High-strength and high-plasticity rare earth magnesium alloy deformed material and preparation method thereof

Abstract

The invention belongs to the technical field of rare earth magnesium alloy materials, and discloses a high-strength and high-plasticity rare earth magnesium alloy deformed material which is prepared from the following raw materials in percentage by mass: 8-9.5% of Gd, 3-4.5% of Y, 2-3.5% of Zn, 0.4-0.6% of Zr, 0.3-0.6% of Ca and the balance of Mg. The invention further discloses a preparation method of the magnesium alloy deformed material. The preparation method comprises the steps of smelting and casting, homogenizing treatment, variable-speed isothermal extrusion treatment, aging treatment and the like. By adding the Ca element and adjusting the proportion of all metal elements in the alloy, the magnesium alloy deformed material shows excellent comprehensive mechanical properties, the yield strength is 416 MPa-420 MPa, the tensile strength is 471 MPa-477 MPa, and the ductility is 13.0%-13.7%.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth magnesium alloy materials, and in particular relates to a high-strength and high-plasticity rare earth magnesium alloy deformed material and a preparation method thereof. Background Art

[0002] Magnesium and magnesium alloys have the advantages of low density, high specific strength, good thermal conductivity, mechanical properties, electromagnetic shielding performance and damping performance, and are easy to recycle. They are known as the "lightest green metal structural materials in the 21st century". At the same time, my country has natural magnesium metal resource advantages. my country's magnesium ore reserves account for about 22.5% of the world's total reserves, ranking first in the world. Therefore, magnesium and magnesium alloys are highly favored in the development of lightweight automobiles. However, the crystal structure of magnesium alloys is hexagonal close-packed, with fewer slip systems that can be activated at room temperature and poor plasticity, which has become a key factor hindering the application of deformed magnesium alloys.

[0003] In the existing high-strength and high-plasticity rare earth magnesium alloys, such as the Chinese patent publication number CN115074588A invention titled "A preparation process of a high-strength and plastic rare earth magnesium alloy and a high-strength and plastic rare earth magnesium alloy", a Mg-Gd-Y-Mn-Sc high-strength rare earth magnesium alloy deformed material is disclosed. After solution treatment and pre-aging treatment, it is extruded and deformed, and then heat treated. Its yield strength can reach a tensile strength of 465MPa and an elongation of about 3.7%. However, its heat treatment process is complicated and the alloy plasticity is poor, which cannot meet the demand for high-strength magnesium alloys in the high-tech field, limiting the large-scale application of high-strength magnesium alloys. Summary of the invention

[0004] In order to solve the technical problem of low comprehensive mechanical properties of current magnesium alloy materials, the present invention provides a high-strength and high-plasticity rare earth magnesium alloy deformed material, by adding Ca element and adjusting the ratio of each metal element in the alloy, wherein the addition of Ca can not only weaken the basal texture of the alloy, promote the opening of sliding of the magnesium alloy cylindrical and conical surfaces, and improve the plastic deformation ability of the alloy, but also improve the corrosion resistance of the alloy and enhance the high-temperature oxidation resistance of the magnesium alloy. At the same time, under the auxiliary effect of Mg2Ca particle phase and Ca segregation, an ultrafine-grained magnesium alloy with weakened texture, dissolved dynamic precipitation phase and eliminated work hardening is obtained through conventional extrusion and annealing. The magnesium alloy deformed material exhibits excellent comprehensive mechanical properties, with a yield strength of 416MPa-420MPa, a tensile strength of 471MPa-477MPa, and an elongation of 13.0%-13.7%.

[0005] The technical solution of the present invention is as follows:

[0006] The invention provides a high-strength and high-plasticity rare earth magnesium alloy deformed material, which is prepared from the following raw materials in mass fraction: Gd: 8%-9.5%, Y: 3%-4.5%, Zn: 2%-3.5%, Zr: 0.4%-0.6%, Ca: 0.3%-0.6%, and the balance is Mg.

[0007] The present invention also provides a method for preparing the above-mentioned high-strength and high-plasticity rare earth magnesium alloy deformed material, comprising the following steps:

[0008] (1) Melting and casting: weighing the raw materials according to the above mass fractions, melting and casting to obtain magnesium alloy ingots;

[0009] (2) Homogenization treatment: The magnesium alloy ingot is placed at 500-520°C for 18-22 hours, then air-cooled and peeled;

[0010] (3) Variable speed isothermal extrusion treatment: preheating the magnesium alloy billet after homogenization treatment to 400-420°C, preheating the mold to 370-390°C, maintaining the temperature of the magnesium alloy billet above 400°C during the extrusion process, and extruding to obtain a rod;

[0011] (4) Aging treatment: The rod is placed at 190-210°C for 35-45 hours, then taken out for air cooling to obtain a high-strength and high-plasticity rare earth magnesium alloy deformed material.

[0012] In one embodiment of the present invention, it is also preferred that the raw materials used in step (1) are Mg ingots, Mg-30Gd master alloy, Mg-30Y master alloy, Mg-30Zr master alloy, Mg-30Ca and Zn ingots.

[0013] In one embodiment of the present invention, it is also preferred that the smelting and casting described in step (1) includes first placing the Mg ingot into the furnace for heating and melting, and passing protective gas, and when the furnace temperature rises to 740-750°C, adding Mg-30Gd intermediate alloy, Mg-30Y intermediate alloy and Zn ingot in sequence, and setting the furnace temperature to 740-750°C after keeping warm for 10 minutes, and continuing to keep warm for 15 minutes, and then adding Mg-30Zr intermediate alloy and Mg-30Ca intermediate alloy in sequence, and continuing to keep warm for 15 minutes for refining, and continuing to stir to obtain alloy liquid, and casting the alloy liquid to obtain magnesium alloy ingot.

[0014] In one embodiment of the present invention, it is also preferred that when the extrusion treatment in step (3) includes extrusion processing, the extrusion ratio is 10-13.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The invention discloses a high-strength and high-plasticity rare earth magnesium alloy deformed material. The Ca element is added and the ratio of each metal element in the alloy is adjusted. The addition of Ca can not only weaken the base surface texture of the alloy, promote the opening of sliding of the magnesium alloy cylinder and cone, and improve the plastic deformation ability of the alloy, but also improve the corrosion resistance of the alloy and enhance the high-temperature oxidation resistance of the magnesium alloy. At the same time, under the auxiliary effect of Mg2Ca particle phase and Ca segregation, an ultrafine-grained magnesium alloy with weakened texture, dissolved dynamic precipitation phase and eliminated work hardening is obtained through conventional extrusion and annealing. The magnesium alloy deformed material exhibits excellent comprehensive mechanical properties, with a yield strength of 416MPa-420MPa, a tensile strength of 471MPa-477MPa and an elongation of 13.0%-13.7%.

[0017] 1) The maximum solid solubility of Ca at the eutectic temperature is 0.82wt%, and the solid solubility is reduced to 0.38wt% at 200℃, so that a small amount of Ca can be added to the Mg-RE alloy to generate a large amount of Mg2Ca particle phase. The Mg2Ca particle phase can provide a large number of nucleation sites for dynamic recrystallization during the extrusion process, which can increase the recrystallization volume fraction on the one hand, and on the other hand, the recrystallized grains nucleated based on the PSN mechanism often have random orientations, which significantly weakens the extrusion texture. It is well known that annealing after extrusion can fully dissolve the dynamic precipitation phase formed during the extrusion process and eliminate work hardening, thereby significantly improving ductility.

[0018] 2) During the annealing process, the recrystallized grains will also grow significantly, resulting in serious strength loss. In the present invention, due to the segregation of Ca at the recrystallized grain boundary, the migration of the recrystallized grain boundary is strongly pinned, which significantly inhibits the growth of the recrystallized grains. Therefore, under the auxiliary effect of the Mg2Ca particle phase and Ca segregation, an ultrafine grain structure with weakened texture, dissolved dynamic precipitated phase, and eliminated work hardening is formed after extrusion and annealing, and excellent elongation is maintained while achieving ultra-high strength.

[0019] 3) The amount of RE added in ultra-high strength Mg-RE alloy is generally around 15wt%, and the expensive price of RE element undoubtedly significantly increases the alloy cost. The present invention reduces the total amount of Gd and Y to around 13wt%, and only adds a trace amount of Ca element to achieve a strength comparable to that of a high RE content Mg-RE alloy, while also maintaining excellent elongation. Ca, as an alkaline earth element, is relatively cheap, so the present invention not only solves the technical bottleneck of the inverted relationship between the strength and toughness of magnesium alloys, but also has certain economic benefits. In addition, the present invention adopts conventional extrusion and annealing treatments, which are easy to implement in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1Microstructure characteristic diagram of the extruded deformed material of the high-strength and high-plasticity rare earth magnesium alloy of Example 1 of the present invention;

[0021] Figure 2 Microstructure characteristic diagram of the extruded magnesium alloy material of Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0023] Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention, so the present invention is not limited to the specific implementation disclosed below.

[0024] A high-strength and high-plasticity rare earth magnesium alloy deformed material according to an embodiment of the present invention comprises the following steps:

[0025] (1) Selection of raw materials: The raw materials used for the alloy are Mg ingots, Mg-30Gd master alloy, Mg-30Y master alloy, Mg-30Zr master alloy, Mg-30Ca and Zn ingots.

[0026] (2) First, the Mg ingot is placed in a furnace for heating and melting, and a protective gas is passed through. When the furnace temperature rises to 740-750°C, Mg-30Gd master alloy, Mg-30Y master alloy and Zn ingot are added in sequence, and the temperature is kept at 10 minutes. The furnace temperature is set to 740-750°C and the temperature is kept at 15 minutes. Then, Mg-30Zr master alloy and Mg-30Ca master alloy are added in sequence, and the temperature is kept at 15 minutes for refining and stirring. After the smelting is completed, a molten alloy is obtained; then, the molten alloy is cast into a magnesium alloy ingot.

[0027] (3) The magnesium alloy ingot is homogenized by keeping the temperature at 500°C-520°C for 18h-22h, followed by air cooling and peeling. The homogenization process is completed.

[0028] (4) During the variable speed isothermal extrusion process, the magnesium alloy ingot after homogenization treatment is preheated to 400℃-420℃, and the mold is preheated to 370-390℃ to ensure that the temperature is maintained above 400℃ during the extrusion process. During the extrusion process, the extrusion ratio is controlled at 10-13.

[0029] (5) After the isothermal extrusion process is completed, an aging treatment is performed, and the process is as follows: the extruded rod is kept at 190-210°C for 35-45 hours, and then taken out for air cooling.

[0030] The profile variable speed isothermal extrusion technology adopted in the present invention controls the extrusion speed in real time based on process simulation, forms a near-isothermal forming environment, and obtains profiles that meet the index performance requirements.

[0031] Example 1

[0032] A high-strength and high-plasticity rare earth magnesium alloy deformed material according to embodiment 1 of the present invention comprises the following steps:

[0033] (1) In terms of mass percentage, the element composition of the high-strength and high-plasticity rare earth magnesium alloy deformed material of Example 1 includes: Gd: 8.0%, Y: 3.0%, Zn: 2.0%, Zr: 0.4%, Ca: 0.3%, and the balance is Mg.

[0034] (2) The method for preparing the high-strength and high-plasticity rare earth magnesium alloy deformed material of Example 1 includes the following steps:

[0035] The total weight of each batch is 5kg. When batching, the burnout ratio is adjusted according to the type and content range of the alloying elements. The raw materials used are: pure Mg ingots, Mg-30Gd master alloys, Mg-30Y master alloys, pure Zn ingots, Mg-30Zr master alloys and Mg-30Ca master alloys. Bake the batches and molds before smelting. Set the initial furnace temperature to 710℃, put pure Mg into the furnace and heat it up with the furnace, and pass the protective gas (N2+SF6). When the furnace temperature rises to 710℃, the pure Mg ingot begins to melt after about 10min-15min, and the furnace temperature drops to 670℃. When the melt temperature rises to 750℃ again, add Mg-30Gd master alloy, Mg-30Y master alloy and pure Zn ingot. After keeping warm for 10min, set the furnace temperature to 750℃, continue to keep warm for 15min, then put Mg-30Zr master alloy and Mg-30Ca master alloy alloying elements, and continue to keep warm for 15min. Then, refining and stirring are carried out. The refining agent is 1.2% of the total weight of the ingredients, that is, 0.06kg. Stirring can be carried out in the following directions: stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times. Take out a small ingot from the melt to measure the direct reading spectrum. If the composition meets the standard, let the melt stand for 45 minutes before casting. If the composition does not meet the standard, add material until the final direct reading composition is close to the nominal composition.

[0036] The magnesium alloy ingot was placed in a muffle furnace at 500°C for 20 hours, followed by air cooling, peeling, and homogenization.

[0037] During the variable speed isothermal extrusion process, the magnesium alloy ingot after homogenization treatment is preheated to 410°C, and the mold is preheated to 380°C to ensure that the temperature is maintained at around 400°C during the extrusion process. During the extrusion process, the extrusion ratio is controlled at 11.

[0038] After extrusion treatment, the extruded rod was placed in a muffle furnace at 200°C for 40 h and then taken out for air cooling.

[0039] At room temperature, according to the test requirements of GB-T 228-2002_Room Temperature Tensile Test Method for Metallic Materials, the yield strength of the deformed magnesium alloy was measured by a tensile mechanical properties testing machine to be 419 MPa, the tensile strength was 471 MPa, and the elongation was 13.7%.

[0040] The mechanical property tests of the following Examples 2 to 8 and Comparative Examples 1 to 2 were all conducted in accordance with GB-T228-2002_Metallic Materials Room Temperature Tensile Test Method.

[0041] Example 2

[0042] A high-strength and high-plasticity rare earth magnesium alloy deformed material of this embodiment 2, the preparation method of which comprises the following steps:

[0043] (1) In terms of mass percentage, the element composition of the high-strength and high-plasticity rare earth magnesium alloy deformed material of Example 2 includes: Gd: 9.5%, Y: 4.5%, Zn: 3.5%, Zr: 0.6%, Ca: 0.6%, and the balance is Mg.

[0044] (2) The method for preparing the high-strength and high-plasticity rare earth magnesium alloy deformed material of Example 2 includes the following steps:

[0045] The total weight of each batch is 5kg. When batching, the burnout ratio is adjusted according to the type and content range of the alloying elements. The raw materials used are: pure Mg ingot, Mg-30Gd master alloy, Mg-30Y master alloy, pure Zn ingot, Mg-30Zr master alloy and Mg-30Ca master alloy. Bake the batch and mold before smelting. Set the initial furnace temperature to 710℃, put the pure Mg ingot into the furnace and heat it up with the furnace, and pass the protective gas (N2+SF6). When the furnace temperature rises to 710℃, the pure Mg ingot begins to melt after about 10min-15min, and the furnace temperature is reduced to 670℃. When the melt temperature rises to 750℃ again, add Mg-30Gd master alloy, Mg-30Y master alloy and pure Zn ingot. After keeping warm for 10min, set the furnace temperature to 750℃, continue to keep warm for 15min, then put Mg-30Zr master alloy and Mg-30Ca master alloy alloying elements, and continue to keep warm for 15min. Then, refining and stirring are carried out. The refining agent is 1.2% of the total weight of the ingredients, that is, 0.06kg. Stirring can be carried out in the following directions: stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times. Take out a small ingot from the melt to measure the direct reading spectrum. If the composition meets the standard, let the melt stand for 45 minutes before casting. If the composition does not meet the standard, add material until the final direct reading composition is close to the nominal composition.

[0046] The magnesium alloy ingot was placed in a muffle furnace at 500°C for 20 hours, followed by air cooling, peeling, and homogenization.

[0047] During the variable speed isothermal extrusion process, the magnesium alloy ingot after homogenization treatment is preheated to 410°C, and the mold is preheated to 380°C to ensure that the temperature is maintained at around 400°C during the extrusion process. During the extrusion process, the extrusion ratio is controlled at 11.

[0048] After extrusion treatment, the extruded rod was placed in a muffle furnace at 200°C for 40 h and then taken out for air cooling.

[0049] At room temperature, the yield strength of the deformed magnesium alloy material was measured by a tensile mechanical properties testing machine to be 416 MPa, the tensile strength was 477 MPa, and the elongation was 13.0%.

[0050] Example 3

[0051] A high-strength and high-plasticity rare earth magnesium alloy deformed material of this embodiment 3, the preparation method of which comprises the following steps:

[0052] (1) In terms of mass percentage, the element composition of the high-strength and high-plasticity rare earth magnesium alloy deformed material of Example 3 includes: Gd: 8%, Y: 3%, Zn: 2%, Zr: 0.4%, Ca: 0.6%, and the balance is Mg.

[0053] (2) The method for preparing the high-strength and high-plasticity rare earth magnesium alloy deformed material of Example 3 includes the following steps:

[0054] The total weight of each batch is 5kg. When batching, the burnout ratio is adjusted according to the type and content range of the alloying elements. The raw materials used are: pure Mg ingot, Mg-30Gd master alloy, Mg-30Y master alloy, pure Zn ingot, Mg-30Zr master alloy and Mg-30Ca master alloy. Bake the batch and mold before smelting. Set the initial furnace temperature to 710℃, put the pure Mg ingot into the furnace and heat it up with the furnace, and pass the protective gas (N2+SF6). When the furnace temperature rises to 710℃, the pure Mg ingot begins to melt after about 10min-15min, and the furnace temperature drops to 670℃. When the melt temperature rises to 745℃ again, add Mg-30Gd master alloy, Mg-30Y master alloy and pure Zn ingot. After keeping warm for 10min, set the furnace temperature to 750℃, continue to keep warm for 15min, then put Mg-30Zr master alloy and Mg-30Ca master alloy alloying elements, and continue to keep warm for 15min. Then, refining and stirring are carried out. The refining agent is 1.2% of the total weight of the ingredients, that is, 0.06kg. Stirring can be carried out in the following directions: stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times. Take out a small ingot from the melt to measure the direct reading spectrum. If the composition meets the standard, let the melt stand for 45 minutes before casting. If the composition does not meet the standard, add material until the final direct reading composition is close to the nominal composition.

[0055] The magnesium alloy ingot was placed in a muffle furnace at 510°C for 20 hours, followed by air cooling, peeling, and homogenization.

[0056] During the variable speed isothermal extrusion process, the magnesium alloy ingot after homogenization treatment is preheated to 420°C, and the mold is preheated to 380°C to ensure that the temperature is maintained at around 400°C during the extrusion process. During the extrusion process, the extrusion ratio is controlled at 10.

[0057] After extrusion treatment, the extruded rods were placed in a muffle furnace at 190°C for 45 h and then taken out for air cooling.

[0058] At room temperature, the yield strength of the deformed magnesium alloy material was measured by a tensile mechanical properties testing machine to be 419 MPa, the tensile strength was 475 MPa, and the elongation was 13.6%.

[0059] Example 4

[0060] A high-strength and high-plasticity rare earth magnesium alloy deformed material of this embodiment 4, the preparation method of which comprises the following steps:

[0061] (1) In terms of mass percentage, the element composition of the high-strength and high-plasticity rare earth magnesium alloy deformed material of Example 4 includes: Gd: 8%, Y: 3%, Zn: 2%, Zr: 0.4%, Ca: 0.4%, and the balance is Mg.

[0062] (2) The method for preparing the high-strength and high-plasticity rare earth magnesium alloy deformed material of Example 4 includes the following steps:

[0063] The total weight of each batch is 5kg. When batching, the burnout ratio is adjusted according to the type and content range of the alloying elements. The raw materials used are: pure Mg ingot, Mg-30Gd master alloy, Mg-30Y master alloy, pure Zn ingot, Mg-30Zr master alloy and Mg-30Ca master alloy. Bake the batch and mold before smelting. Set the initial furnace temperature to 710℃, put the pure Mg ingot into the furnace and heat it up with the furnace, and pass the protective gas (N2+SF6). When the furnace temperature rises to 710℃, the pure Mg ingot begins to melt after about 10min-15min, and the furnace temperature drops to 670℃. When the melt temperature rises to 745℃ again, add Mg-30Gd master alloy, Mg-30Y master alloy and pure Zn ingot. After keeping warm for 10min, set the furnace temperature to 750℃, continue to keep warm for 15min, then put Mg-30Zr master alloy and Mg-30Ca master alloy alloying elements, and continue to keep warm for 15min. Then, refining and stirring are carried out. The refining agent is 1.2% of the total weight of the ingredients, that is, 0.06kg. Stirring can be carried out in the following directions: stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times. Take out a small ingot from the melt to measure the direct reading spectrum. If the composition meets the standard, let the melt stand for 45 minutes before casting. If the composition does not meet the standard, add material until the final direct reading composition is close to the nominal composition.

[0064] The magnesium alloy ingot was placed in a muffle furnace at 510°C for 20 hours, followed by air cooling, peeling, and homogenization.

[0065] During the variable speed isothermal extrusion process, the magnesium alloy ingot after homogenization treatment is preheated to 420°C, and the mold is preheated to 380°C to ensure that the temperature is maintained at around 400°C during the extrusion process. During the extrusion process, the extrusion ratio is controlled at 13.

[0066] After extrusion treatment, the extruded rods were placed in a muffle furnace at 210°C for 38 h and then taken out for air cooling.

[0067] At room temperature, the yield strength of the deformed magnesium alloy material was measured by a tensile mechanical properties testing machine to be 417 MPa, the tensile strength was 473 MPa, and the elongation was 13.2%.

[0068] Example 5

[0069] A high-strength and high-plasticity rare earth magnesium alloy deformed material of this embodiment 5, the preparation method of which comprises the following steps:

[0070] (1) In terms of mass percentage, the element composition of the high-strength and high-plasticity rare earth magnesium alloy deformed material of Example 5 includes: Gd: 9.5%, Y: 4.5%, Zn: 3.5%, Zr: 0.6%, Ca: 0.3%, and the balance is Mg.

[0071] (2) The method for preparing the high-strength and high-plasticity rare earth magnesium alloy deformed material of Example 5 includes the following steps:

[0072] The total weight of each batch is 5kg. When batching, the burnout ratio is adjusted according to the type and content range of the alloying elements. The raw materials used are: pure Mg ingot, Mg-30Gd master alloy, Mg-30Y master alloy, pure Zn ingot, Mg-30Zr master alloy and Mg-30Ca master alloy. Bake the batch and mold before smelting. Set the initial furnace temperature to 710℃, put the pure Mg ingot into the furnace and heat it up with the furnace, and pass the protective gas (N2+SF6). When the furnace temperature rises to 710℃, the pure Mg ingot begins to melt after about 10min-15min, and the furnace temperature drops to 670℃. When the melt temperature rises to 745℃ again, add Mg-30Gd master alloy, Mg-30Y master alloy and pure Zn ingot. After keeping warm for 10min, set the furnace temperature to 750℃, continue to keep warm for 15min, then put Mg-30Zr master alloy and Mg-30Ca master alloy alloying elements, and continue to keep warm for 15min. Then, refining and stirring are carried out. The refining agent is 1.2% of the total weight of the ingredients, that is, 0.06kg. Stirring can be carried out in the following directions: stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times. Take out a small ingot from the melt to measure the direct reading spectrum. If the composition meets the standard, let the melt stand for 45 minutes before casting. If the composition does not meet the standard, add material until the final direct reading composition is close to the nominal composition.

[0073] The magnesium alloy ingot was placed in a muffle furnace at 510°C for 20 hours, followed by air cooling, peeling, and homogenization.

[0074] During the variable speed isothermal extrusion process, the magnesium alloy ingot after homogenization treatment is preheated to 420°C, and the mold is preheated to 380°C to ensure that the temperature is maintained at around 400°C during the extrusion process. During the extrusion process, the extrusion ratio is controlled at 11.

[0075] After extrusion treatment, the extruded rods were placed in a muffle furnace at 205°C for 40 h and then taken out for air cooling.

[0076] At room temperature, the yield strength of the deformed magnesium alloy material was measured by a tensile mechanical properties testing machine to be 420 MPa, the tensile strength was 474 MPa, and the elongation was 13.3%.

[0077] Example 6

[0078] A high-strength and high-plasticity rare earth magnesium alloy deformed material according to Embodiment 6, wherein the preparation method thereof comprises the following steps:

[0079] (1) In terms of mass percentage, the element composition of the high-strength and high-plasticity rare earth magnesium alloy deformed material of Example 6 includes: Gd: 9.5%, Y: 4.5%, Zn: 3.5%, Zr: 0.6%, Ca: 0.5%, and the balance is Mg.

[0080] (2) The method for preparing the high-strength and high-plasticity rare earth magnesium alloy deformed material of Example 6 includes the following steps:

[0081] The total weight of each batch is 5kg. When batching, the burnout ratio is adjusted according to the type and content range of the alloying elements. The raw materials used are: pure Mg ingot, Mg-30Gd master alloy, Mg-30Y master alloy, pure Zn ingot, Mg-30Zr master alloy and Mg-30Ca master alloy. Bake the batch and mold before smelting. Set the initial furnace temperature to 710℃, put the pure Mg ingot into the furnace and heat it up with the furnace, and pass the protective gas (N2+SF6). When the furnace temperature rises to 710℃, the pure Mg ingot begins to melt after about 10min-15min, and the furnace temperature drops to 670℃. When the melt temperature rises to 745℃ again, add Mg-30Gd master alloy, Mg-30Y master alloy and pure Zn ingot. After keeping warm for 10min, set the furnace temperature to 750℃, continue to keep warm for 15min, then put Mg-30Zr master alloy and Mg-30Ca master alloy alloying elements, and continue to keep warm for 15min. Then, refining and stirring are carried out. The refining agent is 1.2% of the total weight of the ingredients, that is, 0.06kg. Stirring can be carried out in the following directions: stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times. Take out a small ingot from the melt to measure the direct reading spectrum. If the composition meets the standard, let the melt stand for 45 minutes before casting. If the composition does not meet the standard, add material until the final direct reading composition is close to the nominal composition.

[0082] The magnesium alloy ingot was placed in a muffle furnace at 510°C for 20 hours, followed by air cooling, peeling, and homogenization.

[0083] During the variable speed isothermal extrusion process, the magnesium alloy ingot after homogenization treatment is preheated to 420°C, and the mold is preheated to 380°C to ensure that the temperature is maintained at around 400°C during the extrusion process. During the extrusion process, the extrusion ratio is controlled at 12.

[0084] After extrusion treatment, the extruded rods were placed in a muffle furnace at 190°C for 45 h and then taken out for air cooling.

[0085] At room temperature, the yield strength of the deformed magnesium alloy material was measured by a tensile mechanical properties testing machine to be 419 MPa, the tensile strength was 476 MPa, and the elongation was 13.5%.

[0086] Example 7

[0087] A high-strength and high-plasticity rare earth magnesium alloy deformed material according to Embodiment 7, wherein the preparation method thereof comprises the following steps:

[0088] (1) In terms of mass percentage, the element composition of the high-strength and high-plasticity rare earth magnesium alloy deformed material of Example 7 includes: Gd: 9%, Y: 4%, Zn: 3%, Zr: 0.5%, Ca: 0.4%, and the balance is Mg.

[0089] (2) The method for preparing the high-strength and high-plasticity rare earth magnesium alloy deformed material of Example 7 includes the following steps:

[0090] The total weight of each batch is 5kg. When batching, the burnout ratio is adjusted according to the type and content range of the alloying elements. The raw materials used are: pure Mg ingot, Mg-30Gd master alloy, Mg-30Y master alloy, pure Zn ingot, Mg-30Zr master alloy and Mg-30Ca master alloy. Bake the batch and mold before smelting. Set the initial furnace temperature to 710℃, put the pure Mg ingot into the furnace and heat it up with the furnace, and pass the protective gas (N2+SF6). When the furnace temperature rises to 710℃, the pure Mg ingot begins to melt after about 10min-15min, and the furnace temperature drops to 670℃. When the melt temperature rises to 745℃ again, add Mg-30Gd master alloy, Mg-30Y master alloy and pure Zn ingot. After keeping warm for 10min, set the furnace temperature to 750℃, continue to keep warm for 15min, then put Mg-30Zr master alloy and Mg-30Ca master alloy alloying elements, and continue to keep warm for 15min. Then, refining and stirring are carried out. The refining agent is 1.2% of the total weight of the ingredients, that is, 0.06kg. Stirring can be carried out in the following directions: stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times. Take out a small ingot from the melt to measure the direct reading spectrum. If the composition meets the standard, let the melt stand for 45 minutes before casting. If the composition does not meet the standard, add material until the final direct reading composition is close to the nominal composition.

[0091] The magnesium alloy ingot was placed in a muffle furnace at 510°C for 20 hours, followed by air cooling, peeling, and homogenization.

[0092] During the variable speed isothermal extrusion process, the magnesium alloy ingot after homogenization treatment is preheated to 420°C, and the mold is preheated to 380°C to ensure that the temperature is maintained at around 400°C during the extrusion process. During the extrusion process, the extrusion ratio is controlled at 12.

[0093] After extrusion treatment, the extruded rods were placed in a muffle furnace at 205°C for 38 h and then taken out for air cooling.

[0094] At room temperature, the yield strength of the magnesium alloy deformed material was measured by a tensile mechanical properties testing machine to be 419 MPa, the tensile strength was 476 MPa, and the elongation was 13.4%.

[0095] Example 8

[0096] A high-strength and high-plasticity rare earth magnesium alloy deformed material according to Embodiment 8, wherein the preparation method comprises the following steps:

[0097] (1) In terms of mass percentage, the element composition of the high-strength and high-plasticity rare earth magnesium alloy deformed material of Example 8 includes: Gd: 8%, Y: 3%, Zn: 2%, Zr: 0.6%, Ca: 0.6%, and the balance is Mg.

[0098] (2) The method for preparing the high-strength and high-plasticity rare earth magnesium alloy deformed material of Example 8 includes the following steps:

[0099] The total weight of each batch is 5kg. When batching, the burnout ratio is adjusted according to the type and content range of the alloying elements. The raw materials used are: pure Mg ingot, Mg-30Gd master alloy, Mg-30Y master alloy, pure Zn ingot, Mg-30Zr master alloy and Mg-30Ca master alloy. Bake the batch and mold before smelting. Set the initial furnace temperature to 710℃, put the pure Mg ingot into the furnace and heat it up with the furnace, and pass the protective gas (N2+SF6). When the furnace temperature rises to 710℃, the pure Mg ingot begins to melt after about 10min-15min, and the furnace temperature is reduced to 670℃. When the melt temperature rises to 750℃ again, add Mg-30Gd master alloy, Mg-30Y master alloy and pure Zn ingot. After keeping warm for 10min, set the furnace temperature to 750℃, continue to keep warm for 15min, then put Mg-30Zr master alloy and Mg-30Ca master alloy alloying elements, and continue to keep warm for 15min. Then, refining and stirring are carried out. The refining agent is 1.2% of the total weight of the ingredients, that is, 0.06kg. Stirring can be carried out in the following directions: stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times. Take out a small ingot from the melt to measure the direct reading spectrum. If the composition meets the standard, let the melt stand for 45 minutes before casting. If the composition does not meet the standard, add material until the final direct reading composition is close to the nominal composition.

[0100] The magnesium alloy ingot was placed in a muffle furnace at 500°C for 20 hours, followed by air cooling, peeling, and homogenization.

[0101] During the variable speed isothermal extrusion process, the magnesium alloy ingot after homogenization treatment is preheated to 410°C, and the mold is preheated to 380°C to ensure that the temperature is maintained at around 400°C during the extrusion process. During the extrusion process, the extrusion ratio is controlled at 12.

[0102] After extrusion treatment, the extruded rod was placed in a muffle furnace at 200°C for 40 h and then taken out for air cooling.

[0103] At room temperature, the yield strength of the magnesium alloy deformed material was measured by a tensile mechanical properties testing machine to be 417 MPa, the tensile strength was 477 MPa, and the elongation was 13.2%.

[0104] Comparative Example 1

[0105] The preparation method of the magnesium alloy material of Comparative Example 1 comprises the following steps:

[0106] (1) In terms of mass percentage, the element composition of the rare earth magnesium alloy material of Comparative Example 1 includes: Gd: 8.0%, Y: 3.0%, Zn: 2.0%, Zr: 0.6%, and the balance is Mg.

[0107] (2) The method for preparing the rare earth magnesium alloy material of Comparative Example 1 comprises the following steps:

[0108] The total weight of each batch is 5kg. When batching, the burnout ratio is adjusted according to the type and content range of the alloying elements. The raw materials used are: pure Mg ingot, Mg-30Gd master alloy, Mg-30Y master alloy, pure Zn ingot, and Mg-30Zr master alloy. Bake the batch and mold before smelting. Set the initial furnace temperature to 710℃, put the pure Mg ingot into the furnace and heat it up with the furnace, and pass the protective gas (N2+SF6). When the furnace temperature rises to 710℃, the pure Mg ingot begins to melt after about 10min-15min, and the furnace temperature drops to 670℃. When the melt temperature rises to 750℃ again, add Mg-30Gd master alloy, Mg-30Y master alloy and pure Zn ingot. After keeping warm for 10min, set the furnace temperature to 750℃, continue to keep warm for 15min, then put in Mg-30Zr master alloy, and continue to keep warm for 15min. Then, refining and stirring are carried out. The refining agent is 1.2% of the total weight of the ingredients, that is, 0.06kg. Stirring can be carried out in the following directions: stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times. Take out a small ingot from the melt to measure the direct reading spectrum. If the composition meets the standard, let the melt stand for 45 minutes before casting. If the composition does not meet the standard, add material until the final direct reading composition is close to the nominal composition.

[0109] The magnesium alloy ingot was placed in a muffle furnace at 500°C for 20 hours, followed by air cooling, peeling, and homogenization.

[0110] During the variable speed isothermal extrusion process, the magnesium alloy ingot after homogenization treatment is preheated to 410°C, and the mold is preheated to 380°C to ensure that the temperature is maintained at around 400°C during the extrusion process. During the extrusion process, the extrusion ratio is controlled at 11.

[0111] After extrusion treatment, the extruded rod was placed in a muffle furnace at 200°C for 40 h and then taken out for air cooling.

[0112] At room temperature, the alloy yield strength of the magnesium alloy deformed material was measured by a tensile mechanical properties testing machine to be 350 MPa, the tensile strength was 392 MPa, and the elongation was 8.7%.

[0113] Comparative Example 2

[0114] The preparation method of the magnesium alloy material of Comparative Example 2 comprises the following steps:

[0115] (1) In terms of mass percentage, the element composition of the rare earth magnesium alloy material of Comparative Example 2 includes: Gd: 8.0%, Y: 3.0%, Zn: 2.0%, Zr: 0.6%, Ca: 0.8%, and the balance is Mg.

[0116] (2) The preparation method of the rare earth magnesium alloy material of this comparative example 2 comprises the following steps:

[0117] The total weight of each batch is 5kg. When batching, the burnout ratio is adjusted according to the type and content range of the alloying elements. The raw materials used are: pure Mg ingot, Mg-30Gd master alloy, Mg-30Y master alloy, pure Zn ingot, Mg-30Zr master alloy and Mg-30Ca master alloy. Bake the batch and mold before smelting. Set the initial furnace temperature to 710℃, put the pure Mg ingot into the furnace and heat it up with the furnace, and pass the protective gas (N2+SF6). When the furnace temperature rises to 710℃, the pure Mg ingot begins to melt after about 10min-15min, and the furnace temperature is reduced to 670℃. When the melt temperature rises to 750℃ again, add Mg-30Gd master alloy, Mg-30Y master alloy and pure Zn ingot. After keeping warm for 10min, set the furnace temperature to 750℃, continue to keep warm for 15min, then put the alloying elements of Mg-30Zr master alloy and Mg-30Ca master alloy, and continue to keep warm for 15min. Then, refining and stirring are carried out. The refining agent is 1.2% of the total weight of the ingredients, that is, 0.06kg. Stirring can be carried out in the following directions: stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times, stirring up and down for about 60 times, stirring left and right for about 100 times. Take out a small ingot from the melt to measure the direct reading spectrum. If the composition meets the standard, let the melt stand for 45 minutes before casting. If the composition does not meet the standard, add material until the final direct reading composition is close to the nominal composition.

[0118] The magnesium alloy ingot was placed in a muffle furnace at 500°C for 20 hours, followed by air cooling, peeling, and homogenization.

[0119] During the variable speed isothermal extrusion process, the magnesium alloy ingot after homogenization treatment is preheated to 410°C, and the mold is preheated to 380°C to ensure that the temperature is maintained at around 400°C during the extrusion process. During the extrusion process, the extrusion ratio is controlled at 11.

[0120] After extrusion treatment, the extruded rod was placed in a muffle furnace at 200°C for 40 h and then taken out for air cooling.

[0121] At room temperature, the alloy yield strength of the magnesium alloy deformed material was measured by a tensile mechanical properties testing machine to be 353 MPa, the tensile strength was 425 MPa, and the elongation was 9.1%.

[0122] The component contents of Examples 1 to 8 are all within the scope of the component contents of the present invention, wherein, in Comparative Example 1, no Ca element is added, and in Comparative Example 2, an excessive amount of Ca element is added, and the rest are the same as in Example 8. As shown in Table 1, it can be seen from the room temperature tensile mechanical property test results that the comprehensive mechanical properties of Examples 1 to 8 are significantly higher than those of Comparative Examples 1 to 2. In the field of magnesium alloy materials, it is difficult to increase the absolute mechanical strength after reaching a limit value, especially the yield strength, tensile strength and elongation are all increased simultaneously. In the present invention, the Ca element is added to the Mg-Gd-Y-Zn-Zr alloy, and the ratio of each metal element in the Mg-Gd-Y-Zn-Zr alloy is adjusted. Compared with comparative examples 1 and 2, the yield strength is increased by nearly 70MPa, the tensile strength is increased by nearly 50MPa, and the elongation is increased by nearly 5%. Therefore, the magnesium alloy deformed material of the present invention exhibits excellent comprehensive mechanical properties, with a yield strength of 416MPa-420MPa, a tensile strength of 471MPa-477MPa, and an elongation of 13.0%-13.7%. Therefore, in the ultra-high strength rare earth magnesium alloy deformation of the present invention, the addition of Ca element in the Mg-Gd-Y-Zn-Zr series rare earth deformed magnesium alloy can significantly improve the comprehensive mechanical properties of the material, and the absolute strength is significantly improved.

[0123] Table 1 Room temperature mechanical properties of the embodiments and comparative examples

[0124] Serial number Tensile strength(MPa) Yield strength(MPa) Elongation(%) Example 1 471 419 13.7 Example 2 477 416 13 Example 3 475 419 13.6 Example 4 473 417 13.2 Example 5 474 420 13.3 Example 6 476 419 13.5 Example 7 476 419 13.4 Example 8 477 417 13.2 Comparative Example 1 392 350 8.7 Comparative Example 2 425 353 9.1

[0125] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high-strength and high-plasticity rare earth magnesium alloy deformed material, characterized in that: It is made from the following raw materials in mass fraction: Gd: 8%-9.5%, Y: 3%-4.5%, Zn: 2%-3.5%, Zr: 0.4%-0.6%, Ca: 0.3%-0.6%, the balance is Mg.

2. A method for preparing a high-strength and high-plasticity rare earth magnesium alloy deformed material as claimed in claim 1, characterized in that: The following steps are involved: (1) Melting and casting: weighing raw materials according to the mass fraction of claim 1, melting and casting to obtain a magnesium alloy ingot; (2) Homogenization treatment: The magnesium alloy ingot is placed at 500-520°C for 18-22 hours, then air-cooled and peeled; (3) Variable speed isothermal extrusion treatment: preheating the magnesium alloy billet after homogenization treatment to 400-420°C, preheating the mold to 370-390°C, maintaining the temperature of the magnesium alloy billet above 400°C during the extrusion process, and extruding to obtain a rod; (4) Aging treatment: The rod is placed at 190-210°C for 35-45 hours, then taken out for air cooling to obtain a high-strength and high-plasticity rare earth magnesium alloy deformed material.

3. The method for preparing a high-strength and high-plasticity rare earth magnesium alloy deformed material according to claim 2, characterized in that: The raw materials used in step (1) are Mg ingots, Mg-30Gd master alloy, Mg-30Y master alloy, Mg-30Zr master alloy, Mg-30Ca and Zn ingots.

4. The method for preparing a high-strength and high-plasticity rare earth magnesium alloy deformed material according to claim 3, characterized in that: The smelting and casting described in step (1) includes first placing the Mg ingot into a furnace for heating and melting, and passing a protective gas, and when the furnace temperature rises to 740-750°C, adding Mg-30Gd master alloy, Mg-30Y master alloy and Zn ingot in sequence, and setting the furnace temperature to 740-750°C after keeping warm for 10 minutes, and continuing to keep warm for 15 minutes, and then adding Mg-30Zr master alloy and Mg-30Ca master alloy in sequence, and continuing to keep warm for 15 minutes for refining, and continuing to stir to obtain alloy liquid, and casting the alloy liquid to obtain a magnesium alloy ingot.

5. The method for preparing a high-strength and high-plasticity rare earth magnesium alloy deformed material according to claim 2, characterized in that: The extrusion treatment in step (3) includes an extrusion process in which the extrusion ratio is 10-13.

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