JP2004083951A - Low thermal expansion alloy, low thermal expansion member and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new low thermal expansion alloy of a Ti-Nb base or the like. <P>SOLUTION: The low thermal expansion alloy comprises, by atom, 20 to 30% group Va elements such as Nb, and the balance group IVa elements such as Ti with inevitable impurities. The alloy having the above composition completely different from that of the conventional low thermal expansion alloy exhibits low thermal expansion properties. <P>COPYRIGHT: (C)2004,JPO

Description

【図面の簡単な説明】
【図１】本発明の実施例に係る試験片Ｎｏ．１の熱膨張率を示すグラフである。
【図２】本発明の実施例に係る試験片Ｎｏ．１の熱膨張係数のサイクル特性を示すグラフである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a low-thermal-expansion alloy and a low-thermal-expansion member mainly composed of a Va-group element and a IVa-group element, and to a method for producing them.
[0002]
[Prior art]
Not only products and members that require high precision such as measuring devices, but also products, members, structures, etc. in general electronic and electrical fields, mechanical fields, chemical fields, etc., in many cases, The smaller the thermal expansion caused by the temperature change, the better. By reducing this thermal expansion, measurement accuracy and reliability are ensured, operating noise is reduced, fatigue fracture is suppressed, bonding strength is secured at the joints of different materials, etc., and design flexibility of various products is expanded. Etc. can be expected. From such a viewpoint, various low thermal expansion alloys have been conventionally proposed. Specifically, it is as follows.
[0003]
First, as a typical low thermal expansion alloy, a ferromagnetic alloy such as an Fe—Ni alloy (a general Invar alloy) or an Fe—Pt alloy is given. Also, as the same ferromagnetic alloy, there is an Fe-based amorphous alloy such as an Fe-B-based alloy, an Fe-P-based alloy, and an Fe-Zr-based alloy. Examples of the antiferromagnetic low thermal expansion alloy include Cr-based alloys such as a Cr-Mn-Fe-based alloy, a Cr-Fe-Ir-based alloy, and a Cr-Fe-4d transition metal (Ru, Rh, Pd) -based alloy. Can be Further, examples of nonmagnetic low thermal expansion alloys include shape memory alloys by martensitic transformation such as Ni-Ti alloys, Cu-Zn alloys, Cu-Al alloys, and Cu-Sn alloys.
There have been many applications for these low thermal expansion alloys. For example, JP-A-50-125908, JP-B-4-57739, JP-B4-65139, JP-A-9-293305, JP-A-2002-38236, JP-A-2002-105561. For example, there is a disclosure regarding a low thermal expansion alloy.
[0004]
[Problems to be solved by the invention]
However, as described above, none of the conventionally proposed low thermal expansion alloys contains a Va-group element and a IVa-group element as main components.
An object of the present invention is to provide a low-thermal-expansion alloy having a completely different composition from the conventional one, which contains the group Va element and the group IVa element as main components. It is another object of the present invention to provide a low thermal expansion member made of the low thermal expansion alloy and a method of manufacturing the low thermal expansion member.
[0005]
Means for Solving the Problems and Effects of the Invention
The inventor of the present invention has conducted intensive research on low thermal expansion members, and as a result of repeated trial and error, has newly found that a specific alloy containing the above-described Va group element and IVa group element as main components exhibits low thermal expansion characteristics. By developing this knowledge, the following invention has been completed.
That is, the low thermal expansion alloy of the present invention is characterized in that when the whole is 100 at%, the group Va element is 20 to 30 at%, and the balance is composed of the group IVa element and unavoidable impurities.
[0006]
It is not yet clear why the alloy having this composition exhibits low thermal expansion characteristics. Further, even if the alloy is within the above range, the temperature range in which the low thermal expansion characteristic is exhibited and the value of the thermal expansion coefficient α may differ depending on the composition. The present inventor is currently studying the low thermal expansion characteristics of alloys having various compositions and is intensively studying the reasons for this.
Here, if the content of the Va group element is less than 20 at% or more than 30 at%, sufficient low thermal expansion characteristics cannot be obtained.
In this specification, unless otherwise specified, the numerical range “x to y” includes a lower limit x and an upper limit y.
[0007]
Further, an alloy containing a predetermined amount of the interstitial element O, N or C can also exhibit low thermal expansion characteristics. That is, the low thermal expansion alloy of the present invention may contain 6 at% or less in total of any one or more of O, N, and C. Depending on the member used of the low thermal expansion alloy of the present invention, it is necessary to ensure strength or the like. However, addition of O or the like is preferable because stable strength and the like are maintained.
Here, if a small amount of O or the like is contained, the strength is improved accordingly, and it is difficult to determine the lower limit value of O or the like, but if it is, it is 0.001 at% or more. However, O and the like are often included as unavoidable impurities depending on the raw materials used and the production method. Taking this into account, the lower limit of O and the like is about 0.1 at%.
[0008]
Incidentally, the Va group elements are vanadium (V), Nb and Ta, and the IVa group elements are Ti, Zr and hafnium (Hf). In the present invention, combinations thereof are not limited, but at present, Nb and / or Ta as a Group Va element and Ti and / or Zr as a Group IVa element seem to be preferable.
In order to obtain excellent low thermal expansion characteristics, Nb as a Va group element is 0 to 30 at%, more preferably 15 to 30 at%, and Ta is 0 to 30 at%, based on the above-described composition range of the Va group element. Desirably, it is preferably about 0 to 15 at%. The group IVa element preferably has Zr of 0 to 50 at%, more preferably 0 to 10 at%, Hf of 0 to 10 at%, and the balance being Ti.
[0009]
The low-thermal-expansion alloy of the present invention is not limited to Al, Sn, Cr, Mo, Mn, Fe, Co in order to obtain desired strength, rigidity, elastic deformability, magnetism, etc. in addition to improving low-thermal expansion characteristics. , Ni, W and the like may be appropriately contained.
[0010]
The term “low thermal expansion” as used in the present invention means that the thermal expansion coefficient α is smaller than that of a conventional alloy containing a Group Va element and a Group IVa element as main components, and specific numerical values are limited. Not something. However, considering the use as a low thermal expansion alloy, the thermal expansion coefficient α is | α |^-6/ K or less, and 4 × 10^-6/ K or less, 3 × 10^-6/ K or less.
The form of the low thermal expansion alloy of the present invention is not limited. Material (ingot, slab, billet, sintered body, rolled product, forged product, wire, bar, square bar, plate, foil, fiber, woven fabric, etc.) Processed products, final products, etc.). As a result, the low thermal expansion member described later can be said to be one form of the low thermal expansion alloy.
[0011]
(Low thermal expansion member)
The present invention is not limited to the low thermal expansion alloy described above, and can be grasped as a low thermal expansion member having a desired shape by appropriately processing an alloy material having the same composition.
That is, the present invention is characterized in that when the whole is set to 100 at%, at least a part includes a low thermal expansion alloy composed of 20 to 30 at% of a group Va element and a balance of a group IVa element and unavoidable impurities. It is also considered an expansion member.
Also in this case, the low thermal expansion alloy may contain a total of 6 at% or less of any one or more of O, N, and C.
[0012]
The form and shape of the low thermal expansion member are determined according to its use. In the present invention, the specific form and the like are not limited. For example, the low-thermal-expansion member may be one in which the entire product or part is cast and molded with the low-thermal-expansion alloy, or the low-thermal-expansion alloy is a lump, plate, or part of the product or part. They may be juxtaposed, mixed, etc. as a film shape, a line shape, a fiber shape, or the like.
[0013]
(Production method)
Further, the present invention can be understood as a method for manufacturing the low thermal expansion alloy or the low thermal expansion member.
First, the present invention provides a material production process for producing an alloy material comprising 20 to 30 at% of a Va group element and the balance being an IVa group element and an unavoidable impurity, when the whole is 100 at%, And a cold working step of performing cold working on the alloy.
[0014]
Next, according to the present invention, when the whole is set to 100 at%, at least cold working is performed on an alloy material containing 20 to 30 at% of a Va group element and the balance being an IVa group element and unavoidable impurities to obtain a desired shape. It may be understood as a method of manufacturing a low thermal expansion member including a processing step of forming a low thermal expansion member.
[0015]
In any case, the alloy material may contain a total of 6 at% or less of one or more of O, N, and C.
The working step here is not limited to the case where cold working is simply performed, but may be cold working after hot working, or a combination of cutting and cold working. In addition, in both methods of manufacturing a low thermal expansion alloy and a low thermal expansion member, cold working is performed, which means that cold working is essential to obtain the low thermal expansion alloy and the like of the present invention. is not.
Note that the description of the low thermal expansion alloy also applies to the low thermal expansion member and each manufacturing method as appropriate.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the present invention will be described in more detail with reference to embodiments. In the following, low-thermal-expansion alloys will be mainly described. However, it is to be noted that the contents also apply to low-thermal-expansion members and their manufacturing methods as appropriate.
(1) Alloy composition
(1) Arbitrary element
The essential elements of the low thermal expansion alloy according to the present invention are the above-described IVa group element and Va group element. In addition to the above-described interstitial elements such as O, Al, Sn, Cr, Mo, Mn, Fe, Co, Elements such as Ni and W may be further contained. Thereby, the low thermal expansion characteristics are improved, and the mechanical characteristics such as strength and rigidity are improved.
[0017]
Cr and Mo are elements that improve the strength and hot forgeability of the alloy. By improving the hot forgeability, the productivity and yield of the low thermal expansion member are improved. However, when these elements increase (for example, when the content exceeds 10 at%), material segregation is likely to occur, and when these elements are low, the above-described effects are not exhibited. In order to improve strength and the like by solid solution strengthening, the total content is preferably 0.5 to 5 at%.
[0018]
Like Mn, Mn, Fe, Co, and Ni are effective elements for improving strength and hot forgeability. Therefore, Mn or the like may be contained instead of or together with Mo or Cr. However, when the content of these elements increases, an intermetallic compound is formed with the metal as the main component (remainder), resulting in a decrease in ductility. In order to improve the strength and the like, the total content is preferably 0.3 to 10 at%.
[0019]
Sn is also an element effective for improving the strength of the low thermal expansion alloy. When the amount of Sn is large, the ductility is reduced. When the amount of Sn is small, the above effect is not exhibited. In order to improve the strength and the like, the content is preferably 1 to 10 at%.
[0020]
Al is also an element effective for improving the strength of the low thermal expansion alloy. When the amount of Al increases, the ductility decreases, and when the amount of Al is low, the above-mentioned effect is not exhibited. In order to improve the strength and the like, the content is preferably 0.5 to 12 at%. When both Al and Sn are added, the strength can be improved while suppressing the decrease in toughness of the low thermal expansion alloy.
[0021]
These elements may be used alone or in combination of two or more. However, the total content is preferably 12 at% or less.
The form of each element contained in the alloy is not limited. It may be in a solid solution state or may be in a precipitated state by forming a compound. Further, it may be in a state of being mixed in the alloy as reinforcing particles. In particular, when a composite material (MMC) is formed with ceramic particles or the like, further lower thermal expansion and higher strength can be achieved. For example, consider the case where the low thermal expansion alloy of the present invention contains Ti as a main component and contains boron (B). B hardly forms a solid solution in the titanium alloy, and almost all of it precipitates as titanium compound particles (TiB particles and the like). The precipitated particles significantly suppress the crystal grain growth of the titanium alloy, and maintain the structure of the titanium alloy finely. As a result, the mechanical properties and hot workability of the low thermal expansion alloy (titanium alloy) can be improved. In this case, it is preferable that B is 0.2 to 6.0 at%. If the amount of B is small, the above effect cannot be obtained. If the amount of B is large, a large amount of TiB is crystallized to lower ductility.
[0022]
(2) Identification of composition by parameters
The composition of the low thermal expansion alloy or the like or the alloy material of the present invention is as described above in terms of atomic ratio (or mol ratio). In addition, the alloy composition can be specified by introducing the following parameters. These parameters can further clarify the composition of the low thermal expansion alloy.
That is, the low thermal expansion alloy or the like of the present invention has a composition average value of the substitution element of 2.430 ≦ Md ≦ 2.490 and the bond order Bo with respect to the energy level Md of the d-electron orbit which is a parameter determined by the DV-Xα cluster method. With respect to the specific composition, the compositional average value of the substitutional element is 2.860 ≦ Bo ≦ 2.900 and the compositional average value of the substitutional element is 4.22 ≦ e / a ≦ 4.26 with respect to the number of valence electrons e / a. Is preferred.
[0023]
Among the above, the energy level Md of the d-electron orbit and the bond order Bo are parameters specific to the substitutional (alloy) element obtained by the DV-Xα cluster method. This substitution type element is, for example, a group IVa element and a group Va element other than the element corresponding to the “remainder” in the present invention.
[0024]
Here, the DV-Xα cluster method is a kind of molecular orbital method, and is a method capable of skillfully simulating a local electronic state around an alloy element (Reference: Introduction to Quantum Materials Chemistry, written by Hirohiko Adachi, Sankyo Publishing (1991)).
Specifically, a model is created using clusters (virtual molecules in the crystal) corresponding to each crystal lattice, and the substitutional alloying element M at the center is changed, so that M and the mother alloy X (in this case, X is The state of chemical bonding with Ti and the like (which will be a Group IVa element constituting the above “remainder”) is examined. The DV-Xα cluster method is a method of obtaining alloy parameters indicating the individuality of M as an alloy component in a master alloy. It is said that the parameters of the energy level Md of d-electron orbit (average composition value) and the bond order Bo (average composition value) are practically effective if the material is mainly composed of transition metal.
[0025]
The energy level Md of the d-electron orbit indicates the energy level of the d-orbit of the substitutional alloy element M, and is a parameter correlated with the electronegativity of atoms and the atomic radius. The bond order Bo is a parameter indicating the degree of overlap of electron clouds between the master alloy element X and the substitutional alloy element M.
[0026]
On the other hand, the valence electron number e / a is a valence electron concentration indicating the number of charges per atom in the alloy. This is a parameter indicating the stability of energy due to the contact between the Fermi surface and the Brillouin zone based on the right @ band model.
As described above, although the detailed reason is not clear, a plurality of satisfies 2.430 ≦ Md ≦ 2490, 2.860 ≦ Bo ≦ 2.900, 4.22 ≦ e / a ≦ 4.26. When the low thermal expansion alloy or the like of the present invention was composed of the elements, excellent low thermal expansion characteristics were obtained.
It is more preferable that 2.440 ≦ Md ≦ 2470, 2.865 ≦ Bo ≦ 2.885, and 2.870 ≦ Bo ≦ 2.880.
[0027]
(2) Manufacturing method
(1) Melting method and sintering method
The low thermal expansion alloy or alloy material according to the present invention may be manufactured by any method such as a melting method involving melting and casting, and a sintering method for sintering a metal powder (raw material powder). The melting method includes an arc melting method, a plasma melting method, an induction skull method, a floating melting method, and the like. As the sintering method, a powder compact formed by the CIP method (cold isostatic pressing method) or the RIP method (rubber type isostatic pressing method) is heated and sintered, or the HIP method (hot isostatic pressing method) is used. And sintering the metal powder. Of course, the raw material powder may be filled in a molding die (filling step), and a powder compact obtained by press-molding the raw material powder (molding step) may be heated and sintered (heating step). The raw material powder used at this time may be a mixed powder prepared by mixing elementary powders to a desired composition, or a powder prepared by mixing an alloy powder to a desired composition. In the case of using a sintered material, hot working such as hot forging may be performed in order to densify the structure according to the density.
[0028]
When the low-thermal-expansion alloy is mainly composed of Ti, if a melting method is used, a special apparatus is required, and sometimes it is necessary to perform multiple melting. In addition, it is difficult to control the composition during melting, and in the case of the low thermal expansion alloy of the present invention containing a relatively large amount of Va group element or the like, macroscopic segregation of components is likely to occur during melting and casting. In this regard, when the sintering method is used, a homogeneous low thermal expansion alloy can be obtained relatively easily.
However, the causal relationship between whether the structure is homogeneous or segregated and the manifestation of low thermal expansion characteristics is not clear at present.
[0029]
(2) Cold working
According to the study of the present inventor, it has been confirmed that low thermal expansion characteristics are more likely to be exhibited when an alloy material having a specific composition is subjected to appropriate cold working. The degree of the cold working can be determined using the following cold working ratio as an index.
Cold working rate = (S₀-S) / S₀ x100 (%),
(S₀: Cross-sectional area before cold working, S: cross-sectional area after cold working)
It is considered that the cold working ratio of 10% or more is preferable for obtaining low thermal expansion characteristics.
[0030]
However, at present, it cannot be asserted that cold working is indispensable for obtaining a low thermal expansion alloy. There is a possibility that some of the low thermal expansion alloys having the above-described composition ranges may exhibit low thermal expansion characteristics without being subjected to cold working. The term "cold" means a temperature lower than the recrystallization temperature (minimum temperature at which recrystallization occurs) of the alloy.
Further, the cold working does not need to be specially performed in order to impart low thermal expansion characteristics. That is, when the alloy material having the above composition is formed into various member shapes, it may be performed together. In any case, it is sufficient if the cold working is performed so that the total cold working ratio is 10% or more. By adjusting the cold working ratio within this range, the coefficient of thermal expansion α of the obtained alloy can be adjusted.
Furthermore, in the case of a low-thermal-expansion alloy containing at least Ti, which is a Group IVa element, as a main component, the workability is extremely excellent, so that the yield of various members is high and the productivity can be improved.
[0031]
(3) Heat treatment
Regardless of the ingot material or sintered material, an appropriate heat treatment may be applied to homogenize the structure and improve various characteristics. Such heat treatment includes, for example, a solution treatment, an aging treatment and the like. Solution treatment is preferred in terms of tissue homogenization. Further, the aging treatment is preferable from the viewpoint of increasing the strength. When performing the cold working described above, the aging treatment may be performed after the cold working, but the solution treatment is preferably performed before the cold working. This is because if the solution treatment is performed after the cold working, the working strain imparted in the alloy by the cold working is lost, which may affect the development of low thermal expansion.
[0032]
(3) Characteristics
Some of the low thermal expansion alloys of the present invention have some other characteristics in addition to the low thermal expansion characteristics. Due to composition differences, some low thermal expansion alloys have multiple different properties, while others do not. Of course, not all low thermal expansion alloys within the composition range of the present invention need to have distinctive properties.
(1) Low thermal expansion characteristics
Even with the low thermal expansion alloy of the present invention, the thermal expansion coefficient α is not always small in all temperature ranges. The temperature range in which the coefficient of thermal expansion α is reduced (low thermal expansion temperature range) is usually specified by the selected composition, manufacturing method, and the like. At this time, the temperature range (temperature range), the center temperature, and the like are not particularly limited in the present invention.
However, as the temperature range is wider and the center temperature is near room temperature, the use range of the low thermal expansion alloy is expanded. Thus, for example, | α |^-6It is preferable that the low thermal expansion temperature range of not more than / K is, for example, 273 to 323K.
[0033]
When the low thermal expansion alloy of the present invention is used for a product, a part, or the like used in an environment having a large temperature fluctuation, the low thermal expansion alloy is not always used only in the low thermal expansion temperature range. However, as long as the alloy is used in a range including the low thermal expansion temperature range, the overall thermal expansion is reduced as compared with the case where another alloy or the like is used. That is, the average value αm of the coefficient of thermal expansion becomes small. Therefore, there is a sufficient advantage in using the low thermal expansion alloy or the like of the present invention even for a member or the like used beyond the low thermal expansion temperature range.
The temperature fluctuation includes a temperature rising process and a temperature falling process. The low thermal expansion alloy of the present invention suffices if at least one of them has a small thermal expansion coefficient α. Considering the case where the alloy of the present invention is used in an environment where the temperature fluctuates, it is preferable that the coefficient of thermal expansion α be small in both steps. That is, it is preferable that the change in the thermal expansion coefficient α is reversible. However, this reversible range is sufficient if the thermal expansion coefficient α is in a stable region.
[0034]
(2) Constant elasticity characteristics (Elimber characteristics)
The low thermal expansion characteristic (invar characteristic) in which the elongation change due to the temperature change is small (the thermal expansion coefficient α is small) has been described above. There is a constant elasticity characteristic (Elimber characteristic) as a characteristic to be mentioned together with this. This is a characteristic that the change in the longitudinal elastic modulus (Young's modulus) E is small even when the temperature changes. Of course, the same applies to the transverse elastic coefficient G.
However, the generation mechanism of the above-mentioned characteristics is not necessarily common. Actually, except for the Fe-B based amorphous alloy, the Cr-based antiferromagnetic alloy, etc., there are few cases where both characteristics are satisfied in a relatively wide temperature range.
[0035]
However, some low-thermal-expansion alloys of the present invention have not only low-thermal-expansion properties but also this constant-elasticity property. For example, it is a Ti-Nb-Ta-Zr alloy (described in detail in Examples described later). The temperature coefficient of the Young's modulus E is -20 × 10^-5~ 20x10^-5(1 / K) is small. This constant elasticity property occurs in a wide temperature range of, for example, 73 to 573K. In particular, in the case of a Ti-23Nb-0.7Ta-2.0Zr alloy (unit: at%), low thermal expansion characteristics and constant elasticity characteristics are exhibited in a temperature range of 73 to 373K, and thus its use is further expanded. It will be.
[0036]
(3) Mechanical properties
By appropriately selecting the composition, the production method, the heat treatment, and the like, the mechanical properties (strength, rigidity, elongation, etc.) of the low thermal expansion alloy of the present invention can be improved. For example, in the case of a low thermal expansion alloy containing Ti as a main component (remainder), it is possible to obtain an alloy having high strength, an alloy having low rigidity, and an alloy having high elastic deformability. For this reason, the degree of freedom in designing the alloy is considerably wide. In addition, since many of the Ti-based alloys have large elongation and excellent cold workability, productivity can be improved. The elastic deformability means elongation within the limit of tensile elasticity.
[0037]
4) Corrosion resistance
In the case of a low-thermal-expansion alloy containing Ti as a main component (remaining portion), corrosion resistance is also extremely excellent. Therefore, it is preferable to apply a Ti-based low-thermal-expansion alloy to a member or the like that has been conventionally difficult to apply in terms of corrosion resistance.
[0038]
▲ 5 ▼ Magnetic
Whether the low thermal expansion alloy of the present invention is nonmagnetic or insensitive is not always known, but it is certain that it is not ferromagnetic. Therefore, it is preferable to apply the low thermal expansion alloy of the present invention to a product or a component that is not preferably ferromagnetic due to the properties of the product.
In addition, Ti-based low-thermal-expansion alloys and the like have low thermal conductivity and are therefore effective as heat insulators.
[0039]
(4) Applications
The low-thermal-expansion alloy (including the low-thermal-expansion member) of the present invention is preferably used for parts, products, devices, structures, and the like used in an environment where temperature changes occur. This ensures the required accuracy according to the characteristics of the product, etc., prevents fatigue fracture due to repeated thermal stress, reduces clearance fluctuations that occur during cold or warm periods, and ensures thermal expansion due to temperature changes. Thus, it is possible to achieve a reduction in the clearance amount, and a reduction in the operation noise due to the appropriate clearance. Furthermore, if a low thermal expansion alloy or the like having constant elastic properties, mechanical properties, corrosion resistance, and the like is used, its use will be further expanded.
[0040]
More specifically, it is preferable to use the low thermal expansion alloy of the present invention for the following. The low thermal expansion alloy of the present invention may be used for the entire part or the like, or may be used for a part thereof. Further, a composite material may be formed with another material. For example, the low thermal expansion alloy may be made into a fibrous form, mixed with another metal powder, resin, or the like, and the low thermal expansion alloy may be used as a composite reinforcing material.
[0041]
(1) Measuring equipment, measuring equipment
Optical devices such as rulers, standard scales, micrometers, distance measuring boards, block gauges, surveying scales, tide gauges, clocks for clocks, pendulums for clocks and gravity measurement, indicators, recording devices, tables, lasers, etc. Precision equipment and other optical related equipment
(2) Electric equipment, electronic equipment, magnetic equipment
CRT shadow masks, overhead transmission lines, semiconductor lead frames, heat spreaders, wiring boards, heat sinks, printing equipment, scanners, etc.
(3) control equipment,
Bimetal elements, various nozzles, frequency stabilizing cavities, watch parts (springs, etc.), etc.
[0042]
(4) Processing equipment, molding equipment
Drawing dies, spindle cases, various components of precision machine tools (bites, drills, tables, bases, etc.), molds, dies, punching dies, molding dies, plungers for high-speed presses, round blade saws, laser processing machines, etc.
(5) Structural member
Liquid gas tanker lining, large gas tank housing, etc.
▲ 6 ▼ Chemical equipment, chemical plant
Food processing machines, etc.
[0043]
(7) Vehicle-related
Gaskets, metal seals, engine valves, valve springs, diaphragms, rails, containers such as fuel tanks, tire linings, tire reinforcements, torsion bars, power transmission belts (CVT hoops, etc.), automotive engine fuel injection parts, Ignition control parts, gas (liquid) and liquid flow rate control parts, etc.
▲ 8 ▼ Others
Various components such as aerospace equipment, spacecraft and satellites, sanitary launching springs, etc., mechanical stressed components interposed between joining surfaces of dissimilar components, sealing materials, glass sealing alloys, gears and other mechanical parts , Springs, firefighters, bellows, hoses, fasteners (hose bands, bolts, screws for FDDs and CDs, clips for documents, etc.), various wires, robots (joint parts, etc.), medical (catheters, guidewires, etc. ), Decorative articles, sporting goods, fuel cell parts, parts for nuclear reactors such as reactor piping, parts for nuclear fusion reactors, and various other products in various fields.
[0044]
【Example】
Next, the present invention will be described more specifically with reference to examples.
(Manufacture of test materials)
As the test material, test piece No. 1-20 and C1-C4 were prepared as follows.
(1) Test piece No. 1-14
Ti powder, Nb powder, Ta powder, Zr powder and the like having an average particle diameter of 45 μm or less were prepared, and these raw material powders were weighed and blended to have an alloy composition shown in Table 1. These powders were mixed by a ball mill for 2 hours to obtain a mixed powder (mixing step). This mixed powder is subjected to a pressure of 400 MPa (4 ton / cm²CIP molding under hydrostatic pressure of の) was performed to obtain a cylindrical powder compact of φ40 × 80 mm (molding step).
This is 1x10^-5torr (1.3 × 10^-3Heating was performed at 1300 ° C. for 16 hours in a vacuum of Pa) to obtain a sintered body (sintering step). Further, the sintered body was hot forged in an atmosphere of 1050 ° C. (hot working step) and forged into a round bar (alloy material) of φ18 mm.
[0045]
After keeping the round bar in an Ar gas atmosphere at 900 ° C. for 30 minutes, the rod was cooled with water to perform a solution treatment (solution treatment step). Then, a part cut out from the round bar (solution-hardened alloy) was subjected to cold swaging to φ8.5 (a cold working step). This was machined to produce a test piece of φ8 × 30 mm. The cold working ratio at this time is about 78%.
Note that a series of steps from the mixing step to the hot working step corresponds to a material manufacturing step in the present invention, and the cold working step corresponds to a working step in the present invention.
[0046]
(2) Test piece No. 15-20
Test piece No. Nos. 15 and 16 were produced by induction skull dissolution. Test piece No. 17 and 18 were produced by plasma melting. Test piece No. 19 and 20 were manufactured by electron beam melting
In each case, the prepared raw material is a high-purity briquette. 1 kg of this raw material was blended to have the composition shown in Table 1 (blending step). This was melted by each of the above-mentioned melting methods (melting step), and after casting in a mold (casting step), a molten material of φ60 × 60 mm was obtained.
In addition, in order to achieve homogenization, five re-dissolution treatments were performed. This melted material was hot forged in the air at 1050 ° C. (hot forging step) and forged into a φ18 mm round bar (alloy material).
The subsequent steps are performed on the test piece No. This is the same as in cases 1 to 14.
[0047]
(3) Test piece No. C1 to C4
Test pieces in which the group Va element was out of the range of 20 to 30 at% were also manufactured. These are also shown in Table 1. The manufacturing method is the same as the test piece No. This is the same as in cases 1 to 14.
[0048]
(Measurement of test material)
(1) Thermal expansion coefficient (Δl / l₀)
The coefficient of thermal expansion of each test piece was determined as follows.
The temperature was increased at a temperature increase rate of 5 K / min from room temperature to 1073 K (800 ° C.), and then decreased at a temperature decrease rate of 5 K / min from 1073 K to room temperature, and the length of each test piece (the length before the start of measurement) Sa: l₀) Is continuously measured, and the rate of change, the thermal expansion coefficient (Δl / l), is measured.₀). As an example, test piece No. The thermal expansion coefficient of No. 1 is shown in FIG. The horizontal axis in FIG. 1 is the temperature (° C.), and the vertical axis is the coefficient of thermal expansion (× 10^-3). Needless to say, the coefficient of thermal expansion α (1 / K) is obtained as the slope of the graph shown in FIG.
Table 1 shows the thermal expansion coefficient α (1 / K) at 273 to 323 K (low thermal expansion temperature range), which is a temperature around room temperature, for other test pieces.
[0049]
(2) Cycle characteristics of thermal expansion coefficient α
The cycle characteristics of the thermal expansion coefficient α of each test piece were determined as follows.
The temperature rise / fall test in the range of 77K (-196 ° C) to 573K (300 ° C) was repeated 500 times for each test piece, and the variation of the thermal expansion coefficient α for each cycle was determined. The temperature rise / fall rate at this time is 5 K / min, and the thermal expansion coefficient α is in the range of 273 to 323 K in the temperature rise process. As an example, the test piece No. The cycle characteristics of No. 1 are shown in FIG.
[0050]
(Evaluation)
(1) For example, test piece No. As is clear from Table 1 and FIG. 1, in the case of the alloy No. 1, 2 × 10 3 was obtained over a wide temperature range from room temperature to 573 K (300 ° C.).^-6/ K, which is a low coefficient of thermal expansion. Further, as can be seen from Table 1, other test pieces and the like were 4 × 10 4 over a wide temperature range around room temperature.^-6/ K, which is a low coefficient of thermal expansion.
Although FIG. 1 and Table 1 show only a practical temperature range, the present inventor has also measured each test piece in other temperature ranges. For example, the test piece No. In the case of 1, the measurement is performed to a temperature sufficiently lower than the temperature shown in FIG. According to this, for example, the test piece No. In the case of the alloy No. 1, a stable low coefficient of thermal expansion (α ≦ 4 × 10^-6/ K) is confirmed to be obtained.
[0051]
(2) For example, test piece No. In the case of alloy No. 1, as shown in FIG. 2, even when the temperature was repeatedly increased and decreased in a temperature range where the thermal expansion coefficient α was small (low thermal expansion temperature range), the variation was very small. That is, the thermal expansion coefficient α was sufficiently stable in that range. Therefore, it was confirmed that the alloy was sufficiently reversible even when the alloy was used in a stable region having a small thermal expansion coefficient α.
[0052]
[Table 1]

[Brief description of the drawings]
FIG. 1 shows a test piece No. according to an embodiment of the present invention. 3 is a graph showing a coefficient of thermal expansion of No. 1.
FIG. 2 shows a test piece No. according to an example of the present invention. 4 is a graph showing cycle characteristics of a thermal expansion coefficient of 1.

Claims (12)

A low-thermal-expansion alloy comprising 20 to 30 at% of a Va group element and the balance of an IVa group element and unavoidable impurities when the whole is 100 atomic% (at%). The low thermal expansion alloy according to claim 1, further comprising at least 6 at% or less of any one of oxygen (O), nitrogen (N), and carbon (C). Further, any one of aluminum (Al), tin (Sn), chromium (Cr), molybdenum (Mo), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), and tungsten (W) The low thermal expansion alloy according to claim 1, comprising at least one kind. With respect to the energy level Md of the d-electron orbit, which is a parameter determined by the DV-Xα cluster method, the average compositional value of the substitutional element is 2.430 ≦ Md ≦ 2.490, and the average compositional value of the substitutional element is 2. 860 ≦ Bo ≦ 2.900 and a specific composition having a composition average of 4.22 ≦ e / a ≦ 4.26 with respect to the number of valence electrons e / a of the substitution element. The low thermal expansion alloy as described. The low thermal expansion alloy according to claim 1, wherein the low thermal expansion alloy has a low thermal expansion temperature range in which the absolute value | α | of the thermal expansion coefficient α is 5 × 10 ⁻⁶ / K or less. The low thermal expansion alloy according to claim 5, wherein the low thermal expansion temperature range includes at least 273 to 323K. The low thermal expansion alloy according to claim 1, obtained after cold working. The low thermal expansion alloy according to claim 1, further exhibiting at least one of constant elasticity, high strength, low rigidity, and high elastic deformability. A low-thermal-expansion member comprising at least part of a low-thermal-expansion alloy containing 20 to 30 at% of a Va group element and the balance being an IVa element and unavoidable impurities when the whole is 100 at%. The low-thermal-expansion member according to claim 9, wherein cold-working is performed so that the total cold-working rate is 10% or more. A raw material manufacturing step of manufacturing an alloy raw material comprising 20 to 30 at% of a group Va element and the balance being a group IVa element and unavoidable impurities, when the whole is 100 at%;
A cold working step of performing cold working on the obtained alloy material,
A method for producing a low thermal expansion alloy comprising: A processing step of subjecting at least cold working to an alloy material composed of 20 to 30 at% of a Va group element and the balance being an IVa group element and an unavoidable impurity when the whole is set to 100 at% to obtain a low thermal expansion member having a desired shape. A method for producing a low thermal expansion member comprising:

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