 10. The low thermal expansion alloy according to claim 8, wherein a total working ratio by the cold working is 0.05 to 40%. 11. The low thermal expansion alloy according to claim 1, wherein the low thermal expansion alloy comprises a multiphase structure containing at least 15% by volume or more of a phase that causes the thermoelastic martensitic transformation.