KR102578486B1 - Iron-copper alloy having network structure and method for manufacturing the same - Google Patents

Abstract

The present invention provides an iron-copper alloy (Fe-Cu alloy) having a network structure and a method for manufacturing the same. The present invention provides iron 65 to 85 atomic%; and 15 to 35 atomic percent of copper, and provides an iron-copper alloy having a network structure formed by copper in the alloy structure. In addition, the present invention provides a melting process for forming molten metal by adding iron and copper to a melting furnace and dissolving them so that the iron-copper alloy contains 65 to 85 atomic% of iron and 15 to 35 atomic% of copper; A casting process of forming a casting by injecting the molten metal into a casting mold; A cooling process of naturally cooling the casting at room temperature; A heat treatment process in which the naturally cooled casting is put into a heat treatment furnace and heat treated at a temperature of 945°C to 980°C; and a quenching process of rapidly cooling the heat-treated casting by quenching it in a cooling medium immediately after the heat treatment, and providing a method for manufacturing an iron-copper alloy having a network structure formed by copper in the alloy structure. According to the present invention, iron (Fe) contains an appropriate amount of copper (Cu), and the alloy structure includes a network structure formed by copper (Cu), thereby improving tensile strength and thermal conductivity while maintaining high hardness. do.

Description

Iron-copper alloy having a network structure and manufacturing method thereof {IRON-COPPER ALLOY HAVING NETWORK STRUCTURE AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to an iron-copper alloy having a network structure and a method for manufacturing the same. According to one embodiment, the present invention includes iron (Fe) and an appropriate amount of copper (Cu), and contains copper (Cu) in the alloy structure. It relates to a high-hardness iron-copper alloy with improved tensile strength and thermal conductivity, including a network structure, and a method of manufacturing the same.

Aluminum alloy is excellent in light weight, thermal conductivity, and ductility, and is used for various purposes in various industrial fields. Aluminum alloys have particularly high thermal conductivity and cool heat quickly. Accordingly, aluminum alloy can minimize deformation and bending of molded products, and is therefore useful as a mold material for injection molding or die casting.

For example, Korean Patent Publication No. 10-2015-0046014 and Korean Patent Registration No. 10-1606525 provide technology related to aluminum alloy for die casting. Aluminum alloy is based on aluminum (Al), but contains small amounts of silicon (Si), iron (Fe), manganese (Mn), and magnesium (Mg), and is called aluminum-silicon-magnesium (Al-Si-Mg). ) type alloy is widely used as a mold material for die casting.

However, aluminum alloy has low mechanical properties such as hardness (wear resistance) and tensile strength. Accordingly, in recent years, beryllium-copper (Be-Cu) alloy, which has good thermal conductivity and excellent mechanical properties such as hardness and tensile strength, has been attracting attention as a mold material. For example, Japanese Patent Publication No. JP2003-003246, Korean Patent Publication No. 10-2012-0048287, Korean Patent Publication No. 10-2015-0053814, etc. describe beryllium-copper (Be-Cu) alloy. This is presented.

However, beryllium-copper alloy has the problem of being difficult to melt and cast, and the cost of the raw materials of beryllium (Be) and copper (Cu) itself is high, making it less economical. Accordingly, beryllium-copper alloy has a problem in that it is used limitedly in high-end products due to its high price, which reduces its versatility.

Meanwhile, iron-copper (Fe-Cu) alloy is easier to melt and cast than beryllium-copper alloy and is economically advantageous. For example, Japanese Patent Application Laid-Open No. 5-331572 discloses an iron-copper alloy using a melt casting method. However, the conventional iron-copper alloy has lower mechanical properties than the beryllium-copper alloy, and its hardness and thermal conductivity are particularly low, making it difficult to apply to mechanical parts that require heat dissipation or cooling.

Republic of Korea Patent Publication No. 10-2015-0046014 Republic of Korea Patent Publication No. 10-1606525 Japanese Patent Publication No. JP2003-003246 Republic of Korea Patent Publication No. 10-2012-0048287 Republic of Korea Patent Publication No. 10-2015-0053814 Japanese Patent Application Laid-Open No. 5-331572

Accordingly, the present invention is a low-cost iron-copper (Fe-Cu) alloy that can replace beryllium-copper (Be-Cu) alloy, and is a high-hardness iron-copper (Fe-Cu) alloy with high hardness and improved tensile strength and thermal conductivity. The purpose is to provide a copper alloy and its manufacturing method.

In order to achieve the above object, the present invention,

iron 65 to 85 atomic%; and

Contains 15 to 35 atomic percent copper,

An iron-copper alloy having a network structure formed by copper in the alloy structure is provided.

In addition, the present invention,

iron 68 to 80 atomic%; and

Contains 20 to 32 atomic percent copper,

It has a network structure formed by copper in the alloy structure,

An iron-copper alloy having the following physical properties (a) to (c) is provided.

(a) Rockwell hardness 30 HRC or higher

(b) Tensile strength of 700 N/㎟ or more

(c) Thermal conductivity is 90 W/mㆍK or more.

In addition, the present invention,

A melting process in which iron and copper are put into a melting furnace and melted to form a molten metal so that the iron-copper alloy contains 65 to 85 atomic% iron and 15 to 35 atomic% copper;

A casting process of forming a casting by injecting the molten metal into a casting mold;

A cooling process of naturally cooling the casting at room temperature;

A heat treatment process in which the naturally cooled casting is put into a heat treatment furnace and heat treated at a temperature of 945°C to 980°C; and

Including a quenching process of rapidly cooling the heat-treated casting by quenching it in a cooling medium immediately after heat treatment,

A method for manufacturing an iron-copper alloy having a network structure formed by copper in the alloy structure is provided.

According to one embodiment, the heat treatment process includes putting the naturally cooled casting into a heat treatment furnace, and then increasing the temperature in the heat treatment furnace to 945°C to 980°C at a rate of 2°C/min to 15°C/min. You can proceed.

According to the present invention, a low-cost iron-copper (Fe-Cu) alloy that can replace beryllium-copper (Be-Cu) alloy is provided. Specifically, according to the present invention, it is an amorphous alloy in which an appropriate content of copper (Cu) is melted and alloyed with iron (Fe), and because it contains a network structure in the alloy structure, it is similar to the conventional iron-copper (Fe-Cu) alloy. Compared to this, it has the effect of improving at least hardness, tensile strength, and thermal conductivity. In addition, according to the present invention, thermal conductivity is improved along with mechanical properties, so that it can be used not only as a mold material but also as cooling machine parts.

Figure 1 is a cut schematic diagram of an Fe-Cu alloy to explain the network structure according to the present invention.
Figure 2 is an SEM photograph of the Fe-Cu alloy manufactured according to an embodiment of the present invention, showing the appearance before heat treatment.
Figure 3 is an SEM photograph of the Fe-Cu alloy manufactured according to an example of the present invention, and is a high-magnification enlarged tissue photograph showing the appearance after heat treatment and quenching.
Figure 4 is an SEM photograph of the Fe-Cu alloy manufactured according to the comparative example of the present invention, and is a high-magnification enlarged tissue photograph showing the appearance after heat treatment and quenching.

The term “and/or” used in the present invention is used to include at least one of the components listed before and after. The term “one or more” used in the present invention means a plurality of one or two or more.

The present invention is an iron-based alloy containing iron (Fe) as a main component, and includes iron (Fe) and copper (Cu) in appropriate amounts, including a network structure formed in the alloy structure, with improved mechanical properties and thermal properties at least. An iron-copper alloy is provided. Additionally, the present invention provides a method for producing the iron-copper alloy.

The iron-copper alloy according to the present invention is an iron-based alloy containing iron (Fe) and copper (Cu), but with a higher content of iron (Fe) than copper (Cu). As a standard, it contains 65 to 85 atomic% of iron (Fe) and 15 to 35 atomic% of copper (Cu). The content unit “atomic %” used in the present invention is based on the total atoms of iron (Fe) and copper (Cu) (total of Fe and Cu 100 atomic %), which is also well-known in the art. As shown, it can be expressed as “volume%”. That is, in the present invention, it can be expressed as atomic% = volume%.

The iron-copper alloy according to the present invention does not contain any other metal elements other than iron (Fe) and copper (Cu), except those that are unavoidable. The iron-copper alloy according to the present invention may contain unavoidable impurities. Inevitable impurities are those contained in the raw materials themselves or introduced from outside during the dissolution process, for example, metal elements such as aluminum (Al) and nickel (Ni) or non-metal elements such as carbon (C) and oxygen (O). It may contain, but these impurities are in very small amounts. Impurities are unavoidably contained in very small amounts, for example, 0.5 atomic% or less, 0.2 atomic% or less, 0.1 atomic% or less, 0.05 atomic% or less, or 0.01 atomic% or less, based on the entire alloy composition (sum of Fe + Cu + impurities). may be included.

The iron-copper alloy according to the present invention is composed of iron (Fe) and copper (Cu) in appropriate amounts and has at least high mechanical and thermal properties due to the network structure formed in the alloy structure. Specifically, the iron-copper alloy according to the present invention has higher hardness, tensile strength, thermal diffusion rate, and thermal conductivity compared to conventional iron-copper alloys, and also has no segregation or cracks.

Hereinafter, while explaining the manufacturing method of the iron-copper alloy according to the present invention, embodiments of the iron-copper alloy according to the present invention will also be described. The manufacturing method described below easily implements the manufacturing of the iron-copper alloy according to the present invention. However, the iron-copper alloy according to the present invention is not limited to that manufactured by the manufacturing method described below.

The method for producing an iron-copper alloy (hereinafter abbreviated as “manufacturing method”) according to the present invention includes a melting process of forming an iron-copper molten metal in a melting furnace; A casting process of casting the molten metal by injecting it into a casting mold; and a cooling process of naturally cooling the casting at room temperature. According to a preferred embodiment, the manufacturing method according to the present invention includes a heat treatment process of heat treating the naturally cooled casting; And it further includes a quenching process of quenching the heat-treated casting. The embodiments for each process are described as follows.

[1] Dissolution process

The alloy raw materials of iron and copper are put into the melting furnace and melted. At this time, high purity pure iron can be used as iron, and high purity electrolytic copper can be used as copper. The melting furnace is not particularly limited, and for example, a melting furnace made of conventional ceramic materials can be used. The melting furnace may preferably be a high-frequency induction heat melting furnace capable of rapid melting through rapid temperature increase. The melting furnace should be maintained at a temperature where iron and copper can be dissolved. For example, it is best to quickly raise the temperature of the melting furnace using high-frequency induction heat and maintain it at about 1,520°C to 1,650°C to dissolve iron and copper. Stirring occurs during this dissolution process. In addition, after iron and copper are completely dissolved, the temperature of the molten metal can be maintained at, for example, 1,450°C to 1,520°C and left to stabilize. By this stabilization, homogenization of iron and copper can be achieved.

In this melting process, iron and copper are added to the melting furnace so that the final iron-copper alloy contains 65 to 85 atomic% (or volume %) of iron and 15 to 35 atomic % (or volume %) of copper. , melts to form molten metal. Specifically, when the total amount of iron and copper input to the melting furnace is 65 to 85% by volume of iron and 15 to 35% by volume of copper (i.e., a volume ratio of iron: copper = 65 to 85: 15 to 35), the alloy composition is obtained. can do. At this time, if the copper content is less than 15 atomic%, a network structure may not be formed and mechanical and thermal properties may become insignificant. Additionally, if the copper content is less than 15 atomic%, cracks may occur during high temperature heat treatment at 860°C or higher after melt casting. And if the copper content exceeds 35 atomic%, it is difficult to form a complete network structure and mechanical properties may be lowered. Accordingly, according to an embodiment of the present invention, when the copper content is set to 15 to 35 atomic%, cracks do not occur even when heat treatment is performed at a high temperature of 860°C or higher after melt casting, and the copper material has high mechanical and thermal properties.

According to a preferred embodiment of the present invention, in the melting process, iron and copper are put into the melting furnace and melted so that the final produced iron-copper alloy contains 68 to 80 atomic% of iron and 20 to 32 atomic% of copper to form a molten metal. It is good to form. That is, it is desirable to set the total amount of iron and copper input to the melting furnace to 68 to 80 vol% of iron and 20 to 32 vol% of copper, so as to have an alloy composition containing 68 to 80 atomic% of iron and 20 to 32 atomic% of copper. . When having such an alloy composition, a complete network structure is formed within the alloy structure, thereby providing excellent mechanical and thermal properties.

The attached Figure 1 is a cross-sectional perspective view showing the Fe-Cu alloy according to the present invention, which is a schematic diagram of the alloy structure to explain the network structure. Referring to Figure 1, in the present invention, the network structure 10 is formed of copper (Cu), which is formed entirely on the surface and inside of the alloy and has a three-dimensional structure. In the present invention, “formed by copper (Cu)” means copper-rich. According to the present invention, the mesh structure 10 improves the mechanical properties (hardness, tensile strength, etc.) of the alloy, and in particular increases the heat diffusion rate of the alloy, thereby significantly improving thermal conductivity.

As shown in FIG. 1, the mesh structure 10 is formed by connecting linear Cu-rich wires 12 in a mesh shape within the alloy structure. The network structure 10 has, for example, a three-dimensional network structure in the form of a cage, which has copper (Cu) as its main component. Specifically, the copper-rich line 12 contains copper (Cu) as its main component. According to one embodiment, the copper-rich line 12 includes copper (Cu) and iron (Fe), but the content of copper (Cu) is greater than that of iron (Fe). The copper-rich line 12 may include, for example, 60 atomic% or more, 70 atomic% or more, or 80 atomic% or more of copper (Cu), and the remainder may be composed of iron (Fe). In addition, the copper-rich line 12 has a thickness of micrometers (㎛), and may have a thickness of, for example, 0.1㎛ ~ 30㎛. These copper-rich wires 12 serve as high-speed tunnels for rapid heat diffusion, which at least increases the heat diffusion rate of the alloy.

[2] Casting process

The molten metal is injected into a casting mold to form an alloy casting having a predetermined shape. This casting process follows a conventional process. The casting mold is not particularly limited, and may have the shape of an ingot or cast piece, or in some cases, may have the shape of an actually applied product (machine parts, etc.). In addition, the casting mold may have a cooling function as usual.

[3] Cooling process

The casting is naturally cooled at room temperature. This cooling process can be performed, for example, by leaving the casting at room temperature while accommodated in a casting mold. In the present invention, the room temperature may be, for example, a temperature of 5°C to 30°C, and, for example, may be a room temperature of about 15°C to 25°C.

[4] Heat treatment process

The naturally cooled casting is heat treated. Heat treatment can be performed by putting the naturally cooled casting into a heat treatment furnace, raising the temperature in the heat treatment furnace to a high temperature, and then maintaining the high temperature for a predetermined time. Heat treatment may be carried out under an atmospheric atmosphere or an inert (non-oxidizing) atmosphere. The heat treatment furnace is not particularly limited as long as it can apply high temperature heat to the casting, and for example, an electric furnace (heating furnace) equipped with a heating wire can be used.

The heat treatment is preferably performed at a temperature of 945°C to 980°C. The heat treatment specifically involves putting the naturally cooled casting into a heat treatment furnace, then raising the temperature in the heat treatment furnace to a temperature of 945°C to 980°C at a temperature increase rate of 2°C/min to 15°C/min, and then This can be done by maintaining 945°C to 980°C for a predetermined period of time. When heat treatment is performed in this temperature range, the mechanical and thermal properties of the alloy are improved. If the heat treatment temperature is below 945°C or above 980°C, the degree of improvement in mechanical properties and thermal properties may be low. Considering this, it is more preferable that the heat treatment is performed at a temperature of 950°C to 970°C. In addition, the heat treatment can be performed for an appropriate time depending on the thickness of the casting, for example, about 30 to 90 minutes per 25 mm thickness of the casting. For example, when the thickness of the casting is 50 mm, heat treatment can be performed for about 1 to 3 hours.

[5] Rapid cooling process

The heat-treated casting is rapidly cooled. Rapid cooling is carried out immediately after heat treatment, and is specifically carried out within 5 minutes after heat treatment. Rapid cooling is performed by quenching the heat-treated casting in a cooling medium. When this rapid cooling is completed, an alloy having a complete network structure 10 and excellent mechanical properties and thermal properties is obtained. At this time, if the heat-treated casting is slowly cooled (slowly natural cooling) rather than rapidly cooled, the network structure 10 may disappear and mechanical properties and thermal properties may deteriorate.

In the present invention, the rapid cooling refers to quenching in a cooling medium immediately after heat treatment, and the cooling medium used here may be selected from liquids having a temperature of 30° C. or lower. The cooling medium may be selected from, for example, water and oil, and may have room temperature.

According to the manufacturing method of the present invention described above, it is a homogeneous amorphous iron-copper alloy without segregation or cracks, and has at least improved mechanical properties (hardness, tensile strength, etc.) and thermal properties (thermal conductivity, etc.). This is manufactured.

According to a preferred embodiment, the iron-copper alloy according to the invention comprises 68 to 80 atomic% iron and 20 to 32 atomic% copper. When having such an alloy composition, properties such as hardness, tensile strength, and thermal conductivity are effectively improved. In addition, the iron-copper alloy according to the present invention preferably has the physical properties (a) to (c) below. When it has the physical properties (a) to (c) below, it can be usefully used not only as a mold material for injection molding and die casting, but also as cooling machine parts that require heat dissipation or cooling.

(a) Rockwell hardness 30 HRC or higher

(b) Tensile strength of 700 N/㎟ or more

(c) Thermal conductivity is 90 W/mㆍK or more.

The Rockwell hardness, tensile strength, and thermal conductivity are determined by conventional measurement methods. The Rockwell hardness may be measured according to KS B 0806, and the tensile strength may be measured according to KS B 0801. And the thermal conductivity may be a value measured at room temperature (20°C to 25°C), for example, in accordance with ASTM E1461 (Laser flash: Thru-plane). The iron-copper alloy according to the present invention may have, for example, a Rockwell hardness of 30 to 48 HRC, a tensile strength of 700 to 750 N/mm2, and a thermal conductivity of 90 to 120 W/m·K.

Hereinafter, examples and comparative examples of the present invention will be illustrated. The following examples are provided by way of example only to aid understanding of the present invention, and are not intended to limit the technical scope of the present invention. In addition, the following comparative examples do not imply prior art, and are provided only for comparison with the examples.

[Example 1]

< Melting / Casting / Cooling >

Iron (pure iron with a purity of about 99.9% by weight) and copper (electrolyzed copper with a purity of about 99.9% by weight) are initially put into the melting furnace (high-frequency induction heat melting furnace) at a volume ratio of 1:1, and while stirring, the power output of the melting furnace is adjusted. It was raised and dissolved quickly. At this time, the dissolution process was carried out by intermittently adding a deoxidizing agent to deoxidize the solution. After confirming through visual observation that the added iron and copper were completely dissolved, add iron to the melting furnace little by little several times while continuing to stir, and maintain the temperature of the molten metal within the range of approximately 1,500℃ to 1,550℃ to dissolve the additional iron. completely dissolved. Next, the power was turned off, and the molten metal was left in the melting furnace for a predetermined period of time to stabilize the alloy structure. Afterwards, the molten metal was taken out of the melting furnace, injected into a casting mold, and then slowly and naturally cooled at room temperature (about 25°C) to obtain an Fe-Cu alloy ingot.

<Heat treatment/Quick cooling>

The naturally cooled ingot (width The heat treatment temperature was set at 845°C through a temperature controller. At this time, the temperature in the heat treatment furnace was maintained in the range of about 840 to 850°C. The ingot was heat treated for about 1 hour in the above temperature range. Immediately after heat treatment (within 1 minute after removal from the heat treatment furnace), the heat-treated ingot was rapidly cooled by quenching it in a water bath containing water (cooling medium) at about 17°C. After quenching and quenching in a water bath for a sufficient period of time, the ingot was taken out of the water bath and the heat treatment/quenching process was completed to prepare an alloy specimen according to this example.

[Examples 2 to 6]

Compared to Example 1, alloy specimens at different temperatures during heat treatment were used as alloy specimens according to these Examples. Specifically, for the Fe-Cu alloy ingot of the same alloy composition as Example 1, the temperature during heat treatment was varied according to each Example. This is as shown in [Table 1] below.

[Examples 7 to 11]

Compared to Example 1, alloy specimens with different Cu content in the synthetic composition and temperature during heat treatment were used as alloy specimens according to these Examples. The specific Cu content and temperature during heat treatment according to each example are shown in [Table 1] below.

[Comparative Examples 1 to 10]

Compared to Example 1, alloy specimens in which one or more of the Cu content of the synthetic composition, temperature during heat treatment, heat treatment method, and cooling method after heat treatment were different were used as alloy specimens according to the comparative examples. This is as shown in [Table 1] below. At this time, in [Table 1] below, the slow cooling of Comparative Examples 8 and 9 was natural cooling performed by gradually cooling the heat-treated ingot at room temperature (about 25°C). And in Table 1 below, the quenching (950) of Comparative Example 10 is a heat treatment performed by quenching the ingot in oil maintained at about 950°C for 1 hour.

For the Fe-Cu alloy specimens according to each Example and Comparative Example obtained as above, component analysis, cracks, network structure, and physical property evaluation were performed as follows, and the results are shown in [Table 1] below. The Cu content shown in [Table 1] below is the at% of Cu (the remainder is Fe) based on the sum of Fe and Cu atoms (= Fe + Cu) of 100 (= Fe + Cu) through the component analysis below, which is a very small amount of metal element ( Unavoidable impurities such as metals other than Fe and Cu), C, and O were not considered.

< Ingredient analysis >

The alloy specimen whose weight was measured was placed in a glass beaker and dissolved by adding 10 mL of aqua regia (hydrochloric acid + sulfuric acid aqueous solution). Then, Fe and Cu were quantified through high-frequency inductively coupled plasma emission spectrometry (ICP-AES) according to the measurement conditions below, converted to concentration in the sample, and analyzed.

* Measurement conditions of ICP-AES

- Measuring device: PerkinElmer Optima 5300DV

- Measurement wavelength: 238.204nm (Fe), 327.393nm (Cu)

- Quantitative method: internal standard method

< crack >

For alloy specimens after heat treatment and quenching, the surface was observed using high-magnification photographs. If cracks occurred, they were evaluated as “occurrence,” and if there were no cracks, they were evaluated as “none,” and are shown in [Table 1].

< Mesh structure >

For alloy specimens after heat treatment and quenching, “○” if a complete network structure is observed through SEM (scanning electron microscope) photographs; “△” if it is difficult to see that it is a complete network structure and agglomerations or breaks are observed; If the network structure was not observed, it was evaluated as “X” and is shown in [Table 1].

The attached Figure 2 is a photograph of the Fe-Cu alloy according to Example 4 before heat treatment, and Figure 3 is a high magnification enlarged tissue photograph after heat treatment and quenching of the Fe-Cu alloy according to Example 4. And the attached Figure 4 is a high magnification enlarged tissue photo after heat treatment and quenching of the Fe-Cu alloy according to Comparative Example 7. In detail about the evaluation of the network structure, as shown in Figure 3, if a complete network structure is clearly shown and Cu forms a network structure with an almost constant thickness, it is designated as "○"; As shown in Figure 4, it is difficult to see a complete network structure, and if a part where Cu is agglomerated is observed, it is designated as "△", and if the network structure is not observed at all, it is designated as "X".

< Physical properties >

Physical properties were evaluated on alloy specimens after heat treatment and quenching. Hardness was evaluated by Rockwell Hardness (HRC) according to KS B 0806, and tensile strength was evaluated according to KS B 0801. Thermal conductivity is a method of measuring the thermal conductivity of a metal sample. The density, specific heat, and thermal diffusion coefficient of the alloy specimen were measured and then evaluated according to ASTM E1461 (Laser flash: Thru-plane).

< Physical property evaluation results according to Cu content and heat treatment of Fe-Cu alloy specimens > note Cu content
(at%) heat treatment
temperature
(℃) After heat treatment
Cooling net
group crack rockwell
Hardness
(HRC) tensile strength
(N/㎟) thermal conductivity
(W/mㆍK) Comparative Example 1 11.54 840-850 rapid cooling X doesn't exist 8.4 287 71.6 Comparative Example 2 11.54 860-870 rapid cooling X generation Cracks occurred
Not measured
(no meaning) 72.1 Comparative Example 3 11.54 950-960 rapid cooling X generation 72.8 Comparative Example 4 14.32 950-960 rapid cooling X generation 75.2 Comparative Example 5 14.32 980-990 rapid cooling X generation 75.6 Example 1 20.12 840-850 rapid cooling ○ doesn't exist 5.8 246 80.2 Example 2 20.12 900-910 rapid cooling ○ doesn't exist 16.4 254 80.7 Example 3 20.12 930-940 rapid cooling ○ doesn't exist 24.4 602 84.3 Example 4 20.12 950-960 rapid cooling ○ doesn't exist 37.3 746 94.8 Example 5 20.12 970-980 rapid cooling ○ doesn't exist 35.1 729 95.7 Example 6 20.12 980-990 rapid cooling ○ doesn't exist 28.7 641 95.9 Example 7 24.88 950-960 rapid cooling ○ doesn't exist 33.1 723 97.0 Example 8 24.88 980-990 rapid cooling ○ doesn't exist 28.9 583 94.6 Example 9 29.64 950-960 rapid cooling ○ doesn't exist 32.4 718 97.3 Example 10 29.64 980-990 rapid cooling ○ doesn't exist 26.2 607 95.8 Example 11 31.26 950-960 rapid cooling ○ doesn't exist 31.6 704 96.4 Comparative Example 6 35.76 950-960 rapid cooling △ doesn't exist 21.8 473 82.3 Comparative Example 7 40.24 950-960 rapid cooling △ doesn't exist 19.4 413 121.5 Comparative Example 8 40.24 950-960 slow cooling X doesn't exist 7.1 275 108.3 Comparative Example 9 20.12 950-960 slow cooling X doesn't exist 17.2 324 76.1 Comparative Example 10 20.12 quenching
(950) rapid cooling △ doesn't exist 24.6 716 73.4

In the present invention, numerous experiments were conducted to determine how the contents of Fe and Cu in the alloy composition, heat treatment conditions after melt casting, and cooling conditions after heat treatment affect the Fe-Cu alloy. For example, in the case of alloy composition, the Cu content was finely divided within the range of 5 to 50 at%, and in the case of heat treatment temperature, it started at 600°C and increased by 10°C until it reached 1,100°C. The above examples and comparative examples show some of the numerous experimental examples of the present invention.

According to the experimental study of the present invention, it was found that the structural state, mechanical properties, and thermal properties of the Fe-Cu alloy vary depending on the Cu content in the alloy composition, heat treatment temperature, and cooling method (rapid cooling or slow cooling) after heat treatment. In particular, a network structure formed by Cu was observed at a specific Cu content and heat treatment conditions, and it was found that at least hardness and thermal conductivity were significantly improved by this network structure. This is explained with reference to [Table 1] above.

Referring to [Table 1], first, it was possible to determine whether a network structure existed depending on the Cu content. Specifically, when the Cu content was less than 15 at% (Comparative Examples 1 to 5), a network structure did not appear in the alloy structure. In addition, it was found that when the Cu content was less than 15 at%, cracks occurred when heat treated at a temperature of 860°C or higher (Comparative Examples 2 to 5). This is believed to be because the Fe structure was segregated rather than finely divided. On the other hand, when the Cu content exceeded 35 at% (Comparative Examples 6 and 7), a network structure appeared, but it was difficult to view it as a complete network structure. Specifically, as shown in Figure 4 (photo of alloy specimen of Comparative Example 7: Cu content 40.24 at%), the shape and thickness of the Cu-rich wire are non-uniform, making it difficult to view it as a complete network structure. This also resulted in agglomeration of Cu and Fe here and there.

On the other hand, when the Cu content was about 20 to 32 at% (Examples 1 to 11), a complete network structure was clearly observed. In addition, as shown in Figure 3 (photo of alloy specimen of Example 4: Cu content 20.12 at%), the copper-rich wire forming the network structure has an almost constant thickness of micrometer (㎛). I could tell that I had it. And as shown in [Table 1], it was found that hardness and tensile strength as well as thermal conductivity were highly evaluated.

In addition, it was found that mechanical properties and thermal properties vary depending on the heat treatment temperature. For example, in comparison with Examples 1 to 6, the case of heat treatment at a temperature of about 950 ℃ to 980 ℃ under all the same conditions (Examples 4 and 5) was the best in all properties of hardness, tensile strength and thermal conductivity. It was seen that the results were visible. In particular, hardness and tensile strength did not continuously increase in proportion to the increase in heat treatment temperature, and were found to be highest at a temperature of approximately 950°C to 960°C, but decreased at temperatures above that. Through these results, it was found that the optimal heat treatment temperature was approximately 945°C to 980°C.

In addition, it was found that rapid cooling is preferable when cooling after heat treatment. For example, when comparing Example 4 (rapid cooling) and Comparative Example 9 (slow cooling), when slow cooling was performed under all the same conditions (Comparative Example 9), the network structure did not appear and the mechanical and thermal properties were deteriorated. Could know. It is believed that the network structure initially formed within the alloy structure disappeared during the gradual cooling process.

Additionally, it was found that mechanical properties and thermal properties vary depending on the heat treatment method. Comparing Example 4 (heat treatment in a heat treatment furnace) with Comparative Example 10 (heat treatment by quenching), when heat treatment by quenching is performed under all the same conditions (Comparative Example 10), a complete network structure does not appear, and the hardness and thermoelectricity I could see that the capital was falling.

Summarizing the above results, the Cu content is set to be within the range of about 20 to 32 at% (the remainder is Fe), and the heat treatment is performed in a heat treatment furnace (electric furnace) at 945°C to 980°C (preferably 950°C to 970°C). It was found that when heat treated in the temperature range and cooled by rapid cooling (quenching in a cooling medium) after heat treatment, it had no cracks, had a complete network structure, and had excellent mechanical and thermal properties. Specifically, in terms of mechanical properties and thermal properties, it was found to have a Rockwell hardness of at least 30 HRC, a tensile strength of at least 700 N/mm2, and a thermal conductivity of at least 90 W/m·K. The iron-copper (Fe-Cu) alloy of the present invention, which has these characteristics, can replace the beryllium-copper (Be-Cu) alloy, and in particular, it has a high hardness of more than 30 HRC and a hardness of more than 90 W/m·K. Because it has high thermal conductivity, it can be usefully used in cooling machine parts.

10: mesh structure 12: copper-rich wire

Claims (7)

delete A melting process in which iron and copper are put into a melting furnace and melted to form a molten metal so that the iron-copper alloy contains 65 to 85 atomic% iron and 15 to 35 atomic% copper;
A casting process of forming a casting by injecting the molten metal into a casting mold;
A cooling process of naturally cooling the casting at room temperature;
A heat treatment process in which the naturally cooled casting is put into a heat treatment furnace and heat treated at a temperature of 945°C to 980°C; and
Including a quenching process of rapidly cooling the heat-treated casting by quenching it in a cooling medium immediately after heat treatment,
A method of manufacturing an iron-copper alloy having a network structure formed by copper in the alloy structure.
According to paragraph 2,
The heat treatment process is performed by putting the naturally cooled casting into a heat treatment furnace and then raising the temperature in the heat treatment furnace to 945°C to 980°C at a rate of 2°C/min to 15°C/min. Iron-copper alloy Manufacturing method.
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