KR900006612B1 - Highly corrosion resistant and high strength aluminium alloys - Google Patents

Abstract

High corrosion resistance and high strength Al alloy is obtained by rapied solidification of a melt contains 0.2-15% or 0.5-15% at least one of Si, Ti, Zr, Nb, Ni, Cu and Mn and the balance Al. The structure comprises alpha-Al phase as mother phase containing superstructured alloying element to improve in the corrosion resistance and strength and intermetallic compoind phase and/or metallic phase dispersed in the mother phase, so alloy has good resistance and high strength and vickers hardness.

Description

High corrosion resistance and high strength aluminum alloy

Figure 1 is a schematic diagram of a design of a device that can be used to fabricate the rapidly solidified alloy of the present invention.

* Explanation of symbols for main parts of the drawings

1: entrance 2: quartz tube

3: nozzle 4: raw materials

5: heater 6: motor

7: wheel

The present invention relates to high corrosion resistance and high strength aluminum alloys produced by solidification through rapid quenching.

Industrially, aluminum is an important metal material, which is light and inexpensive, easy to handle, and widely used in the form of elements and after being produced and manufactured as an alloy by various methods. However, when aluminum and its alloys are exposed to chloride-containing environments, it is very easy for formulas to occur. Thus, sometimes high strength light alloys or aluminum alloys, which are typically used as light alloys, are not suitable for use in applications where high corrosion resistance is required. Low corrosion resistance of the aluminum alloy can be described as accelerated corrosion caused by secondary phases and / or inclusions formed by impurity elements present in the alloy. The addition of alloying elements useful for improving the corrosion resistance is not practical because the solid solution formation range of these elements is narrow.

The inventors believe that the rapid solidification of molten alloys extends their solid solubility and sometimes forms amorphous alloys containing higher amounts of various elements than alloys made by conventional methods, and these amorphous alloys They have found that they have extremely high corrosion resistance due to the addition of effective elements to improve the corrosion resistance and the chemical uniformity of the amorphous alloys. The present inventors have further studied that it is difficult to soften aluminum alloys, but rapidly solidifying molten alloys containing a proper amount of appropriate elements, the ancient type with very high pitting potential and high hardness, which are very fine grains characteristic of supersaturated solid solution It is found that high strength alloys are formed.

The present invention has been accomplished based on this finding.

The present invention contains at least one element selected from the group consisting of Si, Ti, Zr, Nb, Ni, Cu and Mn in an amount of at least 0.2 at.% And at most 15 at.% And the remainder is substantially composed of A1. It is to provide a high corrosion resistance and high strength aluminum alloy produced by the solidification rapidly.

The aluminum melt containing the specific components may be solidified by any rapid quenching technique commonly used in amorphous alloy manufacture, in which molten metal is injected into the outer surface of the rotating wheel. Method, centrifugal quenching method in which the solution is stratified onto the inner surface of the rotating cylinder, double roll method for quenching liquid metal through two closely located rolls, and gas method for producing rapidly solidified f1akes. The piston-anvil method of injecting into a molten metal molten chill medium to produce the powder by rapid quenching, and other methods such as thermal spraying and cavitation.

The aluminum alloy of the present invention, prepared by solidifying certain components quickly, has a slightly higher formal potential than conventionally treated aluminum alloys. The aluminum alloy of the present invention due to this anticorrosion exhibits high mechanical strength due to the formation of supersaturated solid solution.

A suitable method for preparing the rapidly solidified alloy of the present invention, called the rotary wheel method, is as follows:

The alloy solidified with the above-mentioned components and rapidly solidified can be formed by rapidly quenching in the liquid state at a cooling rate higher than 1,000 t / sec. If the cooling rate is lower than 1,000 ° C / sec, it is difficult to form a superamorphous alloy. . In principle, the rapidly solidified alloys of the present invention can be produced by any suitable apparatus that provides cooling rates higher than 1,000 ° C./sec.

One example of a device for fabricating the rapidly solidified alloy of the present invention is shown in the accompanying drawings. The apparatus is located in a vacuum chamber indicated by a rectangular line in the drawing. In the drawing, the quartz tube 2 includes an exposed portion 3 at its lower end in the vertical direction and jets raw material 4 and molten raw material. Inert gas for the gas is supplied from the inlet 1. A heater 5 is positioned around the quartz tube 2 to combust the raw material 4. A high speed wheel 7 of 300 mm diameter is positioned under the nozzle 3 and rotated by the motor 6.

The device is pre-exhausted to about 10 ^-5 torr and then exposed to an inert gas atmosphere, such as argon or nitrogen. The raw material 4 containing the specific components of interest is subjected to the combustor 5 in a quartz tube under an inert gas atmosphere. Melts. The molten alloy collides with the outer surface of the wheel 7 which is rotated at a speed of 500 rpm-10,000 rpm under an inert gas pressure of 0.4 kg / cm ² -2 kg / crn ² , so that the rapidly solidified alloy has a thickness of 0.01 mm, for example. It is formed of elongated plates that can be -0.1 mm, butterfly 1 mm-10 mm and lengths of several m to several tens of meters.

The criticality of the individual components of the aluminum alloy strip according to the invention is as follows. The above-mentioned elements lead Si, Ti, Zr, Nb, Ni, Cu, and Mn are alloy elements porosifying the anticorrosion and mechanical strength by supersaturating the α'-A1 relative, and the α-A1 phase is an aluminum alloy. It is the lightest of the phases with the lowest gluttony.

If the amount of at least one winso selected from the group consisting of Si, Ti, Zr, Nb, Ni, Cu and Mn is lower than 0 2 at%, the corrosion resistance of the aluminum alloy of the manufacturer is not high enough by rapid solidification and the aluminum is rapidly solidified. There is no difference in the corrosion resistance of metals. On the other hand, if the amount of at least one element selected from Si, Ti, Zr, Nb, Ni, Cu, and Mn exceeds 15 at%, the rapidly solidified alloy becomes too fragile, except that only Mn is added. It can be used for purpose.

Therefore, in order to achieve the object of the present invention, the amount of at least one element selected from Si, Ti, Zr, Nb, Ni, Cu, and Mn must be in the range of 0.2at.%-15at.%.

In order to obtain better results, it is preferable to add at least one of these elements in an amount of 0.5at.%-15at.%.

The above rapidly solidified aluminum alloy may contain 4 at% or less of another element such as Mg, V, Cr, Fe, Co or Zn without regenerating the object of the present invention.

According to the present invention, the added elements will be finely distributed along the fine grain boundaries formed in the alloy as a result of rapid solidification, thus preventing them from growing on subsequent heat treatment. Therefore, the alumina alloy of the present invention can be processed into a required shape by sintering or press forming, compression, or extrusion after the rapid solidification, under processing conditions appropriately selected so that the object of the present invention is not impaired.

If the liquid alloy containing one of the aforementioned components is rapidly solidified, the alloying elements will dissolve in the α-A1 matrix to form a supersaturated solid solution and give the matrix a very high corrosion resistance and strength. Moreover, all other phases resulting from the addition of alloying elements possess high corrosion resistance and strength, thereby producing aluminum alloys exhibiting very high corrosion resistance and strength properties.

On the other hand, most of the alloying elements in the conventionally treated aluminum alloy will not be dissolved in the α-Al matrix, and various impurity elements will form a non-uniform phase, thereby deteriorating the purpose of obtaining high corrosion resistance. On the other hand, the elements added in the present invention will be dissolved in the molten aluminum alloy even if their components are complex. Thus, if the molten metal comprising one of the components specified by the present invention is rapidly solidified, then various elements effective for the passivation of the middle steel will dissolve in the most susceptible α-AI phase to form a supersaturated solid solution. The solidified alloy thus exhibits high corrosion resistance and high mechanical strength by forming a passive film having high corrosion resistance and high protection.

The following examples are intended to further illustrate the invention and are not intended to limit the invention.

Example 1

Thirty alloys containing the components listed in Table 1 were typically cast by argon arc melting of metals. The main alloy was remelted in an argon atmosphere, and after being remelted under argon atmosphere, it solidified rapidly by the rotational wheel method, and was thinly formed with a fast solidifying alloy of 0.01mm-0.05mm, butterfly 1mm-3mm, and length 3m_20m. Produce a sheet. X-ray diffraction analysis shows that the added alloying elements are dissolved in large amounts to form supersaturated solid solutions of the α-AI phase because the compound phase composed of vacancy-forming Si and alloying elements and Al has the same compound phase. It has been found to be due to the fact that the diffraction intensity is lower than that of alloys containing components and conventionally treated. Inspection by light microscopy and scanning electron microscopy revealed that the individual alloy samples produced according to the present invention had a microcrystalline structure composed of particles no greater than 0.5 μm.

[Table 1]: Alloy Components (at.%)

Example 2

까지 감소되었고, 생성 α-A1상에는 적어도 3at.% Si가 그 내부에 용해되었다. 급속히 응고된 합금조직은 균일하였고, 크기가 0.5μm 보다 크지 않은 미세 결정립들로 구성되었다.Two samples of 99.999% pure aluminum were fabricated by rapid coagulation and conventional coarse process, and two samples of AI-5at.% Si alloy were also prepared by rapid coagulation and conventional treatment method according to the present invention using the rotary wheel method. It became. The conventionally treated AI-5at.% Si alloy was composed of cubic Si and vacancies of α-A1 and α-A1 phase. In the rapidly solidified Al-5at.% Si alloy, the amount of cubic Si in the vacancy is about the amount of the amount in the agent substitute, as is conventional

And at least 3 at.% Si was dissolved therein in the resulting α-A1 phase. The rapidly solidified alloy structure was uniform and consisted of fine grains not larger than 0.5 μm in size.

The formula potentials of four solidified samples were measured in 0.5 N NaCl degassed at 30 ° C. Their Vickers degree was also measured. The results are shown in Table 2.

TABLE 2 Hardness and formula potential of metals and alloys rapidly solidified and conventionally treated.

As shown in Table 2, the official potential of the solidified source Al-5at.% And Si alloy, which is treated according to the present invention, is 175 mV higher than that of 99.999% pure aluminum conventionally treated. The formula potential was 75mV higher than that of Si alloy. In this high pitting resistance, the alloy of the present invention had a very high hardness that contributes to the high strength of the alloy.

Example 3

In accordance with the present invention, three different aluminite alloy samples, namely A1-6at.% Ti, A1-2at.% Ti-5at.% Si light Al-6at.% Ti-5at.% Si, utilize the rotational wheel method. Prepared by rapid coagulation.

로, 그리고 A1₃Ti상의 양을 약

로 감소시켰다. 예를 들면, 본 발명에 따라서 급속히 응고시키므로써 제조된 A1-6% Ti-5% Si 합금샘플내의 α-A1상은 Ti 약 5at.% 및 Si 약 3at % 함유하었다. 본 발명에 의해 제조된 개개의 합금들은 0.5μm 보다 크지 않은 미세 결정럽으로 구성된 균일 조직을 갖는다. 탈기된 0.5N NaC1 용액내에서 이들의 공식전위 및 빅커스경도를 측정하였다 졀과치는 표3에 나타내어 종래대로 처리된 생플에 대한 데이타와 비교하였다.Al-Ti-Si alloys consisted of three phases: α-Al, A1 ₃ Ti, and vacancies consisting of α-A1 and cubic Si, and rapid solidification resulted in a significant amount of Ti in the α'-A1 phase. And as a result of dissolution of Si,

And the amount of A1 ₃ Ti phase is approximately

Reduced to. For example, the α-A1 phase in the A1-6% Ti-5% Si alloy sample prepared by rapid solidification according to the present invention contained about 5 at% Ti and about 3 at% Si. The individual alloys produced by the present invention have a uniform structure composed of microcrystalline rups not larger than 0.5 μm. Their formula potential and Vickers hardness were measured in degassed 0.5N NaC1 solution. The excursions are shown in Table 3 and compared with data for conventionally treated saules.

TABLE 3 Hardness and formula potential of metals and alloys rapidly solidified and conventionally treated.

Rapidly solidified A1-Ti-Si alloys and A1-Ti alloys in accordance with the present invention contain a large amount of Ti and Si in the α-A1 phase to provide a highly protective antifreeze that can prevent formulas from deteriorating immobility. Provided a film. Therefore, the rapid quenching source alloys of the present invention exhibited a formal potential of 150 mV-250 mV higher than 99.999% pure aluminum of the prior art.

The alloys of the present invention were also characterized by microcrystalline phases containing an α-Al matrix supersaturated with alloying elements and a finely dispersed very hard A1 ₃ Ti phase. As a result, the hardness of the alloys was higher than the maximum obtainable with conventional aluminum alloys.

Example 4

Four different aluminum alloys, namely Al-6at.% Zr, Al-2at.% Zr-5at.% Si, A1-4at.% Zr-5at.% Si and A1-6at.% Zr-5at.% Si was prepared by rapid solidification in accordance with the present invention using the rotary wheel method. Individual rapidly solidified samples exhibited microcrystalline texture consisting of particles no larger than 0.5 μm. Conventionally treated A1-Zr-Si alloys consisted of three phases: vacancies consisting of α-Al, α-A1 and cubic Si, and Al _0.45 Zr _0.33 Si _0.22 . Rapidly solidified A1-Zr-Si alloys according to the present invention consisted of vacancies consisting of α-Al phase, A1 ₃ Zr and α-A1 and cubic Si, with Si content in vacancies more conventionally treated counterparts. This was even more small. In the solidification by rapid quenching, the high-corrosive AI ₃ Zr phase precipitated before Si dissolved, and vacancy and α-A1 phases formed rapidly. Thus the α-A1 phases were supersaturated with Si and Zr. The formula potential and Vickers hardness in the degassed 0.5N NaC1 solution for the alloy samples prepared according to the invention were measured. The results are shown in Table 4 and compared with data for conventionally solidified samples.

[Table 4]: Hardness and formula potential of metals and alloys rapidly solidified and conventionally treated

Since the α-A1 phase is supersaturated with Zr and Si, the alloys of the present invention can form a highly protective floating film on top of the α-A1 to prevent the formula resulting from the passivity breakdown of the α-A1 phase. have. Therefore, the rapidly quenched alloys of the present invention were 160mV-220mV higher than the values for 99.999% pure aluminum with formal potentials treated conventionally. In addition to these high corrosion resistance features, the alloys have improved the hardness significantly due to the dispersion of the microcrystalline A13Zr phase.

Example 5

Two fused aluminum alloy samples, Al-2at.% Nb-5at.% Si light A1-6at.% Nb-5at.% Si, were solidified by rapid quenching using the rotary wheel method. Individual coagulated samples exhibited microcrystalline structure consisting of particles no greater than 0.5 μm. Conventionally treated A1-Nb-Si alloys consisted of vacancies consisting of three phases: αr-Al, A13Nb and α-A1 and cubic Si. According to the present invention, X-ray diffraction tests on A1-Nb-Si alloys solidified by rapid quenching showed no clear detection of Si, and all of the Si present formed supersaturated solid solutions of α-A1 phase. . For the alloy samples prepared according to the invention, the formula potential and Vickers hardness (in degassed 0.5N NaC1 solution) were measured. Results are shown in Table 5 and compared with data for samples solidified by a non-quick hardening technique.

TABLE 5 Hardness and formula potential of metals and alloys rapidly solidified and conventionally treated.

In the alloy of the present invention, the Al ₃ Nb phase having high corrosion resistance and hardness was dispersed as a microcrystalline structure, solutes formed a supersaturated solid solution of the α'-A1 phase. The alloys thus exhibited significantly higher formula potentials and improved hardness.

Example 6

Thirty alloys having the components listed in Table 6 were cast by argon arc melting of conventional metals. The main alloys were remelted in an argon atmosphere and rapidly solidified by a rolling method under an argon atmosphere, producing a thin sheet of rapidly solidified alloys ranging in thickness from 0.01 mm-0.05 mm, butterfly 1 mm-3 mm and length 3 m-20 m. It was. As a result of analysis by X-ray diffractometer, the added alloying elements were dissolved in a large amount to form supersaturated solid solutions on α-A1 because the complex phase composed of vacancy forming Si and alloying elements and A1 had the same components and It has been found to have a lower diffraction intensity than alloys treated as it is. Examination with light microscopy and scanning electron microscopy showed that, according to the present invention, individual alloy samples from the manufacturer had a fine grain structure composed of particles no larger than 0.5 μm. After mechanical polishing in water with silicon carbide paper up to No. 1500, the formula potential and Vickers hardness were measured in a 0.5 N NaCl solution degassed at 30 ° C. for alloy saules. The results are shown in Table 6.

As is apparent from Table 6, the aluminum alloys prepared by solidifying rapidly in accordance with the present invention exhibited a formal potential of 50 mV-330 mV higher than that for conventionally solidified 99.999% pure aluminum, which also showed very high hardness levels. .

TABLE 6 Alloying components (at.%) And their official potentials and hardness.

As described above, aluminium alloys prepared by rapidly solidifying according to the present invention are intermetallics in which the elements added to enhance corrosion resistance and strength are supersaturated in the αr-Al phase and have high corrosion resistance and high mechanical strength. Have the property of forming compounds and vacancies. Because of these features, the alloys of the present invention have a high degree of corrosion resistance and strength that could not be obtained with the prior art.

The rapid quenching required to prepare the alloys of the present invention can be realized by any method well established in the art of rapid sweeping in the liquid state. Thus, the alloys of the present invention can be produced without using any special apparatus. This can be very useful in practical applications.

Claims (2)

Since at least one element selected from the group consisting of Si, Ti, Zr, Nb, Ni, Cu and Mn is contained at least 0.2 at.% And at most 15 at.%, And the remainder rapidly solidifies the melt substantially composed of Al. Manufacturer of high corrosion resistance and high strength aluminum alloy. The high corrosion resistance and high strength aluminum alloy of claim 1, wherein the at least one element is present in an amount of 0.5 at.% -15 at.%.

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