JP7117783B2 - Thermally Conductive Aluminum Alloy Laminated Formed Product, Method for Producing Same, and Heat Dissipator for Electronic Device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a thermally conductive aluminum alloy laminate, a method for producing the same, and a radiator for electronic equipment. In particular, the present invention relates to an aluminum alloy laminate formed by a metal lamination method and having high tensile strength and high thermal conductivity, a method for producing the same, and a radiator for electronic equipment.

Cooling of electronic equipment is usually performed using a heat dissipating body such as a heat sink. For example, it is common practice to absorb heat from a heat generating portion of an electronic device using a heat pipe, transfer the heat to fins of a heat sink connected to a housing, and cool the fins with a fan.
In recent years, despite the increase in the amount of heat generated by electronic devices, there is a demand for smaller and lighter electronic device housings, and the environment surrounding heat sinks used in electronic devices is becoming increasingly severe. be.

In order to reduce the weight of the heat sink, measures such as selection of light materials, reduction in the number of members used, thinning, and devising the shape are conceivable. In addition, there is an increasing demand for thinner housings.
Solder containing Pb is used for the joint of the heat sink, and the elution of Pb when the product is discarded poses an environmental problem that cannot be ignored (see Non-Patent Document 1).

In order to improve the cooling performance of electronic equipment that generates a large amount of heat, in addition to the cooling performance of the heat sink itself, it is also required that the members from the heat source, for example, the semiconductor to the heat sink have high thermal conductivity. Therefore, ceramic members such as silicon nitride are sometimes used as insulators. In addition, considering the prevention of breakage of the insulator or semiconductor due to the difference in thermal expansion between the insulator or semiconductor and the heat sink, it is more convenient for the heat sink to have a smaller coefficient of thermal expansion (see Non-Patent Document 2).
Also, in order to withstand thermal deformation on the heat source side, the heat sink should have a high tensile strength.

Aluminum alloys exhibit a thermal conductivity 20 times or more higher than that of titanium alloys, which are also widely known as lightweight alloys. In particular, when high thermal conductivity is required, Al--Mn alloys, which are 3000 series wrought alloys, are known as materials having high thermal conductivity close to that of pure aluminum. Specifically, the annealed material (O material) of 3003 alloy is 190 W/(m・
K) shows a high coefficient of thermal expansion value. This value is close to the thermal conductivity of 230 W/(m·K) of O material of pure aluminum (1050) material. However, the tensile strength is as low as 110 MP.

On the other hand, the work hardened (H18 treated) 3003 alloy has a high tensile strength of about 200 MPa, but a low thermal conductivity of 150 W/(m·K).
Furthermore, among casting aluminum alloys, there is AC4CH alloy, which has excellent castability and corrosion resistance. See Patent Document 3).

It has been reported that a casting exhibiting a high thermal conductivity of 185 W/(m·K) can be obtained by casting an Al-2% Fe-1% Cu alloy by a die casting method. However, this aluminum alloy casting has low corrosion resistance and exhibits a tensile strength of only about 170 MPa. When this is heat-treated, the tensile strength increases to 240 MPa, but the thermal conductivity decreases to 150 W/(m·K) (see Non-Patent Document 4).

It is also reported that wrought aluminum alloys exhibit high thermal conductivity of 210 W/(m·K) and high tensile strength of 200 MPa. However, although this aluminum alloy wrought material can be formed into a plate material or an extruded material, it is difficult to process it into a complicated fin-shaped product such as a heat sink (see Non-Patent Document 5).

On the other hand, metal powder is used as a raw material, layer by layer, and laser or electron beam is irradiated to heat, melt, and solidify only specific parts to create a product in the final shape without using a mold. Recently, the metal lamination method has attracted attention.

According to this metal lamination method, it is possible to form a product with the light weight and thin wall required for the above-mentioned heat sink. It is easy to obtain a heat sink consisting of a product.
Aluminum alloy is also an alloy suitable for the metal lamination method, and the aluminum alloy laminated compact obtained by the metal lamination method has high tensile strength equal to or higher than that of the compact obtained by casting and rolling without rolling. indicates

Al-10%Si-0.4%Mg alloy is a commonly known aluminum alloy, and its tensile strength exhibits a high value of 340 to 380 MPa (see Non-Patent Document 6). However, according to the inventor's measurements, its thermal conductivity is as low as 131 to 170 W/(m·K).
In addition, the metal lamination method is also suitable for producing complex and precise mesh-like and thin fin-like parts, and members with a thickness of about 1 mm can be produced without problems (see Non-Patent Document 6).

Al--Si binary aluminum alloy castings are generally used as cast without heat treatment.
On the other hand, castings of Al--Si--Mg aluminum alloys are often heat-treated to improve mechanical properties by utilizing the hardening function of Mg--Si precipitates. In this case, heat treatment called T6 treatment, which is a combination of solution treatment, water quenching, and tempering, is generally performed.

In this way, the heat treatment causes the eutectic Si to be granulated, which contributes to improving the ductility, eliminates the non-uniformity of the components when solidified, and adds Mg and Si as solute atoms to the aluminum solid solution. Melt into supersaturation. Therefore, industrially, castings of Al—Si—Mg alloys are heated to 520° C. to 540° C., then quenched by cooling in water (cooling rate of 50° C./s or more), and then tempered at 140° C. C. to 180.degree. C. for age hardening.

However, when the tensile strength is to be slightly increased from that of the as-cast material, only age hardening is performed at 160 to 180° C. as T5 treatment (see Non-Patent Document 7).
In the Al-7%Si-0.35%Mg alloy, when the treatment temperature is changed in the solution treatment stage in the first stage of the T6 treatment, the tensile strength is high at 530 ° C., but solution treatment at 500 ° C. It is low even if the processing time is lengthened. The reason for this is thought to be that Si and Mg, which form precipitates, diffuse insufficiently in the aluminum alloy at 500° C., making solid solution difficult (see Non-Patent Document 8).

A metal laminate of A356 (Al-7%Si-0.3%Mg) alloy was examined for morphological change of eutectic Si when heated at 150° C. to 350° C. for 5 hours. In this case, casting materials require heating to 520° C. or higher to change the shape of Si, but it has been reported that granulation starts at a lower temperature of 300° C. in metal laminated materials. In addition, it is reported that although the material as laminated exhibits high tensile strength, the tensile strength decreases as the heating temperature increases, and the tensile strength decreases to about 200 MPa at 350 ° C. (Non-Patent Document 9) reference). However, thermal conductivity is not mentioned.

Looking at the metal phase diagram of the Al-Si-Mg alloy, when the Mg content is 1% or more, the temperature of the molten metal decreases, and when the final solidification temperature reaches 555 ° C, Mg ₂ Si is also generated in addition to Al and Si. As a result, it is known that a eutectic structure composed of three types is formed (see Non-Patent Document 10).

In this case, it has been reported that heating to a temperature close to 580° C. is necessary to cause the Mg ₂ Si compound generated in the aluminum alloy structure to form a solid solution in the aluminum matrix. That is, at temperatures lower than 580° C., the produced compound undergoes little change in form (see Non-Patent Document 11).
However, in the metal lamination method, since the solidification is rapid, it is presumed that the additive element is dissolved in a larger amount than in the phase diagram. According to the inventor's measurements, the Vickers hardness of the Al-12%Si alloy laminate (as-laminated state) is about 100, whereas the value obtained by the conventional casting method is 60. is shown. It is considered that this is because Si is supersaturated and dissolved in Al. In addition, in the phase diagram of the Al-Si alloy, 2.5% of the additive element is included, which corresponds to 1.5 times the value that dissolves in aluminum at the atomic level, that is, the maximum solid solubility limit of 1.65%. reported by Lee et al. in die casting of ADC12 alloy at a cooling rate 1/10 that of the metal lamination process (see Non-Patent Document 12).

Furukawa Electric Times No. 115 (2005) January Wikipedia: Heatsink Aluminum Handbook (Japan Aluminum Association) Taiki Aluminum Industry Co., Ltd. Product Information [High Thermal Conductivity Alloy HT-2] UACJ product information [High-strength, high-thermal conductivity aluminum alloy plate Fasthermo EM series] Adachi et al.: Keikinzoku, 66 (2016), 360 Tsukuda et al.: Keikinzoku, 28 (1978), 8 Adachi et al.: Keikinzoku, 39 (1989), 487 T. Kimura et al.: Materials and design, 89(2016), 41 Hisato Watanabe, Eiichiro Sato: Practical Alloy State Diagram (Applied Edition) Nikkan Kogyo Shimbun Publishing Adachi et al.: Keikinzoku, 37 (1987), 446 Jeongsoo Lee et al.: Casting Engineering, 88 (2016), 610

The present invention was made against the background as described above.
That is, since the metal laminated molded article has a rapidly solidified structure, it exhibits a fine structure that cannot be obtained by the conventional method, and therefore exhibits a high value of tensile strength in the laminated state. However, the Al--Si alloy, in its laminated state, cannot achieve a high thermal conductivity value close to that of a pure aluminum alloy, which is obtained with the Al--Mn alloy.

On the other hand, Al--Mn alloy laminates exhibit high thermal conductivity suitable for heat dissipation parts, but have lower tensile strength than Al--Si alloy laminates, so they cannot be used for heat dissipation parts. Have difficulty.
Therefore, an aluminum alloy laminate having high tensile strength and high thermal conductivity suitable for use in heat dissipating parts is provided, which utilizes the respective advantages of Al--Mn alloy laminates and Al--Si alloy laminates and overcomes their weaknesses. A body is desired.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an aluminum alloy laminated compact having high tensile strength and high thermal conductivity and a method for producing the same.
Another object of the present invention is to provide a radiator for electronic equipment comprising the aluminum alloy laminated molded body.

A first aspect of the present invention is a laminated compact comprising an aluminum alloy containing 7 to 20% by weight Si and 1.5% by weight or less Mg, wherein the Si is discrete and discrete in the aluminum matrix. and having a thermal conductivity of 185 W/mK or more and a tensile strength of 170 MPa or more.

A second aspect of the present invention is a step of laminate-molding an aluminum alloy powder containing 7 to 20% by weight of Si and 1.5% by weight or less of Mg by a metal lamination method. C.-500.degree. Provided is a method for manufacturing an aluminum alloy laminate.

In the method for producing an aluminum alloy laminate molded body according to the second aspect of the present invention, the temperature for heating the metal laminate molded body can be 360°C to 450°C.
In addition, the coordinates (heating temperature, holding time) are as follows: (360°C, 30 hours), (400°C, 1 hour), (400°C, 20 hours), (500°C, 0.5 hours), (500°C, 10 hours) can be done.
A third aspect of the present invention provides a radiator for an electronic device, comprising the above-described aluminum alloy laminated compact according to the first aspect of the present invention.

INDUSTRIAL APPLICABILITY According to the present invention, an aluminum alloy laminate having high tensile strength and high thermal conductivity, a method for producing the same, and a radiator for electronic equipment having high tensile strength and high thermal conductivity are provided.

1 is a micrograph of an aluminum alloy laminated compact obtained in Example 1. FIG. 2 is a micrograph of an aluminum alloy laminated compact obtained in Example 2. FIG. 2 is a micrograph of an aluminum alloy laminated compact obtained in Example 3. FIG. 1 is a micrograph of an aluminum alloy laminate molded body obtained in Comparative Example 1. FIG. 3 is a micrograph of an aluminum alloy laminated compact obtained in Comparative Example 2. FIG. FIG. 2 is a diagram showing Vickers hardness of Examples 1 to 3 and Comparative Examples 1 and 2; FIG. 2 is a diagram showing the thermal conductivity of Examples 1 to 3 and Comparative Examples 1 and 2;

Hereinafter, embodiments of the present invention will be described in detail.
An aluminum alloy laminate compact according to one embodiment of the present invention is made of an aluminum alloy containing 7 to 20% by weight of Si and 1.5% by weight or less of Mg, and Si is discontinuous in the aluminum matrix. exists as an independent form of In this case, the lamination as it is (as b
In the uilt) material, Si has a network structure, but the network structure is destroyed by heat treatment and transformed into a discontinuous independent form (eg, granular body).

As described above, the aluminum alloy laminate molded body according to the present embodiment is formed by the metal lamination method and has the above-described composition and metal structure, so that it has a thermal conductivity of 185 W / mK or more and a tensile strength of 170 MPa or more. It has excellent properties that make it particularly suitable as a heat sink for electronic equipment. In addition, the thermal conductivity described in this specification is a value at a room temperature of 25°C.

The reason why the aluminum alloy laminate compact according to the present embodiment has excellent properties is as follows.
A compact made of an aluminum alloy containing Si and Mg, which is formed by the metal lamination method, solidifies rapidly, resulting in the following: (1) The eutectic Si becomes fine and is linked in a network, resulting in poor heat conduction. (2) Since a large amount of Si or Mg dissolves in the aluminum matrix, or Si precipitates and Mg--Si precipitates that are consistent with the aluminum matrix are generated, there is a problem of poor thermal conductivity. ing.

However, since the eutectic Si is fine, when the molded body is heat-treated, the network structure collapses due to the morphological change of the eutectic Si at a temperature of 360 ° C. or higher, resulting in a large number of divided, discontinuous independent forms (for example, granular bodies). ), and as a result, the thermal conductivity of the molded body is greatly improved. Furthermore, due to the above heat treatment, the solid solution atoms become coarse precipitates (Si, stable phase Mg ₂ Si), and [fine Mg-Si precipitates of 30 angstrom level consistent with the aluminum matrix] substance] also changes to coarser precipitates (Si, stable phase Mg ₂ Si) with an average size of the order of 0.3 to 3 μm. This also contributes to the improvement of the thermal conductivity of the compact by making it completely unmatched from the aluminum matrix (in a so-called state of being dispersed or mixed in the aluminum matrix). Further, when the Mg content is 1.5% by weight or less, the morphology does not change unless the heat treatment temperature is 550° C. or higher, and the Mg ₂ Si compound, which may lower the thermal conductivity, crystallizes in the final solidified portion. there are few. Therefore, even if the temperature is maintained at 500° C. or less so that the Mg ₂ Si crystallized substances do not redissolve, an aluminum alloy laminate compact with high thermal conductivity can be obtained.

Here, eutectic Si imparts certain tensile strength and hardness to the aluminum alloy laminate. In other words, the eutectic Si is dispersed in the aluminum matrix and contributes to the improvement of hardness and tensile strength through dispersion strengthening. Therefore, Si should be 7% by weight or more. If the Si content is less than 7% by weight, it is not possible to obtain an aluminum alloy laminated compact having satisfactory hardness and tensile strength.

On the other hand, if Si is added in an amount exceeding 20% by weight, a thermal conductivity of 185 W/(m·K) or more cannot be obtained, so the Si content must be 20% by weight or less.
Regarding the amount of Mg to be added, from the above-mentioned Non-Patent Document 12, it is inferred that up to 1.5 times the amount obtained from the metal phase diagram will surely form a solid solution, so the upper limit is 1.5 weight. %.
As described above, the aluminum alloy laminate molded body according to the embodiment of the present invention maximizes the characteristics of the metal laminate molded body that can obtain a molded body with a complicated shape, while maintaining the tensile strength of the Al—Si alloy. It has a high thermal conductivity of 185 W/(m·K) or more, which is at the same level as Al—Mn alloys, although the thickness may be slightly reduced. The thermal conductivity of 185 W/(m·K) is about 80% of that of pure aluminum.

Next, a method for manufacturing the above-described aluminum alloy laminate compact will be described.
The aluminum alloy laminate molded body according to the present embodiment is formed by molding an aluminum alloy powder containing 7 to 20% by weight of Si and 1.5% by weight or less of Mg by a metal lamination method, and the obtained molded body is heated at 360 ° C. Manufactured by heating at ~500°C, holding and cooling to room temperature.
In paragraphs 0031 and 0032, the ranges of Si and Mg components are limited in order to maintain predetermined tensile strength and thermal conductivity. However, if (1) Si is present in the aluminum matrix as a discontinuous, discrete form, or (2) heating, holding, or cooling does not adversely affect the retention of both properties, the aluminum alloy Inevitable impurities and other additives are permitted.

Even if 0.5% by weight or less of unavoidable impurities are dissolved in the aluminum matrix during lamination, under the conditions of (1) and (2), as described above, similar to Si precipitates and Mg—Si precipitates, A small amount of unavoidable impurities and aluminum-based compounds are precipitated, so they have little effect on tensile strength and thermal conductivity.
In addition, additional elements other than Si and Mg, such as transition metals, may in some cases form a solid solution once in aluminum during lamination, but under the conditions of (1) and (2), they are incompatible as compounds with aluminum. precipitate in the state Moreover, even if it occurs as a crystallized product during lamination, its form is not continuous like that of eutectic Si. Cu is a typical example, and from the viewpoint of corrosion resistance, the amount added is preferably 3% by weight or less. Elements that form an intermetallic compound with aluminum during lamination include Ni, Mn, Fe, Cr, Ti, and Zr that crystallize an intermetallic compound during lamination. These elements form a discontinuous compound that is inconsistent with the aluminum matrix, but excessive addition results in a decrease in thermal conductivity and also decreases tensile strength and elongation, so the total amount is preferably 2% by weight or less. is 1% by weight or less.

More specifically, the aluminum alloy laminate compact according to the present embodiment is an as-built laminate obtained by laminate-molding the metal powder having the above composition as a raw material. By applying a heat treatment different from that of the (as built) material, it has a high thermal conductivity at the same level as Al--Mn alloys, although it is somewhat inferior to the mechanical properties of the (as built) material.
Note that the non-conventional heat treatment is a heat treatment whose purpose and method are different from those of a normal heat treatment method. As described above, aluminum alloys are generally subjected to the T6 treatment in many cases. In the case of castings of Al-Si aluminum alloys, in order to improve the ductility of the cast and solidified material, eutectic Si is granulated to eliminate unevenness in the composition when solidified, and solute atoms are added to the aluminum solid solution. It is necessary to dissolve in supersaturation. Therefore, the Al-Si-Mg alloy casting material is heat treated at 525°C to 540°C, then quenched by cooling in water (cooling rate of 50°C/s or more), and further tempered at less than 180°C. hardening it.
Alternatively, only age hardening treatment is performed on the casting material, and T5 treatment is performed at 160 to 180° C. to slightly harden it.

On the other hand, in the laminated compact of the present invention, a heat treatment completely different from the T6 treatment and the T5 treatment is performed. That is, as described above, the decrease in the thermal conductivity of the aluminum alloy laminated compact is caused by the metal lamination method, which is characterized by rapid melting and rapid solidification. crystal structure (Al, Si), and (2)
It is based on the idea that the reason for this is that a large amount of Si or Mg dissolves in the aluminum matrix, or Si precipitates and Mg--Si precipitates that are consistent with the aluminum matrix are generated. For the main purpose of breaking these network structures and converting them into discontinuous independent forms (for example, granular bodies), together with the above-mentioned Si precipitates and Mg-Si precipitates, an aluminum matrix having an average size of 0.3 to 3 µm The heat treatment is carried out in consideration of causing incoherent precipitates (Si, stable phase Mg ₂ Si) to exist and preventing re-solid solution.

In the present invention, as the heat treatment temperature, by selecting a heating temperature of 360 ° C. or higher, which is higher than the conventional T5 treatment, the fine and network-like eutectic structure of (1) is divided and granulated, and further is coarsened, and solid solution Si and Mg of (2) are generated as coarse precipitates (Si, Mg ₂ Si), and are completely unmatched from the aluminum matrix (dispersed and mixed in the aluminum matrix state). However, the upper limit of the heat treatment temperature is 500° C., because if the heating temperature is too high, there is a danger that the non-coherent precipitates will redissolve at the atomic level between aluminum atoms.

Mg imparts tensile strength and hardness to Al—Si alloys, but in the present invention, as described above, the heat treatment after lamination molding is performed to heat to a temperature range where Mg—Si precipitates coarsen, Since it softens, it originally does not play a role of age hardening. However, if the Mg content exceeds 1.5% by weight, a large amount of Mg ₂ Si compound tends to crystallize in the final solidified portion together with eutectic Si and Al. The crystallized Mg ₂ Si compound does not change its form like eutectic Si (changes from a network to a discontinuous independent form, such as a granular form) unless it is heated to 550° C. or higher, particularly about 580° C.

However, as described above, when heated above 500° C., Si and Mg ₂ Si dispersed as coarse precipitates in the aluminum matrix up to 500° C. redissolve between aluminum atoms at the atomic level again. and lower the thermal conductivity. Therefore, it is heated at 500° C. or less. Also, the upper limit of Mg must be 1.5% by weight so as not to crystallize a large amount of Mg ₂ Si compound.
Thus, by setting the heat treatment temperature to 500° C. or less and the Mg amount to 1.5% by weight or less (including the case where Mg is not included), Mg ₂ Si, which lowers the thermal conductivity, is fixed between aluminum atoms. It is possible to prevent melting and to obtain an aluminum alloy laminated compact with high thermal conductivity.

Even if the heat treatment temperature is 300° C. or higher, if it is heated for a long time, the eutectic Si changes to a discontinuous independent form (for example, granulation), and the solid solution Mg and Si are converted into stable phase Mg ₂ Si precipitates. Although it is not impossible to obtain a thermal conductivity of 185 W / (m K) by depositing as a . On the other hand, the heat treatment temperature must be 500° C. or lower so that the Si dispersed as coarse precipitates in the aluminum matrix and the stable phase Mg ₂ Si do not dissolve again between the aluminum atoms.
In particular, in order to obtain a molded body having a thermal conductivity of 185 W/(m·K) or more and a tensile strength of 200 MPa or more (Vickers hardness of 60 Hv), it is necessary to heat and hold at a temperature of 360° C. to 450° C. is preferred.

In the method for manufacturing the aluminum alloy laminate molded body described above, it is desirable to set the heating holding time according to the heating temperature. That is, the heating temperature and holding time conditions for obtaining an aluminum alloy laminate having a thermal conductivity of 185 W/(m·K) or more and a tensile strength of 170 MPa or more (Vickers hardness of 50 Hv or more) are preferably They are as follows. The upper limit time for holding at each temperature is the time required for the size of the eutectic Si to become coarse and the tensile strength not to fall below 170 MPa. It is desirable that the average size of Si at that time does not exceed 3 μm. The lower limit of the time may be any time that allows the network Si to collapse and a discontinuous form to be obtained.

That is, in the coordinates where the horizontal axis is the heating temperature and the vertical axis is the holding time, the coordinates (heating temperature, holding time) are (360 ° C., 6 hours), (360 ° C., 30 hours), (400 ° C., 1 hour ), (400° C., 20 hours), (500° C., 0.5 hours), (500° C., 10 hours) under the heating and holding conditions in the area surrounded by 185 W / (m K) or more It has thermal conductivity and can obtain tensile strength of 170 MPa or more (Vickers hardness of 50 Hv or more). The holding time means the time after reaching the target heating temperature.

Electron beam lamination methods and laser lamination methods are available as metal lamination methods for obtaining the above-described aluminum alloy laminated molded body. However, in the electron beam lamination method, the amount of heat applied during molding is too large and the eutectic Si becomes too coarse. Therefore, the laser lamination method is preferable from the viewpoint of obtaining the desired tensile strength.

Generally, the laser lamination method is performed by the following steps.
(1) Spreading a metal powder layer with a certain thickness.
(2) A portion of the metal powder layer to be solidified is locally irradiated with a Yb--Mg fiber laser under an argon atmosphere to heat the powder layer, thereby instantaneously melting and solidifying the powder. In this case, the beam is scanned based on the 3D data slice data.

(3) lowering the production table and laying down a layer of metal powder;
(4) The above steps are repeated to successively laminate metals to obtain a laminate molded body in the final shape, and then unsolidified powder is removed to obtain a laminated molded body.
By subjecting the aluminum alloy powder to the above steps, it is possible to obtain an aluminum alloy laminate compact having a predetermined shape.
The obtained aluminum alloy laminate compact is heated and held at a predetermined temperature for a predetermined time, and cooled to room temperature, as described above.

Examples of the present invention and comparative examples will be described below.
Example 1
Using an aluminum alloy powder (Al-10Si-0.4Mg), a laminate compact of 20 mm×20 mm×20 mm was produced by a laser lamination method.
Next, this laminate molded body was heated and held at 360° C. for 6 hours, and then cooled to room temperature. FIG. 1 shows a micrograph of the metallographic structure of the obtained laminate. The scale is as shown in FIG. 3 (the same applies to FIGS. 2, 4 and 5).

It can be seen from FIG. 1 that eutectic Si and Mg ₂ Si are granulated.
The Vickers hardness of this laminated molded product was 65 when measured with a Shimadzu micro hardness tester HMV-G21. A Vickers hardness of 65 corresponds to a tensile strength of 210 MPa. Further, the thermal conductivity of this laminated molded body was measured by a laser flash method and found to be 190 W/(m·K).

Example 2
A laminated molded body was produced in the same manner as in Example 1.
Next, this laminate molded body was heated and held at 400° C. for 2 hours, and then cooled to room temperature. FIG. 2 shows a microscopic photograph of the metallographic structure of the obtained laminate.
From FIG. 2, it can be seen that the mesh-like eutectic Si becomes discontinuous and becomes granular.
The Vickers hardness of this laminated molded body was measured and found to be 60. A Vickers hardness of 60 corresponds to a tensile strength of 200 MPa. Moreover, when the thermal conductivity of this laminate molded body was measured, it was 200 W/(m·K).

Example 3
A laminated molded body was produced in the same manner as in Example 1.
Next, this laminate molded body was heated and held at 500° C. for 2 hours, and then cooled to room temperature. FIG. 3 shows a micrograph of the metallographic structure of the laminate molded body obtained.

It can be seen from FIG. 3 that the eutectic Si is further coarsened as it becomes grainy.
The Vickers hardness of this laminated molded body was measured and found to be 55. A Vickers hardness of 55 corresponds to a tensile strength of 188 MPa. Moreover, when the thermal conductivity of this laminate molded body was measured, it was 190 W/(m·K).

Comparative example 1
Using an aluminum alloy powder (Al-10Si-0.4Mg), a laminated compact was produced in the same manner as in Example 1 by laser lamination. FIG. 4 shows a micrograph of the metallographic structure of the obtained laminate.

It can be seen from FIG. 4 that the eutectic Si is in a network state.
When the Vickers hardness of this laminate molded product was measured, it exceeded 80. A Vickers hardness of 80 corresponds to a tensile strength of 270 MPa. Moreover, when the thermal conductivity of this laminate molded body was measured, it was 170 W/(m·K).

Comparative example 2
Using an aluminum alloy powder (Al-10Si-0.4Mg), a laminate compact was produced in the same manner as in Example 1 by laser lamination.
Next, this laminate molded body was heated and held at 300° C. for 2 hours, and then cooled to room temperature. FIG. 5 shows a micrograph of the metallographic structure of the obtained laminate.

From FIG. 5, it can be seen that the heat-treated compact of Comparative Example 2 has a metal structure different from that of Comparative Example 1, but discontinuity of eutectic Si, such as graining, is not confirmed.
When the Vickers hardness of this laminate molded product was measured, it exceeded 80. A Vickers hardness of 80 corresponds to a tensile strength of 270 MPa. Moreover, when the thermal conductivity of this laminate molded body was measured, it was 180 W/(m·K).

FIG. 6 shows the Vickers hardness and FIG. 7 shows the thermal conductivity of the laminated molded bodies of Examples 1 to 3 and Comparative Examples 1 and 2, respectively.
As is clear from FIG. 6, the Vickers hardness decreases as the heat treatment is performed and as the heat treatment temperature is increased, but it is 55 even in the heat treatment at 500° C., which means that the tensile strength is about 180 MPa. Equivalent to. A tensile strength of 180 MPa is a sufficient value for use as a radiator for electronic equipment.
Moreover, as is clear from FIG. 7, the thermal conductivity increases as the heat treatment is performed and as the heat treatment temperature is raised, reaching 200 W/m·K at 400° C., but at 500° C., at 360° C. It has dropped to a value of 190 W/m·K. However, this thermal conductivity of 190 W/m·K is a sufficiently high value for use as a radiator for electronic equipment.

Claims (4)

A radiator formed of a laminated compact made of an aluminum alloy containing 7 to 20% by weight of Si, 1.5% by weight or less of Mg , and a total amount of 0.5% by weight or less of unavoidable impurities, Crystalline Si exists as a discontinuous independent form in the aluminum matrix, non-matching Si precipitates and Mg-Si precipitates exist in the aluminum matrix, thermal conductivity of 185 W / mK or more and tensile strength of 170 MPa or more A heat dissipating component made of an aluminum alloy laminated molded body, characterized by having: A method for manufacturing a heat dissipating component according to claim 1, wherein the aluminum alloy comprises 7 to 20% by weight of Si, 1.5% by weight or less of Mg , and a total amount of 0.5% by weight or less of unavoidable impurities. A step of laminate-molding the powder by a metal lamination method, heating the obtained metal laminate compact at 360 ° C to 500 ° C and holding it, and removing the eutectic Si from the network structure in the as built material. From an aluminum alloy laminated molded body characterized by comprising a step of converting to a continuous independent form, converting Si precipitates and Mg-Si precipitates into a form inconsistent with the aluminum matrix , and a step of cooling to room temperature A method for manufacturing a heat dissipating component. 3. The method for manufacturing a heat dissipating component made of an aluminum alloy laminate compact according to claim 2, wherein the metal laminate compact is heated at a temperature of 360.degree. C. to 450.degree. The temperature for heating and the time for holding the metal laminate molded body are represented by coordinates (heating temperature, holding time), where the horizontal axis is the heating temperature and the vertical axis is the holding time. 360°C, 30 hours), (400°C, 1 hour), (400°C, 20 hours), (500°C, 0.5 hours), (500°C, 10 hours) 4. A method for manufacturing a heat radiating component comprising the aluminum alloy laminated compact according to claim 2 or 3.

Images