JP2011190508A - Titanium copper for electronic component, and electronic component using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide hydrogen-containing titanium copper in which both of strength and electric conductivity are improved. <P>SOLUTION: In the titanium copper containing, by mass, 1 to 6% Ti and 0.01 to 0.2% H, wherein H is comprised in 0.5 to 4 by atomic ratio to Ti, and the balance copper with inevitable impurities, among precipitates made of intermetallic compounds of Ti and Cu, the ones with a particle diameter of ≥5 μm are not present, and in titanium hydroxide, the number of the precipitates of the titanium hydroxide with the dimensions of 5 to 20 nm is 20 to 300 pieces in the field×the thickness of the sample in a thickness of 70 nm observed by a scanning transmission electron microscope (STEM) of 100 nm×100 nm is 20 to 300 pieces, and the area ratio of the titanium hydroxide with the dimensions of 100 nm to 5 μm is 0.25 to 11% in the field of the compositional image of a scanning electron microscope (SEM). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to titanium copper for electronic components and a method for producing the same. The present invention also relates to an electronic component manufactured using titanium copper and a manufacturing method thereof.

  A copper alloy containing titanium (hereinafter referred to as “titanium copper”) has the strength next to beryllium copper in the copper alloy, and has stress relaxation characteristics superior to beryllium copper. In recent years, the demand has been increasing. On the other hand, with the reduction in size and thickness of electronic components, there is a demand for titanium copper that achieves both strength and conductivity at a high level.

As a method of improving the characteristics of titanium copper, a method of containing hydrogen in titanium copper is known. JP 2008-75174 A discloses a titanium hydride (TiCu ₄ ) by precipitating a titanium copper compound (TiCu ₄ ) from a parent phase (supersaturated solid solution phase) of a copper-titanium alloy by heat treatment and at the same time absorbing hydrogen into the alloy. The idea of improving the electrical conductivity of a high-strength copper-titanium alloy by precipitating titanium as TiH ₂ : hereinafter referred to as “titanium hydride” and reducing the titanium (Ti) content in the parent phase. Is disclosed.
In addition, as a method for producing such a copper-titanium-hydrogen alloy, a predetermined amount of titanium is contained in copper as a base material, and rapidly cooled to prepare a copper alloy in which titanium is supersaturated, and this is hydrogenated. A method of incorporating hydrogen by aging treatment in an atmosphere is disclosed.
According to this document, it is said that by adding hydrogen to titanium copper, the electrical conductivity can be increased while maintaining the strength.

In addition, the pamphlet of International Publication No. 2005/098071 discloses a technique for demonstrating the effect of refining crystal grains by incorporating an element having a strong affinity for hydrogen into an alloy mainly composed of an element having a weak affinity for hydrogen. Has been. According to this document, a metal (or alloy) represented by an absolute temperature with respect to an alloy containing an element having a weak affinity for hydrogen as a main constituent and an element having a strong affinity for hydrogen. the melting point of) when expressed as T _M, the alloy by placing the alloy in a hydrogen atmosphere at a temperature range of 0 ℃ ~0.8T _M, hydrogen is absorbed, affinity with and hydrogen contained in the alloy It is said that a strong element reacts with the absorbed hydrogen, and further, from an alloy that absorbs hydrogen and has an element having a weak affinity for hydrogen as a main component, based on the above knowledge, a temperature range of 0 ° C. to 0.8 T _M It is said that the crystal grain size of the alloy can be miniaturized to 1 μm or less by releasing hydrogen at this point. As a result of reducing the crystal grain size, it is said that the strength of the alloy can be increased.

JP 2008-75174 A International Publication No. 2005/098071 Pamphlet

  According to Japanese Patent Laid-Open No. 2008-75174, it is said that by adding hydrogen to titanium copper, the electrical conductivity can be increased while maintaining the strength, but it is described that the strength is also improved. Absent. Rather, as apparent from the data described in FIGS. 3 and 5 of the document, the strength tends to be lower when hydrogen is contained.

  On the other hand, the pamphlet of International Publication No. 2005/098071 states that “by absorbing hydrogen, a hydride or hydrogen solid solution phase is formed in the alloy, and after hydrogen release, a part of the appearance phase is the same as before the hydrogen absorption reaction. Or, by re-forming everything, the crystal grains are refined to 1 μm or less ”(paragraph 0028), and the effect of improving the strength of the alloy is considered to be obtained only after hydrogen is released from the alloy. It was.

  In addition, it has been known for a long time that when hydrogen is contained in a metal, a phenomenon that the ductility toughness of a metal material, called hydrogen embrittlement, is reduced, and hydrogen is actively used to increase the strength of the metal material. Was not added.

  Therefore, it would be epoch-making if not only the conductivity but also the strength can be improved by adding hydrogen to titanium copper. In addition, although the conductivity is improved by hydrogenation as described above, the conductivity of titanium copper is still lower than that of pure copper, and further improvement is desired. The main object of the present invention is to provide hydrogen-containing titanium copper having improved both strength and electrical conductivity.

The inventor has studied to solve the above problems, and in the technique described in Japanese Patent Application Laid-Open No. 2008-75174, a large amount of hydrogen is distributed near the surface of titanium copper, and hydrogen is sufficiently diffused inside the titanium copper. However, it was found that the distribution of hydrogen was uneven in titanium copper. Since hydrogen does not diffuse inside and exists excessively near the surface, it may have adversely affected the strength.
Therefore, the present inventor believes that hydrogen diffuses inside through crystal grain boundaries and dislocations, so that in the production process of titanium copper, the crystal grain boundaries and dislocations can be easily diffused into titanium copper. We thought that the characteristics could be improved by increasing hydrogen and dispersing hydrogen uniformly. In the technique described in the publication, Cu ₄ Ti is precipitated together with TiH _2. However, Ti is not precipitated as Cu ₄ Ti which is a stable phase, but TiH ₂ is precipitated as much as possible, leading to improvement of characteristics. I thought it was possible.

The present inventor has continued examination based on the above hypothesis, and in the production process of titanium copper, the grain boundaries and dislocations are increased to internally diffuse hydrogen, and as a form of precipitated Ti, stable Cu and The ratio of depositing Ti intermetallic compounds (eg Cu ₄ Ti and Cu ₃ Ti), especially coarse Cu and Ti intermetallic compounds, and depositing titanium hydride (TiH ₂ , TiH _4, etc.) instead. In many cases, it has been found that titanium copper improves not only the conductivity but also the strength.

  Furthermore, while avoiding the precipitation of the coarse intermetallic compound of Cu and Ti, a certain amount of the intermetallic compound of Cu and Ti having a size below a specific range is precipitated and hydrogenated. The present inventors have found that further improvement in conductivity can be obtained.

  In one aspect, the present invention completed based on the above knowledge contains 1 to 6% by mass of Ti, 0.01 to 0.2% by mass of H, and 0.5 to 4 in terms of atomic ratio with respect to Ti. Of the precipitates composed of the balance copper and inevitable impurities, and composed of an intermetallic compound of Ti and Cu, titanium copper having substantially no particle size of 5 μm or more, Hydrogenation of 5 to 20 nm titanium hydride precipitates observed with a scanning transmission electron microscope (STEM) of 100 nm × 100 nm × 20 to 300 in a thickness of 70 nm of the sample and a size of 100 nm to 5 μm It is titanium copper whose area ratio of titanium is 0.25 to 11% in the field of view of the composition image of a scanning electron microscope (SEM).

  In one embodiment of titanium copper according to the present invention, the average crystal grain size is 30 μm or less.

  In a further embodiment of the titanium copper according to the present invention, the standard deviation of hardness measured in the thickness direction is 10 or less.

  In yet another embodiment of titanium copper according to the present invention, the third element group further includes Mg, Mn, Fe, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, P, and Ag. 1 type or 2 types or more selected from the group which consists of 0.5 mass% or less in total are contained.

In another aspect of the present invention, Cu is one or more selected from the group consisting of Mg, Mn, Fe, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, P, and Ag. Are optionally added so as to contain 0.5% by mass or less in total, and then added to contain 1-6% by mass of Ti to produce an ingot, and
Step 2 of hot rolling the ingot and cold rolling;
Next, a step 3 of solution treatment by heating to a temperature 30 to 100 ° C. higher than the solid solution limit temperature according to the Ti content,
Step 4 of cold rolling at a working degree of 50% to 90%,
Step 5 of heating at a temperature lower by 0 to 20 ° C. than the solid solution limit temperature according to the Ti content and solution treatment,
Then, step 6 of cold rolling at 10% to 70%,
Next, step 7 of aging treatment at 250 to 450 ° C. for 1 to 100 hours,
Including
Performing a step of introducing hydrogen into the material in step 7 or in a stage prior to step 7;
It is a manufacturing method of titanium copper.

  In another aspect, the present invention is a copper-drawn product made of the above titanium copper.

  Another aspect of the present invention is an electronic component including the titanium copper.

  In another aspect, the present invention is a connector comprising the titanium copper.

  According to the present invention, it is possible to obtain hydrogen-containing titanium copper having improved both strength and electrical conductivity.

Ti hydride (C1: size 5 nm to 20 nm) Ti hydride (C2: size 100 nm to 5 μm, observed with a scanning electron microscope (SEM) 5000 times) Ti hydride (C2: size 100 nm to 5 μm, observed with scanning transmission electron microscope (STEM) 100,000 times)

(1) Composition of copper alloy (a) Ti
If Ti is less than 1% by mass, a sufficient strengthening mechanism cannot be obtained due to the formation of a modulation structure inherent to titanium-copper. On the contrary, if Ti exceeds 5% by mass, a coarse stable phase (TiCu ₄ Or an intermetallic compound of Cu and Ti typified by TiCu ₃ ) is easily precipitated, but the stable phase can be controlled to a size of less than 5 μm up to nearly 6 mass% by appropriately performing the solution treatment. However, when it exceeds 6 mass%, the control becomes difficult, and the strength and bending workability deteriorate. Therefore, the content of Ti in the titanium copper according to the present invention is 1.0 to 6.0 mass%, preferably 3.0 to 5.5 mass%, more preferably 3.5 to 5.0% by mass. Thus, by optimizing the Ti content, both strength and bending workability suitable for electronic components can be realized.

(B) H
Titanium copper is an alloy whose strength and conductivity are improved by developing a modulation structure that is a periodic variation of Ti concentration during aging treatment after sufficiently dissolving Ti in the solution treatment step. However, an intermetallic compound of Ti and Cu such as TiCu ₄ and TiCu ₃ is inevitably deposited during the aging treatment for developing the modulation structure. When the intermetallic compound of Ti and Cu is precipitated, the conductivity is improved by decreasing the amount of solid solution Ti, but hardly contributes to the strength. In particular, in an overaging state where the aging temperature is high or the aging time is long, a coarse intermetallic compound of Ti and Cu such as TiCu ₄ or TiCu ₃ is obtained. Coarse intermetallic compounds are not preferred because they reduce strength.

  Therefore, in the present invention, as titanium copper having high strength and high conductivity, hydrogen exists in the matrix during the aging treatment, so that the solid solution Ti reacts with hydrogen during the aging treatment to precipitate an ultrafine hydride. It has been found that the strength can be increased by suppressing the precipitation of coarse intermetallic compounds of Ti and Cu, which improve the conductivity and reduce the strength. Furthermore, it has been found that a fine intermetallic compound of Ti and Cu of such a size that does not decrease the strength is reversely precipitated and made into fine titanium hydride to further improve the conductivity. It was. Hydrogen has a higher affinity for Ti than Cu and hardly forms copper hydride.

  Moreover, the precipitation of ultrafine titanium hydride can also contribute to the improvement of strength. This is considered to be because H contributing to strengthening is due to the formation of ultrafine titanium hydride in the modulation structure.

  In the present invention, titanium hydride is considered to consist of X = 0.2 to 2 (or 0.5 to 2) as a hydrogen compound TiHx of titanium.

If the content of H is too small, the above-described effects cannot be obtained sufficiently. Therefore, at least 0.5 in terms of the atomic ratio of Ti to Ti should be contained in titanium copper. On the other hand, when excessively added, Ti that contributes to the modulation structure reacts with H and precipitates excess titanium hydride, thereby reducing the strength. Also, it is not preferable to leave a large amount of unreacted H. Since hydrogen has a small atomic radius and is light, it moves relatively freely in the material and reacts with O and C mixed in a trace amount in the base material to form water and methane. When such a liquid or gaseous compound is present in titanium copper, fine voids and cracks are generated in the matrix phase, causing a decrease in strength. Therefore, the H concentration in titanium copper should be less than the concentration required for all the added H to form a compound with Ti, specifically, at most four times the number of Ti atoms. In consideration of the fact that titanium hydride precipitates mainly as TiH ₂ , it is preferable not to contain more than twice the number of Ti atoms.

  Therefore, the content of H contained in titanium copper is 0.5 to 4 in terms of atomic ratio with respect to Ti. More preferably, it is 0.5 to 2. The specific H concentration is preferably 0.01 to 0.2% by mass, and more preferably 0.01 to 0.1% by mass.

(C) Third element group Titanium copper further includes a third element group consisting of Mg, Mn, Fe, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, P, and Ag. You may contain 1 type (s) or 2 or more types selected in total 0.5 mass% or less. The effect of these elements is that the crystal grains are easily refined even when solution treatment is performed at a temperature at which Ti is sufficiently dissolved by addition of a small amount, and is cured by heat treatment at a low temperature after press working described later. The spring property is improved. Here, in titanium copper, Fe has the highest effect of the present invention. Mg, Mn, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, P, and Ag can be expected to have an effect equivalent to Fe, and even when added alone, the effect can be seen. May be added in combination.

  These elements have a small amount of solid solution in titanium copper, and crystal grains are refined with a slight addition amount. And it is an element which does not exert a bad influence with respect to the development of the modulation | alteration structure which draws out the intensity | strength of titanium copper. Further, B and P are hardly effective when added alone, but by adding them in combination with other elements, there is an effect of promoting the function of these elements. Since the effect of the third element group appears significantly when the total content is 0.05% by mass or more, it is preferable to contain the third element group by 0.05% by mass or more in total. However, when too much is added, the solid solubility of Ti is lowered and coarse second phase particles are easily precipitated, and the strength is slightly improved, but the bending workability is deteriorated. Specifically, if the total amount of the third element group exceeds 0.5% by mass, the precipitation of the second phase particles becomes excessive, which adversely affects the bending workability.

(2) Precipitate composed of intermetallic compound of Ti and Cu and titanium hydride (a) Structure of precipitate As the precipitate in titanium copper obtained in the present invention, an intermetallic compound of Ti and Cu and titanium hydride are listed. It is done. Titanium hydride is mainly divided into “ultra-fine” titanium hydride and “fine” titanium hydride, both of which are different from each other in the strength and conductivity of titanium copper, as will be described in detail below. Contribute.

(B) Relationship between titanium copper and “ultrafine” titanium hydride In titanium copper, Ti and Cu intermetallic compounds (TiCu ₄ , TiCu _3, etc.), which are stable phases that precipitate during aging treatment, are as described above. There is almost no improvement to strength, but coarse ones have an adverse effect on strength. In the present invention, by precipitating as ultrafine titanium hydride, it is possible to suppress the precipitation of coarse Ti and Cu intermetallic compounds, and to reduce the ratio of Ti to precipitate as Cu intermetallic compounds. As a result, the adverse effect on the strength due to the intermetallic compound of coarse Ti is reduced, the strength improvement effect derived from the original modulation structure of titanium copper, and the further strength improvement effect due to titanium hydride dispersed in the modulation structure Appear more clearly. This is considered to be because Ti was precipitated as ultrafine titanium hydride in the modulation structure. The precipitated ultrafine titanium hydride was converted from the modulation structure to an intermetallic compound of Ti and Cu. It is considered that the growth is suppressed, that is, the number of intermetallic compounds of Ti and Cu is reduced, and the generation of coarse precipitates is suppressed.

  Specifically, among the precipitates composed of an intermetallic compound of Ti and Cu, those having a particle size of 5 μm or more are substantially absent, and titanium hydride having a size of 5 to 20 nm is a scanning transmission electron having a size of 100 nm × 100 nm. In the field of view of the microscope (STEM) × the thickness of the sample at 70 nm, the number is 20 to 300, preferably 30 to 300, and more preferably 50 to 300. Here, “substantially no” means, for example, that the composition image of a scanning electron microscope (SEM) is 1000 times and the number of particles per unit field (85 μm × 115 μm field) is counted for 10 fields, and the size is 5 μm or more. The average number per field of view is less than 0.2.

In addition, the intermetallic compound of Ti and Cu is a precipitate observed with an electron microscope such as SEM, EPMA, or STEM (HAADF), and is a precipitate in which Cu is detected by 50 mass% or more and Ti is detected by 6 mass% or more. Specific examples include TiCu ₄ and TiCu ₃ , but are not limited thereto.

(C) Relationship between titanium copper and “fine” titanium hydride On the other hand, while suppressing the precipitation of the coarse intermetallic compound of Ti and Cu as described above, the fine Ti and the strength that does not affect the strength By depositing an intermetallic compound of Cu and aging treatment in a hydrogen atmosphere, fine titanium hydride deposits are obtained. Thus, by using titanium hydride as a fine intermetallic compound of Ti and Cu, further improvement in conductivity can be obtained without impairing strength. This is because Ti in the matrix phase is reduced by the precipitation of fine Ti and Cu intermetallic compounds, and Cu ₄ Ti, etc., of the intermetallic compounds in the fine precipitates is hydrogenated to produce Cu. (For example, Cu ₄ Ti + H ₂ → 4Cu + TiH ₂ ).

  Here, about the said fine titanium hydride, the generation amount can be specified by calculating | requiring the area ratio of the titanium hydride of the specific magnitude | size observed in a specific visual field. Specifically, in a composition image of a scanning electron microscope (SEM), titanium hydride appears as a black portion, and the area ratio can be calculated by image processing. If the area ratio is too large, the strength is adversely affected. Conversely, if the area ratio is too small, the effect of improving conductivity cannot be obtained. Specifically, in the fine titanium hydride, the area ratio (%) of titanium hydride having a size of 100 nm to 5 μm is 0.25 to 11.00%, preferably 0.75 to 9.00. %.

(3) Hardness standard deviation measured in the thickness direction In the titanium copper according to the present invention, hydrogen is uniformly diffused to the inside by increasing the grain boundaries and dislocations and increasing the hydrogen diffusion path. Thus, the adverse effects of excessive hydrogen distribution near the surface as in the prior art are eliminated.
However, since it is difficult to measure the distribution of the hydrogen concentration in the plate thickness direction, in the present invention, it is defined by the hardness of the material. Specifically, the standard deviation of the hardness (Hv) measured several times in the thickness direction by measuring the Vickers hardness is 10 or less, more preferably 5 or less.

(4) Average crystal grain size In order to improve the strength of titanium copper, the smaller the crystal grain, the better. Furthermore, in the present invention, the number of crystal grain boundaries increases, which is advantageous for hydrogen internal diffusion. Therefore, the preferable average crystal grain size is 30 μm or less, more preferably 10 μm or less, and even more preferably 7 μm or less. Regarding the lower limit, it is difficult to discriminate the crystal grain size when the degree of work of the final rolling is high. Therefore, such a situation is set to less than 1 μm (<1 μm) and is included in the scope of the present invention. However, if the stress relaxation characteristic is required, it is preferably 1 μm or more since the stress relaxation characteristic is deteriorated if it becomes extremely small.

(5) Characteristics of Titanium Copper According to the Present Invention As described above, hydrogen is present in the titanium copper according to the present invention in an appropriate form and distribution state, and precipitation of coarse intermetallic compounds of Ti and Cu is suppressed. Therefore, as compared with the case where hydrogen is not added, there is a feature that strength is improved in addition to conductivity. In addition, by depositing and hydrogenating a fine intermetallic compound of Ti and Cu, it has a feature that the conductivity is further improved as compared with the case where hydrogen is simply added. For example, the tensile strength can be 800 MPa or more, preferably 1000 MPa or more, and the electrical conductivity (% IACS) can be 30% or more, preferably 35% or more.

  Titanium copper according to the present invention can be processed into copper products having various plate thicknesses, and is useful as a material for various electronic components. The titanium copper according to the present invention is not limited, but can be suitably used as a material for switches, connectors, jacks, terminals, relays and the like.

(6) Manufacturing method In manufacturing titanium copper according to the present invention, as described above, the crystal grain boundaries and dislocations are increased so that hydrogen can uniformly diffuse inside the material, and a spinodal transformation that forms a modulation structure. It is necessary to deposit titanium hydride therein, suppress the precipitation of coarse Cu and Ti intermetallic compounds, and deposit and hydrogenate fine Cu and Ti intermetallic compounds. To that end, in the first solution treatment, Ti is sufficiently dissolved in Cu, and in the final solution treatment, a fine intermetallic compound of Cu and Ti is produced while preventing recrystallized grains from becoming coarse. It is important to form a solution at such a temperature as to remain, to perform an appropriate cold rolling immediately before the aging treatment, and to perform the aging treatment on a relatively low temperature side. In addition, what is necessary is just to perform introduction | transduction of hydrogen to titanium copper before an aging treatment or during an aging treatment.
Below, a suitable manufacture example is demonstrated one by one for every process.

1) Ingot manufacturing process Manufacturing of an ingot by melting and casting is basically performed in a vacuum or in an inert gas atmosphere. If the additive element remains undissolved during melting, it does not effectively act on strength improvement. Therefore, in order to eliminate undissolved residue, it is necessary to add a high-melting-point additive element such as Fe or Cr, and after sufficiently stirring, hold for a certain time. On the other hand, since Ti is relatively easily dissolved in Cu, it may be added after the third element group is dissolved. Therefore, for melting, an appropriate amount of Cu is added as necessary as a third element group from Fe, Mn, Mg, Mo, Co, Ni, Si, Cr, V, Nb, Zr, B, P, and Ag. One or more selected from the group consisting of a total of 0.50% by mass or less is added, and after holding sufficiently, 1 to 6% by mass of Ti is added.

2) Homogenization annealing and hot rolling Here, it is desirable to eliminate solidified segregation and crystallized substances generated during casting as much as possible. This is because in the subsequent solution treatment, the precipitation of the second phase particles represented by the intermetallic compound of Ti and Cu and titanium hydride is dispersed finely and uniformly, and it is also effective in preventing mixed grains. is there.
After the ingot manufacturing process, hot rolling is performed after performing homogenization annealing at 900 to 960 ° C. for 3 hours or longer, typically 3 to 5 hours. Titanium copper has a high diffusion rate and plastic fluidity at 900 ° C. or higher, and there is no difference in deformation resistance due to a difference in Ti concentration. Therefore, the segregation layer is divided and homogenization is promoted. In addition, since the titanium is concentrated in the segregation part and has a low melting point, when heated above 960 ° C., a liquid phase appears, and when hot rolling is performed as it is, liquid metal brittleness is generated that cracks at that part. End up.

3) First solution treatment After that, it is desirable to carry out the solution treatment after appropriately repeating cold rolling and annealing. The reason why the solution is formed in advance is to completely dissolve the Ti and TiCu compounds. If the temperature is too high, the alloy is not preferable because the alloy is locally melted or oxidized from the surface layer by oxygen that has entered and diffused from the surface. If it is too low, the TiCu compound does not dissolve, which is not preferable. In the parallel phase diagram of the Cu—Ti alloy, the solid solution limit temperature of Ti varies depending on the Ti content, and is about 590 ° C. for 1% by mass Ti, about 680 ° C. for 2% by mass Ti, about 760 ° C. for 3% by mass Ti, 4 mass% Ti is about 820 ° C., 5 mass% Ti is about 860 ° C., and 6 mass% Ti is about 880 ° C. Therefore, it is good to carry out for 2 to 10 minutes, preferably 5 to 7 minutes in the temperature range higher than these temperatures by 30 to 100 ° C, more preferably 30 to 90 ° C.

4) Intermediate rolling As the degree of processing in the intermediate rolling before the final solution treatment is increased, the second phase particles in the final solution treatment are precipitated more uniformly and finely. This is because accumulated processing strain becomes a nucleation site for recrystallization. Therefore, when the strain is increased by increasing the degree of processing, a large number of recrystallization nuclei are generated, so that the crystal grains become finer. However, if the final solution treatment is performed with a too high degree of work, a recrystallized texture develops and plastic anisotropy occurs, which may impair press formability. Therefore, the processing degree of intermediate rolling is 50 to 90%. The degree of work is defined by {(thickness before rolling−thickness after rolling) / thickness before rolling) × 100%}.

5) Final solution treatment The crystal grains become finer as the heating rate during the solution treatment is higher. For the purpose of solution formation, it is desirable to completely dissolve the second phase particles, but when heated to a high temperature until complete dissolution, the crystal grains become coarse, and a fine intermetallic compound of Ti and Cu. Therefore, the heating temperature is set to a temperature in the vicinity of the solid solubility line where the second phase particles are dissolved and lower than the vicinity of the solid solubility line. Typically, heating is performed at a temperature lower by 0 to 20 ° C., preferably 0 to 10 ° C. lower than the temperature near the solid solubility limit depending on the Ti content.

  Further, the shorter the heating time in the final solution treatment, the finer the crystal grains. The heating time is 15 seconds to 90 seconds, illustratively 20 to 45 seconds. Even if the second phase particles are generated at this point, if they are finely and uniformly dispersed, they are almost harmless to strength and bending workability. However, since coarse particles tend to grow further in the final aging treatment, the number of second-phase particles at this point must be reduced as much as possible. A higher cooling rate is preferable, and it is advantageous to use water cooling from the viewpoint of operational stability.

6) Final cold rolling degree After the solution treatment step, final cold rolling is performed. The final cold working can increase the strength of titanium copper and increase the hydrogen diffusion path by generating dislocations. At this time, if the degree of work is less than 10%, a sufficient effect cannot be obtained, so that the degree of work is preferably 10% or more. However, the higher the degree of work, the easier it is to form an intermetallic compound of Cu and Ti in the next aging treatment, so the degree of work is 70% or less, preferably 50% or less.

7) Aging treatment The aging treatment is usually performed at 250 to 450 ° C for 1 to 100 hours, although appropriate aging conditions vary depending on the additive element. Although the aging at a low temperature can promote the precipitation of titanium hydride while suppressing the growth of the intermetallic compound of Ti and Cu, a long aging time is required. For example, if it is 300 degreeC or more and less than 400 degreeC, it is desirable to set it as 12 to 75 hours, More desirably, it is set as 30 to 60 hours at 330 to 370 degreeC. When the aging temperature exceeds 450 ° C., hydrogen absorption does not proceed and release starts, making hydrogenation difficult. Therefore, it is preferable to avoid the temperature range exceeding 400 ° C. as much as possible, and to carry out in a short time.

  Hydrogen can be introduced into titanium copper before aging treatment or during aging treatment. For example, by performing an aging treatment in a hydrogen atmosphere, hydrogen reacts with titanium in the material by the heat during the aging treatment while diffusing into the titanium copper, and precipitates as fine titanium hydride. For example, an aging treatment may be performed with a hydrogen partial pressure of 0.1 to 20 MPa. Moreover, it is desirable to use hydrogen having the highest possible purity as the atmospheric gas during the aging treatment. This is to prevent unexpected behavior of hydrogen in the material. In addition, it is possible to introduce hydrogen by a method of electrolytic charging before aging treatment.

  However, even if hydrogen is introduced into titanium copper after aging treatment, for example, hydrogen is introduced after aging treatment in a conventional Ar atmosphere, growth of an intermetallic compound of Ti and Cu cannot be suppressed. There is no effect. Further, even during aging treatment in a hydrogen atmosphere, when the aging temperature exceeds 450 ° C., which is the temperature at which hydrogen release starts, hydrogen cannot be introduced, and growth of an intermetallic compound of Ti and Cu occurs. Therefore, even if hydrogen is subsequently introduced, the conductivity is improved, but the strength is not improved.

  Examples of the present invention will be described below together with comparative examples, but these examples are provided for better understanding of the present invention and its advantages, and are not intended to limit the invention.

  The following properties were measured for the titanium copper test pieces obtained in the examples and comparative examples.

A. H content H content was calculated | required by RH402 by the hydrogen analyzer LECO company using the thermal conductivity system.

B. Average crystal grain size The average crystal grain size is measured by revealing a cross-sectional structure parallel to the rolling direction by etching (water (100 mL) -FeCl ₃ (5 g) -HCl (10 mL)), and crystal per unit area. The number of grains was counted to determine the average equivalent circle diameter of the crystal grains. Specifically, a frame of 100 μm × 100 μm was created, and the number of crystal grains present in this frame was counted. Note that all the crystal grains crossing the frame were counted as ½. The average value of the area per crystal grain is obtained by dividing the frame area of 10,000 μm ² by the total. Since the diameter of the perfect circle having the area is the equivalent circle diameter, this was defined as the average crystal grain size.

C1. Number of Ti hydrides (5 to 20 nm) The number of Ti hydrides having a size of 5 to 20 nm was determined by observation with a scanning transmission electron microscope (STEM). Specifically, the sample was processed to a thickness of 50 to 80 nm, a width of 5 μm, and a length of 6 μm with a FIB (Focused Ion Beam) processing apparatus, and attached to a STEM sample holder. Next, a high angle scattering dark field image (High Angle Annular Dark Field) was observed at 1.2 million magnifications with STEM, and the presence and size of Ti hydride were evaluated at black points (FIG. 1). The range in which the number was measured was 100 nm × 100 nm field of view × sample thickness 70 nm. Regarding the size, the diameter of the smallest circle surrounding the precipitate was taken as the size of the precipitate.

C2. Area ratio of hydride of Ti (100 nm to 5 μm) (FIG. 2-1)
Among the hydrides of Ti, the area ratio of those having a size of 100 nm to 5 μm was observed with a scanning electron microscope (SEM) composition image (5000 times to 20000 times), and the observation field (5000 times: 17 μm × 23 μm, The area ratio was calculated by performing image processing on the black spot portion of the size occupying 20000 times: 4.4 μm × 6 μm). Regarding the size, the diameter of the smallest circle surrounding the precipitate was taken as the size of the precipitate. An intermetallic compound of Ti and Cu (particle size of about 500 nm) was changed to Ti hydride by heat treatment in hydrogen and observed with a scanning transmission electron microscope (STEM) at a magnification of 100,000 times. (Figure 2-2)

C3. Intermetallic compound of Ti and Cu (particle size 5μm or more)
Among the precipitates made of an intermetallic compound of Ti and Cu, the number density of those having a particle diameter of 5 μm or more was calculated by the following method.
After electropolishing the test material, the composition image of a scanning electron microscope (SEM) was obtained by counting 1000 times the number of particles per unit field (85 μm × 115 μm field) for 10 fields. Moreover, about the particle size, the diameter of the minimum circle surrounding a precipitate was made into the particle size of the precipitate. Here, when the average number of relevant objects observed in the visual field was less than 0.2, the number of particles was regarded as substantially zero. In order to identify the intermetallic compound of Ti and Cu, an electron microscope with an analyzer such as EDX or WDX was used. In counting, in addition to visually counting the number distributed in the observation field, it is also possible to count from element mapping information such as EPMA.

D. Diffusion state of H The standard deviation of the hardness was statistically processed by measuring the Vickers hardness of the cross section in the plate thickness direction according to JIS Z-2244.

E. Strength Regarding the strength, a tensile test was performed in the rolling parallel direction to measure the tensile strength.

F. Conductivity Conductivity (EC;% IACS) was determined by measuring volume resistivity with a double bridge.

  When manufacturing a titanium-copper test piece, Ti, which is an active metal, is added as the second component, and therefore a vacuum melting furnace was used for melting. Further, in order to prevent unexpected side effects due to mixing of impurity elements other than the elements specified in the present invention, raw materials having a high purity of 99.99% or more were carefully selected and used.

[No. 1-21]
Under an Ar atmosphere, Ti was added to Cu in a high-frequency melting furnace, melted at 1200 ° C., and cast into a 30 mm thick ingot having a composition of Cu-4.5 mass% Ti. The ingot was subjected to homogenization annealing at 960 ° C. for 3 hours and subsequent hot rolling to obtain a hot rolled sheet having a thickness of 10 mm. After descaling by chamfering, it is cold-rolled to a strip thickness of 1 mm, subjected to the first solution treatment under the conditions shown in Table 1, and cold-rolled to the thickness before final rolling shown in Table 1 Rolled. Thereafter, it is inserted into an annealing furnace capable of rapid heating and subjected to the final solution treatment under the conditions described in Table 1. After descaling by pickling, the final cold rolling is performed under the conditions described in Table 1. The final plate thickness was obtained, and finally, various test pieces were obtained by aging treatment under the conditions shown in Table 1. In addition, when the aging treatment was performed in a hydrogen atmosphere, the hydrogen partial pressure was set to 7.5 MPa. Table 2 shows various characteristics of the obtained test piece.

  Invention Example No. No. No. 1 was finally subjected to a solution treatment before final rolling, performed at an appropriate working degree in final rolling, and subjected to an aging treatment in a hydrogen atmosphere. Nos. 1 to 8 contain H of 0.01% or more, and Ti / H exceeds 0.5, so that sufficient titanium hydrogenation is performed and precipitation of coarse Ti and Cu compounds is suppressed. . On the other hand, fine Ti and Cu compounds are precipitated and hydrogenated. As a result, high strength and high conductivity can be obtained.

  Comparative Example No. Since No. 9 is aging-treated in argon, hydride (C1) is not confirmed, and tensile strength and electrical conductivity are inferior.

  Comparative Example No. No. 10 has a final degree of rolling work that is too high, so that Ti and Cu compounds and hydrides are likely to precipitate even when the same heat treatment as in the invention example is performed in an aging treatment in a hydrogen atmosphere. As a result, excessive hydride precipitation (C2) exceeding the upper limit of the present invention occurs, and the strength is inferior to that of the inventive examples.

  Comparative Example No. Since No. 11 was not subjected to final rolling, the number of dislocations in the material was small, so that hydrogen was not sufficiently diffused, the hydrogen content was small, hydrides were not confirmed, and the strength was insufficient as compared with the invention examples. .

  Comparative Example No. Nos. 12, 18, 19 and 20 have a large crystal grain size because the time for the final solution treatment is long and the temperature is high. Comparative Example No. In No. 12, a hydride (C1) not lower than the lower limit of the present invention was not obtained. As a result, the strength is low. Comparative Example No. In 18, 19, and 20, a hydride (C2) equal to or higher than the lower limit of the present invention was not obtained, and as a result, the conductivity was inferior to that of the inventive examples.

  Comparative Example No. In No. 13, since the temperature of the solution treatment 1 is low, No. 14 has a low final solution treatment temperature and a long time, so that a coarse intermetallic compound of Cu and Ti (C3) having a size of 5 μm or more remains and has a low strength.

  Comparative Example No. 15 and No. No. 16 has an aging treatment temperature exceeding 450 ° C., so that hydride is not generated even when heat treatment is performed in a hydrogen atmosphere, and both strength and conductivity are inferior.

  Comparative Example No. In No. 17, the final rolling is insufficient, the hydrogen uptake is insufficient relative to the amount of Ti added, and the strength and conductivity are inferior.

  Comparative Example No. In No. 21, since the heat treatment temperature of the aging treatment is low, it is not hydrogenated and has poor strength and electrical conductivity.

[No. 22-49]
After adding Mg, Mn, Fe, Co, Ni, Cr, Mo, V, Nb, Zr, Si, B, P and Ag to Cu in the high-frequency melting furnace in an Ar atmosphere with the compositions shown in Table 3, respectively. Ti having the composition shown in the table was added and melted at 1230 ° C., and cast into an ingot having a thickness of 30 mm. The ingot was subjected to homogenization annealing at 960 ° C. for 3 hours and subsequent hot rolling to obtain a hot rolled sheet having a thickness of 10 mm. After descaling by chamfering, it is cold-rolled to the strip thickness (1 mm), and the first solution treatment is performed under the conditions shown in Table 4 until the intermediate thickness (0.1 mm). Cold rolled. Thereafter, it is inserted into an annealing furnace capable of rapid heating and subjected to the final solution treatment under the conditions described in Table 4. After descaling by pickling, the final cold rolling is performed under the conditions described in Table 4. The plate thickness was set to 0.05 mm, and finally, various test pieces were obtained by aging treatment under the conditions described in Table 4. Table 5 shows various characteristics of the obtained test piece.

  Invention Example No. 22 to 42 are examples in the case where the content of Ti is changed or a third element other than Ti is added. Results similar to 1-8 were obtained. Comparative Example No. Since Nos. 43 to 49 are subjected to an aging treatment in an Ar atmosphere, a hydride cannot be obtained, and tensile strength and conductivity are inferior.

Claims (8)

  1 to 6% by mass of Ti, 0.01 to 0.2% by mass of H, 0.5 to 4 in terms of atomic ratio with respect to Ti, and the balance of copper and inevitable impurities. Titanium copper having no particle size of 5 μm or more among precipitates made of intermetallic compounds, and among titanium hydrides, a precipitate of titanium hydride having a size of 5 to 20 nm is 100 nm × 100 nm scanning transmission type Field of view observed with an electron microscope (STEM) × 20 to 300 in a sample thickness of 70 nm, and the area ratio of titanium hydride having a size of 100 nm to 5 μm is within the field of view of a composition image of a scanning electron microscope (SEM) Titanium titanium which is 0.25 to 11%.   Titanium copper according to claim 1, wherein the average crystal grain size is 30 µm or less.   The titanium-copper according to any one of claims 1 to 2, wherein the standard deviation of hardness measured in the thickness direction is 10 or less.   As the third element group, one or two or more selected from the group consisting of Mg, Mn, Fe, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, P, and Ag are added to a total of 0.0. Titanium copper as described in any one of Claims 1-3 which further contains 5 mass% or less. Cu contains 0.5% by mass or less in total of at least one selected from the group consisting of Mg, Mn, Fe, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, P and Ag And optionally adding step 1 to produce an ingot by adding 1 to 6% by mass of Ti,
Step 2 of hot rolling the ingot and cold rolling;
Next, a step 3 of solution treatment by heating to a temperature 30 to 100 ° C. higher than the solid solution limit temperature according to the Ti content,
Step 4 of cold rolling at a working degree of 50% to 90%,
Step 5 of heating at a temperature lower by 0 to 20 ° C. than the solid solution limit temperature according to the Ti content and solution treatment,
Then, step 6 of cold rolling at 10% to 70%,
Next, step 7 of aging treatment at 250 to 450 ° C. for 1 to 100 hours,
Including
Performing a step of introducing hydrogen into the material in step 7 or in a stage prior to step 7;
Titanium copper manufacturing method.   The copper-stretched article which consists of titanium copper as described in any one of Claims 1-4.   The electronic component provided with the titanium copper as described in any one of Claims 1-4.   The connector provided with the titanium copper as described in any one of Claims 1-4.