JPH08225915A - Aluminum-silicon alloy pre-compact low in thermal expansion and its compact - Google Patents

Abstract

PURPOSE: To produce a Al-Si alloy pre-compact low in thermal expansion, excellent in suitability as an electric component material, etc., and capable of plastic working by using spray forming method and to produce a compact low in thermal expansion by using the pre-compact. CONSTITUTION: This pre-compact obtained by the spray forming method consists of the Al-Si alloy of 3-45wt.% Si content, and has a density of 95% to true density. Also oxygen, hydrogen and nitrogen incorporated in the inside of the pre-compact is limited to <=250ppm, <=0.4ppm and <=60ppm respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a low thermal expansion Al-S.
Regarding the i-type alloy preform and its processed body, in detail,
It has a small coefficient of thermal expansion, such as electronic component materials (specifically, heat sinks for hybrid ICs, metal packages,
As a substrate material for substituting ceramics, etc., a low thermal expansion Al-Si alloy preform which has excellent joining properties with stainless steel and ceramics such as Al ₂ O ₃ and which can be plastically processed, as well as forging and pressing The present invention relates to a high-quality processed body obtained by mechanical processing such as extrusion.

[0002]

2. Description of the Related Art In recent years, for the purpose of reducing the weight of sliding parts, improving heat conductivity, corrosion resistance, non-magnetic property, etc., or reducing costs, various Al-based alloys, especially Al showing excellent wear resistance, have been developed. -Demand for Si-based alloys is increasing.

However, the molded body produced by casting the Al--Si alloy has the following drawbacks. (A) In the case of a hypoeutectic Al-Si alloy having a low Si content, the primary phase and eutectic α phase of Al are precipitated, and the dispersed state of Si deteriorates, so that sufficient wear resistance is obtained. It's hard to be beaten. (B) In a hypereutectic Al-Si alloy with a high Si content, the material itself is significantly worn because coarse Si particles fall off from the matrix, the machinability is poor, and precision processing is difficult. In addition, there is a limit to the amount of addition of other elements, and the material properties expected by alloy design cannot be obtained.

Therefore, powder metallurgy has come to be used as a method for uniformly and finely dispersing a relatively large amount of Si and other alloying elements without segregation, and various improved methods for Al-Si alloys. Have been proposed. However, the following problems arise when an Al-Si alloy is manufactured by the powder metallurgy method.

The powder metallurgy method is a method in which an alloy material is made into a fine powder and then compression molding and sintering are performed to obtain a molded body. However, since Al and Si are very easily oxidized, The powder surface is covered with a strong oxide film, and the sinterability is poor. Therefore, in order to sinter the preformed body of Al-Si alloy powder, it is necessary to adopt a sintering temperature at least a part of which is in a liquid phase. Grows and becomes coarse and wear resistance deteriorates. Such a tendency is more remarkable in the case of containing fine Si particles, and no matter how fine the Si particles are in the powdering step, the characteristics as a sintered body are not improved. Moreover, since the oxide dispersed in the preform causes crack propagation and the like, the deformability also deteriorates. In order to avoid the above problems associated with the formation of an oxide film, it is possible to use fine powder with a low oxygen content, but all manufacturing, storage, and use are performed in a non-oxidizing atmosphere. Not only is the work very troublesome because it has to be done, but there is also a safety problem in that it ignites when it comes into contact with the atmosphere.

If the degassing of the preform carried out prior to mechanical processing such as extrusion, forging and pressing is insufficient, swelling occurs during the heat treatment after processing, which reduces the dimensional accuracy and causes internal defects. Becomes Moreover, when the density of the preformed body is 85% or more of the true density, it takes a very long time to remove the gas such as water vapor and air existing in the preformed body.

In order to use it as a billet for extrusion or forging, the preform should be 90% of the true density.
Although the above high density is required, the preform obtained by the CIP method has a low density (about 80%) and may be damaged during loading or handling in an extruder or the like. I can't.

[0008] Other than the above, there are problems that contamination by dust or the like is likely to occur at the time of manufacturing or handling, it is not suitable for manufacturing a large-sized product, and it takes time and cost due to the large number of steps.

As a relatively new technique which does not involve such a difficulty, while letting a molten metal flow down in a non-oxidizing atmosphere, an inert gas jet stream is made to collide with the molten metal in the course of flowing down to form fine particles. A method for obtaining a preformed body by depositing and solidifying on a substrate (hereinafter referred to as a spray molding method in the present specification) has been developed and attracted attention (Japanese Patent Laid-Open No. 62-1849, etc.). .

That is, in the spray molding method, as described above, the molten metal is made to collide with an inert gas jet stream to form fine particles, and the partially molten particles are fused on a substrate to form a preform. Although it is a method similar to the powder metallurgy method, the atomized metal is fused directly on the substrate to form a preformed body of a predetermined shape immediately after that, so that subsequent handling is extremely difficult. It is simple and resistant to oxidation, and even when it is used as a billet for extrusion or forging, it can be applied to a mass production line without being damaged during loading or handling in an extruder, etc. Can enjoy.

Under the circumstances as described above, the present inventors have been conducting various researches on a metal compact using the spray forming method. In particular, the Si content in the preform made of an Al--Si alloy is And how the amount of gas components, and further the size of Si particles contained in the molded body, affect wear resistance, elongation, machinability, extrudability or forgeability, etc. As part of the research results, we previously mentioned JP-A-4-25.
The technique described in 9364 is presented.

The disclosed invention uses an Al-Si alloy melt containing 8 to 30% by weight of Si and is preformed by the above spray forming method. Each content of oxygen, hydrogen, and nitrogen contained in: oxygen: 250ppm or less, hydrogen: 0.4ppm or less, nitrogen: 6
Al-Si alloy preforms, each of which has a particle size of 10 μm or less and a density of 95% or more of the true density and is limited to 0 ppm or less. A molded product or a processed product obtained by further processing it by forging, pressing, extrusion, etc., has good wear resistance, machinability, elongation, etc., and also has good blister resistance during heat treatment and gives no internal defects. Therefore, it can be effectively utilized for various purposes.

The inventors of the present invention have been conducting research for the purpose of improving the physical properties of Al-Si alloy compacts by utilizing the spray molding method and developing the applications thereof, and have succeeded in researching the above with a high density and stable physical properties. Effectively utilizing the above characteristics of the disclosed invention,
We thought that it could be used as a material for electronic parts, and we have pursued research along that line. However Al-Si based alloy of the public invention, since significant contraction and expansion due to the thermal expansion coefficient is high temperature changes, attempts to use this bonded to the ceramics such as stainless steel, Al ₂ O _3, or the as an electronic component material Then, it has been found that reliable and strong joining is difficult between the materials to be joined due to the large thermal expansion, and it is difficult to apply for such applications.

[0014]

SUMMARY OF THE INVENTION The present invention has been made by paying attention to the above problems, and its object is to preform an Al-Si alloy produced by applying a spray forming method. The problem of thermal expansion pointed out in the body or its molded body is solved, and the coefficient of thermal expansion is small.
Excellent suitability as electronic component material such as heat sink for C, metal package, ceramic substitute substrate material,
Another object of the present invention is to provide a low-thermal-expansion Al-Si alloy preform capable of plastic working and a low-thermal-expansion processed body using the preform.

[0015]

The low-thermal-expansion Al-Si alloy preform according to the present invention, which has been able to solve the above-mentioned problems, is formed by dropping an Al-Si alloy molten metal into fine particles and dropping them. In a preform obtained by sequentially solidifying and growing while melting and adhering, the Si content is 30 to 45% by weight, the oxygen content is 250 ppm or less, the hydrogen content is 0.4 ppm or less, the nitrogen content is 60 ppm or less, and the balance is The present invention has a gist in that it is substantially composed of Al, the density is 95% or more with respect to the true density, and the particle diameter of Si contained inside is 10 μm or less.
Other elements such as Cu, Mg, Ni, and
By adding 0.1 to 13% by weight of one or more elements selected from the group consisting of Fe, Mn, Cr, V, Zr, and Ti, the physical properties of the obtained preform are further improved. Can be one. By subjecting this preformed body to processing such as extrusion, forging, and pressing, it is possible to give it excellent physical properties without internal defects, and especially with low thermal expansion electronic component materials such as stainless steel materials and ceramic materials. Even in the case of joining, it is possible to obtain a processed body having excellent joining properties.

[0016]

The spray molding method is, for example, as shown in FIG. 1, in which the metal melt M flowing down from the melting furnace 1 is collided with an inert gas jet stream from the atomizer 2 to form fine particles and is made non-oxidizing. This is a method for producing a preform (a cylindrical billet 4 in FIG. 1) by cooling and solidifying the fine particles while depositing them at a predetermined position in a chamber 3 kept in an atmosphere (in the figure, 5 indicates an exhaust port). Since it does not come into contact with air in the form of fine particles, it does not cause the problem of oxidation as pointed out in the conventional powder metallurgy method, the manufacturing process is simple and efficient, and the subsequent handling is also very easy. Easy to. Moreover, since it is a method of depositing in the state of fine particles, there is an advantage that coarsening of crystal grains and segregation of alloying elements hardly occur.

Further, in this manufacturing process, most of the metal particles which have become fine particles due to the collision of the gas jet flow are partially in a molten state, and when these are deposited, they are fused to each other and solidify while filling the gap. Therefore, the density is higher and the content of the gas component is relatively smaller than that of the CIP molded body or the like obtained by the conventional powder metallurgy method.

However, depending on the flow velocity and flow rate of the gas jet stream for atomizing, the cooling rate during solidification, etc., the mutual fusion of the particles becomes insufficient and the density decreases, or the internal gas component content May increase, resulting in deterioration of workability and subsequent product defects.

Therefore, the inventors of the present invention have targeted the Al--Si alloy and have a density of a preform obtained by a spray forming method or oxygen contained in the interior in a gaseous or solid solution state.
It was investigated how each content of hydrogen and nitrogen influences workability and physical properties of processed products.

As a result, as described in the above-mentioned Japanese Patent Laid-Open No. 4-259364, first, the true density of the alloy was 9%.
It was confirmed that the preform having a content of 5% or more does not break during charging into an extruder or the like or during the handling process, and does not cause any problem even when applied to a mass production line.

Oxygen, hydrogen, which are present in the preform,
Each nitrogen content is closely related to the elongation rate during processing and the amount of blister that may occur during heat treatment. Especially, the oxygen content is 250ppm or less, the hydrogen content is 0.4ppm or less, and the nitrogen content is 60ppm. It was clarified that the preforms each limited to the following have high elongation and excellent workability, and give a processed product of excellent quality without causing the blister phenomenon in the heat treatment step. Figure 2
[Fig. 4] is a graph showing the results of examining the relationship between the oxygen content of an Al-Si alloy preform (Si content: 35% by weight) obtained by the spray forming method and the elongation rate during extrusion processing. The preform having an amount of 250 ppm or less shows a high elongation rate, but when the oxygen content exceeds 250 ppm, the elongation rate sharply decreases and there is a possibility that breakage or cracking may occur in the extrusion molding process or the like.

3 and 4, the Si content is 35 as well.
It is a graph showing the results of examining the relationship between the hydrogen content or nitrogen content in the Al-Si alloy preform which is wt% and the blister generation amount during heat treatment, wherein the hydrogen content is 0.4 ppm or less and nitrogen. The amount of blister generated in the extruded product obtained by using the preform having the content of 60 ppm is very small, whereas the amount of blister generated in the case where the hydrogen content and the nitrogen content exceed the specified amount. It increases rapidly.

As is clear from FIGS. 2 to 4 above, A
The more preferable content of each component in the 1-Si alloy preform is that oxygen is 200 ppm or less, hydrogen is 0.3 ppm or less, and nitrogen is nitrogen in order to more surely suppress the decrease in elongation and prevent blister. It is particularly desirable that the content be 40 ppm or less.

Among the above-mentioned components, nitrogen is related to not only the nitrogen content of the preform as a whole but also the amount of nitrogen in the residual pores in the preform, to the blister generation amount,
In order to more reliably achieve the above object, it is desirable to control the amount of nitrogen in the residual holes to 4 ppm or less. By the way, according to the investigation by the present inventors of the relationship between the amount of nitrogen in the residual pores and the amount of blister generated, the amount of blister generated when the amount of nitrogen is 4 ppm or less is maintained at a low level. It has been confirmed that the blister generation amount increases sharply when the amount exceeds this. The amount of nitrogen in the residual pores is, for example, first measured by dissolving the mother phase with hydrochloric acid and measuring the amount of nitrogen in the mother phase (at this time, since nitrogen is hardly dissolved in the Al mother phase, It becomes the measurement of the amount of nitrogen). The amount of solid-dissolved nitrogen can be determined by a method of dissolving the residue (mainly primary crystal Si) using sulfuric acid and measuring the amount of nitrogen in the residue after the above treatment.

The Al-Si alloy preform as described above is
It can be obtained by appropriately controlling the flow rate and flow rate of the atomizing gas during spray molding, the ambient temperature, the cooling rate after deposition, and the like. Although Si contained as an essential alloying element exists in the preformed body in a eutectic or dispersed state with Al, when the particle size of Si existing in the dispersed state becomes large, wear resistance,
Since machinability and precision machinability are adversely affected, it is desirable to control the spray molding conditions so that the particle size of Si is 10 μm or less.

By the way, in the above-mentioned Japanese Unexamined Patent Publication No. 4-259364, in order to improve extrusion moldability, forging workability or press workability, aiming at application to various uses, A
The Si content contained in the 1-Si alloy was specified to be in the range of 8 to 30% by weight. This has a Si content of 30% by weight.
The reason above is that the moldability is poor and the versatility is lacking.

However, according to further researches conducted by the inventors of the present invention, when the Al--Si alloy preform as described above is applied as a material for electronic parts as described above, it takes a lot of time. Al with a relatively low Si content
-Si-based alloy due to thermal expansion coefficient is large, for example, bonding between the stainless steel and Al ₂ O _3, or the like packaging material made of a ceramic material or the like is poor, a large problem easily peeled off during use It was confirmed that Therefore, by improving the physical properties of such a high coefficient of thermal expansion to reduce the coefficient of thermal expansion, we believe that it can be effectively utilized as a material for electronic parts, and so on. I proceeded with my research.

As a result, the Si content is 30 to 45% by weight.
It has been found that the above-mentioned problem of thermal expansion can be solved by increasing the number of materials to 1, and a material exhibiting excellent bondability with various materials can be obtained even when used as an electronic component material.

Incidentally, FIG. 5 is a graph showing the results of examining the relationship between the Si content and the coefficient of thermal expansion in the Al--Si alloy preform obtained by the spray forming method as shown in FIG. As is clear from this figure, the coefficient of thermal expansion of the preform decreases sharply as the Si content increases, and if the Si content is increased to 30% by weight or more, a casing material for electronic parts, etc. As a result, it is possible to obtain an Al-Si alloy preform having a low coefficient of thermal expansion lower than that of stainless steel, which is widely used as a material. Therefore, peeling due to a difference in thermal expansion at the time of joining or thereafter is suppressed, and excellent joining properties are obtained. It seems to be secured. However, if the Si amount is excessively large, not only nozzle clogging during the molding and variation of components are apt to occur, but not only the billet manufacturing surface is impaired, but also the plastic workability after molding is deteriorated.
The i content should be kept below 45% by weight.

That is, in the present invention, the Si content is 30.
If it is less than 10% by weight, the thermal expansion cannot be satisfactorily reduced, and the purpose of improving the bondability due to the low thermal expansion cannot be fulfilled. Molding workability becomes worse as the Si content increases, but if the Si content is up to about 45% by weight, plastic working becomes possible by devising the molding processing conditions. That is, in the present invention, the Si content is set to 30% by weight or more as a means for ensuring the low thermal expansion property even if the molding processability is sacrificed to some extent.
It is different from the above-mentioned published invention as an alloy in such a unique physical property of low thermal expansion, and is very useful in practice as a new application of the Al-Si alloy obtained by the spray forming method. is there. However, S
If the i content exceeds 45% by weight and becomes excessive, deterioration of plastic workability becomes a serious obstacle to practical use, so the upper limit was set to 45% by weight from the viewpoint of practicality. Considering both low thermal expansion and plastic workability, the more preferable Si content is in the range of 30 to 40% by weight.

In the Al-Si alloy used in the present invention, an appropriate amount of Cu, Mg, Ni, Fe, Mn or the like is selected according to the required characteristics of the obtained preformed body or its processed body. One or two or more kinds of elements can be contained. That is, Cu, Mg, and Ni are useful as heat resistance improving elements, and Fe and Mn act effectively as strength improving elements. The effect of addition of them is to add about 0.1% by weight or more to the Al-Si alloy material. It is effectively demonstrated by However, if the content of these components is too large, the corrosion resistance, elongation, drawing, etc. of the obtained preform tend to deteriorate, so the total amount of these components must be suppressed to about 13% by weight or less. It is good to

As the shape of the preform, in addition to the solid bar-shaped billet as shown in FIG.
As disclosed in Japanese Unexamined Patent Publication No. 2-1849, while rotating a tubular (or rod-shaped) substrate, the sprayed Al-Si alloy fine particles are deposited and solidified by cooling, and then the substrate is removed from the substrate. A tubular preform can be obtained by adopting a demolding method, and a plate-like preform can be obtained by spray molding similarly using a flat plate-like substrate. 56-1
It is also possible to obtain a preform for forging by depositing Al-Si alloy fine particles on a substrate that also serves as a die as described in Japanese Patent Publication No. 220-220, and by devising a spray forming method. Preforms of various shapes can be obtained.

By extruding the thus-obtained preform and subjecting it to a forming process such as forging or pressing, the density can be easily increased to almost 100% of the true density. The content of the three components present in the molded product is almost the same as the amount of these three components contained in the pre-molded product before the molding process, but the amount is extremely small as described above. Therefore, internal defects do not adversely affect mechanical properties.

[0034]

EXAMPLES Hereinafter, the constitution and working effects of the present invention will be described more specifically with reference to examples, but the present invention is not limited by the following examples, and is applicable to the gist of the preceding and the following. It is also possible to carry out appropriate modifications within the range to be obtained, and all of them are included in the technical scope of the present invention.

Example 1 The Al-Si alloys shown in Table 1 were melted in a vacuum melting furnace, and using this as a base material, a spray molding method (hereinafter, referred to as S / F method) and a conventional powder metallurgy method (hereinafter, referred to as S / F method). A billet-shaped preform was manufactured by the P / M method. The S / F method employs the method shown in FIG. 1 (using nitrogen as the atomizing gas), while the P / M method employs the method of CIP molding the powder obtained by the nitrogen gas atomizing method. did.

FIG. 6 shows an example of the density of each part of the obtained preform obtained by the S / F method. In addition, a preform (billet) obtained by the above S / F method and P / M method
Was heated to 450 ° C. and then directly extruded at an extrusion ratio of 15, and a test piece was cut out from each of the obtained extruded materials to analyze the chemical components and contained gas components and examine the mechanical properties. Table 2 shows the gas analysis results of the obtained extruded materials.

[0037]

[Table 1]

[0038]

[Table 2]

As is clear from Table 1, the S / F material and the P / M material both use the same base material. From Table 2, it can be seen that hydrogen, oxygen and nitrogen in the extruded material Each content is P
The amount of the S / F material is smaller than that of the / M material, and in particular, the amount of oxygen is extremely small. And these data are shown in FIG.
As is clear from comparison with Nos. 4 to 4, it can be seen that the S / F material of the present invention is remarkably superior in elongation and blister resistance to the conventional P / M material.

Example 2 As shown in Table 3 below, after performing melting in the same manner as above using Al--Si type alloys having different Si contents, S /
Preforms were prepared by the F method and the P / M method, and the plastic workability and the bondability with Al ₂ O ₃ ceramics were examined for each. The plastic workability was evaluated as the difficulty when a billet having a diameter of 67 mm was extruded into a plate shape of 22 mm ^w x 5 mm ^t (○: easy to extrude, x: extruding is difficult and cracking occurs during extrusion). Further, the bondability was evaluated by brazing the Al ₂ O ₃ ceramics substrate and each Al-Si alloy preform with an Au-Sn alloy brazing material, and checking the presence or absence of peeling of the bonding surface after brazing (○: (Peeling does not occur at all, Δ: Peeling occurs locally, ×: Peeling is remarkable).

The results are shown in Table 3, and the preform of the present invention (S having a Si content in the range of 30 to 45% by weight) (S
It can be seen that the / F material) is excellent in both plastic workability and bondability, and has very excellent characteristics as a material for electronic parts. Incidentally, while the density of the S / F material shown in Table 3 is almost 100% of the true density,
In the case of the P / M material, the bondability is slightly worse than that of the S / F material, probably because some peeling occurred due to the generation of gas due to oxygen contained during brazing of the Au-Sn alloy.

[0042]

[Table 3]

[0043]

The present invention is constituted as described above, and the thermal expansion coefficient is reduced by relatively increasing the Si content contained in the Al-Si alloy obtained by the spray forming method. Furthermore, by specifying the density of the preformed body and limiting the contents of oxygen, hydrogen, and nitrogen contained in the preformed body, it has low thermal expansion and excellent bondability with stainless steel and ceramics, and plastic processing is possible. It is possible to obtain a preformed body that gives a good processed product such as blister resistance and abrasion resistance, and by extruding this preformed body and subjecting it to processing such as forging and pressing, there is no internal defect. It has become possible to provide a low thermal expansion processed product having excellent physical properties.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view illustrating a spray molding method adopted in the present invention.

FIG. 2 is a graph showing the relationship between the oxygen content in the preform and the elongation.

FIG. 3 is a graph showing the relationship between the hydrogen content in the preform and the amount of blisters generated.

FIG. 4 is a graph showing the relationship between the nitrogen content in the preform and the blister generation amount.

FIG. 5 is a graph showing the relationship between the Si content and the coefficient of thermal expansion in an Al-Si alloy preform.

FIG. 6 shows an example of the density of each part of the preform according to the present invention.

[Explanation of symbols]

 1 Melting furnace 2 Atomizer 3 Chamber 4 Billet 5 Exhaust port

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuhiko Morita 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobe Steel Works, Ltd. Kobe Research Institute

Claims (3)

[Claims] 1. A preformed article obtained by dropping an Al-Si alloy molten metal while making it into fine particles, and successively solidifying and growing them while melting and adhering them, and having a Si content of 30 to 45% by weight and an oxygen content of 250ppm or less, hydrogen content is 0.4ppm or less, nitrogen content is 60ppm or less, and the balance is substantially Al, and the density is 95% of the true density.
The low-thermal-expansion Al-Si alloy preform, characterized in that the particle size of Si contained therein is 10 μm or less. 2. An Al-Si based alloy containing C as another element.
One or more elements selected from the group consisting of u, Mg, Ni, Fe, Mn, Cr, V, Zr, and Ti may be used as the element.
The low-thermal-expansion Al-Si alloy preform according to claim 1, which contains 1 to 13% by weight. 3. A low-thermal-expansion Al—Si based alloy processed product obtained by machining the preformed product according to claim 1 or 2.