CN116024471A - High-strength plastic multi-water-soluble channel magnesium alloy and preparation method thereof - Google Patents

Abstract

The invention discloses a magnesium alloy with high strength and plastic and multiple water-soluble channels and a preparation method thereof, wherein the magnesium alloy comprises the following components in percentage by mass: the alloy comprises 1% -4% of X element, 0.1% -0.4% of Y element, 0% -2% of Z element, the balance of Mg element, at least one of Nd, sm and Zn, at least one of Cu, ni and Sr and at least one of Al and Sn. The preparation method comprises the following steps: and taking required raw materials, and sequentially carrying out uniform mixing, melting, refining, casting, homogenization treatment, high-temperature deformation, low-temperature deformation, aging treatment or creep aging treatment to obtain the magnesium alloy. The magnesium alloy has high plasticity and high dissolution rate, is a novel magnesium alloy with excellent performance, and the preparation method has the advantages of simple process, convenient operation, high production efficiency and the like, is suitable for large-scale preparation, and is convenient for industrial application.

Description

High-strength and plastic magnesium alloy with multiple water-soluble channels and preparation method thereof

Technical Field

The invention belongs to the technical field of nonferrous metal materials and processing, and relates to a magnesium alloy having both high strength and plasticity and a high dissolution rate and a preparation method thereof.

Background Art

Due to its easy corrosion, magnesium alloys have been gradually used to prepare soluble products. In order to accelerate the dissolution rate of magnesium alloys, the current method is to add transition elements to form compounds with the Mg matrix as the cathode of the microgalvanic couple, and the Mg matrix is used as the anode of the microgalvanic couple. However, the solid solubility limit of transition elements in the Mg matrix is low, and the microgalvanic cathode formed often causes brittle fracture of magnesium alloys, and the strength and plasticity are not ideal, which increases the probability of product damage. To this end, researchers adopted the idea of adding rare earth elements to enhance plasticization and designed the Mg-RE-TM system. However, due to the easy diffusion of rare earth elements, this type of alloy usually has a grain boundary non-precipitation zone along the grain boundary after aging treatment, and it is difficult to weaken or eliminate it through subsequent heat treatment. In addition, based on the previous research results of the inventor of this application, it is found that the existing method for weakening or eliminating the grain boundary non-precipitation zone has the consequence that the grain boundary compound content cannot be formed or is formed is low, resulting in fewer corrosion channels inside the magnesium alloy, and there is still a defect of poor water solubility. Therefore, how to effectively eliminate the non-precipitation zone at the grain boundary and obtain a magnesium alloy with both high strength and plasticity and high dissolution rate, as well as a matching preparation method with simple process, convenient operation and high production efficiency, is of great significance for expanding the wide application of magnesium alloys.

Summary of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a magnesium alloy having both high strength and plasticity and a high dissolution rate and a preparation method thereof.

In order to solve the above technical problems, the technical solution adopted by the present invention is:

A high-strength, plastic, and multi-water-soluble channel magnesium alloy, the magnesium alloy comprising the following components in terms of mass percentage: X element with a total content of 1% to 4%, Y element with a total content of 0.1% to 0.4%, Z element with a total content of 0 to 2%, and the balance being Mg element; the X element is at least one of Nd element, Sm element, and Zn element; the Y element is at least one of Cu element, Ni element, and Sr element; and the Z element is at least one of Al element and Sn element.

The above high-strength, plastic, multi-water-soluble channel magnesium alloy is further improved in that, when the X element does not include the Zn element, the total content of the X element is 1% to 3%, and the total content of the Z element is 1% to 2%.

The above high-strength, plastic, multi-water-soluble channel magnesium alloy is further improved in that when the X element only contains the Sm element, the content of the Sm element is 2% to 3%, and the total content of the Z element is 1% to 2%.

The above high-strength, plastic, multi-water-soluble channel magnesium alloy is further improved in that when the X element only contains the Zn element, the content of the Zn element is 2% to 4%, and the total content of the Z element is 0 to 1%.

The above-mentioned high-strength, plastic, multi-water-soluble channel magnesium alloy is further improved in that when the Y element is any one of Cu, Ni, and Sr, the content of the Y element is 0.2% to 0.4%.

The above-mentioned high-strength and plastic multi-water-soluble channel magnesium alloy is further improved, wherein the grain boundary of the magnesium alloy contains a MgY phase composed of Y element;

More than 40% of the grains in the magnesium alloy contain twins.

The above-mentioned high-strength, plastic, and multi-water-soluble channel magnesium alloy is further improved in that more than 50% of the grains in the magnesium alloy contain twins, and more than 50% of the twins have no precipitation zone at the twin boundary.

As a general technical concept, the present invention also provides a method for preparing the above-mentioned high-strength, plastic, and multi-water-soluble channel magnesium alloy, which is prepared by any of the following methods:

Method 1 includes the following steps:

S1. According to the mass percentage of each component in the magnesium alloy, weigh the required raw materials, mix them evenly, melt, refine, and cast them to obtain an ingot;

S2, homogenizing the ingot; the temperature of the homogenizing treatment is 400°C to 490°C; the time of the homogenizing treatment is 6 hours to 48 hours;

S3, subjecting the homogenized material to high temperature deformation; the temperature of the high temperature deformation is 300°C to 450°C, and the true strain is 0.5 to 1.2;

S4, performing low-temperature deformation on the material after high-temperature deformation; the temperature of the low-temperature deformation is 20°C to 150°C, and the true strain is 0.02 to 0.2;

S5. Performing aging treatment on the material after low-temperature deformation to obtain a high-strength, plastic, and multi-water-soluble channel magnesium alloy; the aging treatment temperature is 150° C. to 220° C.; and the aging treatment time is 6 hours to 60 hours.

Method 2 includes the following steps:

(1) weighing the required raw materials according to the mass percentage of each component in the magnesium alloy, mixing them uniformly, melting, refining, and casting to obtain an ingot;

(2) performing homogenization treatment on the ingot; the temperature of the homogenization treatment is 400° C. to 490° C.; the time of the homogenization treatment is 6 hours to 48 hours;

(3) subjecting the homogenized material to high temperature deformation; the temperature of the high temperature deformation is 300° C. to 450° C., and the true strain is 0.5 to 1.2;

(4) performing low-temperature deformation on the material after high-temperature deformation; the temperature of the low-temperature deformation is 20° C. to 150° C., and the true strain is 0.02 to 0.2;

(5) The material after low-temperature deformation is subjected to creep aging treatment to obtain a high-strength, plastic, and multi-water-soluble channel magnesium alloy; the creep aging treatment temperature is 150° C. to 220° C., and the true strain is 0.1 to 0.6.

The above-mentioned method for preparing a high-strength, plastic, and multi-water-soluble channel magnesium alloy is further improved. When the high-strength, plastic, and multi-water-soluble channel magnesium alloy is prepared by method 1, when the X element does not contain the Zn element, the temperature of the homogenization treatment in step S2 is 440°C to 490°C, and the temperature of the high-temperature deformation in step S3 is 390°C to 450°C; when the X element only contains the Zn element, the temperature of the homogenization treatment in step S2 is 400°C to 440°C, and the temperature of the high-temperature deformation in step S3 is 300°C to 390°C.

The above-mentioned method for preparing a high-strength, plastic, and multi-water-soluble channel magnesium alloy is further improved. When the high-strength, plastic, and multi-water-soluble channel magnesium alloy is prepared by method 2, when the X element does not contain the Zn element, the temperature of the homogenization treatment in step (2) is 440°C to 490°C, and the temperature of the high-temperature deformation in step (3) is 390°C to 450°C; when the X element only contains the Zn element, the temperature of the homogenization treatment in step (2) is 400°C to 440°C, and the temperature of the high-temperature deformation in step (3) is 300°C to 390°C.

Compared with the prior art, the advantages of the present invention are:

(1) In view of the fact that the grain boundary no precipitation zone usually damages the strength and plasticity of magnesium alloys, and the defect that the existing magnesium alloys cannot have both high strength and plasticity and high dissolution rate, the present invention turns harm into benefit and creatively proposes a high-strength and plastic magnesium alloy with multiple water-soluble channels. By transferring the grain boundary no precipitation zone that is originally harmful to the strength and plasticity of the magnesium alloy to the twin boundary no precipitation zone, while eliminating the grain boundary no precipitation zone and improving the strength and plasticity of the magnesium alloy, the twin boundary no precipitation zone and the grain boundary compound can be used as corrosion channels at the same time to improve the dissolution rate of the magnesium alloy. Specifically: In the present invention, by adding a total content of 1% to 4% of X element (X element is at least one of Nd element, Sm element, and Zn element), on the one hand, Nd element and Sm element are both light rare earth elements, and their solid solubility limit in the Mg matrix does not exceed 6%. Therefore, adding a total amount of Nd element and Sm element not exceeding 4% can form a columnar precipitation phase and a twin boundary no precipitation zone. Compared with heavy rare earth elements, the development cost has been greatly reduced. On the other hand, as a non-rare earth element, the price of Zn element is lower, and compared with other non-rare earth elements, the diffusion rate of Zn atoms in the Mg matrix is higher, and it is easier to obtain the twin boundary non-precipitation zone required by the present invention; in the present invention, there is no need to add a large amount of transition elements, and only a total content of 0.1% to 0.4% of Y element (Y element is at least one of Cu element, Ni element, and Sr element) is added to form a grain boundary compound with the Mg matrix, and at the same time, the twin boundary non-precipitation zone is used as a corrosion channel, which can not only realize the rapid reaction between magnesium alloy and water, but also avoid damaging the strong plasticity of magnesium alloy, and also save the cost of adding transition elements, so that the magnesium alloy has both strong plasticity and rapid water solubility; in the present invention, a total content of 0 to 2% of Z element (Z element is at least one of Al element and Sn element) is also added to further increase the number of twins in the magnesium alloy. Therefore, in the present invention, by optimizing the type and amount of each added element, the harmful grain boundary non-precipitation zone can be converted into a beneficial twin boundary non-precipitation zone, so that the twin boundary non-precipitation zone and the grain boundary compound can serve as corrosion channels together, which can not only improve the strength and plasticity of the magnesium alloy, but also improve the dissolution rate of the magnesium alloy in water. At the same time, the precipitation phase inside the grains and the twins can further improve the strength, thereby obtaining a magnesium alloy with both high strength and plasticity and high dissolution rate. The magnesium alloy has a tensile strength of ≥220MPa, a yield strength of ≥120MPa, and an elongation of ≥15% at room temperature, and a dissolution rate of ≥15mg·cm ^-2 ·h ^-1 in water at 50°C, and is a new type of magnesium alloy with excellent performance.

(2) In the magnesium alloy of the present invention, when the X element does not contain the Zn element, the total content of the X element is optimized to be 1-3%, and the total content of the Z element is 1-2%. By reducing the content of the rare earth element (X element) and increasing the content of the Z element, the number of twins is increased. When the X element only contains the Sm element, the Sm element content is optimized to be 2-3%, and the total content of the Z element is 1-2%. The price of Sm is lower than that of Nd. By optimizing the content of the Sm element and the Z element, the cost of using rare earth elements can be reduced. Increasing the total content of the Z element is more likely to induce twinning, increase the number of twins and the number of non-precipitated zones at the twin boundary. When the X element only contains the Zn element, the content of the Zn element is optimized to be 2-4%, and the total content of the Z element is 0-1%. By using the Zn element as a non-rare earth element and appropriately reducing the content of the Z element, the types of added elements can be reduced, and the base surface texture strength can also be reduced, which is beneficial to improving the strength and plasticity of the magnesium alloy. When the Y element is any one of Cu, Ni and Sr, the content of the Y element is optimized to be 0.2-0.4%, which is beneficial to increase the grain boundary compounds and accelerate the dissolution rate of the magnesium alloy.

(3) In the magnesium alloy of the present invention, more than 50% of the grains contain twins, and more than 50% of the twins have no precipitation zone at the twin boundary. At this time, the no precipitation zone at the twin boundary can increase the corrosion channel and accelerate the reaction rate of the magnesium alloy with water.

(4) The present invention also provides a method for preparing a magnesium alloy with high strength, plasticity and multiple water-soluble channels. According to the mass percentage of each component in the magnesium alloy, the required raw materials are weighed, and the magnesium alloy with high strength, plasticity and high dissolution rate can be prepared by mixing, melting, refining, casting, homogenization, high temperature deformation, low temperature deformation, aging treatment or creep aging treatment in sequence. In the preparation method of the present invention, the deformation amount used in the high temperature deformation is small, which can save energy consumption, improve processing efficiency, and facilitate the preparation of large-scale components. At the same time, there is no need to use severe plastic deformation to achieve grain refinement. On the contrary, the present invention does not need to change the grain size. Secondly, high-density twins are generated by subsequent low-temperature deformation, and twins are used as a strengthening mechanism. Further, aging (i.e. static aging) or creep aging (i.e. stress-induced dynamic aging) is used to produce precipitation strengthening effects, especially the formation of precipitation phases inside the twins, which can pin the twin boundaries, so that the twin boundaries can become high-density interfaces to strengthen the magnesium alloy and can also serve as corrosion channels to improve the water dissolution rate of the magnesium alloy. In addition, the preparation method of the present invention has the advantages of simple process, convenient operation, high production efficiency, etc., is suitable for large-scale preparation, and is convenient for industrial application.

(5) In the preparation method of the present invention, when the X element does not contain the Zn element, the temperature of the homogenization treatment is 440°C to 490°C, and the temperature of the high-temperature deformation is 390°C to 450°C, which is more conducive to improving the strength and plasticity of the rare earth magnesium alloy. This is because the rare earth magnesium alloy has high strength and is difficult to process. Therefore, by increasing the homogenization and deformation temperature, it is more conducive to improving the strength and plasticity of the rare earth magnesium alloy; when the X element only contains the Zn element, the temperature of the homogenization treatment is 400°C to 440°C, and the temperature of the high-temperature deformation is 300°C to 390°C, which is more conducive to improving the strength and plasticity of the non-rare earth magnesium alloy. This is because the non-rare earth magnesium alloy has low strength and the magnesium alloy containing Zn has high-temperature brittleness. Therefore, by reducing the homogenization and deformation temperature, it is more conducive to improving the strength and plasticity of the non-rare earth magnesium alloy.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

FIG1 is a schematic diagram of the microstructure of a high-strength, plastic, multi-water-soluble channel magnesium alloy prepared in Example 1 of the present invention.

DETAILED DESCRIPTION

The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

In the following examples, unless otherwise specified, the materials and instruments used are commercially available, the processes used are conventional processes, the equipment used are conventional equipment, and the data obtained are the average values of more than three repeated experiments.

Example 1

A high-strength, plastic, and multi-water-soluble channel magnesium alloy contains, by mass percentage, 3% of Nd element, 0.3% of Ni element, 2% of Al element, and the balance is Mg element.

A method for preparing the high-strength, plastic, multi-water-soluble channel magnesium alloy of the present embodiment comprises the following steps:

S1. Melting and casting: according to the mass percentage of each component in the magnesium alloy, the required raw materials are weighed, mixed evenly, melted, refined, and cast to obtain an ingot.

S2. Homogenization: The ingot is subjected to homogenization treatment, wherein the homogenization treatment temperature is 470° C. and the time is 12 hours.

S3. High temperature deformation: The homogenized material is subjected to high temperature deformation, wherein the temperature of the high temperature deformation is 450°C and the true strain is 1.2.

S4. Low temperature deformation: low temperature deformation is performed on the material after high temperature deformation, where the temperature of low temperature deformation is 20°C and the true strain is 0.2.

S5. Aging: The material after low-temperature deformation is subjected to aging treatment, wherein the aging treatment temperature is 220°C and the time is 12 hours, to obtain a high-strength, plastic, and multi-water-soluble channel magnesium alloy, referred to as Mg-3Nd-0.3Ni-2Al alloy, marked as sample No. 1.

Fig. 1 is a schematic diagram of the microstructure of the high-strength, plastic, multi-water-soluble channel magnesium alloy prepared in Example 1 of the present invention. As shown in Fig. 1, there is a MgNi phase at the grain boundary of the magnesium alloy, 60% (the percentage refers to the number percentage) of the grains contain twins, and in these twins, all twin boundaries have no precipitation zone, and at the same time, the grains and the twins also contain MgNd phases.

Comparative Example 1

A magnesium alloy contains, by mass percentage, 6% of Nd element, 0.3% of Ni element, 2% of Al element, and the balance of Mg element.

The preparation method of the magnesium alloy is the same as that of Example 1.

The obtained Mg-6Nd-0.3Ni-2Al alloy is marked as sample No. 2.

The test shows that the magnesium alloy has MgNi phase at the grain boundary, 20% of the grains contain twins, and 30% of the twin boundaries have no precipitation zone. At the same time, the grains and the twins also contain MgNd phase.

Comparative Example 2

A magnesium alloy contains, by mass percentage, 3% of Nd element, 0.3% of Ni element, 5% of Al element, and the balance of Mg element.

The preparation method of the magnesium alloy is the same as that of Example 1.

The obtained Mg-3Nd-0.3Ni-5Al alloy was marked as sample No. 3.

The test shows that the magnesium alloy has MgNi and MgAl phases at the grain boundaries, and 70% of the grains contain twins. Among these twins, all twin boundaries have precipitation-free zones. At the same time, the grains and twins also contain MgNd and MgAl phases.

The three magnesium alloys obtained in Example 1 and Comparative Examples 1-2 were subjected to a uniaxial tensile test at room temperature and a water solubility test at 50° C. The results are shown in Table 1.

Table 1

As can be seen from Table 1, the high-strength and plastic multi-water-soluble channel magnesium alloy (Sample No. 1) prepared in Example 1 has both high strength and plasticity and high dissolution rate. However, the magnesium alloy (Sample No. 2) prepared in Comparative Example 1 has an excessively high Nd content, which enhances corrosion resistance and interrupts the dissolution of the magnesium alloy in water; and the magnesium alloy (Sample No. 3) prepared in Comparative Example 2 has an excessively high Al content, which leads to an excessive number of twins and the formation of MgAl brittle phases, which also weakens the solid solution strengthening effect and damages the strength and plasticity of the magnesium alloy.

Example 2

A high-strength, plastic, and multi-water-soluble channel magnesium alloy contains, by weight percentage, 4% of Zn element, 0.4% of Sr element, 0.4% of Sn element, and the balance is Mg element.

A method for preparing a high-strength, plastic, multi-water-soluble channel magnesium alloy of this embodiment comprises the following steps:

S1. Melting and casting: according to the mass percentage of each component in the magnesium alloy, the required raw materials are weighed, mixed evenly, melted, refined, and cast to obtain an ingot.

S2. Homogenization: homogenizing the ingot, wherein the homogenization temperature is 400° C. and the time is 6 hours.

S3. High temperature deformation: The homogenized material is subjected to high temperature deformation, wherein the temperature of the high temperature deformation is 300°C and the true strain is 0.5.

S4. Low temperature deformation: low temperature deformation is performed on the material after high temperature deformation, where the temperature of low temperature deformation is room temperature and the true strain is 0.1.

S5. Aging: The material after low-temperature deformation is subjected to aging treatment, wherein the aging treatment temperature is 150°C and the time is 48 hours, to obtain a high-strength, plastic, and multi-water-soluble channel magnesium alloy, referred to as Mg-4Zn-0.4Sr-0.4Sn alloy, marked as sample No. 2.

After testing, it was found that MgSr phase existed at the grain boundaries of the magnesium alloy, and 70% (the percentage refers to the percentage in number) of the grains contained twins. Among these twins, 90% (the percentage refers to the percentage in number) of the twin boundaries had no precipitation zone. At the same time, MgZn phase existed both inside the grains and inside the twins.

Example 3

A high-strength, plastic, and multi-water-soluble channel magnesium alloy contains, by weight percentage, 4% of Zn element, 0.4% of Sr element, 1.4% of Sn element, and the balance is Mg element.

A method for preparing the high-strength, plastic, multi-water-soluble channel magnesium alloy of this embodiment is the same as that of Example 2.

The obtained Mg-4Zn-0.4Sr-1.4Sn alloy is marked as sample No. 5.

The test shows that the magnesium alloy has MgSr phase at the grain boundaries, 95% of the grains contain twins, and 80% of the twins have no precipitation zone at the twin boundaries. At the same time, MgZn phase exists both inside the grains and inside the twins.

Comparative Example 3

A magnesium alloy contains, by mass percentage, 0.4% of Zn element, 0.4% of Sr element, 0.4% of Sn element, and the balance of Mg element.

The preparation method of the magnesium alloy is the same as that of Example 2.

The obtained Mg-0.4Zn-0.4Sr-0.4Sn alloy was marked as sample No. 6.

The test shows that the magnesium alloy has MgSr phase at the grain boundary, and 60% of the grains contain twins. Among these twins, all twin boundaries do not contain non-precipitation zones.

Comparative Example 4

A magnesium alloy contains, by mass percentage, 0.4% of Zn element, 0.04% of Sr element, 0.4% of Sn element, and the balance of Mg element.

The preparation method of the magnesium alloy is the same as that of Example 2.

The obtained Mg-4Zn-0.04Sr-0.4Sn alloy is marked as sample No. 7.

The test shows that there is no MgSr phase at the grain boundaries of the magnesium alloy, 80% of the grains contain twins, and 90% of the twin boundaries have no precipitation zones. At the same time, there is MgZn phase inside the grains and the twins.

The four magnesium alloys obtained in Examples 2-3 and Comparative Examples 3-4 were subjected to uniaxial tensile tests at room temperature and water solubility tests at 50°C. The results are shown in Table 2.

Table 2

As shown in Table 2, the high-strength plastic multi-water-soluble channel magnesium alloy (sample No. 4) prepared in Example 2 has both high strength plasticity and high dissolution rate; the high-strength plastic multi-water-soluble channel magnesium alloy (sample No. 5) prepared in Example 3 forms more twins due to the increase in Sn content, but the Sn element is not easy to diffuse, which weakens the diffusion of the Zn element, and the number of MgZn phases and twin boundary non-precipitation zones is reduced simultaneously, causing the strength plasticity and dissolution rate to decrease simultaneously. The magnesium alloy (sample No. 6) prepared in Comparative Example 3 has insufficient Zn content, resulting in no precipitation zone at the twin boundary, and the dissolution rate decreases; the magnesium alloy (sample No. 7) prepared in Comparative Example 4 has insufficient Sr content, resulting in no MgSr phase at the grain boundary, and the dissolution rate decreases.

Example 4

A high-strength, plastic, and multi-water-soluble channel magnesium alloy contains, by mass percentage, 2% of Sm element, 0.2% of Cu element, 1% of Al element, 0.2% of Sn element, and the balance is Mg element.

A method for preparing a high-strength, plastic, multi-water-soluble channel magnesium alloy according to the present embodiment comprises the following steps:

S1. Melting and casting: according to the mass percentage of each component in the magnesium alloy, the required raw materials are weighed, mixed evenly, melted, refined, and cast to obtain an ingot.

S2. Homogenization: The ingot is subjected to homogenization treatment, wherein the homogenization treatment temperature is 490° C. and the time is 24 hours.

S3. High temperature deformation: The homogenized material is subjected to high temperature deformation, wherein the temperature of the high temperature deformation is 420°C and the true strain is 0.8.

S4. Low temperature deformation: low temperature deformation is performed on the material after high temperature deformation, wherein the temperature of low temperature deformation is 120°C and the true strain is 0.05.

S5. Aging: The material after low-temperature deformation was subjected to creep aging treatment, wherein the creep aging treatment temperature was 200°C and the true strain was 0.2, to obtain a high-strength, plastic, and multi-water-soluble channel magnesium alloy, referred to as Mg-2Sm-0.2Cu-1Al-0.2Sn alloy, marked as sample No. 8.

The test shows that the magnesium alloy has MgCu phase at the grain boundaries, 60% of the grains contain twins, and 70% of the twins have no precipitation zone at the twin boundaries. At the same time, MgSm phase exists both inside the grains and inside the twins.

Example 5

A high-strength, plastic, and multi-water-soluble channel magnesium alloy contains, by weight percentage, 1% of Sm element, 0.2% of Cu element, and the balance is Mg element.

A method for preparing the high-strength, plastic, multi-water-soluble channel magnesium alloy of this embodiment is the same as that of Example 4.

The obtained Mg-1Sm-0.2Cu alloy was labeled as sample No. 9.

The test shows that the magnesium alloy has MgCu phase at the grain boundary, 70% of the grains contain twins, and 20% of the twins have no precipitation zone at the twin boundaries. Meanwhile, MgSm phase exists both inside the grains and inside the twins.

Example 6

A high-strength, plastic, and multi-water-soluble channel magnesium alloy contains, by mass percentage, 2% of Sm element, 0.1% of Cu element, 0.1% of Ni element, 1% of Al element, 0.2% of Sn element, and the balance is Mg element.

A method for preparing the high-strength, plastic, multi-water-soluble channel magnesium alloy of this embodiment is the same as that of Example 4.

The obtained Mg-2Sm-0.1Cu-0.1Ni-1Al-0.2Sn alloy was marked as sample No. 10.

The test showed that MgCu and MgNi phases existed at the grain boundaries of the magnesium alloy, 40% of the grains contained twins, and 70% of the twins had no precipitation zones at the twin boundaries. Meanwhile, MgSm phases existed both inside the grains and inside the twins.

Comparative Example 5

A magnesium alloy contains, by mass percentage, 2% of Sm element, 0.2% of Cu element, 0.2% of Ni element, 0.2% of Sr element, 1% of Al element, 0.2% of Sn element, and the balance is Mg element.

The preparation method of the magnesium alloy is the same as that of Example 4.

The obtained Mg-2Sm-0.2Cu-0.2Ni-0.2Sr-1Al-0.2Sn alloy was marked as sample No. 11.

The test showed that MgCu, MgNi and MgSr phases existed at the grain boundaries of the magnesium alloy, 30% of the grains contained twins, and 70% of the twins had no precipitation zones at the twin boundaries. Meanwhile, MgSm phases existed both inside the grains and inside the twins.

The four magnesium alloys obtained in Examples 4-6 and Comparative Example 5 were subjected to uniaxial tensile tests at room temperature and water solubility tests at 50° C. The results are shown in Table 3.

Table 3

It can be seen from Table 3 that the high-strength, plastic, and multi-water-soluble channel magnesium alloy (Sample No. 8) prepared in Example 4 has both high strength and plasticity and high dissolution rate; the high-strength, plastic, and multi-water-soluble channel magnesium alloy (Sample No. 9) prepared in Example 5 reduces the Sm element content, reduces the MgSm phase, leads to a decrease in the number of non-precipitation zones at the twin boundaries, and significantly reduces the dissolution rate; the high-strength, plastic, and multi-water-soluble channel magnesium alloy (Sample No. 10) prepared in Example 5 contains Cu and Ni elements at the same time, which leads to a decrease in the number of twins, a decrease in corrosion channels, and a decrease in the dissolution rate; the magnesium alloy prepared in Comparative Example 5 (Sample No. 11) has an excessively high total content of Cu, Ni, and Sr, which leads to an increase in the number of grain boundary compounds, causing the magnesium alloy to fracture brittlely, and thus does not have high strength and plasticity.

Example 7

A high-strength, plastic, and multi-water-soluble channel magnesium alloy contains, by mass percentage, 0.5% of Nd element, 3% of Sm element, 0.4% of Ni element, 1% of Al element, and the balance is Mg element.

A method for preparing a high-strength, plastic, multi-water-soluble channel magnesium alloy of this embodiment comprises:

S1. Melting and casting: according to the mass percentage of each component in the magnesium alloy, weigh the required raw materials, mix them evenly, melt, refine and cast them to obtain an ingot;

S2. Homogenization: homogenization treatment is performed on the ingot, wherein the homogenization treatment temperature is 450° C. and the time is 36 hours;

S3, high temperature deformation: the homogenized material is subjected to high temperature deformation, wherein the temperature of high temperature deformation is 400°C and the true strain is 0.5;

S4, low temperature deformation: low temperature deformation is performed on the material after high temperature deformation, wherein the temperature of low temperature deformation is 150°C and the true strain is 0.08;

S5. Aging: The material after low-temperature deformation was subjected to creep aging treatment, wherein the creep aging treatment temperature was 180°C and the true strain was 0.6, to obtain a high-strength, plastic, and multi-water-soluble channel magnesium alloy, referred to as Mg-0.5Nd-3Sm-0.4Ni-1Al alloy, marked as sample No. 12.

The test shows that the magnesium alloy has MgNi phase at the grain boundaries, 60% of the grains contain twins, and 80% of the twins have no precipitation zone at the twin boundaries. At the same time, MgSm phase exists both inside the grains and inside the twins.

Example 8

A high-strength, plastic, and multi-water-soluble channel magnesium alloy, whose composition is the same as that of Example 7.

A method for preparing a high-strength, plastic, multi-water-soluble channel magnesium alloy of this embodiment comprises:

S1. Melting and casting: same as Example 7.

S2. Homogenization: temperature is 420°C, time is 48 hours.

S3, high temperature deformation: temperature is 300℃, true strain is 0.5.

S4, low temperature deformation: same as Example 7.

S5. Creep aging: same as Example 7.

The obtained Mg-0.5Nd-3Sm-0.4Ni-1Al alloy was marked as sample No. 13.

The test showed that the magnesium alloy contained MgNi phase at the grain boundaries, and 50% of the grains contained twins, most of which were intersecting twins. Only 20% of the twin boundaries had no precipitation zone. At the same time, MgSm phase existed both inside the grains and inside the twins.

Comparative Example 6

A magnesium alloy whose composition is the same as that of Example 7.

The preparation method of the magnesium alloy comprises:

S1, smelting and casting: the same as in Example 7;

S2, homogenization: same as in Example 7;

S3, high temperature deformation: temperature is 490℃, true strain is 0.5;

S4, low temperature deformation: same as Example 7;

S5. Creep aging: same as Example 7.

The obtained Mg-0.5Nd-3Sm-0.4Ni-1Al alloy was marked as sample No. 14.

The test shows that the magnesium alloy has MgNi phase at the grain boundary, and 20% of the grains contain twins. In these twins, there is no precipitation-free zone at the twin boundary. At the same time, MgSm phase exists both inside the grains and inside the twins.

The three magnesium alloys obtained in Examples 7-8 and Comparative Example 6 were subjected to uniaxial tensile tests at room temperature and water solubility tests at 50°C. The results are shown in Table 4.

Table 4

It can be seen from Table 4 that the high-strength, plastic, and multi-water-soluble channel magnesium alloy (Sample No. 12) prepared in Example 7 has both high strength and plasticity and high dissolution rate; the high-strength, plastic, and multi-water-soluble channel magnesium alloy (Sample No. 13) prepared in Example 8, due to the decrease in both the homogenization temperature and the high-temperature deformation temperature, causes the twins to be arranged in parallel inside the grains, but to cross each other, thereby reducing the number of precipitation-free zones, and simultaneously reducing the strength and plasticity and the dissolution rate; the magnesium alloy (Sample No. 14) prepared in Comparative Example 2, due to the excessively high deformation temperature and the excessively high degree of grain refinement, causes the twins and the precipitation-free zones at the twin boundaries to be reduced at the same time, thereby greatly reducing the dissolution rate.

Example 9

A high-strength, plastic, multi-water-soluble channel magnesium alloy contains, by mass percentage, 0.5% Nd element, 0.5% Sm element, 1.5% Zn element, 0.1% Cu element, 0.1% Ni element, 0.1% Sr element, 0.5% Al element, 0.5% Sn element, and the balance is Mg element.

A method for preparing a high-strength, plastic, multi-water-soluble channel magnesium alloy of this embodiment comprises the following steps:

S1. Melting and casting: according to the mass percentage of each component in the magnesium alloy, the required raw materials are weighed, mixed evenly, melted, refined, and cast to obtain an ingot.

S2. Homogenization: The ingot is subjected to homogenization treatment, wherein the homogenization treatment temperature is 410° C. and the time is 36 hours.

S3. High temperature deformation: The homogenized material is subjected to high temperature deformation, wherein the temperature of the high temperature deformation is 340°C and the true strain is 1.

S4. Low temperature deformation: low temperature deformation is performed on the material after high temperature deformation, wherein the temperature of low temperature deformation is 20°C and the true strain is 0.03.

S5. Aging: The material after low-temperature deformation was subjected to creep aging treatment, wherein the creep aging treatment temperature was 150°C and the true strain was 0.4, to obtain a high-strength, plastic, and multi-water-soluble channel magnesium alloy, referred to as Mg-0.5Nd-0.5Sm-1.5Zn-0.1Cu-0.1Ni-0.1Sr-0.5Al-0.5Sn alloy, marked as sample No. 15.

The test showed that MgCu, MgNi and MgSr phases existed at the grain boundaries of the magnesium alloy, 50% of the grains contained twins, and 60% of the twin boundaries had no precipitation zones. Meanwhile, MgZn phases existed both inside the grains and inside the twins.

Comparative Example 7

A magnesium alloy having the same composition as that of Example 9.

The preparation method of the magnesium alloy comprises:

S1, smelting and casting: the same as in Example 9;

S2, homogenization: same as in Example 9;

S3, high temperature deformation: the same as in Example 9;

S4, low temperature deformation: the temperature is room temperature, the true strain is 0.01;

S5. Creep aging: same as Example 9.

The obtained Mg-0.5Nd-0.5Sm-1.5Zn-0.1Cu-0.1Ni-0.1Sr-0.5Al-0.5Sn alloy was marked as sample No. 16.

The test shows that MgCu, MgNi and MgSr phases exist at the grain boundaries of the magnesium alloy, and 10% of the grains contain twins. In these twins, there are precipitation-free zones at all twin boundaries. At the same time, MgZn phases exist inside the grains and the twins.

Comparative Example 8

A magnesium alloy having the same composition as that of Example 9.

The preparation method of the magnesium alloy comprises:

S1, smelting and casting: the same as in Example 9;

S2, homogenization: same as in Example 9;

S3, high temperature deformation: the same as in Example 9;

S4, low temperature deformation: the same as in Example 9;

S5, creep aging: temperature is 150℃, true strain is 0.8.

The obtained Mg-0.5Nd-0.5Sm-1.5Zn-0.1Cu-0.1Ni-0.1Sr-0.5Al-0.5Sn alloy was marked as sample No. 17.

The test showed that MgCu, MgNi and MgSr phases existed at the grain boundaries of the magnesium alloy, 50% of the grains contained twins and grain boundary non-precipitation zones, and among these twins, only 30% of the twin boundaries had non-precipitation zones. Meanwhile, MgZn phases existed both inside the grains and inside the twins.

The three magnesium alloys obtained in Example 9 and Comparative Examples 7-8 were subjected to a uniaxial tensile test at room temperature and a water solubility test at 50°C. The results are shown in Table 5.

Table 5

It can be seen from Table 5 that the high-strength, plastic, and multi-water-soluble channel magnesium alloy (Sample No. 15) prepared in Example 2 has both high-strength, plasticity, and high dissolution rate; the magnesium alloy (Sample No. 16) prepared in Comparative Example 7 has an insufficient number of twins and too few corrosion channels due to the low true strain of low-temperature deformation, which significantly reduces the number of reactions between the magnesium alloy and water; the magnesium alloy (Sample No. 17) prepared in Comparative Example 7 has an excessively high true strain of creep aging, which results in the formation of a precipitation-free zone at the grain boundary, which seriously damages the strength of the magnesium alloy.

It can be seen from the above results that in the present invention, by optimizing the type and amount of each added element, the harmful grain boundary non-precipitation zone can be converted into a beneficial twin boundary non-precipitation zone, so that the twin boundary non-precipitation zone and the grain boundary compound can serve as corrosion channels together, which can not only improve the strength and plasticity of the magnesium alloy, but also improve the dissolution rate of the magnesium alloy in water. At the same time, the precipitation phase inside the grains and the twins can further improve the strength, thereby obtaining a magnesium alloy with both high strength and plasticity and high dissolution rate. The magnesium alloy has a tensile strength of ≥220MPa, a yield strength of ≥120MPa, and an elongation of ≥15% at room temperature, and a dissolution rate of ≥15mg·cm ^-2 ·h ^-1 in water at 50°C, and is a new type of magnesium alloy with excellent performance.

The above is only a preferred embodiment of the present invention, but it is not intended to limit the present invention. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention using the methods and technical contents disclosed above. Therefore, any simple modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims (10)

1. The magnesium alloy with the high-strength plastic multi-water-soluble channel is characterized by comprising the following components in percentage by mass: 1 to 4 percent of X element, 0.1 to 0.4 percent of Y element, 0 to 2 percent of Z element and the balance of Mg element; the X element is at least one of Nd element, sm element and Zn element; the Y element is at least one of Cu element, ni element and Sr element, and the Z element is at least one of Al element and Sn element.

2. The high-strength multi-water-soluble channel magnesium alloy according to claim 1, wherein when the element X does not contain Zn, the total content of the element X is 1% to 3%, and the total content of the element Z is 1% to 2%.

3. The high-strength multi-water-soluble channel magnesium alloy according to claim 1, wherein when the element X only comprises the element Sm, the content of the element Sm is 2% -3%, and the total content of the element Z is 1% -2%.

4. The high-strength multi-water-soluble channel magnesium alloy according to claim 1, wherein when the element X only contains the element Zn, the content of the element Zn is 2% -4%, and the total content of the element Z is 0-1%.

5. The high-strength multi-water-soluble channel magnesium alloy according to claim 1, wherein when the element Y is any one of Cu, ni and Sr, the content of the element Y is 0.2-0.4%.

6. The high-strength multi-aqueous channel magnesium alloy according to any one of claims 1 to 5, wherein grain boundaries of the magnesium alloy contain MgY phase composed of Y element;

the magnesium alloy contains 40% or more of twin crystals in the interior of crystal grains.

7. The high-strength multi-water-soluble channel magnesium alloy according to claim 6, wherein 50% or more of grains in the magnesium alloy contain twin crystals, and 50% or more of twin crystals have twin-crystal-boundary non-precipitation zones.

8. A method for preparing the magnesium alloy with high strength and high plasticity and multiple water-soluble channels according to any one of claims 1 to 7, wherein the magnesium alloy with high strength and high plasticity and multiple water-soluble channels is prepared by adopting any one of the following modes;

the first mode comprises the following steps:

s1, weighing required raw materials according to the mass percentage of each component in the magnesium alloy, uniformly mixing, melting, refining and casting to obtain an ingot;

s2, homogenizing the cast ingot; the homogenization treatment temperature is 400-490 ℃; the homogenization treatment time is 6-48 hours;

s3, carrying out high-temperature deformation on the homogenized material; the high-temperature deformation temperature is 300-450 ℃, and the true strain is 0.5-1.2;

s4, carrying out low-temperature deformation on the material subjected to the high-temperature deformation; the temperature of the low-temperature deformation is 20-150 ℃, and the true strain is 0.02-0.2;

s5, aging the material subjected to low-temperature deformation to obtain the high-strength plastic multi-water-soluble channel magnesium alloy; the temperature of the aging treatment is 150-220 ℃; the time of the aging treatment is 6-60 hours;

mode two, including the following step:

(1) Weighing required raw materials according to the mass percentage of each component in the magnesium alloy, uniformly mixing, melting, refining and casting to obtain an ingot;

(2) Homogenizing the cast ingot; the homogenization treatment temperature is 400-490 ℃; the homogenization treatment time is 6-48 hours;

(3) Carrying out high-temperature deformation on the homogenized material; the high-temperature deformation temperature is 300-450 ℃, and the true strain is 0.5-1.2;

(4) Carrying out low-temperature deformation on the material subjected to high-temperature deformation; the temperature of the low-temperature deformation is 20-150 ℃, and the true strain is 0.02-0.2;

(5) Creep aging treatment is carried out on the material after low-temperature deformation, and the magnesium alloy with high strength and high plasticity and multiple water-soluble channels is obtained; the temperature of the creep aging treatment is 150-220 ℃, and the true strain is 0.1-0.6.

9. The method for preparing a magnesium alloy with high strength and multiple water-soluble channels according to claim 8, wherein when the magnesium alloy with high strength and multiple water-soluble channels is prepared in the first mode, when the element X does not contain the element Zn, the homogenization treatment temperature in the step S2 is 440-490 ℃, and the high-temperature deformation temperature in the step S3 is 390-450 ℃; when the element X contains only Zn, the homogenization treatment temperature in the step S2 is 400-440 ℃, and the high-temperature deformation temperature in the step S3 is 300-390 ℃.

10. The method for producing a high-strength, high-plasticity, multi-water-soluble channel magnesium alloy according to claim 8, wherein when the high-strength, high-plasticity, multi-water-soluble channel magnesium alloy is produced in mode two, when the element X does not contain the element Zn, the temperature of the homogenization treatment in step (2) is 440 ℃ to 490 ℃, and the temperature of the high-temperature deformation in step (3) is 390 ℃ to 450 ℃; when the element X contains only Zn, the temperature of the homogenization treatment in the step (2) is 400 to 440 ℃ and the temperature of the high-temperature deformation in the step (3) is 300 to 390 ℃.

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