CN117448641A - Ultrahigh-strength corrosion-resistant multielement low-alloyed magnesium alloy and preparation method thereof - Google Patents
Ultrahigh-strength corrosion-resistant multielement low-alloyed magnesium alloy and preparation method thereof Download PDFInfo
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- 229910000861 Mg alloy Inorganic materials 0.000 title claims abstract description 130
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- 238000005260 corrosion Methods 0.000 title claims abstract description 82
- 238000002360 preparation method Methods 0.000 title abstract description 32
- 239000000956 alloy Substances 0.000 claims abstract description 176
- 238000010438 heat treatment Methods 0.000 claims abstract description 49
- 239000011777 magnesium Substances 0.000 claims abstract description 45
- 238000012545 processing Methods 0.000 claims abstract description 36
- 238000000034 method Methods 0.000 claims abstract description 34
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 23
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims abstract description 22
- 239000012535 impurity Substances 0.000 claims abstract description 17
- 238000003723 Smelting Methods 0.000 claims abstract description 16
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- 229910045601 alloy Inorganic materials 0.000 claims description 167
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- 238000005242 forging Methods 0.000 claims description 7
- 238000003754 machining Methods 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- 239000002893 slag Substances 0.000 claims description 6
- 239000002904 solvent Substances 0.000 claims description 6
- 238000009749 continuous casting Methods 0.000 claims description 4
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- 229910052688 Gadolinium Inorganic materials 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
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- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 1
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- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
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- 239000003063 flame retardant Substances 0.000 description 1
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 description 1
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- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
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- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 230000001954 sterilising effect Effects 0.000 description 1
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- SFZCNBIFKDRMGX-UHFFFAOYSA-N sulfur hexafluoride Chemical compound FS(F)(F)(F)(F)F SFZCNBIFKDRMGX-UHFFFAOYSA-N 0.000 description 1
- 229960000909 sulfur hexafluoride Drugs 0.000 description 1
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- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C23/00—Alloys based on magnesium
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y40/00—Manufacture or treatment of nanostructures
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
- C22C1/03—Making non-ferrous alloys by melting using master alloys
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C23/00—Alloys based on magnesium
- C22C23/04—Alloys based on magnesium with zinc or cadmium as the next major constituent
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/06—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of magnesium or alloys based thereon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C2200/00—Crystalline structure
Abstract
An ultra-high-strength corrosion-resistant multielement low-alloyed magnesium alloy and a preparation method thereof, wherein the magnesium alloy comprises the following chemical components in percentage by mass: 0.2 to 1.8 percent of Cu, 0.3 to 2.0 percent of Zn, 0.15 to 0.7 percent of Ca, 0.2 to 0.8 percent of Mn, less than or equal to 0.05 percent of impurity content and the balance of Mg, wherein the content of Zn is not lower than the content of Cu. By multi-element microalloying, smelting, heat treatment and deformation processing, a large amount of in-situ endogenous nano phase is introduced into the magnesium base material, and Ca is constructed at the grain boundary and subgrain boundary,And a segregation structure formed by one or more elements of Cu, mn and Zn, wherein Zn and Ca are dissolved in the matrix. The prepared magnesium alloy material has low cost, simple processing technique and low minimum corrosion rate of 0.5mL/cm 2 And/d, the tensile yield strength can reach 545MPa, and the elongation is about 10%.
Description
Technical Field
The invention relates to the field of metal materials and metal material processing, in particular to a preparation technology of an ultra-high-strength corrosion-resistant multi-element low-alloyed magnesium alloy.
Background
The magnesium alloy is used as the lightest metal structural material for the current engineering structure, has the advantages of higher specific strength and specific rigidity, good anti-magnetic interference, excellent damping and shock absorption performance, high thermal conductivity, easy recycling, environmental friendliness and the like, has a huge application prospect in the fields of aerospace, military equipment, transportation equipment manufacturing, 3C products, biomedicine and the like, and becomes one of the metal materials with the most development potential in the 21 st century. The ultrahigh-strength magnesium alloy material is an advanced base material for supporting continuous upgrading and development of high-end equipment such as aviation, aerospace, new generation weapon equipment, high-speed trains, new energy automobiles and the like. The development and application of ultrahigh-strength wrought magnesium alloy in China are in the front of the world, ultrahigh-strength magnesium alloy materials and toughening wrought processing technology thereof are main directions of development in the field of magnesium alloy, and the quantity of the ultrahigh-strength magnesium alloy materials replacing similar common materials is expected to exceed 20% by 2035. However, from the perspective of further expanding the application of magnesium alloy materials, the existing high-strength magnesium alloy materials have obvious defects in specific strength, specific rigidity, fracture toughness, corrosion resistance and the like, so that the magnesium alloy materials are severely restricted in the application of the fields and the improvement of the competitiveness of terminal products, and are development problems to be solved currently. The development and utilization of the ultra-high strength corrosion-resistant magnesium alloy are attractive, and meanwhile, great challenges exist.
In recent years, a great deal of research has been done to prepare high strength and resistance by various methodsThe magnesium-etched alloy includes adding great amount of RE element and adopting powder metallurgy, large deformation, etc. Some high-strength magnesium alloys are developed successively in China. For example, chinese patent CN111254333A discloses a multi-element high-strength corrosion-resistant wrought magnesium alloy and a preparation method thereof, wherein the wrought magnesium alloy comprises the following components in percentage by mass: 2.8 to 4.8 percent of Sn, 0.8 to 2.2 percent of Zn, 0.3 to 1.0 percent of Zr, 0.2 to 2.2 percent of RE (rare earth metal), 0.05 to 0.15 percent of Mn, less than or equal to 0.2 percent of impurity content and the balance of Mg. The tensile strength at room temperature is 322-372 MPa, the yield strength is 243-318 MPa, and the elongation is 16.82-26.15%; the corrosion rate of the magnesium alloy is 0.181-0.332 (mg cm) -2 ·d -1 ). The alloy has higher content of alloying elements, contains noble Zr element and rare earth element, has lower strength, has yield strength less than 320MPa, and does not reach the ultra-high strength level. Chinese patent CN114395667a discloses a high-strength corrosion-resistant magnesium alloy based on coherent precipitation phase regulation and control and a preparation method thereof, the magnesium alloy comprises the following components in percentage by mass: 1.3 to 2.9 percent of Al, 0 to 0.8 percent of Zn, 0.1 to 0.8 percent of Ca, 0.3 to 0.6 percent of Mn, less than 0.02 percent of unavoidable impurities and the balance of magnesium. The tensile strength of the magnesium alloy plate prepared by the corresponding method is more than or equal to 280MPa, the corrosion rate is less than or equal to 6 mm/year, and the synchronous improvement of the corrosion resistance and the high strength of the magnesium alloy is realized. Although the corrosion resistance is better, the strength grade which can be achieved on the whole is lower, and the grade of the high-strength or ultra-high-strength magnesium alloy is far from being achieved. Chinese patent CN114525437a discloses a corrosion-resistant high-performance magnesium alloy with low alloy content and a preparation method thereof. The magnesium alloy comprises the following components in percentage by mass: 0.15 to 0.55 percent of Al, 0.01 to 0.5 percent of Mn, 0.03 to 0.1 percent of Ca, and the balance of magnesium, additive elements and unavoidable impurities, wherein the additive elements are one or a combination of tin, zinc, gadolinium and yttrium, and the addition amount is as follows in percentage: 0 to 0.4 percent of Sn, 0 to 0.5 percent of Zn, 0 to 0.35 percent of Gd, 0 to 0.35 percent of Y, less than or equal to 2.8 percent of total alloy element, simple heat treatment process before and after extrusion, short time, extrusion speed of the profile reaching 4 to 50m/min, effective saving of production time and cost and suitability for large scaleFor mass production application, the yield strength of the extruded section reaches 200-250MPa, the tensile strength reaches 275-290MPa, the elongation reaches 7-16%, and the corrosion rate in 3.5% sodium chloride solution is 0.86-3.6 mL/cm 2 And/d, which is significantly lower than that of AZ31 alloy under the same conditions (hydrogen evolution rate of 8.67mL/cm after 3 days of soaking in 3.5% sodium chloride solution) 2 And/d), the corrosion resistance and the strong plasticity are synchronously improved to a certain extent, but the alloy strength and the plasticity are still lower, which is far lower than the mechanical properties of commercial high-strength magnesium alloys such as AZ80, ZK60 and the like, and the grade of ultrahigh strength cannot be achieved. Chinese patent CN114540683a discloses a micro-alloyed corrosion-resistant low-cost magnesium alloy and a method for preparing the same. The magnesium alloy comprises the following components in percentage by mass: 0.55-1.2% of Al, 0.5-0.65% of Mn, 0-0.4% of Zn, 0.01-0.03% of Ca, and the balance of magnesium, additive elements and unavoidable impurities; the additive elements are one or the combination of samarium and lanthanum, and the addition amount is as follows according to the mass percent: 0.01 to 0.2% of Sm and 0.01 to 0.2% of La. The average hydrogen evolution amount of the alloy after 3 days of soaking in 3.5 percent sodium chloride solution is 2.27-4.5mL/cm 2 And/d. The mechanical property, the average yield strength is 208-215MPa, the tensile strength is 270-279MPa, and the elongation is 9.8-10.9%. The alloy of the invention has better corrosion resistance than AZ31 alloy, but the corrosion rate is still higher, and the corrosion resistance is not enough; meanwhile, the strength and plasticity of the alloy are still lower, which is far lower than the mechanical properties of commercial high-strength magnesium alloys such as AZ80, ZK60 and the like, and the alloy still cannot reach the level of ultra-high strength. Chinese patent CN115466890a discloses a rapidly degradable high-strength and high-toughness Cu-containing magnesium alloy material and a preparation method thereof, which comprises the following raw materials in percentage by mass: 2-10wt% of Al, 0.1-5.0wt% of Cu and 0.1-5.0wt% of Mn; the balance being magnesium and unavoidable impurity elements. The room temperature tensile strength of the alloy of the invention: 318-377MPa and elongation of 12-21%. The strength is still lower, and the corrosion resistance is very poor due to the existence of MgAlCu ternary phases, so that the alloy material with good corrosion resistance cannot be controlled.
Therefore, in order to better meet the requirements of the fields of traffic, aerospace, electronics, electric appliances, weaponry and the like on the high-strength magnesium alloy, such as low cost, easy processing and high performance, the development of the ultrahigh-strength corrosion-resistant magnesium alloy which can be prepared by using simple and continuous production and processing processes and the preparation method thereof are urgently needed, and the ultrahigh-strength corrosion-resistant magnesium alloy has important significance for improving the application of the expanded deformation magnesium alloy.
Disclosure of Invention
The invention aims to solve the problems of poor corrosion resistance, insufficient strength, difficult combination of corrosion resistance and high mechanical property and high cost existing in the existing high-strength magnesium alloy.
The invention relates to an ultra-high-strength corrosion-resistant multi-element low-alloyed magnesium alloy and a preparation method thereof, wherein the ultra-high-strength corrosion-resistant multi-element low-alloyed magnesium alloy comprises the following components in percentage by mass: 0.2 to 1.8 percent of Cu, 0.3 to 2.0 percent of Zn, 0.15 to 0.7 percent of Ca, 0.2 to 0.8 percent of Mn, less than or equal to 0.05 percent of impurity content and the balance of Mg, wherein the content of Zn is not lower than the content of Cu.
The preparation method of the ultra-high-strength corrosion-resistant multi-element low-alloyed magnesium alloy comprises the following steps:
and (3) proportioning: pure Mg ingot, pure Cu or Mg-Cu intermediate alloy, pure Zn block, pure Ca or Mg-Ca intermediate alloy and Mg-Mn intermediate alloy are used as raw materials, and after surface pretreatment, the raw materials are prepared according to the mass percentage of the magnesium alloy components;
smelting: placing a pure Mg ingot into a crucible of a smelting furnace, setting the furnace temperature to 700-800 ℃ and keeping, and after the pure Mg ingot is melted, gradually adding pure Ca or Mg-Ca intermediate alloy, pure Cu or Mg-Cu intermediate alloy, pure Zn blocks and Mg-Mn intermediate alloy which are preheated to 50-200 ℃ into a magnesium melt; preserving heat for 5-50 minutes, stirring for 1-7 minutes after the intermediate alloy is melted, cooling to 680-750 ℃ after slag skimming, refining for 1-20 minutes, preserving heat for 10-80 minutes at 680-730 ℃ after slag skimming again to obtain uniform alloy melt, and preparing for casting; melting, stirring and standing the alloy are carried out under the protection of a protective solvent or protective atmosphere;
and (3) pouring: casting the magnesium alloy melt which is uniformly smelted under the protection of protective atmosphere by adopting sand casting, metal mold casting or semi-continuous casting to obtain an as-cast blank;
and (4) heat treatment: performing heat treatment on the alloy cast ingot prepared in the step (3) in a heat treatment furnace, wherein the heat treatment temperature is 380-530 ℃ and the time is 2-48 hours, and then cooling to room temperature in an air cooling or water cooling mode;
and (5) machining: cutting the blank obtained by heat treatment into corresponding specifications and removing surface oxide skin;
and (6) deforming: heating the blank subjected to oxide removal obtained in the step (5) to 200-450 ℃, and then placing the blank into a deformation die to perform thermal deformation processing, wherein the deformation strain rate is 0.01s -1 -4s -1 And the accumulated deformation is more than 0.8, and the ultrahigh-strength corrosion-resistant multielement low-alloyed magnesium alloy is obtained after deformation and cooling.
Compared with the prior art, the invention has the following remarkable progress and advantages:
1) The novel Mg-Cu-Zn-Ca-Mn magnesium alloy successfully introduces a large amount of low-potential in-situ endophytic nanoparticle reinforcing phases into the magnesium alloy through a simple alloying means, is dispersed and distributed on a matrix, breaks through the restriction that the size of a precipitation strengthening phase in the magnesium alloy is generally larger (more than 100 nm), and is generated in situ and well bonded with an interface. On one hand, a large number of nano reinforced phases can effectively pin grain boundaries and dislocation movement, and play a reinforcing role; on the other hand, the deformation and recrystallization process of the matrix can be regulated, a large amount of ultrafine grain structures are regulated in the matrix, meanwhile, due to the lower potential difference between the ultrafine grain structures and the matrix, no obvious micro-couple corrosion is caused, and the uniform dispersion characteristic can enable the corrosion process to be lighter and more uniform, so that the occurrence of local severe potential is avoided.
2) The novel Mg-Cu-Al-Ca-Mn magnesium alloy has a large number of solute segregation structures at the grain boundaries of recrystallized grains and at the subgrain boundaries of deformed grains, and the solute segregation structures are synergistic with the nano precipitated phases, so that the grains are obviously refined, the mechanical properties of the alloy are greatly improved, and in addition, a compact oxide film is formed in the corrosion process, so that the corrosion resistance of the alloy is improved.
3) The alloy system has lower element content, the highest content of each alloy element is not more than 2wt%, and the size of the micron-sized second phase in the alloy is smaller by combining the regulation and control of a processing preparation process, so that the alloy structure is optimized, the mechanical property of the alloy is improved, the matrix is not obviously cracked, and the local severe punctiform corrosion is avoided, so that the corrosion resistance of the alloy is improved.
4) Through the cooperative regulation and control of alloy components and a processing preparation process, a large number of ultrafine grain structures with the size below 500nm are successfully constructed in the alloy, and a small number of deformed grains with strong textures are also present in the alloy, so that the multi-scale microstructure cooperative effect is achieved, and the toughness performance of the alloy is remarkably improved; in addition, the large number of ultrafine grains in the microstructure of the alloy provides a large number of grain boundaries to enable a small amount of impurity elements to be diluted and dispersed more, and the effects can enable the corrosion process to be lighter and uniform, so that the adverse effect of the trace impurity elements on the Jin Naishi performance is weakened.
5) The alloy has excellent mechanical property, the yield strength of the commercial high-strength magnesium alloy AZ31 at present under the same extrusion condition is only about 213MPa, and the minimum corrosion rate of the alloy can be as low as 0.5mL/cm 2 And/d, the tensile yield strength can reach 545MPa, the elongation percentage is about 10 percent, the strength and plasticity are excellent, the toughening level matched with the ultrahigh-strength aluminum alloy is achieved, the corrosion resistance is excellent, and the method has important significance for development and industrialization application of the ultrahigh-performance structural function integrated magnesium alloy and products thereof.
6) The alloy is more uniform and stable in smelting, and because Ca element has better flame retardant effect in the magnesium alloy, the melt is also more stable; meanwhile, as Zn, ca and Cu element raw materials of one of the main alloying elements are easy to react with the magnesium melt to be melted, the melting point of the intermediate alloy is lower, and the alloy melt is easy to be uniform. Meanwhile, part of Zn, ca and Mn elements can react with impurity elements in the melt, so that adverse effects of the impurity elements in the alloy on alloy structure and performance are reduced, and harmful effects of the impurity elements in the alloy are further weakened.
7) The total content of alloy elements in the alloy is not more than 5wt percent, and the second phase in the alloy has high thermal stability, so that the alloy has excellent plastic processing performance, and can be subjected to thermal processing deformation in a wider temperature range, thereby reducing the thermal deformation resistance and improving the processing or production efficiency.
8) The novel high-strength magnesium alloy does not contain any rare earth elements and high-price alloy elements, the corresponding element resources are rich, the raw materials come widely, and the metal Mg, zn, pure Cu, mg-Cu intermediate alloy, pure Ca, mg-Ca intermediate alloy and Mg-Mn intermediate alloy have low price, so that the production cost of the alloy can be reduced.
9) The component design of the magnesium alloy adopts the principle of multi-element micro-alloying, fully plays the roles of the elements, does not generate mutual reduction effect, plays the role of mutual promotion, has lower total alloy element, higher solidus temperature of the alloy, and higher alloyed magnesium alloy is closer to the melting point of pure magnesium, and meanwhile, the solute segregation structure at the grain boundary can further improve the strength of the grain boundary, so that the material for the high-strength heat-resistant magnesium alloy parts is expected.
10 The Cu element in the constituent elements of the magnesium alloy also has a sterilization effect, and Zn and Ca are elements for promoting bone healing, so that the magnesium alloy can be used as potential biomedical appliance materials.
11 The magnesium alloy preparation process is simple, the limitation of special processing modes such as large plastic deformation required by most high-strength magnesium alloys is broken through, meanwhile, the ultrahigh strength, good plasticity and corrosion resistance can be achieved without special heat treatment after deformation processing, the existing magnesium alloy extrusion equipment, rolling equipment and forging equipment can be used for continuous processing production, additional improvement is not required, and the requirement on production equipment is low.
Drawings
Fig. 1 is a typical tensile stress strain curve of the magnesium alloy of example 2, fig. 2 is an SEM microstructure of the deformation region and the recrystallization region of the magnesium alloy of example 2, fig. 3 is an SEM microstructure of the recrystallization region of the magnesium alloy of example 2, fig. 4 is a TEM bright field photograph of the magnesium alloy of example 2, fig. 5 is a high angle annular dark field photograph of the magnesium alloy of example 2, and fig. 6 is a typical tensile stress strain curve of the magnesium alloy of example 3.
Description of the embodiments
The invention relates to an ultra-high-strength corrosion-resistant multi-element low-alloyed magnesium alloy and a preparation method thereof, wherein the ultra-high-strength corrosion-resistant multi-element low-alloyed magnesium alloy comprises the following components in percentage by mass: 0.2 to 1.8 percent of Cu, 0.3 to 2.0 percent of Zn, 0.15 to 0.7 percent of Ca, 0.2 to 0.8 percent of Mn, less than or equal to 0.05 percent of impurity content and the balance of Mg, wherein the content of Zn is not lower than the content of Cu.
The preparation method of the ultra-high-strength corrosion-resistant multi-element low-alloyed magnesium alloy comprises the following steps:
and (3) proportioning: pure Mg ingot, pure Cu or Mg-Cu intermediate alloy, pure Zn block, pure Ca or Mg-Ca intermediate alloy and Mg-Mn intermediate alloy are used as raw materials, and after surface pretreatment, the raw materials are prepared according to the mass percentage of the magnesium alloy components;
smelting: placing a pure Mg ingot into a crucible of a smelting furnace, setting the furnace temperature to 700-800 ℃ and keeping, and after the pure Mg ingot is melted, gradually adding pure Ca or Mg-Ca intermediate alloy, pure Cu or Mg-Cu intermediate alloy, pure Zn blocks and Mg-Mn intermediate alloy which are preheated to 50-200 ℃ into a magnesium melt; keeping the temperature for 5 to 50 minutes, stirring for 1 to 7 minutes after the intermediate alloy is melted, cooling to 680 to 750 ℃ after slag skimming, refining for 1 to 20 minutes, keeping the temperature for 10 to 80 minutes at 680 to 750 ℃ after slag skimming again to obtain uniform alloy melt, and preparing for casting; melting, stirring and standing the alloy are carried out under the protection of a protective solvent or protective atmosphere;
and (3) pouring: casting the magnesium alloy melt which is uniformly smelted under the protection of protective atmosphere by adopting sand casting, metal mold casting or semi-continuous casting to obtain an as-cast blank;
and (4) heat treatment: performing heat treatment on the alloy cast ingot prepared in the step (3) in a heat treatment furnace, wherein the heat treatment temperature is 380-530 ℃ and the time is 2-48 hours, and then cooling to room temperature in an air cooling or water cooling mode;
and (5) machining: cutting the blank obtained by heat treatment into corresponding specifications and removing surface oxide skin;
and (6) deforming: heating the blank subjected to oxide removal obtained in the step (5) to 200-450 ℃, and then placing the blank into a deformation die to perform thermal deformation processing, wherein the deformation strain rate is 0.01s -1 -4s -1 Between, the accumulated deformationAnd (3) cooling after deformation by more than 0.8 to obtain the high-strength corrosion-resistant multielement low-alloyed magnesium alloy.
The preparation method comprises the steps of (1) preparing the Mg-Ca master alloy, the Mg-20Ca master alloy, the Mg-Mn master alloy, the Mg-5Mn master alloy and the Mg-Cu master alloy, namely Mg-30Cu.
In the preparation method, the stirring in the step (2) is mechanical stirring or air blowing stirring or electromagnetic stirring or a combination thereof.
The protective solvent in step (2) is preferably RJ-5 in the preparation method.
In the preparation method, the protective atmosphere in the step (2) is preferably CO in volume ratio 2 ：SF 6 =50 to 100:1 mixing the gases.
In the preparation method, the protective atmosphere in the step (3) is preferably CO in volume ratio 2 ∶SF 6 Mixed gas of 50-100:1.
In the preparation method, the heat treatment in the step (4) is single-stage heat treatment or double-stage heat treatment, wherein the single-stage heat treatment is carried out at a certain constant temperature of 410-500 ℃ for 2-48 hours, then cooling is carried out, the double-stage heat treatment is carried out at a certain constant temperature of 380-430 ℃ for 2-24 hours, and then the temperature is raised to a certain temperature of 460-530 ℃ for 1-24 hours.
The deforming in the step (6) may be extrusion deforming, rolling deforming, forging or a combination thereof.
The preparation method comprises the step (6), wherein the die is used for forming plates, bars, tubes, wires, sectional materials or cylindrical parts.
The invention has the substantial characteristics that:
the preparation of a large proportion of ultrafine grain structure, a plurality of low-potential nano precipitated phases distributed in a dispersing way and corresponding solute segregation gas clusters are important measures for endowing the alloy with excellent strength and corrosion resistance, and the microstructure is generally difficult to construct in magnesium alloy. At the same time throughThe magnesium alloy with excellent corrosion resistance can be obtained by regulating and controlling the second phase type, solute segregation gas mass at the interface and solid solution atom and impurity content in the matrix. Under general conditions, the corrosion resistance of the alloy is seriously deteriorated by introducing Cu element into the magnesium alloy, and the invention ensures that Zn and Cu element in the alloy and Mg in the alloy form nano MgZnCu of 5-100 nm in situ through comprehensive regulation and control of alloy components and processing technology, thereby avoiding Mg with higher potential 2 Cu is generated, so that the potential difference between the second phase and the matrix in the alloy is reduced; the impurity element content in the alloy is reduced through the regulation and control of the preparation process, so that the damage of the impurity element and the compound thereof to the corrosion resistance of the alloy is reduced; in addition, a large number of tiny Mn particles are induced in the alloy matrix, and solute segregation gas groups of Zn, ca and Mn atoms are constructed at the grain boundary and phase boundary to inhibit the corrosion of the micro-couple; finally, the compactness of the corrosion product is improved through the synergistic effect of Cu, zn, ca, mn elements, so that the corrosion resistance of the alloy is further improved.
The nano precipitated phase and solute bias aggregation structure in the alloy can play a role in strengthening on one hand, and can regulate and control the deformation and recrystallization process of the matrix on the other hand, and a large amount of superfine crystal structures and unrecrystallized deformed structures with residual dislocation are obtained in the alloy at the same time. In addition, the fine micro-matrix second phase which is not dissolved into the matrix in the heat treatment process is further crushed and refined in the deformation process and then is dispersed and distributed on the matrix, and the fine micro-matrix second phase and the nano-particles and grain boundary segregation elements which are dynamically separated out in the heat deformation process act cooperatively, so that the recrystallization nucleation is effectively promoted, the growth of recrystallization grains is inhibited, and the formation of an ultrafine grain structure is facilitated. Meanwhile, the second phases can weaken the adverse effect of the second phases on corrosion resistance, provide more interfaces, and can pin dislocation in crystal boundaries and matrixes when the alloy is deformed by external force, so that the comprehensive mechanical property and corrosion resistance of the alloy are improved. Through the cooperative regulation and control of alloy components and a processing preparation process, a large amount of ultrafine grain structures with the size below 500 and nm are successfully constructed in the alloy, and a small amount of deformed grains with strong textures also exist in the alloy. Finally, a small amount of Cu, zn, ca, mn elements dissolved in the matrix can play a certain solid solution strengthening role and improve the compactness of the corrosion product film. By combining the above factors, the prepared Mg-Cu-Zn-Ca-Mn alloy shows excellent toughening effect and corrosion resistance.
The technical scheme of the invention is described in detail by the following specific examples, which are all implemented on the premise of the technical scheme of the invention, and detailed implementation modes and specific operation processes are given, but the protection scope of the invention is not limited to the following examples.
Examples
The Mg-0.25Cu-0.6Zn-0.25Ca-0.35Mn (wt%) alloy composition is designed and selected to be proportioned into magnesium alloy, and the preparation method comprises the following steps:
(1) And (3) batching: pure Mg (99.99 wt%) ingot, pure Zn (99.99 wt%) block, pure Ca (99.98 wt%) granule, mg-20Cu intermediate alloy (Cu actual detection content is 20.1 wt%) and Mg-10Mn intermediate alloy (Mn actual detection content is 10.1 wt%) are used as raw materials, after surface pretreatment (for removing dirt, oxide skin and the like, the following examples are identical), the above-mentioned magnesium alloy is proportioned according to weight percentage;
(2) Alloy smelting: cleaning and preheating a crucible, putting a magnesium ingot preheated to 150 ℃ into the crucible of a smelting furnace, setting the furnace temperature to 720 ℃ to heat the magnesium ingot, and starting to introduce Ar when the temperature rises to 500 ℃: SF (sulfur hexafluoride) 6 The mixed gas of 100:1 (volume flow ratio) is protected against combustion, pure Ca preheated to 60 ℃ is added into the melt after magnesium is completely melted, pure Zn blocks are added after melting, mg-20Cu intermediate alloy is added after melting, mg-10Mn intermediate alloy is added after melting, mechanical stirring is carried out for 2 minutes after melting, surface scum is scraped, the heat is preserved and kept stand for 35 minutes, all alloy elements are uniformly distributed in the magnesium alloy melt,
(3) Pouring: skimming the dross on the surface of the melt and then adding CO 2 ：SF 6 Under the protection of mixed gas of (volume flow ratio) 90:1Casting by adopting a metal mold, and pouring into a cylindrical mold with the diameter of 60mm to obtain an as-cast blank;
(4) And (3) heat treatment: removing a riser of the alloy cast ingot prepared in the step (3), heating to 400 ℃ along with a furnace, preserving heat at the temperature for 24 hours for homogenization treatment, quenching with warm water, and cooling to room temperature, wherein the temperature rising time is 60 minutes, and the heat treatment process does not need gas protection;
(5) Machining: removing an oxide layer on the surface of the alloy cast ingot after the heat treatment in the step (4) by turning, and processing the alloy cast ingot into a bar suitable for extrusion;
(6) Plastic working: heating the blank for 30 minutes to reach the required extrusion temperature, and putting the blank into an extrusion cylinder of an extruder for extrusion processing to obtain a bar with the diameter of 10mm, wherein main technological parameters are as follows: the temperature of the blank is 280 ℃, the temperature of the extrusion barrel is 280 ℃, the temperature of the die is 280 ℃, the extrusion speed is 3m/min, the extrusion ratio is 36, and the extruded material is cooled by adopting air cooling, so that the low-cost non-rare earth high-strength magnesium alloy is obtained.
Alloy performance testing and microstructure analysis: a sample with the length of 70mm is cut from the prepared extruded magnesium alloy bar, a round bar-shaped tensile sample with the gauge length of 20mm is processed into a diameter of 4mm, and the axial direction of the round bar of the sample is the same as the extrusion streamline direction of the material. The tensile strength of the magnesium alloy is 512+/-4 MPa, the yield strength is 503+/-3 MPa, and the elongation is 9.8+/-1%; the corrosion rate in 3.5wt% NaCl solution is 0.5mL/cm 2 And/d, the ultra-high strength plastic performance and the excellent corrosion resistance are shown.
Examples
The Mg-0.45Cu-0.65Zn-0.35Ca-0.45Mn (wt%) alloy composition is designed and selected to be proportioned into magnesium alloy, and the preparation method comprises the following steps:
(1) And (3) batching: taking pure Mg (99.99 wt%) ingots, pure Zn (99.99 wt%) blocks, mg-20Ca intermediate alloy (the actual detection content of Ca is 19.98 wt%), mg-20Cu intermediate alloy (the actual detection content of Cu is 20.1 wt%) and Mg-10Mn intermediate alloy (the actual detection content of Mn is 10.1 wt%) as raw materials, and carrying out surface pretreatment (such as removing dirt, oxide skin and the like, the same with the following examples) to prepare the magnesium alloy according to the weight percentage of the magnesium alloy;
(2) Alloy smelting: cleaning and preheating a crucible, putting a magnesium ingot preheated to 150 ℃ into the crucible of a smelting furnace, setting the furnace temperature to 740 ℃ to heat the magnesium ingot, and covering the surface of the magnesium alloy with an RJ-5 solvent. Adding pure Zn blocks and Mg-20Ca intermediate alloy which are preheated to 150 ℃ into the melt after magnesium is completely melted, adding the Mg-30Cu intermediate alloy after melting, adding the Mg-5Mn intermediate alloy after melting, mechanically stirring for 2 minutes after melting, standing for 5 minutes, then introducing argon to the bottom of the melt for 2 minutes, then stripping out surface scum, and introducing CO above the surface of the melt 2 ：SF 6 The mixed gas of the ratio of the flow to the flow of the alloy is protected by the mixed gas of the ratio of the flow to the flow of the alloy, and the mixture is kept warm and stand for 25 minutes, so that all alloy elements are uniformly distributed in the magnesium alloy melt.
(3) Pouring: skimming the dross on the surface of the melt and then adding CO 2 ：SF 6 Metal mold casting is adopted under the protection of mixed gas of (volume flow ratio) 95:1, and then metal mold casting is adopted to prepare a non-rare earth magnesium alloy cast ingot with the diameter of 60 mm.
(4) And (3) heat treatment: removing a riser of the alloy cast ingot prepared in the step (3), heating to 460 ℃ along with a furnace, preserving heat for 36 hours, and quenching with warm water;
(5) Machining: removing an oxide layer on the surface of the alloy ingot after the heat treatment in the step (4) by turning, and processing the alloy ingot into a size suitable for extrusion processing;
(6) Plastic working: heating the blank for 30 minutes to reach the required extrusion temperature, putting the blank into an extrusion cylinder of an extruder for extrusion processing to obtain a bar with the diameter of 10mm, wherein main technological parameters are as follows: the blank temperature is 300 ℃, the extrusion barrel temperature is 300 ℃, the die temperature is 300 ℃, the extrusion speed is 2m/min, the extrusion ratio is 36, and the extruded material is cooled by air cooling, so that the low-cost non-rare earth high-strength magnesium alloy is obtained.
Alloy performance testing and microstructure analysis: a sample with the length of 70mm is cut from the prepared extruded magnesium alloy bar, a round bar-shaped tensile sample with the gauge length of 20mm and the diameter of the gauge length part of 4mm is processed, a tensile test is carried out, and the axial direction of the round bar of the sample is the same as the extrusion streamline direction of the material. The tensile strength of the magnesium alloy is 526+/-4 MPa, and the bending strength is measuredThe strength of the product is 518+ -3 MPa, the elongation is 10.3+ -0.5%, and the corrosion rate in 3.5wt% NaCl solution is 0.8 mL/cm 2 And/d, the ultra-high strength plastic performance and the excellent corrosion resistance are shown. Typical tensile curves of the magnesium alloy obtained in this example are shown in fig. 1, and the magnesium alloy obtained in this example combines ultra-high strength and good elongation. FIG. 2 shows SEM microstructures of the deformed and recrystallized regions of the magnesium alloy obtained in this example, and it can be seen from the golden phase diagram that a large amount of second phases are dispersed and distributed on the deformed grains for recrystallization, and the grains in the dynamic recrystallized region are extremely fine and the grain size is below 1. Mu.m; FIG. 3 shows the SEM microstructure of the recrystallized region of the magnesium alloy obtained in this example, which shows that the average grain size is about 500nm and that the matrix has a large number of fine white precipitated phases. FIG. 4 is a TEM bright field photograph of an alloy of this example, in which grains having a grain size of 1 μm or more are found, grains having a grain size of less than 500nm are also found, and a large number of nano-precipitates having a size of about 10 to 50nm are present on a matrix, and these precipitates are MgZnCu nano-precipitates, mg 2 Ca nano precipitated phase and Mn nano precipitated phase. Fig. 5 is a photograph of a high angle annular dark field image of the alloy of this example, which shows that there is a significant solute bias at the grain boundaries of the fine recrystallization, mainly formed by the combined bias of one or more of the Ca, zn, cu, mn elements. The microstructure of the alloy can be specifically regulated and controlled through alloy components and a processing technology, so that a mixed crystal structure with an ultrafine crystal structure is obtained, and a microstructure containing various nano precipitated phases and solute bias coalescence structures is constructed, so that an alloy blank with ultrahigh strength, good plasticity and excellent corrosion resistance is obtained.
Examples
The Mg-0.8Cu-0.9Zn-0.35Ca-0.6Mn (wt%) alloy composition is designed and selected to be proportioned into magnesium alloy, and the preparation method comprises the following steps:
(1) And (3) batching: taking pure Mg (99.99 wt%) ingots, pure Zn (99.99 wt%) blocks, mg-20Ca intermediate alloy (the actual detection content of Ca is 19.98 wt%), mg-20Cu intermediate alloy (the actual detection content of Cu is 20.1 wt%) and Mg-10Mn intermediate alloy (the actual detection content of Mn is 10.1 wt%) as raw materials, and carrying out surface pretreatment (such as removing dirt, oxide skin and the like, the same with the following examples) to prepare the magnesium alloy according to the weight percentage of the magnesium alloy;
(2) Alloy smelting: cleaning and preheating a crucible, putting a magnesium ingot preheated to 150 ℃ into the crucible of a smelting furnace, setting the furnace temperature to 720 ℃ to heat the magnesium ingot, and starting to introduce CO when the temperature rises to 500 DEG C 2 ：SF 6 Mixed gas protection of =100:1 (flow ratio) prevents combustion. After magnesium is completely melted, adding the Mg-20Ca intermediate alloy preheated to 150 ℃ into the melt, adding pure Zn blocks after melting, adding the Mg-30Cu intermediate alloy after melting, adding the Mg-5Mn intermediate alloy after melting, mechanically stirring for 2 minutes after melting, taking off surface scum, keeping the temperature and standing for 20 minutes, and uniformly distributing all alloy elements in the magnesium alloy melt.
(3) Pouring: skimming the dross on the surface of the melt and then adding CO 2 ：SF 6 Metal mold casting is adopted under the protection of mixed gas of the ratio of the flow rate of the metal to the flow rate of the mixed gas, and the metal mold casting is poured into a cylindrical mold with the diameter of 60mm to prepare a non-rare earth magnesium alloy cast ingot.
(4) And (3) heat treatment: removing the riser of the alloy cast ingot prepared in the step (3), heating to 410 ℃ along with a furnace, preserving heat at the temperature for 12 hours, heating to 450 ℃ for 10 minutes, preserving heat for 24 hours, quenching with warm water, and cooling to room temperature;
(5) Machining: removing an oxide layer on the surface of the alloy ingot after the heat treatment in the step (4) by turning, and processing the alloy ingot into a size suitable for extrusion processing;
(6) Plastic working: heating the blank for 30 minutes to reach the required extrusion temperature, putting the blank into an extrusion cylinder of an extruder for extrusion processing to obtain a bar with the diameter of 12 mm, wherein main technological parameters are as follows: the temperature of the blank is 330 ℃, the temperature of the extrusion barrel is 330 ℃, the temperature of the die is 330 ℃, the extrusion speed is 3m/min, the extrusion ratio is 25, and the extruded material is cooled by adopting air cooling, so that the low-cost non-rare earth high-strength magnesium alloy is obtained.
Alloy performance testing and microstructure analysis: cutting out a 50mm long sample from the prepared extruded magnesium alloy bar, processing the sample into a round bar-shaped tensile sample with a gauge length of 20mm and a diameter of a gauge length part of 4mm, and carrying out a tensile test on the round bar-shaped tensile sample, wherein the axial direction of the round bar is the axis direction of the sampleThe same direction as the extrusion streamline of the material. The magnesium alloy of the present invention has a tensile strength of 556±4MPa, a yield strength of 545±2MPa, and an elongation of 12.7±1%, and the typical tensile curve of the magnesium alloy obtained in this example is shown in fig. 6, and the magnesium alloy obtained in this example has both ultra-high strength and good elongation. Further measured to have a corrosion rate of 1.4. 1.4 mL/cm in a 3.5wt% NaCl solution 2 And/d, the ultra-high strength plastic performance and the excellent corrosion resistance are shown.
Examples
The Mg-1.5Cu-1.6Zn-0.35Ca-0.5Mn (wt%) alloy composition is designed and selected to be proportioned into magnesium alloy, and the preparation method comprises the following steps:
(1) And (3) batching: taking pure Mg (99.99 wt%) ingots, pure Zn (99.99 wt%) blocks, mg-20Ca intermediate alloy (the actual detection content of Ca is 19.98 wt%), mg-20Cu intermediate alloy (the actual detection content of Cu is 20.1 wt%) and Mg-10Mn intermediate alloy (the actual detection content of Mn is 10.1 wt%) as raw materials, and carrying out surface pretreatment (such as removing dirt, oxide skin and the like, the same with the following examples) to prepare the magnesium alloy according to the weight percentage of the magnesium alloy;
(2) Alloy smelting: cleaning and preheating a crucible, putting a magnesium ingot preheated to 150 ℃ into the crucible of a smelting furnace, setting the furnace temperature to 720 ℃ to heat the magnesium ingot, and starting to introduce CO when the temperature rises to 500 DEG C 2 ：SF 6 Mixed gas protection of =100:1 (flow ratio) prevents combustion. After magnesium is completely melted, adding the Mg-20Ca intermediate alloy preheated to 150 ℃ into the melt, adding pure Zn blocks after melting, adding the Mg-30Cu intermediate alloy after melting, adding the Mg-5Mn intermediate alloy after melting, mechanically stirring for 2 minutes after melting, taking out surface scum, preserving heat and standing for 25 minutes, so that all alloy elements are uniformly distributed in the magnesium alloy melt.
(3) Pouring: skimming the dross on the surface of the melt and then adding CO 2 ：SF 6 A cylindrical semi-continuous cast alloy ingot with a diameter of 70mm was prepared by a crystallizer by semi-continuous casting under the protection of a mixed gas of =100:1 (flow ratio).
(4) And (3) heat treatment: removing a riser of the alloy cast ingot prepared in the step (3), heating to 460 ℃ along with a furnace, preserving heat for 36 hours, and quenching with warm water;
(5) Machining: removing an oxide layer on the surface of the alloy ingot after the heat treatment in the step (4) by turning, and processing the alloy ingot into a size suitable for extrusion processing;
(6) Plastic working: and (3) placing the machined cylindrical blank with the height of 110mm and the diameter of 65mm into a die for forging deformation processing, wherein the temperature of the blank is 350 ℃, the temperature of the forging die is 350 ℃, forging is carried out at the pressing head pressing speed of 10mm/s, a cake-shaped sample with the height of 20mm is obtained after forging, and then the cylindrical blank is subjected to heat preservation at 120 ℃ for 10 minutes and then is subjected to air cooling to room temperature, so that the low-cost non-rare earth high-strength magnesium alloy is obtained.
Alloy performance testing and microstructure analysis: a sample with the length of 60mm is cut from the obtained forged magnesium alloy blank, and is processed into a round bar-shaped tensile sample with the gauge length of 20mm, wherein the diameter of the gauge length part is 4mm, and the tensile test is carried out. The tensile strength of the magnesium alloy is 507+/-4 MPa, the yield strength is 488+/-3 MPa, and the elongation is 12.6+/-0.5%. Further measured to have a corrosion rate of 3.0. 3.0 mL/cm in a 3.5wt% NaCl solution 2 And/d, the ultra-high strength plastic performance and the good corrosion resistance are shown.
Comparative example 1
The comparative example is a current commercial magnesium alloy: mg-2.9Al-0.45Zn-0.3Mn (wt%, AZ 31) magnesium alloy. Pure Mg (99.99 wt%) ingots, pure Al (99.99 wt%) blocks, pure Zn (99.99 wt%) blocks and Mg-5Mn intermediate alloy (Mn actual detection content is 5.1 wt%) are taken as raw materials, and the magnesium alloy of the comparative example is prepared according to the weight percentage after surface pretreatment; the remaining processing and preparation steps were the same as those of the AZ31 alloy obtained under the same processing conditions as in example 1, and the tensile strength was 294+ -3 MPa, the yield strength was 213+ -2 MPa, and the elongation was 16.2+ -1.5%. Further measured to have a corrosion rate of 9.2. 9.2 mL/cm in a 3.5wt% NaCl solution 2 And/d, compared with the conventional commercial AZ31 magnesium alloy, the magnesium alloy has obviously higher strength and plasticity, achieves the mechanical property similar to that of the ultrahigh-strength deformed aluminum alloy, has excellent corrosion resistance, and is the ultrahigh-strength corrosion-resistant magnesium alloy with very high market competitiveness.
Comparative example 2
Design choice of Mg-1CuThe alloy composition of-0.6 Zn-0.35Ca-0.5Mn (wt%) was formulated into magnesium alloy, and the rest of the processing preparation steps were conducted under the same processing conditions as in example 3 to obtain the alloy of this comparative example, and the tensile strength was 577+ -3 MPa, the yield strength was 548+ -2 MPa, and the elongation was 11.6+ -1%. Further measured to have a corrosion rate of 107. 107 mL/cm in a 3.5wt% NaCl solution 2 As can be seen from comparison, the mechanical properties of the alloy are not greatly changed when the Cu content in the alloy is higher than the Zn content, but the corrosion resistance is rapidly deteriorated mainly due to the presence of Mg in the alloy 2 Cu phase causes significant galvanic corrosion, resulting in deterioration of corrosion resistance of the alloy.
The starting materials and equipment used in the above examples were all obtained by known means and the operating procedures used are within the skills of a person skilled in the art.
Claims (10)
1. An ultra-high-strength corrosion-resistant multielement low-alloyed magnesium alloy is characterized in that: the mass percentages of the components are as follows: 0.2 to 1.8 percent of Cu, 0.3 to 2.0 percent of Zn, 0.15 to 0.7 percent of Ca, 0.2 to 0.8 percent of Mn, less than or equal to 0.05 percent of impurity content and the balance of Mg, wherein the content of Zn is not lower than the content of Cu.
2. The method for preparing the ultra-high-strength corrosion-resistant multi-element low-alloyed magnesium alloy according to claim 1, which is characterized by comprising the following steps:
and (3) proportioning: pure Mg ingot, pure Cu or Mg-Cu intermediate alloy, pure Zn block, pure Ca or Mg-Ca intermediate alloy and Mg-Mn intermediate alloy are used as raw materials, and after surface pretreatment, the raw materials are prepared according to the mass percentage of the magnesium alloy components;
smelting: placing a pure Mg ingot into a crucible of a smelting furnace, setting the furnace temperature to 700-800 ℃ and keeping, and after the pure Mg ingot is melted, gradually adding pure Ca or Mg-Ca intermediate alloy, pure Cu or Mg-Cu intermediate alloy, pure Zn blocks and Mg-Mn intermediate alloy which are preheated to 50-200 ℃ into a magnesium melt; keeping the temperature for 5 to 50 minutes, stirring for 1 to 7 minutes after the intermediate alloy is melted, cooling to 680 to 750 ℃ after slag skimming, refining for 1 to 20 minutes, keeping the temperature for 10 to 80 minutes at 680 to 750 ℃ after slag skimming again to obtain uniform alloy melt, and preparing for casting; melting, stirring and standing the alloy are carried out under the protection of a protective solvent or protective atmosphere;
and (3) pouring: casting the magnesium alloy melt which is uniformly smelted under the protection of protective atmosphere by adopting sand casting, metal mold casting or semi-continuous casting to obtain an as-cast blank;
and (4) heat treatment: performing heat treatment on the alloy cast ingot prepared in the step (3) in a heat treatment furnace, wherein the heat treatment temperature is 380-530 ℃ and the time is 2-48 hours, and then cooling to room temperature in an air cooling or water cooling mode;
and (5) machining: cutting the blank obtained by heat treatment into corresponding specifications and removing surface oxide skin;
and (6) deforming: heating the blank subjected to oxide removal obtained in the step (5) to 200-450 ℃, and then placing the blank into a deformation die to perform thermal deformation processing, wherein the deformation strain rate is 0.01s -1 -4s -1 And the accumulated deformation is more than 0.8, and the high-strength corrosion-resistant multielement low-alloyed magnesium alloy is obtained after deformation and cooling.
3. The method for preparing the ultra-high-strength corrosion-resistant multi-element low-alloyed magnesium alloy according to claim 2, wherein the method comprises the following steps: the Mg-Ca master alloy Mg-20Ca master alloy, the Mg-Mn master alloy Mg-5Mn master alloy and the Mg-Cu master alloy Mg-30Cu in the step (1).
4. The method for preparing the ultra-high-strength corrosion-resistant multi-element low-alloyed magnesium alloy according to claim 2, wherein the method comprises the following steps: the stirring in the step (2) is mechanical stirring or air blowing stirring or electromagnetic stirring or a combination thereof.
5. The method for preparing the ultra-high-strength corrosion-resistant multi-element low-alloyed magnesium alloy according to claim 2, wherein the method comprises the following steps: the protective solvent in step (2) is preferably RJ-5.
6. The method for preparing the ultra-high-strength corrosion-resistant multi-element low-alloyed magnesium alloy according to claim 2The method is characterized in that: the protective atmosphere in the step (2) is preferably CO in volume ratio 2 ：SF 6 =50 to 100:1 mixing the gases.
7. The method for preparing the ultra-high-strength corrosion-resistant multi-element low-alloyed magnesium alloy according to claim 2, wherein the method comprises the following steps: the protective atmosphere in the step (3) is preferably CO in volume ratio 2 ∶SF 6 Mixed gas of 50-100:1.
8. The method for preparing the ultra-high-strength corrosion-resistant multi-element low-alloyed magnesium alloy according to claim 2, wherein the method comprises the following steps: the heat treatment in the step (4) is single-stage heat treatment or double-stage heat treatment, wherein the single-stage heat treatment is carried out at a certain constant temperature of 410-500 ℃ for 2-48 hours, then cooling is carried out, the double-stage heat treatment is carried out at a certain constant temperature of 380-430 ℃ for 2-24 hours, and then the temperature is raised to a certain temperature of 460-530 ℃ for 1-24 hours.
9. The method for preparing the ultra-high-strength corrosion-resistant multi-element low-alloyed magnesium alloy according to claim 2, wherein the method comprises the following steps: the deforming process in step (6) may be extrusion deforming, rolling deforming, forging, or a combination thereof.
10. The method for preparing the ultra-high-strength corrosion-resistant multi-element low-alloyed magnesium alloy according to claim 2, wherein the method comprises the following steps: the die in the step (6) is a die for forming a plate, a bar, a pipe, a wire, a section bar or a cylindrical part.
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