KR101788156B1 - Aluminum alloy with excellent compression strengths and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a high strength aluminum alloy and a method of manufacturing the same. More particularly, the present invention relates to a high strength aluminum alloy comprising 3 to 20% by weight of magnesium (Mg), silicon (Si), copper (Cu), zinc (Zn), unavoidable impurities, Wherein the value of the entropy (DELTA S) is 0.7R to 1.3R, and a method of manufacturing the same.

Description

[0001] The present invention relates to a high strength aluminum alloy,

The present invention relates to a high strength aluminum alloy and a method of manufacturing the same.

Today, aluminum is the second most commonly used metal material after steel industry. Aluminum can be made into various kinds of alloys such as high strength, corrosion resistance and workability according to the kind and amount of added elements such as Cu, Si, Mn, Mg, Zn, and Li. Change.

In other words, aluminum can be made lightweight due to its low density, but it is difficult to use as a material for a structure because of its low tensile strength. On the other hand, aluminum alloy can be strengthened by processing and heat treatment after addition of other elements in spite of low density In recent years, aluminum alloys have attracted attention as lightweight materials having high strength.

These aluminum alloys are used in building materials, automobiles, railway vehicles, aircraft, spacecraft, ships and the like because of their high formability, corrosion resistance and non-corrosive strength. In addition, And is being studied as a measure to cope with various regulations worldwide.

On the other hand, in order to use aluminum alloys as materials for lightweight parts of various machines and materials for large structures, it is necessary to further improve the mechanical properties.

Aluminum alloys are mainly divided into casting alloys suitable for casting production and processing alloys suitable for production methods such as rolling and forging. Among them, since the casting alloy does not have a strengthening effect by processing, precipitation strengthening elements such as Mg, Cu, Zn and the like are added and precipitation of fine intermetallic compounds is used to improve the strength.

Korean Utility Model Publication No. 2012-0020406 discloses that 0.35-0.5% by weight of silicon (Si), magnesium (Mg) is contained in order to provide aluminum and a zinc alloy with good castability while maintaining high strength without heat treatment, 0.5 to 0.9 wt% copper, 2.0 to 2.1 wt% copper, 19.5 to 40.5 wt% zinc, 0.6 wt% max iron, 0.2 wt% max manganese (Mn) 0.03 to 0.05% by weight of titanium (Ti), 0.05% by weight of other impurities, and the balance aluminum.

However, the aluminum alloy has a low configurational entropy of mixing (entropy) value of 0.7R or less and a maximum tensile strength of 434 MPa or less.

Al-Li-Mg-based aluminum alloys are disclosed in X. Yang and X. Zhang et al., JOM, 66 (2014) p.2009-2020, and have an entropy value of 0.78R, cm < ³ > and a high room temperature compressive strength of 500 MPa or more.

A high entropy alloy is an alloy containing five or more kinds of alloying elements having an atomic ratio of about 5 to 35% and an entropy value of 1.5R or more. This alloy stabilizes the solid solution phase and increases the degree of freedom of microstructure by the effect of high entropy due to mixing of different elements, distortion of crystal lattice due to difference in atomic size, low diffusion rate, etc., This is a very good advantage.

However, since the above-described aluminum alloy contains lithium (Li), the vacuum state must be maintained at the time of casting, so that it is difficult to process and there is a disadvantage that only a small amount can be produced.

The inventors of the present invention have been studying to improve the mechanical properties of aluminum alloy as a lightweight material and have found that aluminum alloys which do not contain lithium and can be cast in an atmospheric state, And completed the present invention.

Korean Patent Publication No. 2012-0020406

X. Yang and X. Zhang et al., JOM, 66 (2014) p.2009-2020

SUMMARY OF THE INVENTION

Strength aluminum alloy and a method of manufacturing the same.

In order to achieve the above object,

(Si), copper (Cu), zinc (Zn), unavoidable impurities, and the remainder aluminum, and having an entropy (DELTA S) value of 0.7R to 1.3R And a high strength aluminum alloy.

In addition,

Aluminum (Al), magnesium (Mg) in an amount of 3 to 20% by weight and aluminum (Si), copper (Cu), zinc (Zn), unavoidable impurities and residual aluminum, Preparing an ingot containing an aluminum alloy component of R (step 1); And

 And melting and casting the ingot of the step 1 in an atmospheric state (step 2). The present invention also provides a method of manufacturing a high strength aluminum alloy.

The high strength aluminum alloy of the present invention is an aluminum alloy having an improved strength through improvement of entropy. The composition and the content of the alloy are adjusted so that the value of entropy (DELTA S) is 0.7R to 1.3R, The strength is remarkably excellent. In addition, the method for producing the high strength aluminum alloy is advantageous in that it can be dissolved and cast in the atmospheric state, and the alloy can be manufactured more easily.

1 is a graph showing a nominal stress-strain curve of an aluminum alloy produced according to Examples and Comparative Examples of the present invention,
FIG. 2 is a graph showing the maximum compressive stress of an aluminum alloy produced according to Examples and Comparative Examples of the present invention,
3 is an optical microscope photograph showing the microstructure of an aluminum alloy produced according to an embodiment of the present invention,
4 is an optical microscope photograph showing the microstructure of the aluminum alloy produced according to the comparative example of the present invention,
5 is a scanning electron microscope (SEM) image of a microstructure before and after solution treatment of an aluminum alloy produced according to an embodiment of the present invention,
6 is a scanning electron microscope (SEM) image and a transmission electron microscope (SEM) image showing microstructures of the aluminum alloy produced according to the embodiment of the present invention,
FIG. 7 is a graph comparing the sizes of the crystallized phase and the precipitated phase according to the solution treatment time of the aluminum alloy produced according to the embodiment of the present invention,
8 is a graph comparing the area fraction of the crystallized phase and the precipitated phase according to the solution treatment time of the aluminum alloy produced according to the embodiment of the present invention,
9 is a graph comparing the crystallization phase of the crystallized phase and the crystallized phase according to the solution treatment time of the aluminum alloy produced according to the embodiment of the present invention,
FIG. 10 is a photograph of a microstructure before and after ultrasonic treatment of an aluminum alloy produced according to an embodiment of the present invention, and an electron backscattering diffraction (EBSD) analysis result.

The present invention

(EN) having an entropy (DELTA S) value of 0.7R to 1.3R, which contains 3 to 20% of magnesium (Mg) and contains silicon (Si), copper (Cu), zinc (Zn), unavoidable impurities, High-strength aluminum alloy.

Hereinafter, the high strength aluminum alloy of the present invention will be described in detail.

The aluminum alloy of the present invention contains magnesium (Mg) in an amount of 3 to 20% by weight so as to have a low density and a high entropy value and can control the mechanical properties such as silicon (Si), copper (Cu) and zinc It is a high strength aluminum alloy with improved compressive strength.

That is, the aluminum alloy of the present invention has a low density of 2.5 to 3.5 g / cm ³ and a high content of magnesium (Mg), silicon (Si), copper (Cu) and zinc (Zn) And the like.

Conventional aluminum alloys are highly promising as materials for lightweight construction materials, automobiles, railway vehicles, aircraft, spacecraft, ships and the like because they are excellent in moldability, corrosion resistance and non-strength. there is a problem.

On the other hand, the aluminum alloy of the present invention stabilizes the solid solution phase due to the effects of high entropy due to mixing of different elements, distortion of the crystal lattice due to difference in atomic size, low diffusion rate, etc., There are advantages. Further, there is an advantage that a crystallized phase having high strength at high temperature such as Mg ₂ Si and Al ₅ Cu ₂ Mg ₈ Si ₆ is generated in a large amount and the strength at room temperature and high temperature is high. Also, precipitation phases such as Al ₂ Cu and Zn are finely formed during the aging, and the strength at room temperature and low temperature is high.

The high strength aluminum alloy of the present invention is a high strength aluminum alloy having an entropy (ΔS) value of 0.7R to 1.3R, wherein R is a gas constant and the entropy (ΔS) is a configurational entropy DELTA S _conf ), which can be defined by the following equation (1).

<Formula 1>

k: Boltzmann constant

The number of _A: N A

N _B : Number of B

The entropy value is intended to improve the mechanical properties of aluminum,

If the entropy (? S) value is less than 0.7R, the secondary phase fraction having a strengthening effect is small and the effect of improving the mechanical properties may be insufficient. When the entropy (? S) The mechanical property improving effect can be maximized. However, by reducing the aluminum content to raise the entropy value, the density of the aluminum alloy may increase. Or may contain a light component to maintain a low density, but if it contains, for example, lithium (Li), or if it contains magnesium (Mg) in a larger amount, There is a drawback that it is not easy.

For example, in the aluminum alloy, the aluminum alloy contains 20% by weight of magnesium (Mg). 10% by weight of silicon (Si). 5% by weight of copper (Cu), 5% by weight of zinc (Zn), unavoidable impurities and aluminum.

The aluminum alloy contains 10% by weight of magnesium (Mg). 10% by weight of silicon (Si). 5% by weight of copper (Cu) and 5% by weight of zinc (Zn), or 8% by weight of magnesium (Mg). Silicon (Si) 9 wt%. 10% by weight of copper (Cu), 10% by weight of zinc (Zn), an aluminum alloy having an entropy of 1.01R including unavoidable impurities and aluminum.

Wherein the aluminum alloy comprises 3 to 9 wt% of magnesium (Mg), 5 to 12 wt% of silicon (Si), 5 to 11 wt% of copper (Cu), 5 to 11 wt% of zinc % &Lt; / RTI &gt; by weight.

For example, the aluminum alloy contains 5% by weight of magnesium (Mg). 5% by weight of silicon (Si). 5% by weight of copper (Cu), 5% by weight of zinc (Zn), unavoidable impurities and the balance aluminum, and the aluminum alloy contains 4% by weight of magnesium (Mg). 5% by weight of silicon (Si). 10% by weight of copper (Cu), 10% by weight of zinc (Zn), an aluminum alloy having an entropy of 0.78R including unavoidable impurities and the remainder aluminum.

The aluminum alloy may contain magnesium (Mg) in an amount of 5 to 7 wt%, silicon (Si) in an amount of 8 to 10 wt%, copper (Cu) in an amount of 10 to 11 wt%, zinc To 11% by weight.

For example, the aluminum alloy may include magnesium (Mg) in an amount of 6.9% by weight based on the total weight of the aluminum alloy. Silicon (Si) 9.5% by weight. 10.2 wt% of copper (Cu), 10.5 wt% of zinc (Zn), an aluminum alloy having an entropy of 0.98R including unavoidable impurities and the remainder aluminum.

This is a composition and content for improving the mechanical properties by allowing the aluminum alloy to have a low density and a high entropy at the same time.

On the other hand, the high strength aluminum alloy of the present invention contains 3 to 20% by weight of magnesium (Mg).

In this case, the content of magnesium is intended to improve the strength of the aluminum alloy but to enable casting in the atmosphere. The magnesium is used to improve the main composition of the aluminum alloy and to increase the magnesium content of the Mg ₂ Si or Al ₅ Cu ₂ Mg ₈ Si ₆ Thereby making it possible to contribute to the improvement of the strength of aluminum.

If the content of magnesium is less than 3% by weight, there is a problem that the fraction of the formed phase is small and the strengthening effect is deteriorated. When the magnesium content is more than 20% by weight, There is a problem in that casting is performed in a vacuum state or a step of injecting a separate protective gas for preventing the oxidation of the molten metal in the atmosphere has to be added.

At this time, the magnesium (Mg) is preferably contained in an amount of 3 to 9% by weight based on the total weight of the aluminum alloy, more preferably 5 to 7% by weight based on the total weight of the aluminum alloy.

In addition, the high strength aluminum alloy of the present invention includes silicon (Si), and the main composition can be secured through the production of the aluminum alloy.

At this time, the silicon (Si) is preferably contained in an amount of 5 to 12% by weight based on the total weight of the aluminum alloy, more preferably 8 to 10% by weight based on the total weight of the aluminum alloy.

If the amount of silicon is less than 5% by weight, not only the phase fraction of Mg ₂ Si becomes small, but also the effect of improving the mechanical properties is not produced because no process Si phase is produced If the content of silicon is more than 12 wt%, there is a problem that the Si phase is poured at a high temperature to increase the casting temperature. If the casting temperature is increased, the hydrogen concentration in the molten metal is increased, which may cause a problem of promoting the occurrence of pores in the casting

The high strength aluminum alloy of the present invention comprises copper (Cu).

The copper is an age-precipitation-type alloying element, and when added in a certain amount, it can contribute to the improvement of the strength of aluminum by forming precipitates such as Al ₂ Cu or Al ₅ Cu ₂ Mg ₈ Si ₆ .

At this time, the copper (Cu) is preferably contained in an amount of 5 to 11% by weight based on the total weight of the aluminum alloy, more preferably 10 to 11% by weight based on the total weight of the aluminum alloy.

If the content of copper is less than 5% by weight, the aging hardenability is lowered and the strength is lowered. On the other hand, when the copper content is more than 11% by weight, the density of the alloy is increased, There may arise a problem that the main composition of the catalyst is lowered.

In addition, the high strength aluminum alloy of the present invention includes zinc, and through this, it is possible to secure the main composition in the production of the aluminum alloy.

At this time, the zinc (Zn) is preferably contained in an amount of 5 to 11% by weight based on the total weight of the aluminum alloy, more preferably 10 to 11% by weight based on the total weight of the aluminum alloy.

If zinc is contained in an amount of less than 5% by weight, there may arise a problem that the Zn strengthening effect and the effect of improving the mechanical properties are not obtained because no Zn phase is formed as an aging strengthening phase. When the zinc content is less than 11% , The density of the alloy is increased and the main composition of the alloy may be deteriorated.

The high strength aluminum alloy of the present invention is a high strength aluminum alloy exhibiting a high compressive strength of 350 to 700 MPa at a temperature of 25 to 200 캜.

The compressive strength value is a value of 19 to 32% higher than that of A390 aluminum alloy containing 0.3% by weight of magnesium and 7.0% by weight of silicon with respect to the total weight of aluminum as a conventional aluminum heat-resistant alloy, and the high- Lt; RTI ID = 0.0 &gt; 200 C &lt; / RTI &gt;

Further, the high strength aluminum alloy has a low density of 2.5 to 3.5 g / cm &lt; ^{3 &} gt ;.

Therefore, the high-strength aluminum alloy of the present invention exhibits low density and excellent strength, and can be used for lightening construction materials, automobiles, railway vehicles, aircraft, spacecraft, ships and the like. By using the high strength aluminum alloy, It is possible to increase the fuel efficiency and to suppress environmental pollution caused by exhaust gas and global warming.

Further, the high strength aluminum alloy of the present invention has an advantage that it can be manufactured by casting in a standby state.

That is, since the aluminum alloy does not contain an element easily oxidized during casting like lithium (Li), vacuum casting is not necessary in melting and casting, which is advantageous in that it can be manufactured more easily.

The high-strength aluminum alloy of the present invention is preferably produced by ultrasonic treatment of the molten alloy component and then casting.

The ultrasonic treatment is for reducing the porosity present in the aluminum alloy and further refining the crystallization phase. It is preferable that the high strength aluminum alloy of the present invention is manufactured by ultrasonication and casting the molten alloy component as described above.

In addition,

Wherein the aluminum contains 3 to 20% of magnesium (Mg), and contains silicon (Si), copper (Cu), zinc (Zn), unavoidable impurities and the remainder aluminum, (Step 1) of preparing an ingot containing an aluminum alloy component whose content is controlled so that the content of the aluminum alloy component becomes equal to that of the aluminum alloy component; And

 And melting and casting the ingot of the step 1 in an atmospheric state (step 2). The present invention also provides a method of manufacturing a high strength aluminum alloy.

Hereinafter, the method for producing the high strength aluminum alloy of the present invention will be described in detail in stages.

In the method for manufacturing a high strength aluminum alloy according to the present invention, step 1 is a step in which aluminum is contained in an amount of 3 to 20% of magnesium (Mg), and silicon (Si), copper (Cu), zinc (Zn), inevitable impurities, , And an ingot containing an aluminum alloy component whose content is adjusted such that the value of entropy (? S) is 0.7R to 1.3R.

On the other hand, the high strength aluminum alloy of the present invention contains 3 to 20% by weight of magnesium (Mg). Magnesium may contribute to the improvement of the strength of aluminum by enhancing the casting of the aluminum alloy and forming a crystallization phase such as Mg ₂ Si or Al ₅ Cu ₂ Mg ₈ Si _{6 in} the aluminum alloy.

The composition and the content are intended to make the aluminum alloy have low density and high mechanical properties, in particular, to have a high compression strength of from 350 to 700 MPa at a density of from 2.5 to 3.5 g / cm &lt; ³ &gt;

At this time, the magnesium content has a strengthening effect, but it prevents the problem of oxidation when casting the aluminum alloy. If the magnesium content is less than 3% by weight, the fraction in which the crystallized phase is formed is small, When the magnesium content is more than 20 wt%, there is a problem that magnesium is oxidized during casting in the atmospheric state. Therefore, casting in a vacuum state or a separate protective gas for preventing oxidation of the molten metal in the atmosphere There is a disadvantage in that a step of injecting must be added.

The composition and the content are intended to perform the casting of the aluminum alloy in a standby state. Therefore, it is preferable that the aluminum alloy composition does not contain, for example, lithium (Li) which is well oxidized during casting.

In the method of manufacturing a high strength aluminum alloy according to the present invention, step 2 is a step of melting and casting the ingot of step 1 in the atmospheric state.

At this time, the dissolution is preferably performed at 700 to 800 ° C, for example, it may be dissolved by heat treatment at 750 ° C for 10 minutes, but the temperature and time for dissolving are not limited thereto.

On the other hand, it is preferable that the manufacturing method is performed after ultrasonic treatment after the dissolution or casting.

This is to improve the strength by lowering the porosity of the aluminum alloy and further refining the precipitation phase.

The ultrasonic treatment may be performed at 750 DEG C for about 1 minute using an ultrasonic processor, but the temperature and time are not limited thereto.

Thereafter, the molten ingot may be cast to produce an aluminum alloy.

At this time, the casting is preferably performed at a temperature of 700 to 800 ° C. and in an atmospheric state, for example, at a temperature of 700 ° C. and in an atmospheric state. However, the casting temperature is not limited thereto.

The composition and content of the aluminum alloy of the present invention can be manufactured even when casting in an atmospheric state, and include a highly oxidizable element such as lithium (Li), so that it is easier to manufacture an alloy than when it is cast in a vacuum state There are advantages.

It is preferable that the manufacturing method further includes a solution treatment step after the casting in the step 2.

The solution treatment is intended to spheroidize the crystallized phase produced during casting and to produce a fine precipitate phase at room temperature to 200 ° C to further improve the mechanical properties.

The solution treatment is preferably carried out at a temperature of 400 to 500 ° C, more preferably 400 to 450 ° C.

The solution treatment may be performed for 1 to 10 hours, but is not limited thereto.

As the solubilization time increases in the solution treatment, the crystallized phase in the aluminum alloy becomes finer or spheroidized, and the mechanical properties can be further improved.

In addition,

It is preferable to further include an aging step after the casting of step 2 above.

This is for improving the ductility of the cast aluminum alloy.

For example, the aging treatment may be performed at a temperature of 120 to 170 DEG C for 8 to 24 hours, but is not limited thereto.

The method of manufacturing a high strength aluminum alloy according to the present invention is characterized in that magnesium (Mg), silicon (Si), copper (Mg), and aluminum are mixed so that the value of entropy (? S) of the aluminum alloy is 3 to 20% Wherein the aluminum alloy has a low density and at the same time has excellent mechanical properties and can be cast in an atmospheric state by controlling the content of aluminum (Cu) and zinc (Zn) ³ and exhibits a high compressive strength of 350 to 700 MPa at a temperature of 25 to 200 ° C.

For example, the aluminum alloy contains 20% by weight of magnesium (Mg). 10% by weight of silicon (Si). 5% by weight of copper (Cu), 5% by weight of zinc (Zn), unavoidable impurities and aluminum of the remainder, and having an entropy of 1.03R.

The aluminum alloy contains 10% by weight of magnesium (Mg). 10% by weight of silicon (Si). 5% by weight of copper (Cu), 5% by weight of zinc (Zn), unavoidable impurities and the balance aluminum or 8% by weight of magnesium (Mg). Silicon (Si) 9 wt%. 10% by weight of copper (Cu), 10% by weight of zinc (Zn), an aluminum alloy having an entropy of 1.01R including unavoidable impurities and aluminum.

At this time, the aluminum alloy component may contain 3 to 9 wt% of magnesium (Mg), 5 to 12 wt% of silicon (Si), 5 to 11 wt% of copper (Cu) 5 to 11% by weight.

For example, the aluminum alloy contains 5% by weight of magnesium (Mg). 5% by weight of silicon (Si). 5% by weight of copper (Cu), 5% by weight of zinc (Zn), unavoidable impurities and the balance aluminum or 4% by weight of magnesium (Mg). 5% by weight of silicon (Si). 10% by weight of copper (Cu), 10% by weight of zinc (Zn), an aluminum alloy having an entropy of 0.78R including unavoidable impurities and the remainder aluminum.

The aluminum alloy component may contain magnesium (Mg) in an amount of 5 to 7% by weight, silicon (Si) in an amount of 8 to 10% by weight, copper (Cu) in an amount of 10 to 11% 10 to 11% by weight.

For example, the aluminum alloy contains 6.9% by weight of magnesium (Mg). Silicon (Si) 9.5% by weight. 10.2 wt% of copper (Cu), 10.5 wt% of zinc (Zn), an aluminum alloy having an entropy of 0.98R including unavoidable impurities and the remainder aluminum.

Hereinafter, the present invention will be described in detail with reference to Examples and Experimental Examples.

However, the following Examples and Experimental Examples are merely illustrative of the present invention, and the contents of the present invention are not limited by the following Examples.

Table 1 shows examples and comparative examples of the present invention.

Mg
(weight%) Si
(weight%) Cu
(weight%) Zn
(weight%) Ni
(weight%) Solution treatment Aging treatment ultrasonic wave
process density
(g / cm ³⁾ Entropy Example 1 6.9 9.5 10.2 10.5 - - - - 3.0 0.98R Example 2 5.8 8.9 10.0 10.0 2.8 - - - 3.1 0.99R Example 3 6.9 9.5 10.2 10.5 - 440 ° C
1 hours - - 3.0 0.98R Example 4 6.9 9.5 10.2 10.5 - 440 ° C
4 hours - - 3.0 0.98R Example 5 6.9 9.5 10.2 10.5 - 440 ° C
10 hours - - 3.0 0.98R Example 6 6.9 9.5 10.2 10.5 - 440 ° C
4 hours 120 DEG C
24 hours - 3.0 0.98R Example 7 6.9 9.5 10.2 10.5 - 440 ° C
4 hours 170 ℃
8 hours - 3.0 0.98R Example 8 5.8 8.9 10.0 10.0 - 440 ° C
1 hours - - 3.1 0.99R Example 9 5.8 8.9 10.0 10.0 - 440 ° C
4 hours - - 3.1 0.99R Example 10 5.8 8.9 10.0 10.0 - 440 ° C
10 hours - - 3.1 0.99R Example 11 5.8 8.9 10.0 10.0 - 440 ° C
4 hours 120 DEG C
24 hours - 3.1 0.99R Example 12 5.8 8.9 10.0 10.0 - 440 ° C
4 hours 170 ℃
8 hours - 3.1 0.99R Example 13 6.9 9.5 10.2 10.5 - - - 750 ℃ 1 min 3.1 0.98R Example 14 3.9 5.0 9.9 10.5 - - - - 3.0 0.78R Comparative Example 1 24.3 9.4 10.6 10.9 - - - - 2.7 1.24R Comparative Example 2 0.3 7.0 - - - - - - 2.7 0.27R Comparative Example 3 0.5 18.5 3.9 - - - - - 2.8 0.59R Comparative Example 4 0.8 12.0 3.7 - 2.5 - - - 2.8 0.55R Comparative Example 5 0.8 18.0 3.8 - 2.7 - - - 0.8 0.67R

&Lt; Example 1 >

The high strength aluminum alloy of the present invention was produced through the following steps.

Step 1: 6.9 wt% of magnesium (Mg), 9.5 wt% of silicon (Si), 10.2 wt% of copper (Cu), 10.5 wt% of zinc (Zn), inevitable impurities and aluminum .

Step 2: The ingot of step 1 was inductively melted at a temperature of about 750 캜 for about 10 minutes and then temperature stabilized for about 3 minutes. Then, casting was carried out in molds of 245 mm, 200 mm, and 70 mm in width, height and height at 700 ° C. and atmospheric conditions, respectively, and then air-cooled to produce a high strength aluminum alloy.

&Lt; Example 2 >

(Mg), 8.9 wt% of silicon (Si), 10.0 wt% of copper (Cu), 10.0 wt% of zinc (Zn), 2.8 wt% of nickel, An aluminum alloy was produced in the same manner as in Example 1, except that the content of the ingot was varied to include aluminum (Al).

&Lt; Example 3 >

The aluminum alloy was produced in the same manner as in Example 1, except that the solution treatment was further carried out at 440 占 폚 for 1 hour after the step 2 of Example 1 above.

<Example 4>

The aluminum alloy was prepared in the same manner as in Example 1, except that the solution treatment was further carried out at 440 占 폚 for 4 hours after the step 2 of Example 1 above.

&Lt; Example 5 >

An aluminum alloy was prepared in the same manner as in Example 1, except that the solution treatment was further carried out at 440 占 폚 for 10 hours after Step 2 of Example 1.

&Lt; Example 6 >

The procedure of Example 1 was repeated except that the solution was subjected to a solution treatment at 440 占 폚 for 4 hours after the step 2 of Example 1 and then for 24 hours at 120 占 폚 to obtain an aluminum alloy .

&Lt; Example 7 >

The procedure of Example 1 was repeated except that the solution was subjected to a solution treatment at 440 占 폚 for 4 hours and then an aging treatment at 170 占 폚 for 8 hours after Step 2 of Example 1 to obtain an aluminum alloy .

&Lt; Example 8 >

(Mg), 8.9 wt% of silicon (Si), 10.0 wt% of copper (Cu), 10.0 wt% of zinc (Zn), 2.8 wt% of nickel, The aluminum alloy was produced in the same manner as in Example 1, except that the content of the ingot was changed so as to contain aluminum (Al), and then the solution treatment was performed at 440 占 폚 for 1 hour after Step 2 Respectively.

&Lt; Example 9 >

An aluminum alloy was produced in the same manner as in Example 8, except that the solution treatment in Example 8 was carried out at 440 캜 for 4 hours.

&Lt; Example 10 >

An aluminum alloy was prepared in the same manner as in Example 8 except that the solution treatment was carried out at 440 캜 for 10 hours in Example 8.

&Lt; Example 11 >

The procedure of Example 8 was repeated except that the solution treatment was carried out at 440 占 폚 for 4 hours and then the aging treatment was conducted at 120 占 폚 for 24 hours to prepare an aluminum alloy Respectively.

&Lt; Example 12 >

The procedure of Example 8 was repeated except that the solution treatment was carried out at 440 占 폚 for 4 hours in the Example 8 and then aged at 170 占 폚 for 8 hours to obtain an aluminum alloy .

&Lt; Example 13 >

In step 2 of Example 1, except that after melting and before casting, the molten ingot was ultrasonicated at about 750 占 폚 for about 1 minute using an ultrasonic processor exhibiting an output of about 350 W Was prepared in the same manner as in Example 1 to prepare an aluminum alloy.

&Lt; Example 14 >

3.9 wt% of magnesium (Mg), 5.0 wt% of silicon (Si), 9.9 wt% of copper (Cu), 10.5 wt% of zinc (Zn) Except that the content of the components of the ingot was varied so as to include the aluminum alloy.

&Lt; Comparative Example 1 &

(Mg), 9.4 wt% of silicon (Si), 10.6 wt% of copper (Cu), 10.9 wt% of zinc (Zn) and the balance of aluminum (Al) in step 1 of Example 1, Except that the content of the aluminum alloy was changed so as to include the aluminum alloy.

&Lt; Comparative Example 2 &

Except that in Step 1 of Example 1, 0.3 wt% of magnesium (Mg), 7.0 wt% of silicon (Si), and the balance of aluminum (Al), aluminum alloy A356 The aluminum alloy was produced in the same manner as in Example 1.

&Lt; Comparative Example 3 &

In step 1 of Example 1, an aluminum alloy A390 was prepared to contain 0.5 wt% of magnesium (Mg), 18.5 wt% of silicon (Si), 3.9 wt% of copper (Cu), and the balance aluminum The aluminum alloy was prepared in the same manner as in Example 1 except that the component content was changed.

&Lt; Comparative Example 4 &

In step 1 of Example 1, the composition was prepared so that the piston alloy contained 0.8 wt% of magnesium (Mg), 12.0 wt% of silicon (Si), 3.7 wt% of copper (Cu) The aluminum alloy was prepared in the same manner as in Example 1 except that the content was changed.

&Lt; Comparative Example 5 &

In step 1 of Example 1, a mixture of 0.8 wt% of magnesium (Mg), 18.0 wt% of silicon (Si), 3.8 wt% of copper (Cu), and the balance of aluminum (Al) The aluminum alloy was prepared in the same manner as in Example 1 except that the content was changed.

<Experimental Example 1> At room temperature compressive strength analysis

In order to compare the compression characteristics of the aluminum alloy produced according to the present invention and the aluminum alloy of the conventional heat-resistant material, the aluminum alloy produced in Examples 1, 2 and 14 and Comparative Examples 1 to 4 was subjected to the following experiment Respectively.

The aluminum alloys prepared in Examples 1, 2 and 14 and Comparative Examples 1 to 5 were measured for compressive strength at room temperature using Thermec-mastor Z, and the results are shown in Fig. 1 and Table 2 below.

σ _{0 .2} σ _peak 竜_peak Example 1 414 697 6.7 Example 2 408 600 6.2 Example 14 358 644 11.9 Comparative Example 1 105 582 50.0 Comparative Example 2 293 571 23.3 Comparative Example 3 307 566 24.4 Comparative Example 4 313 568 16.7 Comparative Example 5 308 566 16.8

σ _{0 .2:} Compression yield strength

σ _peak : maximum compressive stress

ε _peak : Strain at maximum compressive stress

Here, (σ _{0. 2)} The compression yield strength refers to the stress value when the plastic deformation of about 0.2%.

The nominal stress-strain curves of FIG. 1 and the aluminum alloys produced by Examples 1, 2 and 14, as shown in Table 2, have higher yield strength values than the aluminum alloys of Comparative Examples 1 to 4, It can be seen that the stress, that is, the compressive strength value is as high as 600 MPa or more.

As a result, it can be seen that the aluminum alloy of the present invention exhibits remarkably excellent compressive strength at room temperature.

&Lt; Experimental Example 2 >

In order to compare the compression characteristics of the aluminum alloy produced according to the present invention and the conventional aluminum alloy according to the temperature, the following experiment was conducted on the aluminum alloy produced in Example 1 and Comparative Examples 2 to 4.

The maximum compressive stress at 25 ° C to 300 ° C was measured using the Thermec-mastor Z of the aluminum alloy produced in Example 1 and Comparative Examples 2 to 4. The results are shown in Fig.

As shown in FIG. 2, in the case of a high temperature of 300 ° C., the maximum compressive stress values of the aluminum alloy produced by Example 1 and Comparative Examples 2 to 4 are similar, but at a temperature of 25 ° C. to 200 ° C., It can be seen that the maximum compressive stress value of the aluminum alloy produced by Example 1 is significantly higher than the maximum compressive stress value of the aluminum alloy produced by Comparative Examples 2 to 4. [

As a result, it can be seen that the aluminum alloy of the present invention is significantly superior in compressive strength at a temperature of 25 ° C to 200 ° C to that of the conventional aluminum alloy.

&Lt; Experimental Example 3 > Characterization of alloy casted in the atmospheric state

In order to compare the properties of the aluminum alloy produced according to the present invention and the cast alloy in the atmospheric state of the aluminum alloy containing 20 wt% or more of magnesium, the aluminum alloy produced according to Example 1 and Comparative Example 1, The following experiment was carried out.

The microstructures of the aluminum alloy prepared in Example 1 and Comparative Example 1 were observed using an optical microscope (OM). The results are shown in FIGS. 3 and 4, respectively. Were measured.

As shown in Fig. 3, in the case of the aluminum alloy produced by Example 1, there are a large amount of fine crystallization phases, whereas in the case of the aluminum alloy produced by Comparative Example 1, Mg Oxidation and pore formation, and a coarse Mg ₂ Si crystallization phase was formed.

As a result of measuring the maximum compressive stress and the strain at the maximum compressive stress, the aluminum alloy produced by Example 1 and Comparative Example 1 exhibited a maximum compressive stress of 697 MPa and a strain of 6.2% and a strain of 3.8%, respectively, of 459 MPa .

That is, when magnesium (Mg) in the aluminum alloy is contained in an amount of 20 wt% or more, magnesium is oxidized, and a coarse Mg ₂ Si crystallization phase is formed on the matrix and the compressive strength is lowered to 500 MPa or lower. On the other hand, The high-strength aluminum alloy shows a high compressive strength of 600 MPa or more because a large amount of fine precipitate exists in the matrix even when cast in the atmospheric state.

As a result, it can be seen that the high strength aluminum alloy of the present invention can be cast in the atmospheric state and is easy to manufacture.

 <Experimental Example 4> Effect of solution treatment and aging treatment

In order to confirm the effect of solution treatment or aging treatment of the aluminum alloy produced according to the present invention, the following experiment was conducted on the aluminum alloy produced in Examples 1 to 12.

The aluminum alloys prepared in Examples 1 to 12 were measured for compressive strength at room temperature using Thermec-mastor Z, and the results are shown in Table 3 below.

σ _{0 .2} σ _peak 竜_peak Example 1 414 697 6.7 Example 3 417 744 6.8 Example 4 417 742 8.0 Example 5 406 723 8.4 Example 6 454 711 8.5 Example 7 424 677 11.8 Example 2 408 660 6.2 Example 8 427 727 6.5 Example 9 412 732 7.8 Example 10 413 632 8.6 Example 11 436 669 6.4 Example 12 426 649 8.9

σ _{0 .2:} Compression yield strength

σ _peak : maximum compressive stress

ε _peak : Strain at maximum compressive stress

Here, (σ _{0. 2)} The compression yield strength refers to the stress value when the plastic deformation of about 0.2%.

As shown in Table 3, compared with the case of Example 1 in which the solution treatment was not performed, in the case of Examples 3 to 5 where the solution treatment was performed and in the case of Example 2 where the solution treatment was not performed In the cases of Examples 8 to 10 in which the solution treatment was performed and in Examples 6 and 11 in which the solution treatment and aging treatment were performed, the strain values at the maximum compressive stress and the maximum compressive stress were both increased, And aged Examples 12 and 11, the maximum compressive stress was somewhat reduced, but the strain was increased.

As a result, it can be seen that the coarse precipitate phase is redissolved, and then the fine precipitates of several nm in size are generated at room temperature, thereby improving the strength and ductility of the aluminum alloy.

  Experimental Example 5 Effect of Solution Treatment (1)

In order to confirm the effect of solution treatment of the aluminum alloy produced according to the present invention, the following experiment was conducted on the aluminum alloy produced in Examples 1 and 4.

The microstructure of the aluminum alloy prepared in Examples 1 and 4 was observed using a scanning electron microscope (SEM) and a transmission electron microscope (TEM), and the results are shown in FIG.

As shown in Fig. 5, in the case of Example 1 in which the solution treatment was not performed, an acicular and a plate-like precipitate phase were observed, whereas in the case of Example 4 in which the solution treatment was carried out, this shape was not observed and a transmission electron microscope TEM). As a result, it was confirmed that spherical θ 'phase, that is, Al ₂ Cu phase was formed.

As a result, it can be seen that when the solution treatment is carried out, the precipitation phase is spheroidized, and the strength and ductility of the aluminum alloy are improved by spheroidization of the precipitate phase.

 Experimental Example 6 Effect of Solution Treatment (2)

In order to confirm the change of the microstructure according to the solution treatment time of the aluminum alloy produced according to the present invention, the following experiment was conducted.

The aluminum alloy produced by heat treating the aluminum alloy prepared in Example 1 and Example 1 at 440 ° C. for 1, 3, 4, 6, 8, and 10 hours was observed through a scanning electron microscope (SEM) FIG. 6 shows the case where the aluminum alloy produced in Example 1 and Example 1 was heat-treated at 440 ° C. for 1, 4, and 10 hours, and an i-solition program was used to measure the precipitate phase The size, area fraction and spheroidization are calculated and are shown in Figures 7 to 9.

As shown in FIG. 6, the crystallization phases of Mg ₂ Si (1), Al ₅ Cu ₂ Mg ₈ Si ₆ (2), Al ₂ Cu (3) and Si (4) It can be confirmed that the Mg ₂ Si (1) phase is redissolved and Al ₅ Cu ₂ Mg ₈ Si ₆ (2) grows as it gets longer.

7 shows the sizes of the crystallization phases. As shown in FIG. 7, it can be seen that the size of Mg ₂ Si (1) decreases as the solution treatment time becomes longer, and the fraction of the area occupied by the crystallization phase In FIG. 8, it can be seen that the longer the solution treatment time is, the smaller the fraction of Mg ₂ Si (1) is. 9 shows the degree of spheroidization. As shown in FIG. 9, it can be seen that the spheroidization degree of the crystallization phases increases as the solution treatment time becomes longer.

As a result, it can be seen that when the aluminum alloy of the present invention is subjected to the solution treatment, the Mg ₂ Si (1) phase is refined and the crystallized phase is spheroidized, thereby improving the mechanical properties of the aluminum alloy.

Experimental Example 7 Effect of Ultrasonic Processing

In order to confirm the change of the microstructure according to the ultrasonic treatment of the aluminum alloy produced according to the present invention, the following experiment was conducted.

The microstructures of the aluminum alloy prepared according to Examples 1 and 13 were observed through a naked eye and an electron backscattering diffraction (EBSD) analyzer, and this is shown in FIG.

As shown in Fig. 10, it can be confirmed that the porosity of the alloy after ultrasonic treatment is reduced and the crystallized phase is made finer.

It is expected that the mechanical properties of the aluminum alloy can be further improved by ultrasonic treatment of the ingot dissolved before the casting step, by further reducing the casting defects such as pores, and further reducing the size of the crystallized phase and crystal grains.

1: Mg ₂ Si
2: Al ₅ Cu ₂ Mg ₈ Si ₆
3: Al ₂ Cu
4: Si

Claims (16)

5 to 7% by weight of magnesium (Mg), 8 to 10% by weight of silicon (Si), 10 to 11% by weight of copper (Cu) and 10 to 11% by weight of zinc (Zn) And an inevitable impurity and residual aluminum, wherein the value of entropy (DELTA S) is 0.7R to 1.3R.
delete delete The method according to claim 1,
The aluminum alloy
Wherein a compressive strength at a temperature of 25 to 200 占 폚 is as high as 19 to 32% as compared with the A390 aluminum alloy.
The method according to claim 1,
The aluminum alloy
And a density of 2.5 to 3.5 g / cm &lt; ³ &gt;.
The method according to claim 1,
The aluminum alloy
Wherein the aluminum alloy is cast in a standby state.
The method according to claim 1,
The aluminum alloy
Characterized in that the molten alloy component is ultrasonically treated and then cast.
5 to 7% by weight of magnesium (Mg), 8 to 10% by weight of silicon (Si), 10 to 11% by weight of copper (Cu) and 10 to 11% by weight of zinc (Zn) (Step 1) of preparing an ingot including an aluminum alloy component whose content is controlled so that the value of entropy (? S) is 0.7R to 1.3R, including inevitable impurities and residual aluminum; And
And melting and casting the ingot of the step 1 in an atmospheric state (step 2).
delete delete 9. The method of claim 8,
The above-
Wherein the ultrasonic treatment is performed after the dissolution and before the casting.
9. The method of claim 8,
The above-
Wherein the melting and casting is performed at 700 to 800 占 폚.
9. The method of claim 8,
The above-
Further comprising the step of performing a solution treatment after casting in the step (2).
14. The method of claim 13,
Wherein the solution treatment is performed at a temperature of 400 to 500 占 폚.
14. The method of claim 13,
The above-
Further comprising the step of aging the solution after the solution treatment step.
16. The method of claim 15,
The aging treatment
Wherein the heat treatment is performed at a temperature of 120 to 170 占 폚.

Images