Magnesium alloy and preparation method thereof

Abstract

The invention relates to the field of metal, in particular to a magnesium alloy and a preparation method thereof. The preparation method provided by the invention comprises the following steps: burdening according to the target alloy composition: 1.0-2.5% of Gd; 0.03% to 0.15% of Ni; the balance is Mg and inevitable impurities; then smelting, refining and casting are carried out, and then first-time extrusion deformation treatment and second-time extrusion deformation treatment are carried out in sequence. According to the invention, the composition proportion of the alloy is adjusted, meanwhile, the preparation of the alloy is completed by controlling technological conditions in the preparation process, especially by two times of extrusion and controlling different extrusion ratios, the mechanical property and the elongation of the alloy are improved, and the finally obtained alloy has moderate strength and high elongation and can be dissolved.

Description

Technical Field

[0001] The present invention relates to the field of metals, and in particular to a magnesium alloy and a preparation method thereof. Background Art

[0002] The elongation of commonly used magnesium alloys is generally between 5% and 15% due to the influence of alloying elements, impurities and oxides, grain size, processing technology and other factors. At present, from the existing technical solutions for improving elongation, all of them are experiments through the ratio of different chemical components. The main chemical elements are gadolinium, yttrium, aluminum, zinc, zirconium, silicon, copper, iron, nickel, gallium, indium, beryllium, lanthanum, cerium, manganese, calcium, lithium and the like. Among them, the elongation of magnesium alloys with aluminum, manganese and calcium can be less than 25%, and the elongation of magnesium alloys with lithium as the main element can be 50%-70%, but its strength is low, the preparation cost is high, and some solutions will cause the solubility of magnesium alloys to deteriorate. In general, the existing technologies either cannot effectively improve the elongation or need to sacrifice strength. The tensile strength is below 200MPa, and sometimes it is difficult to take into account solubility. In addition, some solutions are costly and difficult to mass produce, which are not suitable for industrial mass production. Summary of the invention

[0003] In view of this, the present invention provides a magnesium alloy and a preparation method thereof. The preparation method provided by the present invention can effectively improve the elongation ratio of the magnesium alloy to ensure good strength and solubility, and has low cost and is suitable for industrial mass production.

[0004] The present invention provides a method for preparing a magnesium alloy, comprising the following steps:

[0005] A) proportioning the raw materials according to the target alloy composition;

[0006] in,

[0007] In terms of mass percentage, the composition of the target alloy is as follows:

[0008] Gd: 1.0%~2.5%;

[0009] Ni: 0.03%~0.15%;

[0010] The balance is Mg and unavoidable impurities;

[0011] The raw materials include: magnesium ingot, magnesium-gadolinium master alloy and magnesium-nickel master alloy;

[0012] B) adding magnesium ingot and refining agent into the smelting furnace for the first smelting; after the magnesium ingot is completely melted, adding the preheated magnesium-nickel master alloy for the first refining; then raising the temperature, adding the preheated magnesium-gadolinium master alloy for the second refining;

[0013] C) casting the alloy melt obtained in step B) to obtain cast rods; processing qualified cast rods into extruded cast rods;

[0014] D) performing a first extrusion deformation treatment on the extruded cast rod;

[0015] The conditions of the first extrusion deformation treatment are: extrusion temperature of 350-410°C, extrusion speed of 0.4-1.5 mm / s, and extrusion ratio of 4-5;

[0016] E) subjecting the alloy obtained in step D) to a second extrusion deformation process to obtain a magnesium alloy;

[0017] The conditions of the second extrusion deformation treatment are: extrusion temperature of 350-390° C., extrusion speed of 0.4-0.8 mm / s, and extrusion ratio of 6-12.

[0018] Preferably, in step B), the temperature of the first smelting is 720-750°C.

[0019] Preferably, in step B), the refining agent is RJ-2 solvent.

[0020] Preferably, in step B), the preheating temperature of the preheated magnesium-nickel master alloy is 100-160° C.;

[0021] The temperature of the first refining is 700~720℃.

[0022] Preferably, in step B), the preheating temperature of the preheated magnesium-gadolinium master alloy is 100-160° C.;

[0023] The temperature of the second refining is 730~780℃.

[0024] Preferably, in step C), before the casting, the following treatment is further performed: passing argon gas and then standing.

[0025] Preferably, the argon gas passing time is 5 to 15 minutes; the standing time is 15 to 20 minutes.

[0026] The present invention also provides a magnesium alloy prepared by the preparation method described in the above technical solution.

[0027] The magnesium alloy prepared by the present invention is a deformable soluble magnesium alloy with high elongation at room temperature. The present invention adjusts the alloy composition ratio, and at the same time, controls the process conditions during the preparation process, especially performs two extrusions and controls different extrusion ratios to complete the preparation of the alloy, thereby improving the mechanical properties and elongation of the alloy. Specifically, the alloy composition is as follows: Gd 1.0%~2.5%, Ni 0.03%~0.15%, and the balance is Mg and inevitable impurities; after the semi-continuous casting is completed, two hot extrusions are performed, the extrusion ratio of the first extrusion is 4-5, and the extrusion ratio of the second extrusion is 6-12, so that an ultra-high elongation magnesium alloy with a tensile strength of more than 180MPa, a yield strength of more than 130MPa, and an elongation of more than 28% (the elongation after the first extrusion is 15-20%) can be obtained, which is nearly 100% higher than that of conventional magnesium alloys and has moderate strength, effectively solving the problem of low elongation of conventional magnesium alloys, and the alloy has a dissolution rate of 20~80 mg / (cm in a 93℃×3% KCl solution. 2 ·h), that is, under the condition of medium strength and high elongation, it can be dissolved under certain conditions. In addition, there are few types of elements in the alloy, the amount of each element added is small, and the price is relatively low. Therefore, the preparation cost of the magnesium alloy is relatively low, the preparation method is relatively simple, and it is suitable for large-scale mass production. DETAILED DESCRIPTION

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0029] In this article, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0030] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0031] Herein, when it comes to numerical ranges, unless otherwise specified, the numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0032] In this article, when referring to the unit of a data range, if there is a unit only after the right endpoint, it means that the units of the left and right endpoints are the same. For example, 720~750℃ means that the units of the left endpoint "720" and the right endpoint "750" are both ℃.

[0033] Only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and likewise any upper limit can be combined with any other upper limit to form an unspecified range. In addition, each separately disclosed point or single value can itself be combined as a lower limit or upper limit with any other point or single value or with other lower limits or upper limits to form an unspecified range.

[0034] The present invention provides a method for preparing a magnesium alloy, comprising the following steps:

[0035] A) proportioning the raw materials according to the target alloy composition;

[0036] in,

[0037] In terms of mass percentage, the composition of the target alloy is as follows:

[0038] Gd: 1.0%~2.5%;

[0039] Ni: 0.03%~0.15%;

[0040] The balance is Mg and unavoidable impurities;

[0041] The raw materials include: magnesium ingot, magnesium-gadolinium master alloy and magnesium-nickel master alloy;

[0042] B) adding magnesium ingot and refining agent into the smelting furnace for the first smelting; after the magnesium ingot is completely melted, adding the preheated magnesium-nickel master alloy for the first refining; then raising the temperature, adding the preheated magnesium-gadolinium master alloy for the second refining;

[0043] C) casting the alloy melt obtained in step B) to obtain cast rods; processing qualified cast rods into extruded cast rods;

[0044] D) performing a first extrusion deformation treatment on the extruded cast rod;

[0045] E) subjecting the alloy obtained in step D) to a second extrusion deformation process to obtain a magnesium alloy.

[0046] [About Step A]:

[0047] A) The raw materials are prepared according to the target alloy composition.

[0048] In the present invention, the composition of the target alloy is as follows in terms of mass percentage:

[0049] Gd: 1.0%~2.5%;

[0050] Ni: 0.03%~0.15%;

[0051] The balance is Mg and inevitable impurities.

[0052] in,

[0053] The Gd (gadolinium) content may specifically be 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, or 2.5%.

[0054] The Ni (nickel) content may specifically be 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, or 0.15%.

[0055] The balance is Mg (magnesium) and inevitable impurities.

[0056] In one embodiment of the present invention, the composition of the target alloy is as follows: Gd 1.00%, Ni 0.03%, the balance is Mg and inevitable impurities. In another embodiment of the present invention, the composition of the target alloy is as follows: Gd 1.50%, Ni 0.03%, the balance is Mg and inevitable impurities. In another embodiment of the present invention, the composition of the target alloy is as follows: Gd 2.50%, Ni 0.03%, the balance is Mg and inevitable impurities. In another embodiment of the present invention, the composition of the target alloy is as follows: Gd 1.00%, Ni 0.10%, the balance is Mg and inevitable impurities. In another embodiment of the present invention, the composition of the target alloy is as follows: Gd 1.50%, Ni 0.10%, the balance is Mg and inevitable impurities. In another embodiment of the present invention, the composition of the target alloy is as follows: Gd 2.50%, Ni 0.10%, the balance is Mg and inevitable impurities. In another embodiment of the present invention, the composition of the target alloy is as follows: Gd 1.00%, Ni 0.15%, the balance is Mg and inevitable impurities. In another embodiment of the present invention, the composition of the target alloy is as follows: Gd 1.50%, Ni 0.15%, the balance is Mg and inevitable impurities. In another embodiment of the present invention, the composition of the target alloy is as follows: Gd 2.50%, Ni 0.15%, the balance is Mg and inevitable impurities.

[0057] In the present invention, the raw materials used for batching include: magnesium ingot, magnesium-gadolinium master alloy and magnesium-nickel master alloy. Among them, the purity of the magnesium ingot is preferably 99.95%. The magnesium-gadolinium master alloy is preferably Mg-Gd30% master alloy. The magnesium-nickel master alloy is preferably Mg-Ni23% master alloy. The present invention has no special restrictions on the method of batching, and it can be carried out according to conventional means in the field, for example, the proportion of each raw material is calculated according to the target composition, and the corresponding amount of raw materials is weighed for use.

[0058] [About step B]:

[0059] B) Adding magnesium ingots and refining agents into a smelting furnace for the first smelting; after the magnesium ingot is completely melted, adding preheated magnesium-nickel master alloy for the first refining; then raising the temperature, adding preheated magnesium-gadolinium master alloy for the second refining.

[0060] In the present invention, the refining agent is preferably RJ-2 solvent (also known as No. 2 solvent, or RJ-2 flux). In the present invention, the amount of the refining agent is preferably 3.0% to 4.0% of the mass of the magnesium ingot, specifically 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, and more preferably 3.5%. In the present invention, the temperature of the first smelting is preferably 720 to 750°C, specifically 720°C, 725°C, 730°C, 735°C, 740°C, 745°C, 750°C.

[0061] In the present invention, after the first smelting until the magnesium ingot is completely melted, the preheated magnesium-nickel master alloy is added for the first refining. The preheating temperature of the preheated magnesium-nickel master alloy is preferably 100-160°C, specifically 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C. In the present invention, a refining agent is preferably added in the first refining. The refining agent is preferably RJ-2 solvent (also known as No. 2 solvent, or RJ-2 flux). The amount of the refining agent is preferably 8%-10% of the mass of the refining agent used in the first smelting, specifically 8%, 9%, 10%. In the present invention, the temperature of the first refining is preferably 700-720°C, specifically 700°C, 705°C, 710°C, 715°C, 720°C. The time for the first refining is preferably 5 to 10 minutes, specifically 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, or 10 minutes.

[0062] In the present invention, after the first refining is completed, the temperature is raised, and the preheated magnesium-gadolinium master alloy is added to carry out the second refining. Wherein, the temperature is raised to the temperature of the second refining, preferably to 730-780°C, specifically 730°C, 735°C, 740°C, 745°C, 750°C, 755°C, 760°C, 765°C, 770°C, 775°C, 780°C. The preheating temperature of the preheated magnesium-gadolinium master alloy is preferably 100-160°C, specifically 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C. In the present invention, a refining agent is preferably added in the second refining. The refining agent is preferably RJ-2 solvent (also known as No. 2 solvent, or RJ-2 flux). The amount of the refining agent is preferably 8% to 10% of the mass of the refining agent used in the first smelting, specifically 8%, 9%, and 10%. In the present invention, the temperature of the second refining is the above-mentioned temperature rise, that is, 730 to 780°C. In the present invention, the time of the second refining is preferably 5 to 10 minutes, specifically 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, and 10 minutes. After the above refining, an alloy melt is obtained.

[0063] [About Step C]:

[0064] C) casting the alloy melt obtained in step B) to obtain cast rods; and processing qualified cast rods into extruded cast rods.

[0065] In the present invention, before the casting, the following treatment is preferably performed: passing argon gas and then standing. The time for passing argon gas is preferably 5 to 15 minutes, specifically 5 minutes, 10 minutes, and 15 minutes. After passing argon gas, stand for a period of time. The standing time is preferably 15 to 20 minutes, specifically 15 minutes and 20 minutes. After the above treatments, casting production is carried out to obtain magnesium alloy cast rods. In the present invention, during the casting process, a protective gas is preferably also passed. The protective gas is preferably SF6, or a mixed gas of CO2 and SF6, more preferably a mixed gas of CO2 and SF6. In the mixed gas, the volume ratio of CO2:SF6 is 1:1.5. Passing the above-mentioned protective gas can prevent the magnesium alloy liquid from burning after contacting with oxygen during the casting process.

[0066] In the present invention, after obtaining the magnesium alloy cast rod, it is preferred to sample and test the composition, that is, to test whether the alloy composition meets the target alloy requirements. If it is unqualified, dilute or supplement the material. If it is qualified, proceed to the next process. The present invention processes the qualified cast rod into an extruded cast rod to prepare for the subsequent two extrusion deformation processes. The present invention has no special restrictions on the processing method, and it can be a conventional method in the art.

[0067] [About Step D]:

[0068] D) performing a first extrusion deformation treatment on the extruded cast rod.

[0069] In the present invention, the conditions of the first extrusion deformation treatment are preferably: the extrusion temperature is 350-410°C, the extrusion speed is 0.4-1.5 mm / s, and the extrusion ratio is 4-5. Wherein, the extrusion temperature can be specifically 350°C, 355°C, 360°C, 365°C, 370°C, 375°C, 380°C, 385°C, 390°C, 395°C, 400°C, 405°C, 410°C. The extrusion speed can be specifically 0.4 mm / s, 0.5 mm / s, 0.6 mm / s, 0.7 mm / s, 0.8 mm / s, 0.9 mm / s, 1.0 mm / s, 1.1 mm / s, 1.2 mm / s, 1.3 mm / s, 1.4 mm / s, 1.5 mm / s. The extrusion ratio can be specifically 4.0, 4.5, 5.0. After the above extrusion deformation treatment, the first deformation of the cast magnesium alloy is completed.

[0070] [About Step E]:

[0071] E) subjecting the alloy obtained in step D) to a second extrusion deformation process to obtain a magnesium alloy.

[0072] In the present invention, the conditions of the second extrusion deformation treatment are preferably: the extrusion temperature is 350-390°C, the extrusion speed is 0.4-0.8mm / s, and the extrusion ratio is 6-12. Among them, the extrusion temperature can be specifically 350°C, 355°C, 360°C, 365°C, 370°C, 375°C, 380°C, 385°C, 390°C. The extrusion speed can be specifically 0.4mm / s, 0.5mm / s, 0.6mm / s, 0.7mm / s, 0.8mm / s. The extrusion ratio can be specifically 6, 7, 8, 9, 10, 11, 12. After the above extrusion deformation treatment, the second deformation of the magnesium alloy is completed. The present invention further refines the product structure grains without changing the chemical composition through the above two hot extrusion treatments, thereby improving the elongation; moreover, the alloy obtained by the present invention has moderate mechanical properties, and the mechanical properties and elongation are improved simultaneously, while taking into account dissolution.

[0073] The present invention also provides a magnesium alloy prepared by the preparation method described in the above technical solution.

[0074] The magnesium alloy prepared by the present invention is a deformable soluble magnesium alloy with high elongation at room temperature. The present invention adjusts the alloy composition ratio, and at the same time, controls the process conditions during the preparation process, especially performs two extrusions and controls different extrusion ratios to complete the preparation of the alloy, thereby improving the mechanical properties and elongation of the alloy. Specifically, the alloy composition is as follows: Gd 1.0%~2.5%, Ni 0.03%~0.15%, and the balance is Mg and inevitable impurities; after the semi-continuous casting is completed, two hot extrusions are performed, the extrusion ratio of the first extrusion is 4-5, and the extrusion ratio of the second extrusion is 6-12, so that an ultra-high elongation magnesium alloy with a tensile strength of more than 180MPa, a yield strength of more than 130MPa, and an elongation of more than 28% (the elongation after the first extrusion is 15-20%) can be obtained, which is nearly 100% higher than that of conventional magnesium alloys and has moderate strength, effectively solving the problem of low elongation of conventional magnesium alloys, and the alloy has a dissolution rate of 20~80 mg / (cm in a 93℃×3% KCl solution. 2 ·h), that is, under the condition of medium strength and high elongation, it can be dissolved under certain conditions. In addition, there are few types of elements in the alloy, the amount of each element added is small, and the price is relatively low. Therefore, the preparation cost of the magnesium alloy is relatively low, the preparation method is relatively simple, and it is suitable for large-scale mass production.

[0075] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0076] Examples 1-9

[0077] A) The raw materials are prepared according to the target alloy composition.

[0078] The target alloy compositions of Examples 1-9 are shown in Table 1 (corresponding to the alloy compositions of the 9 samples from top to bottom in Table 1).

[0079] B) Add pure magnesium ingot (purity 99.95%) and RJ-2 solvent refining agent (accounting for 3.5% of the mass of magnesium ingot) to the melting furnace, and melt at 730℃ until the magnesium ingot is completely melted. Then, add the preheated (preheating temperature is 140℃) Mg-Ni23% master alloy and RJ-2 solvent refining agent (accounting for 10% of the mass of the refining agent added for the first time) to carry out the first refining (refining temperature is 710℃, time is 8min). After that, increase the temperature, add the preheated (preheating temperature is 140℃) Mg-Gd30% master alloy and RJ-2 solvent refining agent (accounting for 10% of the mass of the refining agent added for the first time), and carry out the second refining (refining temperature is 750℃, time is 8min) to obtain the alloy melt.

[0080] C) Pass argon gas for 10 minutes, then let stand for 20 minutes, then cast to obtain cast rods. Take samples to test the composition, and process qualified cast rods into extruded cast rods for storage.

[0081] D) The extruded cast rod was subjected to the first extrusion deformation treatment under the following conditions: extrusion temperature of 360°C, extrusion speed of 1.0 mm / s, and extrusion ratio of 4.

[0082] E) The alloy obtained in step D) is subjected to a second extrusion deformation treatment under the following conditions: extrusion temperature of 370° C., extrusion speed of 0.5 mm / s, extrusion ratio of 8, to obtain a magnesium alloy product.

[0083] The products obtained in Examples 1 to 9 were subjected to room temperature mechanical property tests and dissolution rate tests. The results are shown in Table 1.

[0084] Table 1: Sample composition and performance test results of Examples 1-9

[0085]

[0086] Note: In the dissolution rate test, three samples with Ni content of 0.03%, three samples with Ni content of 0.10%, and three samples with Ni content of 0.15% were grouped together, and the average value of the test results of each group of samples was taken as the test result of the group of samples.

[0087] It can be seen from the test results in Table 1 that the tensile strength of the magnesium alloy obtained by the present invention is above 180 MPa, the yield strength is above 130 MPa, and the elongation is above 28%, which not only improves the elongation but also ensures good strength; at the same time, its dissolution rate in 93℃×3% KCl solution reaches 20 mg / (cm 2 h) and above, showing good solubility.

[0088] Comparative Example 1

[0089] The implementation is carried out according to Example 1, except that the conditions of the first extrusion deformation treatment in step D) and the second extrusion deformation treatment in step E) are changed as follows:

[0090] In step D), the extrusion speed of the first extrusion deformation treatment is adjusted to 0.2 mm / s, and the extrusion ratio is adjusted to 2;

[0091] In step E), the extrusion speed of the second extrusion deformation treatment is adjusted to 0.2 mm / s, and the extrusion ratio is adjusted to 4.

[0092] Comparative Example 2

[0093] The implementation is carried out according to Example 1, except that the conditions of the first extrusion deformation treatment in step D) and the second extrusion deformation treatment in step E) are changed as follows:

[0094] In step D), the extrusion speed of the first extrusion deformation treatment is adjusted to 1.0 mm / s, and the extrusion ratio is adjusted to 7;

[0095] In step E), the extrusion speed of the second extrusion deformation treatment is adjusted to 1.5 mm / s, and the extrusion ratio is adjusted to 14.

[0096] The products obtained in Comparative Example 1-2 were subjected to room temperature mechanical property tests and dissolution rate tests. The results are shown in Table 2.

[0097] Table 2: Performance test results of comparative examples 1-2

[0098]

[0099] It can be seen from the test results in Table 2 that compared with Example 1, the mechanical properties and dissolution rates of Comparative Examples 1-2 are significantly worse, wherein the sample surface of step E) of Comparative Example 2 cracks during the second extrusion and the test fails. This proves that the present invention controls the two extrusion deformation processes as specific condition parameters, which is beneficial to improving the mechanical properties and solubility of the product.

[0100] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enable any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method for preparing a magnesium alloy, characterized in that: The following steps are involved: A) proportioning the raw materials according to the target alloy composition; in, In terms of mass percentage, the composition of the target alloy is as follows: Gd: 1.0%~2.5%; Ni: 0.03%~0.15%; The balance is Mg and unavoidable impurities; The raw materials include: magnesium ingot, magnesium-gadolinium master alloy and magnesium-nickel master alloy; B) adding magnesium ingot and refining agent into the smelting furnace for the first smelting; after the magnesium ingot is completely melted, adding the preheated magnesium-nickel master alloy for the first refining; then raising the temperature, adding the preheated magnesium-gadolinium master alloy for the second refining; C) casting the alloy melt obtained in step B) to obtain cast rods; processing qualified cast rods into extruded cast rods; D) performing a first extrusion deformation treatment on the extruded cast rod; The conditions of the first extrusion deformation treatment are: extrusion temperature of 350-410°C, extrusion speed of 0.4-1.5 mm / s, and extrusion ratio of 4-5; E) subjecting the alloy obtained in step D) to a second extrusion deformation process to obtain a magnesium alloy; The conditions of the second extrusion deformation treatment are: extrusion temperature of 350-390° C., extrusion speed of 0.4-0.8 mm / s, and extrusion ratio of 6-12.

2. The preparation method according to claim 1, characterized in that: In step B), the temperature of the first smelting is 720-750°C.

3. The preparation method according to claim 1, characterized in that: In step B), the refining agent is RJ-2 solvent.

4. The preparation method according to claim 1, characterized in that: In step B), the preheating temperature of the preheated magnesium-nickel master alloy is 100-160° C.; The temperature of the first refining is 700~720℃.

5. The preparation method according to claim 1, characterized in that: In step B), the preheating temperature of the preheated magnesium-gadolinium master alloy is 100-160° C.; The temperature of the second refining is 730~780℃.

6. The preparation method according to claim 1, characterized in that: In step C), before the casting, the following treatment is further performed: passing argon gas and then standing.

7. The preparation method according to claim 6, characterized in that: The argon passing time is 5 to 15 minutes; the standing time is 15 to 20 minutes.

8. A magnesium alloy obtained by the preparation method according to any one of claims 1 to 7.

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