KR20180102425A - Aluminum alloy - Google Patents

Abstract

The present invention relates to aluminum alloy. The present invention provides the aluminum alloy comprising: at most 0.2 wt% of Si; at most 0.2 wt% of Fe; at most 0.6 wt% of Mn; 1.5-2.1 wt% of Mg, 5.5-6.5 wt% of Zn; at most 0.1 wt% of Ti; at most 0.1 wt% of Cr; at most 0.1 wt% of Zr; conventional impurities; and the balance being Al.

Description

Aluminum alloy {ALUMINUM ALLOY}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy, and relates to a high strength aluminum alloy used for an outer material of an electronic apparatus.

2. Description of the Related Art In general, various electronic devices are provided with external appearance materials such as a cover case, a case frame, and a bezel in order to protect various components mounted inside the electronic device. These exterior materials are required to have high strength because they must prevent damage to electronic devices from impact when an impact is applied.

On the other hand, as the structure of electronic devices has become complicated, and miniaturization and thinness have been realized, the implementation of the appearance material by the conventional press processing has reached its limit. Therefore, various extruded materials for appearance materials of electronic devices using an extrusion method that is relatively free to implement a shape have been developed. The extruded material using the extrusion method is advantageous in that the dimensions of the product to be produced are precise, the product need not be trimmed, the mechanical properties are excellent, the mass production is possible, and the production cost is low.

When the external appearance material of the electronic device is manufactured by the above extrusion method, mainly an aluminum alloy is used, and aluminum is classified according to the kind of the alloy. In detail, 1000 series is pure aluminum containing 99.00wt% or more of aluminum, 2000 series is Al-Cu alloy, 3000 series is Al-Mn alloy, 4000 series is Al-Si alloy, 5000 series is Al-Mg A method of classifying and displaying an Al-Mg-Si-based alloy as a 6000-based alloy and an Al-Zn-Mg-based alloy as a 7000-based alloy is widely used.

In order to secure high strength and easiness of manufacture, the high-strength 6000-series aluminum alloy is used as the outer material. In detail, the 6000-series aluminum alloy (Al-Mg-Si) obtains high strength properties through the age hardening effect by controlling the precipitation phase of magnesium silicate (MgSi). However, when the content of Mg and Si is increased to secure high rigidity, It is difficult to implement and there is a problem that the strength of the 7000 series Al alloy is low. Therefore, efforts are being made to apply high strength 7000 aluminum alloy, which is widely applied as structural materials such as automobiles, aircraft, and building materials, to electronic devices.

 On the other hand, the 7000-series aluminum alloy (Al-Zn-Mg- (Cu)) has defects such as stains, solid spots, black spots or spots on the surface of the 7000-series aluminum alloy after anodizing depending on the shape of the high- . Further, in order to secure the strength of the 7000-series aluminum alloy, the strength can be improved by adding copper (Cu) to form an aluminum copper alloy (Al 2 Cu) phase. However, the 7000-series aluminum alloy with copper added is yellowish after the anodizing. Although the copper-added 7000-series aluminum alloy has sufficient strength, it is somewhat unreasonable for the electronic equipment to have a high-quality aesthetic due to surface defects and yellowing. Thus, the present invention proposes an aluminum alloy having high strength and high esthetics through the control of the 7000-series aluminum alloy.

An object of the present invention is to provide an aluminum alloy outer appearance material of an electronic device having high strength.

Another object of the present invention is to provide an aluminum alloy outer appearance material of an electronic appliance in which yellowing is prevented after anodizing.

Another object of the present invention is to provide an aluminum alloy outer appearance material of an electronic device in which the metal texture and defects are not exposed on the surface.

According to an aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising the steps of: depositing at most 0.2% Si, 0.2% Fe, 0.6% Mn, 1.5-2.1% Mg, Zn, at most 0.1% Ti, at most 0.1% Cr, at most 0.1% Zr and conventional impurities, the remainder being Al.

In one embodiment, it may further comprise up to 0.1% Cu.

In one embodiment, the alloy may be of an equiaxed crystal.

In one embodiment, the average aspect ratio of the particles forming the alloy may be 0.6 to 1.3.

In one embodiment, the mean grain size of the particles forming the alloy may be between 30 and 500 μm.

In one embodiment, the alloy may have b in the range of -0.5 to 0.5 in Lab colorimetric stereochemistry.

In one embodiment, based on the Mg content, the weight content ratio of Mg to Zn may be from 3 to 4.

The aluminum alloy outer material according to the present invention can control the strength by lowering the content of copper and adjusting the content of magnesium (Mg) and zinc (Zn). Through this, the strength of the aluminum alloy outer material can be improved.

Further, the present invention can reduce the content of copper (Cu) and prevent yellowing due to copper after anodizing. As a result, when painting a dye on an aluminum alloy outer material, the inherent color of the dye is expressed, and the aesthetics of the outer appearance of the aluminum alloy can be greatly improved.

Further, the present invention can control the metal structure by controlling the content of the alloy. Through this, the outer material of the aluminum alloy can be made of equiaxed crystals. Therefore, the appearance of the metal structure on the surface of the aluminum alloy outer appearance material is not exposed and does not include surface defects such as spots and black spots. Accordingly, when a dye is painted on the outer appearance material of the aluminum alloy, it can be uniformly painted without being affected by surface defects, so that the aesthetics of the outer appearance material of the aluminum alloy can be greatly improved.

1 is an embodiment of an electronic device using an aluminum alloy outer appearance material of the present invention.
Figs. 2A and 2B are images of the tissue shapes of Comparative Example 1 and Example 1, which are shown in Table 1, respectively.
3 is an image of an anodized specimen of Comparative Example 2 and Example 2, each having a composition ratio shown in Table 3.
Fig. 4 is a process drawing for producing an outer appearance material of an aluminum alloy electronic device of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals are used to designate identical or similar elements, and redundant description thereof will be omitted. In the following description of the embodiments of the present invention, a detailed description of related arts will be omitted when it is determined that the gist of the embodiments disclosed herein may be blurred. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. , ≪ / RTI > equivalents, and alternatives.

Terms including ordinals, such as first, second, etc., may be used to describe various elements, but the elements are not limited to these terms. The terms are used only for the purpose of distinguishing one component from another.

The singular expressions include plural expressions unless the context clearly dictates otherwise.

In the present application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

1 is an embodiment of an electronic device using an aluminum alloy outer appearance material of the present invention.

Referring to FIG. 1, an embodiment of the present invention is a mobile terminal using an aluminum alloy outer appearance material. The aluminum alloy outer material can protect the inner parts of the outer casing of the electronic device such as the cover case 100 or the bezel 200 of the mobile terminal.

The cover case 100 and the bezel 200 should have strength enough to protect the internal parts of the electronic device. From this point of view, copper has been widely used as a component of the outer appearance of the alloy because it strengthens the strength of the outer appearance of the alloy. However, when copper is added to the outer appearance material of the alloy, the outer appearance of the alloy becomes yellowed.

Specifically, the outer appearance of the alloy used for the cover case 100 and the bezel 200 should be such that the original colors of the dyes can be saved when the dyes are painted. At this time, the yellowing of the outer appearance of the alloy becomes a factor that hinders the original color of the dye when the dye is painted. Therefore, when the outer appearance material of the alloy which is not yellowed is used for the cover case 100 and the bezel 200, the color inherent in the dye can be expressed and the aesthetics can be improved when the dye is painted.

On the other hand, the metallic structure of the cover case 100 and the bezel 200 may be deteriorated by surface defects such as grain boundaries, spots, and black spots. Specifically, due to an external pressure or the like in the production of the outer appearance material of the alloy, the grain shape of the metal structure may be exposed on the surface, and spots and black spots may be formed. When the particle shape of the metal structure is exposed on the surface of the outer material as it is, it becomes a factor to deteriorate the aesthetics of the outer appearance material of the alloy upon dyeing, and the unevenness and the black spot also become a factor to hinder the aesthetics of the outer appearance material of the alloy.

Here, when the crystals forming the metal structure are in the form of equiaxed crystals, it is possible to prevent the phenomenon that the particle shape of the metal structure is exposed on the surface of the outer appearance material of the alloy, and the occurrence of unevenness and solid state.

The present invention provides an outer appearance material of an alloy which is not yellowed and has a degree of strength that can protect the inner parts of the mobile terminal while preventing the appearance of a particle form of the metal structure on the surface.

To this end, the outer appearance of the alloy according to one embodiment of the present invention comprises at most 0.2% Si, 0.2% Fe, 0.6% Mn, 1.5-2.1% Mg, 5.5-5.5 Zn, An aluminum alloy composed of at most 0.1% of Cr, at most 0.1% of Ti, at most 0.1% of Zr and Al containing ordinary impurities.

Hereinafter, each configuration will be described in detail. The content of Si and Fe may be at most 0.2% per total weight fraction, respectively. If the content of each of Si and Fe exceeds 0.2% per total weight portion, an intermetallic compound is formed and the high-temperature formability can be deteriorated. Therefore, it is preferable that the content of each of Si and Fe does not exceed a maximum of 0.2% per a total weight portion.

Also, the content of Mn may be up to 0.6% per total weight. Mn binds with Al to form various dispersed particles. As a result, grain refinement is effected and a fine precipitate dispersion effect occurs, and the strength of the alloy can be increased through the fine precipitate dispersion effect. On the other hand, when the content of Mn is more than 0.6% by weight, the recrystallization of the alloy is inhibited and the strength of the alloy is lowered. Therefore, it is preferable that the content of Mn is not more than 0.6% at the maximum per a total weight portion.

The content of Mg may be 1.5 to 2.1% per total weight fraction. Mg is an element added for solid solution curing, and when it is added in an amount of less than 1.5%, the effect of aging hardening is drastically reduced, and the strength of the alloy can be reduced. On the other hand, when the content of Mg exceeds 2.1%, a coarse precipitate phase is formed, so that the pressure is increased during extrusion and the extrudability is lowered. Therefore, the content of Mg is preferably at most 1.5 to 2.1% per a total weight.

The content of Zn may be from 5.5 to 6.5% per total weight fraction. Zn is an element added to improve strength without loss of corrosion resistance. When added at less than 5.5%, the strength of the alloy can be reduced. On the other hand, when the content of Zn exceeds 6.5%, the stress corrosion cracking property deteriorates, and the productivity of extrusion may also be lowered. Therefore, it is preferable that Zn contains 5.5 to 6.5% by weight of the total weight.

Further, in one embodiment of the present invention, the weight ratio of Mg to Zn may be 3 to 4, based on the Mg content. Specifically, when the weight ratio of Zn / Mg in the aluminum alloy is less than 3, the strength may be lowered. On the other hand, when the weight content ratio of Zn / Mg exceeds 4, the stress corrosion cracking resistance in the alloy may be deteriorated. Further, by adjusting the weight content ratio of Zn / Mg in the aluminum alloy of the present invention, even if the content of Cu to be described later is low, the strength of the target alloy can be satisfied. That is, by controlling the content of Mg, Zn and Cu, the present invention can exhibit extrusion molding properties and greatly improved mechanical strength.

Also, the content of Ti may be up to 0.1% per total weight. Ti is an element that causes grain refinement by reducing the size of large intermetallic compounds. Therefore, the strength of the aluminum alloy can be improved by Ti addition. On the other hand, if the content of Ti is more than 0.1% by weight, the extrudability of the alloy is deteriorated, and a coarse compound is produced, resulting in a decrease in toughness. Therefore, it is preferable that the content of Ti is not more than 0.1% at the maximum per a total weight portion.

The content of each of Cr and Zr may be up to 0.1% per total weight. Cr and Zr are elements added to suppress grain refinement and a recrystallization layer and to form fibrous crystals by inhibiting recrystallization during extrusion. On the other hand, when the content of each of Cr and Zr exceeds 0.1% per weight part, an undesired dispersed phase may precipitate in the grain boundaries, resulting in a decrease in strength. Therefore, it is preferable that the content of each of Cr and Zr does not exceed 0.1% at the maximum per a total weight portion.

Also, the content of Cu may be up to 0.1% per total weight. Cu is an element that increases the strength of an alloy by generating an Al2Cu phase in the aluminum alloy. However, when the content of Cu exceeds 0.1% per total weight, yellowish occurs after anodizing, making it difficult to apply the Cu as an external material for electronic equipment. Therefore, it is preferable that the content of Cu does not exceed 0.1% at the maximum per a total weight portion. In addition, the aluminum alloy of the present invention made of the above composition may have an equiaxed crystal structure having a yield strength of 350 to 450 MPa.

In one embodiment, the aluminum alloy according to the present invention may be made of equiaxed crystals. Therefore, the surface of the aluminum alloy of the present invention does not reveal the shape of particles constituting the metal structure, and surface defects such as black spots are not generated.

Meanwhile, in the present specification, the alloy is made of equiaxed crystals. The average aspect ratio of the particles constituting the alloy can be defined as 0.6 to 1.3. Here, the aspect ratio of the particles constituting the alloy can be calculated by analyzing the image of the cross section of the alloy using a well-known image analysis program.

On the other hand, the average crystal grain size of the particles constituting the alloy may be 30 to 500 mu m. If the average crystal grain size is less than 30 탆, steeping may occur on the surface of the alloy, and if the average crystal grain size exceeds 500 탆, the possibility of staining on the alloy surface is increased.

On the other hand, the aluminum alloy of the present invention can be inhibited from yellowing after anodizing by controlling the Cu content. Specifically, the aluminum alloy of the present invention does not discolor to yellow after anodizing, and the color of the alloy after anodizing may be -0.5 to 0.5 in the L * a * b * color coordinate system stereogram. The L * a * b * color system will be described in detail in Fig.

Hereinafter, embodiments of the present invention will be described. In order to confirm the characteristics of the aluminum alloy according to the present invention, specimens having composition ratios as shown in Table 1 were produced within the scope of the present invention.

weight% Si Fe Cu Mn Mg Zn Cr Ti Zr Al Comparative Example 1
(Commercial 7041) 0.03 0.06 0.74 0.04 1.94 5.87 0.13 0.03 0.11 Honey. Example 1 0.05 0.1 0.02 0.12 1.16 5.95 ≪ 0.05 0.03 ≪ 0.1 Honey.

In order to compare the characteristics of Comparative Example 1 (commercial 7041) having composition ratios shown in Table 1 with those of Example 1, tensile strength and yield strength were measured with a universal testing machine (Specimen Specification: E8 / E8M Standard Specimen) And the elongation was calculated by calculating the result through measurement. Table 2 shows the texture of these specimens.

Tensile Strength [MPa] Yield strength [MPa] Elongation [%] Tissue shape Comparative Example 1
(Commercial 7041) 538 512 15 Surface roughness (recrystallization), internal fibrous phase 538 512 15 529 504 14 530 503 16 507 485 15 494 476 15 524 499 16 481 464 16 483 466 16 Example 1 425 367 18 Isometric 432 377 19 435 384 20 453 431 17 457 435 17

 According to Table 2, the yield strength of Comparative Example 1 (commercial 7041) is 450 to 550 MPa, and the yield strength of Example 1 is 350 to 450 MPa. That is, it can be seen that Example 1 satisfies sufficient yield strength even though Cu, which is a main additive element for increasing the strength, is added in a small amount compared with Comparative Example 1. In addition, it can be seen that Example 1 has an equiaxed texture, but Comparative Example 1 has a surface roughness or an internal fibrous phase. This will be described in detail later with reference to FIGS. 2A and 2B.

FIGS. 2A and 2B are images of the tissue shapes of Comparative Example 1 and Example 1, each having a composition ratio shown in Table 1.

Referring to FIG. 2A, it can be seen that Comparative Example 1 is in the form of surface roughness or internal fibrous structure. Therefore, in the outer appearance of the electronic device using the comparative example 1, the extruded texture appears due to the structure of FIG. 2A, and it is somewhat unreasonable that the outer appearance material of the extruded product has high quality aesthetics.

On the other hand, referring to FIG. 2B, it can be seen that Example 1 has an equiaxed crystal structure. In detail, the average crystal grain size of the particles forming equiaxed crystals may be 30 to 500 탆. In addition, the equiaxed microstructure has a dense structure compared to a structure having a coarse-grained or internal fibrous phase. On the surface of Example 1 having the above equiaxed crystal structure, the grain shape of the metal structure is not revealed, and no defect is generated.

In another embodiment, specimens having the composition ratios shown in Table 3 below were produced within the scope of the present invention.

weight% Si Fe Cu Mn Mg Zn Cr Ti Zr Al Comparative Example 2 0.6 to 00.9 <0.15 0.5 to 0.8 0.2 to 0.5 0.9 to 1.3 &Lt; 0.1 &Lt; 0.1 &Lt; 0.1 - Honey. Example 2 <0.2 <0.2 &Lt; 0.1 <0.2 1.5 to 2.1 5.5 to 6.5 &Lt; 0.1 &Lt; 0.1 - Honey.

In order to compare the characteristics of Comparative Example 2 and Example 2 having composition ratios as shown in Table 3, tensile strength and yield strength of the specimens of Comparative Examples 2 and 2 were measured by a tensile tester, And the mechanical properties such as elongation were calculated. Further, after these specimens were anodized, the hue and surface state are shown in Table 4 below.

characteristic Comparative Example 2 Example 2 Mechanical properties Tensile Strength [MPa] 360 453 Yield strength [MPa] 310 432 Elongation [%] 12.6 17.0 Anodizing quality
(Appearance characteristics) color L * = 79.0
b * = 2.73 L * = 87.7
b * = - 0.17 Extrusion has exist none

According to Table 4, it can be seen that Example 2 has a higher yield strength than Comparative Example 2, although Cu, which is a principal additive element for increasing the strength, is added in a small amount as compared with Comparative Example 2. That is, in Example 2, the content of Mg and Zn is controlled, and the mechanical strength can be greatly improved. In addition, it can be seen that Example 2 had better appearance characteristics without extrusion, compared with Comparative Example 2, and that yellowing did not occur after anodizing. The characteristics related to the yellowing will be described in detail in FIG. 3 which will be described later.

3 is an image of an anodized specimen of Comparative Example 2 and Example 2, each having a composition ratio shown in Table 3.

Referring to FIG. 3, the color of the specimen of Comparative Example 2 and Example 2 after anodizing can be compared. In detail, when yellowing occurs in Comparative Example 2 after anodizing and is used as an appearance material of electronic equipment, it is somewhat unreasonable to have high quality aesthetics. On the other hand, in the case of Example 2, yellowing does not occur after anodizing, so that the original color of the dye can be saved when the dye is painted.

The measurement of the degree of yellowing can be performed with the L * a * b * colorimetric system. The L * a * b * colorimetric system uses L * as an indicator of brightness, and the L * value has a value of 0 for a black color with little brightness and a value of 100 for a white color . Also, a * b * indicates chromaticity such as hue and saturation, and a * indicates an index indicating red, and -a * indicates an indicator indicating green. Furthermore, the indicator for the degree of yellowing is the value of b *, and the degree of yellowing between the specimens can be compared through the b * value. Specifically, b * indicates yellow and - b * indicates blue. That is, when the colors of Example 2 and Comparative Example 2 shown in Table 4 are compared, it can be seen that almost no yellow color appears in Example 2.

As described above, the aluminum alloy according to the present invention is not yellowed after anodizing. In addition, the aluminum alloy according to the present invention does not reveal the shape of particles forming the metal structure on the surface, and does not cause defects on the surface. Therefore, the aluminum alloy according to the present invention makes it possible to make use of the inherent color of the dye and to uniformly paint the dye when the dye is painted. Therefore, when the aluminum alloy according to the present invention is used as a case of a mobile terminal, the aesthetics can be improved.

At the same time, the aluminum alloy according to the present invention has sufficient strength to protect the internal parts of the mobile terminal, and thus is suitable for being used as a case of the mobile terminal.

Hereinafter, a method for producing an alloy according to the present invention will be briefly described.

Fig. 4 is a process drawing for producing an outer appearance material of an aluminum alloy electronic device of the present invention.

Referring to FIG. 4, the aluminum alloy of the present invention having the above composition is manufactured as a billet through a known casting process. The aluminum alloy is subjected to homogenization heat treatment, extrusion, cooling, Stretching, and heat treatment.

In one embodiment, after the billet is produced from the aluminum alloy with the above-mentioned composition, the aluminum alloy outer material can be produced through extrusion. The production of aluminum alloy by extrusion is a method which can obtain the same extruded material as the mold shape by injecting metal into a precisely machined die according to the required shape. Therefore, the outer appearance material can be freely manufactured without departing from the limitation of the design.

According to the extrusion method, since the dimension of the extruded shape is accurate, it is possible to shorten the subsequent treatment, to have an excellent mechanical property, and to be capable of mass production. Furthermore, since the production cost is low, it can be utilized in various fields such as a cover case of a electronic device, a case frame, a bezel, an automobile part, an optical instrument, and a measuring instrument. The above listed matters regarding the molded shape are only illustrative and the present invention is not limited thereto.

In one embodiment, a billet of the aluminum alloy of the present invention is cast and subjected to a homogenization heat treatment at 440-550 ° C for 1 to 12 hours, and a hot extrusion process for the billet is performed at 300-550 ° C. After the hot extrusion step, the aluminum alloy electronic appearance material of the present invention can be produced by cooling the aluminum alloy to room temperature by water cooling or air cooling, and then performing heat treatment at 80 to 150 ° C for 12 to 100 hours.

It will be apparent to those skilled in the art that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof.

In addition, the above detailed description should not be construed in all aspects as limiting and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

Claims (7)

By weight,
At most 0.2% Si, at most 0.2% Fe, at most 0.6% Mn, at 1.5-2.1% Mg, at 5.5-6.5 Zn, at most 0.1% Ti, at most 0.1% Cr, at most 0.1% Zr, And the balance being Al. The method according to claim 1,
0.0 &gt; 1% &lt; / RTI &gt; Cu. 3. The method of claim 2,
Wherein the alloy is in equiaxed crystal form. 3. The method of claim 2,
Wherein the average aspect ratio of the particles constituting the alloy is 0.6 to 1.3. 5. The method of claim 4,
Wherein an average crystal grain size of the particles constituting the alloy is 30 to 500 m. The method according to claim 1,
Wherein the alloy has a b value of -0.5 to 0.5 in Lab colorimetric solid-state coordinates. The method according to claim 1,
Wherein the weight ratio of Mg to Zn is 3 to 4 based on the Mg content.

Images