CN110205528B - A kind of Al-Mg alloy with high intergranular corrosion resistance and preparation method thereof - Google Patents

Abstract

The invention discloses a high intergranular corrosion resistant Al-Mg alloy material, which consists of Ru, Mg, Mn, Zn, Ti and Al, wherein in a corrosive medium, Ru can improve the cathode reaction current density, so that the α (Al) surface can spontaneously generate Al with the thickness of 300nm₂O₃·3H₂O and has a dense, self-repairing and highly corrosion-resistant passive film, effectively blocks the β (Al) pair of corrosive media₃Mg₂) The corrosion of the phase greatly improves the intergranular corrosion resistance of the alloy. Tau (Mg) can be precipitated from the alloy by adjusting the proportion of M (Mg), M (Mn), M (Zn)₃₂(Al,Zn)₄₉) Phase, inhibition β (Al)₃Mg₂) The precipitation of the phase reduces the potential difference between the second phase and the aluminum matrix, and further improves the intergranular corrosion resistance of the alloy.

Description

A kind of Al-Mg alloy with high intergranular corrosion resistance and preparation method thereof

technical field

The invention relates to the field of materials, in particular to an Al-Mg alloy with high intergranular corrosion resistance and a preparation method thereof.

Background technique

耐腐蚀的钝化膜(Al₂O₃·3H₂O)，在合金受到腐蚀时，β(Al₃Mg₂)相溶解反应和钝化膜成膜反应会同时进行，但是β相的溶解速度比基体的氧化速度快的多，导致合金的耐腐蚀性较差。Al-Mg-based alloys are widely used as lightweight alternatives to steel due to their high strength-to-weight ratio, excellent formability and weldability, and good corrosion resistance. The required mechanical strength of Al-Mg alloys is mainly achieved by solution strengthening and cold work hardening. The maximum solubility of Mg decreases to about 1.7 wt% at room temperature. When the Al-Mg alloy contains more than 3.5wt% Mg, Mg atoms preferentially diffuse from the supersaturated solid solution α(Al) to the grain boundary (GB), and finally the β(Al ₃ Mg ₂ ) phase can be formed. The potential (-1.24V) of the β(Al ₃ Mg ₂ ) phase is lower than the α(Al) potential (-0.812V), and in a corrosive environment, the matrix is preferentially corroded, causing local intergranular corrosion. At the same time, the aluminum alloy surface will spontaneously form a thickness of

Corrosion-resistant passivation film (Al ₂ O ₃ ·3H ₂ O), when the alloy is corroded, the β (Al ₃ Mg ₂ ) phase dissolution reaction and the passivation film formation reaction will proceed simultaneously, but the dissolution rate of the β phase The oxidation rate is much faster than that of the matrix, resulting in poor corrosion resistance of the alloy.

Intergranular corrosion is a type of localized corrosion. Corrosion that propagates inward along the interface between metal grains. Mainly due to the difference in chemical composition between the grain surface and the interior and the existence of grain boundary impurities or internal stress. Intergranular corrosion destroys the bond between grains and greatly reduces the mechanical strength of the metal. Moreover, after the corrosion occurs, the surface of the metal and alloy still maintains a certain metallic luster, and no signs of damage can be seen, but the bonding force between grains is significantly weakened, the mechanical properties deteriorate, and it cannot withstand percussion, so it is a very dangerous corrosion. . Intergranular corrosion is an important factor affecting the properties of Al-Mg alloys.

On the one hand, platinum group metals (Pt, Pd, Os, Ir, Ru, Rh) can play an effective cathode role on the surface of the alloy, and on the other hand, the exchange current density of the cathodic reaction on platinum group metals is much larger. At the same time, platinum group metals have the effect of promoting the formation of Al alloy passivation film, so as to improve the corrosion resistance of the alloy.

The price of Ru is the lowest among the platinum group metals. Considering the actual production cost, adding Ru to the Al-Mg alloy has great practical production significance. However, the melting point of Ru is as high as 2334 °C, while the boiling point of Al is only 2327 °C, which is lower than the melting point of Ru, so it is difficult to directly add Ru to aluminum alloys by ordinary smelting methods. The existing main methods for adding Ru into aluminum alloys include eutectic metallurgy, powder metallurgy and mechanical alloying. However, these parties require expensive equipment support, and are limited by the size of the equipment and cannot prepare large-scale samples.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art, and to provide an Al-Mg alloy with high resistance to intergranular corrosion and a preparation method thereof.

The technical scheme adopted by the present invention is:

An Al-Mg alloy resistant to intergranular corrosion, its mass composition is: Ru 0.01-0.2%, Mg 3.5-6.5%, Mn 0.3-1.5%, Zn 0.2-0.5%, Ti 0.05-0.3%, unavoidable impurities, the remainder being Al.

In some examples of intergranular corrosion resistant Al-Mg alloys, wherein Ru 0.05-0.1%, Mg 3.5-4.5%, Mn 0.3-0.85%, Zn 0.2-0.35%, Ti 0.09-0.17%.

In some examples of intergranular corrosion resistant Al-Mg alloys, M(Ti):M(Ru)=(65~99):(1~35), preferably M(Ti):M(Ru)=(65) ~80):(20~35).

In some examples of intergranular corrosion resistant Al-Mg alloys, the mass ratio of the three elements Mg, Mn, and Zn is: M(Mg):M(Mn):M(Zn)=(13～35):(3 ): (1～2).

In some examples of intergranular corrosion resistant Al-Mg alloys, the content of the unavoidable impurities does not exceed 0.1%.

A preparation method of an intergranular corrosion-resistant Al-Mg alloy, the composition of the intergranular corrosion-resistant Al-Mg alloy is as described above, including the following operations:

1) Ingredients: Weigh the raw materials according to the composition of the intergranular corrosion-resistant Al-Mg alloy, wherein Ru is introduced in the form of Ru-Ti master alloy, and mixed uniformly;

2) Smelting: place the raw materials in a smelting furnace to smelt, the smelting temperature does not exceed 900°C, and after the smelting is completed, the ingot is obtained by pouring;

3) The ingot is subjected to homogenization heat treatment and quenched to obtain an Al-Mg alloy resistant to intergranular corrosion.

In some examples of preparation methods, the smelting temperature is 760°C to 850°C.

In some examples of the preparation method, the temperature of the homogenization heat treatment is 550-580°C;

In some examples of the preparation method, the time for the homogenization heat treatment is 18h-48h.

The beneficial effects of the present invention are:

The Al-Mg alloy material of the present invention can enhance the hydrogen evolution (H ⁺ + 2e ^- →H ₂ ). The cathodic reaction is higher than the critical anode current density, the critical anode circuit is avoided, the corrosion potential and corrosion current in the actual corrosion process are smaller, and the corrosion rate of the alloy is slowed down. At the same time, in corrosive medium, Ru element takes precedence over the matrix to produce Ru-2e ^- →Ru ²⁺ , and the catalytic synergy of the cathodic reaction causes the α(Al) surface to spontaneously undergo 2Al+3Ru ²⁺ +3H ₂ O→Al ₂ O ₃ +3Ru+6H ⁺ reaction, through XPS tomography, it is found that a (Al ₂ O ₃ ·3H ₂ O) passivation film with a thickness of up to 300nm will be formed on the α(Al) surface. (Al ₂ O ₃ ·3H ₂ O) passivation film has the characteristics of dense, self-healing and high corrosion resistance, which can effectively block the erosion of β(Al ₃ Mg ₂ ) phase by corrosive media, which greatly improves the The alloy's resistance to intergranular corrosion.

The Al-Mg alloy material of the present invention is based on the traditional Al-Mg alloy by controlling the content ratio of element components M(Mg):M(Mn):M(Zn)=(13～35):(3) : (1～2), β(Al ₃ Mg ₂ ) phase and τ(Mg ₃₂ (Al,Zn) ₄₉ ) phase can be precipitated in α(Al), and τ(Mg ₃₂ (Al,Zn) ₄₉ ) phase can be precipitated at the same time It is also possible to suppress the precipitation of the β(Al ₃ Mg ₂ ) phase and partially replace the β (Al ₃ Mg ₂ ) phase. The corrosion potential (-0.813V) of the τ(Mg ₃₂ (Al,Zn) ₄₉ ) phase is basically the same as the corrosion potential of α(Al), which can reduce the potential difference between the second phase and the aluminum matrix and optimize the intergranular corrosion resistance of the alloy. performance.

The Al-Mg alloy material of the present invention has a tensile strength range of 310-340 MPa and an elongation of 18-25%. According to GB/T7998-2005 "Method for Determination of Intergranular Corrosion of Aluminum Alloys", the sample is placed at a temperature of 35° C. After soaking in 30g/L NaCl+10mL/L HCl corrosion solution for 24h, no intergranular corrosion appeared.

In the preparation method of the present invention, the Ru element is introduced into the Al alloy by the traditional smelting method for the first time, combined with the solid solubility of Ru in Al, the addition amount of Ru is controlled at 0.05wt% to 0.2wt% of Ru, and the smelting temperature is controlled at 760 From ℃ to 850℃, Ru can be sufficiently dissolved in Al and dispersed. Low-cost large-scale production of RuAl-Mg alloys is realized.

Description of drawings

Fig. 1 is the alloy structure diagram of the Al-Mg alloy prepared in Example 5;

Fig. 2 is the intergranular corrosion diagram after the Al-Mg alloy prepared in Example 5 is soaked in 30g/L NaCl+10ml/L HCl corrosion solution at 35°C for 24h;

3 is a diagram showing the composition and thickness of the passivation film of the Al-Mg alloy prepared in Example 5 after being measured by intergranular corrosion.

Detailed ways

The present invention will be described in detail below with reference to examples, comparative examples and experimental data.

The percentage by weight of alloy chemical composition in each embodiment, Mg 3.5wt%～6.5wt%; Mn 0.3wt%～1.5wt%; Zn 0.2wt%～0.5wt%; Ti 0.05wt%～0.3wt%; Ru 0.05wt% ~0.2 wt%; balance is Al.

For the convenience of comparison, Ru in the Al-Mg alloy in the following examples and comparative examples is introduced in the form of Ru-Ti master alloy. The preparation method of Ru-Ti master alloy is as follows: pure Ti powder and pure Ru powder are used as raw materials, and the proportions are M(Ti):M(Ru)=(65-99):(1-35) by weight percentage. The above materials are pressed into consumable electrodes and then smelted twice in a vacuum consumable melting furnace to obtain a Ti-Ru master alloy.

The multi-component refining agent and the degassing agent are the multi-component refining agent and the degassing agent commonly used in the art. For the convenience of comparison, in the following examples and comparative examples, the composition of the multi-component compound refining agent includes: 20wt% NaCl, 20wt% KCl, 35wt% NaF, 25wt% LiF; the mass ratio of refining agent to smelting ingredients is (1 ~ 3): 100. The degassing agent is hexachloroethane, and the mass ratio of the degassing agent to the smelting ingredients is 1:100. When the purity of the raw material is relatively high, the multi-component refining agent and degassing agent may not be added. The multi-component refining agents and degassing agents themselves have basically no effect on the properties of the alloy.

In order to make the alloy more uniform during the pouring process, low frequency electromagnetic stirring can be performed. Of course, other methods commonly used in the art can also be used to achieve uniform mixing.

Example 1

1) According to the weight percentage of the constituent elements, take Mg: 3.5wt%, Mn: 0.3wt%, Zn: 0.2wt%, Ti: 0.09wt%, Ru: 0.05wt%, and the balance is Al. The above-mentioned materials are smelted in a smelting furnace, and the smelting temperature is 780 ° C until melting;

2) After adding multiple refining agents and degassing agents to the alloy melt, after refining, degassing and slag removal, let it stand for 8 minutes;

3) pour the alloy melt in the cylindrical mold in the electromagnetic stirring device, carry out low-frequency electromagnetic stirring for 15Hz, the time is 30s, and then water-cool to become an ingot;

4) The ingot is subjected to homogenization treatment, the homogenization temperature is 560°C, and the time is 48h, and after the treatment is completed, water quenching at room temperature.

Example 2

1) According to the weight percentage of the constituent elements, take Mg: 4.2wt%, Mn: 0.6wt%, Zn: 0.25wt%, Ti: 0.09wt%, Ru: 0.05wt%, and the balance is Al. The above-mentioned materials are smelted in a smelting furnace, and the smelting temperature is 760 ° C until melting;

2) After adding multiple refining agents and degassing agents to the alloy melt, after refining, degassing and slag removal, let it stand for 8 minutes;

3) pour the alloy melt in the cylindrical mold in the electromagnetic stirring device, carry out low-frequency electromagnetic stirring for 15Hz, the time is 30s, and then water-cool to become an ingot;

4) The ingot is subjected to homogenization treatment, the homogenization temperature is 570°C, and the time is 18h, and after the treatment is completed, water quenching at room temperature.

Example 3

1) Mg: 4.2 wt %, Mn: 0.6 wt %, Zn: 0.3 wt %, Ti: 0.15 wt %, Ru: 0.08 wt %, and the balance is Al according to the weight percentage of the constituent elements. The above-mentioned materials are smelted in a smelting furnace, and the smelting temperature is 800 ° C until melting;

2) After adding multiple refining agents and degassing agents to the alloy melt, after refining, degassing and slag removal, let it stand for 8 minutes;

3) pour the alloy melt in the cylindrical mold in the electromagnetic stirring device, carry out low-frequency electromagnetic stirring for 15Hz, the time is 30s, and then water-cool to become an ingot;

4) The ingot is subjected to homogenization treatment, the homogenization temperature is 550°C, and the time is 48h, and after the treatment is completed, water quenching at room temperature.

Example 4

1) According to the weight percentage of the constituent elements, Mg: 4.3wt%, Mn: 0.44wt%, Zn: 0.35wt%, Ti: 0.15wt%, Ru: 0.08wt%, and the balance is Al. The above-mentioned materials are smelted in a smelting furnace, and the smelting temperature is 780 ° C until melting;

2) After adding multiple refining agents and degassing agents to the alloy melt, after refining, degassing and slag removal, let it stand for 8 minutes;

3) pour the alloy melt in the cylindrical mold in the electromagnetic stirring device, carry out low-frequency electromagnetic stirring for 15Hz, the time is 30s, and then water-cool to become an ingot;

4) The ingot is subjected to homogenization treatment, the homogenization temperature is 580 DEG C, and the time is 18h, and after the treatment is completed, water quenching at room temperature.

Example 5

1) According to the weight percentage of the constituent elements, Mg: 4.3wt%, Mn: 0.64wt%, Zn: 0.28wt%, Ti: 0.17wt%, Ru: 0.1wt%, and the balance is Al. The above-mentioned materials are smelted in a smelting furnace, and the smelting temperature is 780 ° C until melting;

2) After adding multiple refining agents and degassing agents to the alloy melt, after refining, degassing and slag removal, let it stand for 8 minutes;

3) pour the alloy melt in the cylindrical mold in the electromagnetic stirring device, carry out low-frequency electromagnetic stirring for 15Hz, the time is 30s, and then water-cool to become an ingot;

4) The ingot is subjected to homogenization treatment, the homogenization temperature is 580° C., the time is 24 hours, and after the treatment is completed, water quenching at room temperature.

Example 6

1) According to the weight percentage of the constituent elements, Mg: 4.3 wt %, Mn: 0.64 wt %, Zn: 0.32 wt %, Ti: 0.17 wt %, Ru: 0.1 wt %, and the balance is Al. The above-mentioned materials are smelted in a smelting furnace, and the smelting temperature is 780 ° C until melting;

2) After adding multiple refining agents and degassing agents to the alloy melt, after refining, degassing and slag removal, let it stand for 8 minutes;

3) pour the alloy melt in the cylindrical mold in the electromagnetic stirring device, carry out low-frequency electromagnetic stirring for 15Hz, the time is 30s, and then water-cool to become an ingot;

4) The ingot is subjected to homogenization treatment, the homogenization temperature is 580° C., the time is 24 hours, and after the treatment is completed, water quenching at room temperature.

Example 7

1) According to the weight percentage of the constituent elements, Mg: 4.5wt%, Mn: 0.65wt%, Zn: 0.2wt%, Ti: 0.17wt%, Ru: 0.1wt%, and the balance is Al. The above-mentioned materials are smelted in a smelting furnace, and the smelting temperature is 820 ° C until melting;

2) After adding multiple refining agents and degassing agents to the alloy melt, after refining, degassing and slag removal, let it stand for 8 minutes;

3) pour the alloy melt in the cylindrical mold in the electromagnetic stirring device, carry out low-frequency electromagnetic stirring for 15Hz, the time is 30s, and then water-cool to become an ingot;

4) The ingot is subjected to homogenization treatment, the homogenization temperature is 580° C., the time is 24 hours, and after the treatment is completed, water quenching at room temperature.

Example 8

1) According to the weight percentage of the constituent elements, Mg: 4.0wt%, Mn: 0.5wt%, Zn: 0.33wt%, Ti: 0.17wt%, Ru: 0.1wt%, and the balance is Al. The above-mentioned materials are smelted in a smelting furnace, and the smelting temperature is 850 ° C until melting;

2) After adding multiple refining agents and degassing agents to the alloy melt, after refining, degassing and slag removal, let it stand for 8 minutes;

3) pour the alloy melt in the cylindrical mold in the electromagnetic stirring device, carry out low-frequency electromagnetic stirring for 15Hz, the time is 30s, and then water-cool to become an ingot;

4) The ingot is subjected to homogenization treatment, the homogenization temperature is 560 DEG C, and the time is 36h, and after the treatment is completed, water quenching at room temperature.

Example 9

1) According to the weight percentage of the constituent elements, take Mg: 4.0wt%, Mn: 0.85wt%, Zn: 0.28wt%, Ti: 0.17wt%, Ru: 0.1wt%, and the balance is Al. The above-mentioned materials are smelted in a smelting furnace, and the smelting temperature is 780 ° C until melting;

2) After adding multiple refining agents and degassing agents to the alloy melt, after refining, degassing and slag removal, let it stand for 8 minutes;

3) pour the alloy melt in the cylindrical mold in the electromagnetic stirring device, carry out low-frequency electromagnetic stirring for 15Hz, the time is 30s, and then water-cool to become an ingot;

4) The ingot is subjected to homogenization treatment, the homogenization temperature is 575°C, and the time is 24h, and after the treatment is completed, water quenching at room temperature. Comparative Example 1:

1) Mg: 4.3 wt %, Mn: 0.64 wt %, Zn: 0.28 wt %, Ti: 0.17 wt %, and the balance is Al according to the weight percentage of the constituent elements. The above-mentioned materials are smelted in a smelting furnace, and the smelting temperature is 780 ° C until melting;

2) After adding multiple refining agents and degassing agents to the alloy melt, after refining, degassing and slag removal, let it stand for 8 minutes;

3) pour the alloy melt in the cylindrical mold in the electromagnetic stirring device, carry out low-frequency electromagnetic stirring for 15Hz, the time is 30s, and then water-cool to become an ingot;

4) The ingot is subjected to homogenization treatment, the homogenization temperature is 580° C., the time is 24 hours, and after the treatment is completed, water quenching at room temperature. Comparative Example 2:

1) Mg: 4.3 wt %, Mn: 0.64 wt %, Ti: 0.17 wt %, Ru: 0.1 wt %, and the balance is Al according to the weight percentage of the constituent elements. The above-mentioned materials are smelted in a smelting furnace, and the smelting temperature is 780 ° C until melting;

2) After adding multiple refining agents and degassing agents to the alloy melt, after refining, degassing and slag removal, let it stand for 8 minutes;

3) pour the alloy melt in the cylindrical mold in the electromagnetic stirring device, carry out low-frequency electromagnetic stirring for 15Hz, the time is 30s, and then water-cool to become an ingot;

4) The ingot is subjected to homogenization treatment, the homogenization temperature is 580° C., the time is 24 hours, and after the treatment is completed, water quenching at room temperature.

Comparative Example 3:

1) According to the weight percentage of the constituent elements, Mg: 4.3 wt %, Mn: 0.64 wt %, and the balance is Al. The above-mentioned materials are smelted in a smelting furnace, and the smelting temperature is 780 ° C until melting;

2) After adding multiple refining agents and degassing agents to the alloy melt, after refining, degassing and slag removal, let it stand for 8 minutes;

3) pour the alloy melt in the cylindrical mold in the electromagnetic stirring device, carry out low-frequency electromagnetic stirring for 15Hz, the time is 30s, and then water-cool to become an ingot;

4) The ingot is subjected to homogenization treatment, the homogenization temperature is 580° C., the time is 24 hours, and after the treatment is completed, water quenching at room temperature.

Experimental results:

Fig. 1 is the alloy structure diagram of the Al-Mg alloy prepared in Example 5. It can be seen from the figure that a kind of Al-Mg alloy with high intergranular corrosion resistance prepared by the present invention has fine and uniform grain size without excessive The phenomenon of burning occurs, and there is no obvious coarse, reticulated primary phase at the grain boundary. β(Al ₃ Mg ₂ ) and τ(Mg ₃₂ (Al,Zn) ₄₉ ) phases appear in the grains, and the number of τ(Mg ₃₂ (Al,Zn) ₄₉ ) phases is significantly larger than that of β(Al ₃ Mg ₂ ) The number of phases is beneficial to reduce the potential difference between the second phase and the aluminum matrix, optimize the intergranular corrosion resistance of the alloy, and improve the intergranular corrosion resistance of the alloy.

Fig. 2 is the intergranular corrosion diagram after the Al-Mg alloy prepared in Example 5 is soaked in 30g/L NaCl+10ml/L HCl corrosion solution at 35°C for 24h,

Fig. 3 is the measurement diagram of the composition and thickness of the passivation film of the Al-Mg alloy prepared in Example 5 after the intergranular corrosion measurement. It can be seen from the figure that from the sample surface to the depth of 450 nm from the surface, the Ru element has been It exists in the matrix in elemental form (0 valence). Elemental Ru effectively guarantees the progress of Ru-2e ^- →Ru ²⁺ reaction. At the same time, from the sample surface to 300nm from the sample surface, there is always a strong Al ₂ O ₃ peak in the passivation film, and at 450 nm from the surface, the Al ₂ O ₃ peak has disappeared, and the peak of the matrix aluminum has been strong. This shows that an Al-Mg alloy with high intergranular corrosion resistance prepared by the present invention has a passivation film with a thickness of at least 300 nm on the surface.

As can be seen from Figures 1 to 3, the Al-Mg alloy with high intergranular corrosion resistance prepared by the present invention has no intergranular corrosion phenomenon after the intergranular corrosion performance is measured, and the comparison groups have different Grades of intergranular corrosion appear. This fully shows that the composition ratio of the present invention is scientific and the heat treatment system is reasonable. It greatly improves the shortcomings of traditional Al-Mg alloys with insufficient resistance to intergranular corrosion.

Comparison of Properties of Different Al-Mg Alloys

The Al-Mg alloys prepared in the examples and the comparative examples are respectively taken for performance testing, wherein, the determination standard of intergranular corrosion is determined according to GBT7998-2005 "Method for Determination of Intergranular Corrosion of Aluminum Alloys"; the test methods of strength and elongation are determined according to GB /T 228.1-2010 "Tensile Test of Metal Materials Part 1: Test Method at Room Temperature" for judgment.

Numbering Intergranular corrosion grade Strength/Mpa Elongation/% Example 1 No intergranular corrosion 320 19.6 Example 2 No intergranular corrosion 328 25.0 Example 3 No intergranular corrosion 342 24.4 Example 4 No intergranular corrosion 333 19.2 Example 5 No intergranular corrosion 350 21.8 Example 6 No intergranular corrosion 345 24.2 Example 7 No intergranular corrosion 325 22.2 Example 8 No intergranular corrosion 337 20.9 Example 9 No intergranular corrosion 328 23.1 Comparative Example 1 2 324 18.2 Comparative Example 2 2 311 21.0 Comparative Example 3 3 311 21.0

By comparing the performances of the implementation group and the control group, it can be found that an Al-Mg alloy with high intergranular corrosion resistance prepared by this issue was immersed in a 30g/L NaCl+10ml/L HCl corrosion solution at 35°C for 24h, There is no intergranular corrosion phenomenon. It also increases the strength and elongation of the alloy. Control group 1 was without Ru element added, control group 2 was without Zn element added, and control group 3 was without Ru and Zn elements added. The three control groups have different degrees of intergranular corrosion, and the intensity is not as high as that of the example group. This shows that the intergranular corrosion resistance of the alloy can be improved only through the joint action of Ru and Zn elements. On the one hand, by adding Zn element to form τ(Mg ₃₂ (Al,Zn) ₄₉ ) phase, which partially replaces β(Al ₃ Mg ₂ ) phase, the potential difference between the second phase and the aluminum matrix can be reduced. On the other hand, by adding Ru element, the hydrogen evolution evolution of the alloy in the corrosive environment can be enhanced, so that the corrosion potential and corrosion current in the actual corrosion process are smaller, and the corrosion rate of the alloy is slowed down. At the same time, in corrosive media, the α(Al) surface will spontaneously undergo dense, self-healing, high corrosion resistance (Al ₂ O ₃ ·3H ₂ O) passivation with a thickness of up to 300 nm due to the catalytic effect of Ru. membrane. Both are indispensable. Therefore, the composition ratio of the alloy of the present invention is scientific and the performance is excellent.

Claims (7)

1. An Al-Mg alloy resistant to intergranular corrosion, its mass composition is: Ru 0.01～0.2%, Mg 3.5～6.5%, Mn 0.3～1.5%, Zn 0.2～0.5%, Ti 0.05～0.3%, unavoidable The remaining amount is Al, the weight percentage of M(Ti):M(Ru)=(65～80):(20～35); the mass ratio of Mg, Mn, Zn is: M(Mg) :M(Mn):M(Zn) =(30～35):3:(1～2), can precipitate β(Al ₃ Mg ₂ ) phase and τ(Mg ₃₂ (Al,Zn) in α(Al) ) ₄₉ ) phase, while the τ(Mg ₃₂ (Al,Zn) ₄₉ ) phase can also inhibit the precipitation of β (Al ₃ Mg ₂ ) phase and partially replace the β (Al ₃ Mg ₂ ) phase. 2. An intergranular corrosion resistant Al-Mg alloy according to claim 1, characterized in that: wherein Ru 0.05-0.1%, Mg 3.5-4.5%, Mn 0.3-0.85%, Zn 0.2-0.35%, Ti 0.09～0.17%. 3. a kind of intergranular corrosion resistant Al-Mg alloy according to claim 1, is characterized in that: the mass ratio of three kinds of elements of Mg, Mn, Zn is: M (Mg): M (Mn): M (Zn ) = (30～35):3:2. 4 . The intergranular corrosion-resistant Al-Mg alloy according to claim 1 , wherein the content of the unavoidable impurities does not exceed 0.1%. 5 . 5. A method for preparing an intergranular corrosion-resistant Al-Mg alloy, wherein the composition of the intergranular corrosion-resistant Al-Mg alloy is as described in any one of claims 1 to 4, comprising the following operations: 1) Ingredients: Weigh the raw materials according to the composition of the intergranular corrosion-resistant Al-Mg alloy, wherein Ru is introduced in the form of Ru-Ti master alloy, and mixed uniformly; 2) Smelting: place the raw materials in a smelting furnace to smelt, the smelting temperature does not exceed 900°C, and after the smelting is completed, the ingot is obtained by pouring; 3) The ingot is subjected to homogenization heat treatment and quenched to obtain an Al-Mg alloy resistant to intergranular corrosion. 6 . The preparation method according to claim 5 , wherein the smelting temperature is 760° C. to 850° C. 7 . 7 . The preparation method according to claim 5 , wherein the temperature of the homogenization heat treatment is 550-580° C.; the time of the homogenization heat treatment is 18h to 48h. 8 .

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