Corrosion-resistant high-strength magnesium alloy material and preparation method thereof

Abstract

The application discloses a kind of corrosion-resistant high-strength magnesium alloy material and preparation method thereof, it is related to magnesium alloy material technical field, by the following chemical components: Al, Zn, Mn, Y, Ce, Ca, Zr, Sb, Sr, Ta, In, Mg and other inevitable impurities.It is prepared using vacuum induction melting, ternary compound refining agent impurity removal, high-pressure die casting forming, vacuum fine-grain heat treatment, then through phytic acid-potassium permanganate-cerium nitrate-ammonium metavanadate composite passivation treatment.Ta, In, Sb, Sr cooperates to refine grain, weakens micro-electrochemical corrosion, nanometer fluorine carbon cerium ore refining agent purifies melt, and cerium-vanadium compound passivation film is dense and stable.The obtained material has high tensile strength and excellent corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of magnesium alloy materials technology, and in particular to a corrosion-resistant high-strength magnesium alloy material and its preparation method. Background Technology

[0002] Magnesium alloys have broad application prospects in aerospace, automotive, and electronic communications due to their low density, high specific strength, and high specific stiffness. However, pure magnesium has relatively low strength and is highly susceptible to oxidation corrosion in humid, salty, and other corrosive environments. The oxide film formed on its surface is loose and porous, which cannot effectively prevent the intrusion of corrosive media, severely limiting its large-scale application.

[0003] Existing technologies typically enhance the strength of magnesium alloys by adding alloying elements such as aluminum, zinc, and manganese. However, the addition of aluminum can lead to the formation of β-Mg at grain boundaries. 17 Al 12 The zinc phase has a higher potential than the magnesium matrix, making it prone to galvanic corrosion. Excessive zinc addition increases intergranular brittleness and reduces the alloy's plasticity. Furthermore, single alloying methods offer limited improvement in the corrosion resistance of magnesium alloys, failing to meet the demands of harsh corrosive environments such as marine engineering and automotive chassis applications. To further improve the corrosion resistance of magnesium alloys, researchers have attempted to prepare protective layers on the alloy surface using surface treatment techniques (such as micro-arc oxidation and chemical conversion coatings). However, surface treatment processes are complex and costly, and the protective layer is prone to damage during processing or use. Once damaged, the corrosion rate of the substrate far exceeds that of untreated magnesium alloys, posing a significant safety hazard.

[0004] To address the aforementioned problems, invention patent document CN108559897B discloses a high-strength corrosion-resistant magnesium alloy and its preparation method. The high-strength corrosion-resistant magnesium alloy is prepared from the following raw material components by mass percentage: 7.0–7.5% Sn, 0.2–0.6% Bi, 0.1–0.3% Sb, with the balance being Mg and unavoidable impurities. In this invention, the components magnesium, tin, bismuth, and antimony of the high-strength corrosion-resistant magnesium alloy are melted and cast to obtain a cast alloy; then, the cast alloy is heat-treated to obtain the high-strength corrosion-resistant magnesium alloy. This high-strength corrosion-resistant magnesium alloy exhibits good room temperature strength and corrosion resistance, with a room temperature tensile strength exceeding 270 MPa and a corrosion rate of less than 0.6 mm / a in a 3.5 wt% NaCl solution. Compared to commercial magnesium alloy AZ91, it has higher strength and better corrosion resistance, showing broad application prospects in fields such as electronic products. However, the high tin content in this alloy not only significantly increases the cost of raw materials, but also makes it difficult for conventional casting and heat treatment processes to completely eliminate dendrite segregation, resulting in poor uniformity of the alloy structure. Its corrosion resistance stability in extreme corrosive environments still needs further improvement.

[0005] Therefore, developing a magnesium alloy material with both high strength and excellent corrosion resistance, and its preparation method, has become an urgent technical problem to be solved in the field of magnesium alloys. Summary of the Invention

[0006] The main objective of this invention is to overcome the shortcomings of the prior art and provide a corrosion-resistant high-strength magnesium alloy material and its preparation method. This magnesium alloy material has excellent corrosion resistance, good mechanical properties, and a long service life.

[0007] To achieve the above objectives, the present invention provides a corrosion-resistant high-strength magnesium alloy material, which, by weight percentage, is composed of the following chemical composition: Al 8.5~9.5%, Zn 0.4~0.8%, Mn 0.2~0.4%, Y 0.1~0.3%, Ce 0.05~0.15%, Ca 0.08~0.12%, Zr 0.05~0.1%, Sb 0.02~0.08%, Sr 0.01~0.05%, Ta 0.01~0.05%, In 0.02~0.06%, with the balance being Mg and other unavoidable impurities.

[0008] Preferably, the corrosion-resistant high-strength magnesium alloy material is composed of the following chemical components by weight percentage: Al 9%, Zn 0.6%, Mn 0.3%, Y 0.2%, Ce 0.1%, Ca 0.1%, Zr 0.08%, Sb 0.05%, Sr 0.03%, Ta 0.03%, In 0.04%, with the balance being Mg and other unavoidable impurities.

[0009] Another object of the present invention is to provide a method for preparing the corrosion-resistant high-strength magnesium alloy material, comprising the following steps: Step S1, Smelting and Material Preparation: According to the chemical composition ratio, preheat pure magnesium ingots, pure aluminum ingots, pure zinc ingots, pure antimony blocks, pure strontium blocks, pure tantalum powder, pure indium ingots, magnesium-manganese alloy, magnesium-yttrium alloy, magnesium-cerium alloy, magnesium-calcium alloy, and magnesium-zirconium alloy to 120~150℃ to remove surface oil and oxide scale. Step S2, Vacuum Melting: Add the preheated raw material to a vacuum induction melting furnace and evacuate to 1×10⁻⁶. -3 Pa, heat to 720~750℃, melt the raw material and then introduce high-purity argon gas for protection, stir the melt for 10~15 minutes; Step S3, Refining and Impurity Removal: Add composite refining agent to the melt, keep it at a constant temperature for 15-20 minutes, and skim off the surface scum; Step S4, High-pressure die casting: The melt is transferred to a high-pressure die casting machine and die-cast under the following conditions: melt temperature 680~700℃, mold temperature 220~240℃, injection speed 3~5m / s, injection pressure 40~60MPa, and holding time 8~12s. Step S5, Shaping and Trimming: The casting is hot-shaped at 300~320℃, and then trimmed by CNC. Step S6, Grain Refinement Heat Treatment: Heat the casting to 380~400℃ in a vacuum heat treatment furnace, hold for 2~3 hours, and then cool to room temperature with the furnace. Step S7, Environmental passivation treatment: After pretreatment, the casting is immersed in the composite passivation solution for 15-20 minutes, then rinsed and dried; Step S8, Subsequent finishing: Perform CNC engraving, polishing, spraying, film application, and laser engraving processes to obtain the final product.

[0010] Preferably, the composite refining agent in step S3 is a mixture of hexachloroethane, calcium fluoride, and nano-fluorocarbon cerium ore powder in a mass ratio of 7:3:(0.4-0.6), and the amount used is 0.2-0.3% of the total mass of the melt; the particle size of the hexachloroethane is D50=0.8-1.5mm, the particle size of the calcium fluoride is D50=30-80μm, and the particle size of the nano-fluorocarbon cerium ore powder is D50=80-300nm.

[0011] Preferably, the vacuum degree of the vacuum heat treatment furnace in step S6 is 1×10⁻⁶. -2 Pa.

[0012] Preferably, the composite passivation solution in step S7 comprises: 15-20 g / L phytic acid, 3-5 g / L potassium permanganate, 1-2 g / L cerium nitrate, 0.8-1.5 g / L ammonium metavanadate, pH=2.5-3.5, and temperature 25-30℃.

[0013] Preferably, the mass ratio of the casting to the composite passivation solution in step S7 is 1:(10-20).

[0014] Due to the application of the above technical solution, the present invention has the following beneficial effects: (1) The corrosion-resistant high-strength magnesium alloy material and its preparation method disclosed in this invention adopts an eight-element micro-synergistic alloying system of Y, Ce, Ca, Zr, Sb, Sr, Ta, and In and precisely matches it with the main elements of the AZ91 matrix. This achieves multiple benefits such as grain refinement, grain boundary corrosion channel blocking, and simultaneous improvement of matrix plasticity. The four types of alloying elements, namely rare earth, alkaline earth, transition, and main group, work together to form a highly matched heterogeneous nucleation core of Ta-Zr-Sb, which greatly refines the grains. In, together with Ca and Sb, breaks the continuous network β and reduces the resistance to dislocation movement. This solves the industry contradiction that the strength improvement of traditional magnesium alloys inevitably sacrifices plasticity. As a result, the material has excellent corrosion resistance, good mechanical properties, and long service life.

[0015] (2) The corrosion-resistant high-strength magnesium alloy material and its preparation method disclosed in this invention, through the combination of gradient particle size ternary composite refining agent with vacuum melting and high temperature homogenization heat treatment process to purify the melt, achieves the purification and efficiency enhancement effect of significantly removing micro inclusions in the melt, reducing the loss of precious Ta / In / rare earth elements, and significantly reducing the pitting corrosion initiation sites of castings. The large particle size hexachlorocyclohexane long-term degassing, medium particle size calcium fluoride to break the oxide film, and nano fluorocarbon cerium ore to capture submicron rare earth inclusions work together to make up for the defect of traditional binary refining agents that cannot remove fine oxides of high melting point alloys, reduce the risk of electrochemical corrosion of the matrix from the source, and achieve a leapfrog improvement in the intrinsic corrosion resistance of the alloy after being adapted to the octet alloy system. The synergistic effect of purification and corrosion resistance cannot be achieved by using binary refining agents alone.

[0016] (3) The corrosion-resistant high-strength magnesium alloy material and its preparation method disclosed in this invention achieve a long-term protective effect with multi-layer gradient densification of the passivation film, self-repair of micro-scratches, and highly uniform salt spray performance of batch products by using a vanadium-based self-healing passivation liquid containing ammonium metavanadate and limiting the mass bath ratio of castings to passivation liquid to 1:(10~20). The phytic acid chelating layer, rare earth oxide barrier layer and vanadium ion self-healing layer work together to ensure a continuous and stable supply of vanadium and rare earth active ions in the passivation liquid within the mass ratio range, solving the shortcoming of complete failure of protection after damage of conventional phytic acid passivation film. The multi-element corrosion resistance strengthening of the alloy matrix and the surface self-healing passivation film form a dual corrosion resistance synergistic system inside and outside. The salt spray tolerance time is significantly improved compared with ordinary phytic acid passivated magnesium alloy, forming a long-term corrosion resistance synergistic advantage that cannot be achieved by existing single matrix modification or single passivation technology. Detailed Implementation

[0017] The preferred embodiments of the present invention will now be described in detail so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0018] Example 1: A corrosion-resistant high-strength magnesium alloy material, by weight percentage, is composed of the following chemical components: Al 8.5%, Zn 0.4%, Mn 0.2%, Y 0.1%, Ce 0.05%, Ca 0.08%, Zr 0.05%, Sb 0.02%, Sr 0.01%, Ta 0.01%, In 0.02%, with the balance being Mg and other unavoidable impurities.

[0019] A method for preparing the corrosion-resistant high-strength magnesium alloy material includes the following steps: Step S1, Smelting and Material Preparation: According to the chemical composition ratio, preheat pure magnesium ingots, pure aluminum ingots, pure zinc ingots, pure antimony blocks, pure strontium blocks, pure tantalum powder, pure indium ingots, magnesium-manganese alloy, magnesium-yttrium alloy, magnesium-cerium alloy, magnesium-calcium alloy, and magnesium-zirconium alloy to 120°C to remove surface oil and oxide scale. Step S2, Vacuum Melting: Add the preheated raw material to a vacuum induction melting furnace and evacuate to 1×10⁻⁶. -3 Pa, heat to 720℃, melt the raw material and then introduce high-purity argon gas for protection, stir the melt for 10 minutes; Step S3, Refining and Impurity Removal: Add composite refining agent to the melt, keep it at a constant temperature for 15 minutes, and skim off the surface slag; Step S4, High-pressure die casting: The melt is transferred to a high-pressure die casting machine and die-cast under the following conditions: melt temperature 680℃, mold temperature 220℃, injection speed 3m / s, injection pressure 40MPa, and holding time 8s. Step S5, Shaping and Trimming: The casting is hot-shaped at 300℃, and then trimmed by CNC. Step S6, Grain Refinement Heat Treatment: Heat the casting to 380°C in a vacuum heat treatment furnace, hold for 2 hours, and then cool to room temperature with the furnace. Step S7, Environmental passivation treatment: After pretreatment, the casting is immersed in the composite passivation solution for 15 minutes, then rinsed and dried; Step S8, Subsequent finishing: Perform CNC engraving, polishing, spraying, film application, and laser engraving processes to obtain the final product.

[0020] The composite refining agent mentioned in step S3 is composed of hexachloroethane, calcium fluoride, and nano-fluorocarbon cerium ore powder mixed in a mass ratio of 7:3:0.4, and the amount used is 0.2% of the total mass of the melt; the particle size of the hexachloroethane is D50=0.8mm, the particle size of the calcium fluoride is D50=30μm, and the particle size of the nano-fluorocarbon cerium ore powder is D50=80nm; the vacuum degree of the vacuum heat treatment furnace mentioned in step S6 is 1×10 -2 Pa; The composite passivation solution in step S7 contains: 15 g / L phytic acid, 3 g / L potassium permanganate, 1 g / L cerium nitrate, 0.8 g / L ammonium metavanadate, pH=2.5, and temperature 25℃; The mass ratio of the casting to the composite passivation solution in step S7 is 1:10.

[0021] Example 2: A corrosion-resistant high-strength magnesium alloy material, by weight percentage, is composed of the following chemical components: Al 8.8%, Zn 0.5%, Mn 0.25%, Y 0.15%, Ce 0.08%, Ca 0.09%, Zr 0.07%, Sb 0.04%, Sr 0.02%, Ta 0.02%, In 0.03%, with the balance being Mg and other unavoidable impurities.

[0022] A method for preparing the corrosion-resistant high-strength magnesium alloy material includes the following steps: Step S1, Smelting and Material Preparation: According to the chemical composition ratio, preheat the pure magnesium ingot, pure aluminum ingot, pure zinc ingot, pure antimony block, pure strontium block, pure tantalum powder, pure indium ingot, magnesium manganese alloy, magnesium yttrium alloy, magnesium cerium alloy, magnesium calcium alloy, and magnesium zirconium alloy to 130°C to remove surface oil and oxide scale. Step S2, Vacuum Melting: Add the preheated raw material to a vacuum induction melting furnace and evacuate to 1×10⁻⁶. -3 Pa, heat to 730℃, melt the raw material and then introduce high-purity argon gas for protection, stir the melt for 12 minutes; Step S3, Refining and Impurity Removal: Add composite refining agent to the melt, keep it at a constant temperature for 16 minutes, and skim off the surface slag; Step S4, High-pressure die casting: The melt is transferred to a high-pressure die casting machine and die-cast under the following conditions: melt temperature 685℃, mold temperature 225℃, injection speed 3.5m / s, injection pressure 45MPa, and holding time 9s. Step S5, Shaping and Trimming: The casting is hot-shaped at 305℃, and then trimmed by CNC. Step S6, Grain Refinement Heat Treatment: Heat the casting to 385°C in a vacuum heat treatment furnace, hold for 2.3 hours, and then cool to room temperature with the furnace. Step S7, Environmental passivation treatment: After pretreatment, the casting is immersed in the composite passivation solution for 16 minutes, then rinsed and dried; Step S8, Subsequent finishing: Perform CNC engraving, polishing, spraying, film application, and laser engraving processes to obtain the final product.

[0023] The composite refining agent mentioned in step S3 is composed of hexachloroethane, calcium fluoride, and nano-fluorocarbon cerium ore powder mixed in a mass ratio of 7:3:0.45, and the amount used is 0.23% of the total melt mass; the particle size of the hexachloroethane is D50=1mm, the particle size of the calcium fluoride is D50=40μm, and the particle size of the nano-fluorocarbon cerium ore powder is D50=130nm; the vacuum degree of the vacuum heat treatment furnace mentioned in step S6 is 1×10 -2 Pa; The composite passivation solution in step S7 contains: 17 g / L phytic acid, 3.5 g / L potassium permanganate, 1.2 g / L cerium nitrate, 1 g / L ammonium metavanadate, pH=2.8, and temperature 27℃; The mass ratio of the casting to the composite passivation solution in step S7 is 1:13.

[0024] Example 3: A corrosion-resistant high-strength magnesium alloy material, by weight percentage, is composed of the following chemical composition: Al 9%, Zn 0.6%, Mn 0.3%, Y 0.2%, Ce 0.1%, Ca 0.1%, Zr 0.08%, Sb 0.05%, Sr 0.03%, Ta 0.03%, In 0.04%, with the balance being Mg and other unavoidable impurities.

[0025] A method for preparing the corrosion-resistant high-strength magnesium alloy material includes the following steps: Step S1, Smelting and Material Preparation: According to the chemical composition ratio, preheat the pure magnesium ingots, pure aluminum ingots, pure zinc ingots, pure antimony blocks, pure strontium blocks, pure tantalum powder, pure indium ingots, magnesium-manganese alloy, magnesium-yttrium alloy, magnesium-cerium alloy, magnesium-calcium alloy, and magnesium-zirconium alloy to 135°C. Add the preheated raw materials to a vacuum induction melting furnace and evacuate to 1×10⁻⁶. -3 Pa, heat to 735℃, melt the raw material and then introduce high-purity argon gas for protection, stir the melt for 13 minutes; Step S3, Refining and Impurity Removal: Add composite refining agent to the melt, keep it at a constant temperature for 18 minutes, and skim off the surface scum; Step S4, High-pressure die casting: The melt is transferred to a high-pressure die casting machine and die-cast under the following conditions: melt temperature 690℃, mold temperature 230℃, injection speed 4m / s, injection pressure 50MPa, and holding time 10s. Step S5, Shaping and Trimming: The casting is hot-shaped at 310℃, and then trimmed by CNC. Step S6, Grain Refinement Heat Treatment: Heat the casting to 390°C in a vacuum heat treatment furnace, hold for 2.5 hours, and then cool to room temperature with the furnace. Step S7, Environmental passivation treatment: After pretreatment, the casting is immersed in the composite passivation solution for 18 minutes, then rinsed and dried; Step S8, Subsequent finishing: Perform CNC engraving, polishing, spraying, film application, and laser engraving processes to obtain the final product.

[0026] The composite refining agent mentioned in step S3 is composed of hexachloroethane, calcium fluoride, and nano-fluorocarbon cerium ore powder mixed in a mass ratio of 7:3:0.5, and the amount used is 0.25% of the total melt mass; the particle size of the hexachloroethane is D50=1.2mm, the particle size of the calcium fluoride is D50=50μm, and the particle size of the nano-fluorocarbon cerium ore powder is D50=160nm; the vacuum degree of the vacuum heat treatment furnace mentioned in step S6 is 1×10 -2 Pa; The composite passivation solution in step S7 contains: 18 g / L phytic acid, 4 g / L potassium permanganate, 1.5 g / L cerium nitrate, 1.2 g / L ammonium metavanadate, pH=3, and temperature 28℃; The mass ratio of the casting to the composite passivation solution in step S7 is 1:15.

[0027] Example 4: A corrosion-resistant high-strength magnesium alloy material, by weight percentage, is composed of the following chemical composition: Al 9.3%, Zn 0.7%, Mn 0.35%, Y 0.25%, Ce 0.13%, Ca 0.11%, Zr 0.09%, Sb 0.07%, Sr 0.04%, Ta 0.04%, In 0.05%, with the balance being Mg and other unavoidable impurities.

[0028] A method for preparing the corrosion-resistant high-strength magnesium alloy material includes the following steps: Step S1, Smelting and Material Preparation: According to the chemical composition ratio, preheat pure magnesium ingots, pure aluminum ingots, pure zinc ingots, pure antimony blocks, pure strontium blocks, pure tantalum powder, pure indium ingots, magnesium-manganese alloy, magnesium-yttrium alloy, magnesium-cerium alloy, magnesium-calcium alloy, and magnesium-zirconium alloy to 145°C to remove surface oil and oxide scale. Step S2, Vacuum Melting: Add the preheated raw material to a vacuum induction melting furnace and evacuate to 1×10⁻⁶. -3 Pa, heat to 745℃, melt the raw material and then introduce high-purity argon gas for protection, stir the melt for 14 minutes; Step S3, Refining and Impurity Removal: Add composite refining agent to the melt, keep it at a constant temperature for 19 minutes, and skim off the surface slag; Step S4, High-pressure die casting: The melt is transferred to a high-pressure die casting machine and die-cast under the following conditions: melt temperature 695℃, mold temperature 235℃, injection speed 4.5m / s, injection pressure 55MPa, and holding time 11s. Step S5, Shaping and Trimming: The casting is hot-shaped at 315℃, and then trimmed by CNC. Step S6, Grain Refinement Heat Treatment: Heat the casting to 395°C in a vacuum heat treatment furnace, hold for 2.8 hours, and then cool to room temperature with the furnace. Step S7, Environmental passivation treatment: After pretreatment, the casting is immersed in the composite passivation solution for 19 minutes, then rinsed and dried; Step S8, Subsequent finishing: Perform CNC engraving, polishing, spraying, film application, and laser engraving processes to obtain the final product.

[0029] The composite refining agent mentioned in step S3 is composed of hexachloroethane, calcium fluoride, and nano-fluorocarbon cerium ore powder mixed in a mass ratio of 7:3:0.55, and the amount used is 0.28% of the total melt mass; the particle size of the hexachloroethane is D50=1.4mm, the particle size of the calcium fluoride is D50=70μm, and the particle size of the nano-fluorocarbon cerium ore powder is D50=260nm; the vacuum degree of the vacuum heat treatment furnace mentioned in step S6 is 1×10 - 2 Pa; The composite passivation solution in step S7 contains: 19 g / L phytic acid, 4.5 g / L potassium permanganate, 1.8 g / L cerium nitrate, 1.3 g / L ammonium metavanadate, pH=3.3, and temperature 29℃; The mass ratio of the casting to the composite passivation solution in step S7 is 1:18.

[0030] Example 5: A corrosion-resistant high-strength magnesium alloy material, by weight percentage, is composed of the following chemical composition: Al 9.5%, Zn 0.8%, Mn 0.4%, Y 0.3%, Ce 0.15%, Ca 0.12%, Zr 0.1%, Sb 0.08%, Sr 0.05%, Ta 0.05%, In 0.06%, with the balance being Mg and other unavoidable impurities.

[0031] A method for preparing the corrosion-resistant high-strength magnesium alloy material includes the following steps: Step S1, Smelting and Material Preparation: According to the chemical composition ratio, preheat pure magnesium ingots, pure aluminum ingots, pure zinc ingots, pure antimony blocks, pure strontium blocks, pure tantalum powder, pure indium ingots, magnesium-manganese alloy, magnesium-yttrium alloy, magnesium-cerium alloy, magnesium-calcium alloy, and magnesium-zirconium alloy to 150°C to remove surface oil and oxide scale. Step S2, Vacuum Melting: Add the preheated raw material to a vacuum induction melting furnace and evacuate to 1×10⁻⁶. -3 Pa, heat to 750℃, melt the raw material and then introduce high-purity argon gas for protection, stir the melt for 15 minutes; Step S3, Refining and Impurity Removal: Add composite refining agent to the melt, keep it at a constant temperature for 20 minutes, and skim off the surface scum; Step S4, High-pressure die casting: The melt is transferred to a high-pressure die casting machine and die-cast under the following conditions: melt temperature 700℃, mold temperature 240℃, injection speed 5m / s, injection pressure 60MPa, and holding time 12s. Step S5, Shaping and Trimming: The casting is hot-shaped at 320℃, and then trimmed by CNC. Step S6, Grain Refinement Heat Treatment: Heat the casting to 400°C in a vacuum heat treatment furnace, hold for 3 hours, and then cool to room temperature with the furnace. Step S7, Environmental passivation treatment: After pretreatment, the casting is immersed in the composite passivation solution for 20 minutes, then rinsed and dried; Step S8, Subsequent finishing: Perform CNC engraving, polishing, spraying, film application, and laser engraving processes to obtain the final product.

[0032] The composite refining agent mentioned in step S3 is composed of hexachloroethane, calcium fluoride, and nano-fluorocarbon cerium ore powder mixed in a mass ratio of 7:3:0.6, and the amount used is 0.3% of the total mass of the melt; the particle size of the hexachloroethane is D50=1.5mm, the particle size of the calcium fluoride is D50=80μm, and the particle size of the nano-fluorocarbon cerium ore powder is D50=300nm; the vacuum degree of the vacuum heat treatment furnace mentioned in step S6 is 1×10 -2Pa; The composite passivation solution in step S7 contains: 20 g / L phytic acid, 5 g / L potassium permanganate, 2 g / L cerium nitrate, 1.5 g / L ammonium metavanadate, pH=3.5, and temperature 30℃; The mass ratio of the casting to the composite passivation solution in step S7 is 1:20.

[0033] Comparative Example 1 A corrosion-resistant high-strength magnesium alloy material and its preparation method are basically the same as those in Example 5, except that an equal amount of Ta is used instead of In.

[0034] Comparative Example 2 A corrosion-resistant high-strength magnesium alloy material and its preparation method are basically the same as those in Example 5, except that an equal amount of In is used instead of Ta.

[0035] Comparative Example 3 A corrosion-resistant high-strength magnesium alloy material and its preparation method are basically the same as those in Example 5, except that an equal amount of Sb is used instead of Sr.

[0036] Comparative Example 4 A corrosion-resistant high-strength magnesium alloy material and its preparation method are basically the same as those in Example 5, except that an equal amount of Sr is used instead of Sb.

[0037] Comparative Example 5 A corrosion-resistant high-strength magnesium alloy material and its preparation method are basically the same as those in Example 5, except that an equal amount of calcium fluoride is used instead of nano-fluorocarbon cerium ore powder.

[0038] Comparative Example 6 A corrosion-resistant high-strength magnesium alloy material and its preparation method are basically the same as those in Example 5, except that an equal amount of cerium nitrate is used instead of ammonium metavanadate.

[0039] To further illustrate the beneficial technical effects of the corrosion-resistant high-strength magnesium alloy materials involved in the embodiments of the present invention, relevant performance tests were conducted on the corrosion-resistant high-strength magnesium alloy materials prepared in each example. The test results are shown in Table 1; the test methods are as follows: (1) Mechanical property test: In accordance with GB / T 228.1-2021 "Metallic materials, tensile testing - Part 1: Room temperature test method", the room temperature tensile properties were tested using a universal testing machine. The specimen was a standard φ10mm×50mm cylindrical tensile specimen. The tensile rate was 2mm / min. Each specimen was tested 3 times and the average value was taken. (2) Corrosion resistance test: According to GB / T 10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test", a neutral salt spray (NSS) test was adopted. The test conditions were: 5% NaCl solution, pH value 6.5~7.2, test temperature 35℃±2℃, and salt spray deposition rate 1~2mL / (80cm). 2The sample size was 50mm×50mm×2mm. Before the test, the sample was cleaned, dried and weighed with anhydrous ethanol. After the test, the sample was rinsed, dried and weighed with deionized water. The corrosion rate was calculated and the time when white rust appeared on the sample surface was recorded.

[0040] Table 1

[0041] As shown in Table 1, Example 5, through synergistic modification with multiple trace elements (Ta, In, Sb, Sr), purification of the melt with a composite refining agent containing nano-fluorocarbon cerium ore powder, and film protection using a phytic acid-cerium-vanadium composite passivation system, achieved a tensile strength of 422 MPa, a neutral salt spray white rust appearance time of 975 hours, and a corrosion rate as low as 0.030 mg / cm². 2 The overall performance of the sample ·d is significantly better than that of the comparative examples 1 to 6, which only retain Ta or In, interchange Sb and Sr, lack nano-fluorocarbon cerium ore powder in the refining system, and do not contain ammonium metavanadate in the passivation solution. This indicates that there is a strong synergistic effect between the Ta-In-Sb-Sr micro alloy composite, the refining and purification of nano-fluorocarbon cerium ore, and the cerium-vanadium synergistic corrosion inhibition and passivation. The absence of any key component will cause coarsening of alloy grains, aggravation of micro-galvanic corrosion, and a decrease in the density of the passivation film, resulting in a significant decrease in tensile strength, a significant shortening of salt spray corrosion resistance time, and a multiple increase in corrosion rate.

[0042] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A corrosion-resistant high-strength magnesium alloy material, characterized by comprising, in mass %, By weight percentage, it consists of the following chemical components: Al 8.5~9.5%, Zn 0.4~0.8%, Mn 0.2~0.4%, Y 0.1~0.3%, Ce 0.05~0.15%, Ca 0.08~0.12%, Zr 0.05~0.1%, Sb 0.02~0.08%, Sr 0.01~0.05%, Ta 0.01~0.05%, In 0.02~0.06%, with the balance being Mg and other unavoidable impurities; The preparation method of the corrosion-resistant high-strength magnesium alloy material includes the following steps: Step S1, Smelting and Material Preparation: According to the chemical composition ratio, preheat pure magnesium ingots, pure aluminum ingots, pure zinc ingots, pure antimony blocks, pure strontium blocks, pure tantalum powder, pure indium ingots, magnesium-manganese alloy, magnesium-yttrium alloy, magnesium-cerium alloy, magnesium-calcium alloy, and magnesium-zirconium alloy to 120~150℃ to remove surface oil and oxide scale. Step S2, Vacuum Melting: Add the preheated raw material to a vacuum induction melting furnace and evacuate to 1×10⁻⁶. -3 Pa, heat to 720~750℃, melt the raw material and then introduce high-purity argon gas for protection, stir the melt for 10~15 minutes; Step S3, Refining and Impurity Removal: Add a composite refining agent to the melt, keep it at a constant temperature for 15-20 minutes, and skim off the surface scum; the composite refining agent is a mixture of hexachloroethane, calcium fluoride, and nano-fluorocarbon cerium ore powder in a mass ratio of 7:3:(0.4-0.6); Step S4, High-pressure die casting: The melt is transferred to a high-pressure die casting machine and die-cast under the following conditions: melt temperature 680~700℃, mold temperature 220~240℃, injection speed 3~5m / s, injection pressure 40~60MPa, and holding time 8~12s. Step S5, Shaping and Trimming: The casting is hot-shaped at 300~320℃, and then trimmed by CNC. Step S6, Grain Refinement Heat Treatment: Heat the casting to 380~400℃ in a vacuum heat treatment furnace, hold for 2~3 hours, and then cool to room temperature with the furnace. Step S7, Environmental passivation treatment: After pretreatment, the casting is immersed in a composite passivation solution for 15-20 minutes, rinsed and dried; the composite passivation solution contains: 15-20 g / L phytic acid, 3-5 g / L potassium permanganate, 1-2 g / L cerium nitrate, 0.8-1.5 g / L ammonium metavanadate, pH=2.5-3.5, temperature 25-30℃; Step S8, Subsequent finishing: Perform CNC engraving, polishing, spraying, film application, and laser engraving processes to obtain the final product.

2. The corrosion resistant high strength magnesium alloy material of claim 1, wherein, The corrosion-resistant high-strength magnesium alloy material, by weight percentage, is composed of the following chemical composition: Al 9%, Zn 0.6%, Mn 0.3%, Y 0.2%, Ce 0.1%, Ca 0.1%, Zr 0.08%, Sb 0.05%, Sr 0.03%, Ta 0.03%, In 0.04%, with the balance being Mg and other unavoidable impurities.

3. The corrosion resistant high strength magnesium alloy material of claim 1, wherein, In step S3, the amount of the composite refining agent is 0.2-0.3% of the total mass of the melt; the particle size of the hexachloroethane is D50=0.8-1.5mm, the calcium fluoride is D50=30-80μm, and the nano fluorocarbon cerium ore powder is D50=80-300nm.

4. The corrosion resistant high strength magnesium alloy material of claim 1, wherein, The vacuum degree of the vacuum heat treatment furnace in step S6 is 1 x 10 -2 Pa.

5. The corrosion-resistant high-strength magnesium alloy material according to claim 1, characterized in that, The mass ratio of the casting and the composite passivation solution in step S7 is 1:(10-20).

6. The corrosion-resistant high-strength magnesium alloy material according to claim 1, characterized in that, The corrosion-resistant high-strength magnesium alloy material has a room temperature tensile strength ≥422MPa and a time of white rust appearance ≥975h in the neutral salt spray test.

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