A micro-arc oxidation treatment method for an LPSO phase-containing magnesium alloy

Abstract

A micro-arc oxidation treatment method for a magnesium alloy containing an LPSO phase, which adopts an electrolyte system mixed with three kinds of salts, i.e., a metallate, a silicate and a phosphate, and combines two-step micro-arc oxidation treatment to control the generation of ceramic phases in the oxide film layer structure and embed a large number of exposed LPSO phases in the micro-arc oxidation film, so that the obtained micro-arc oxidation film has small porosity and pore size, a smooth surface and no micro-cracks, the porosity is less than or equal to 9%, the micro-arc oxidation film has a pore size of 140-1100 nm and an average pore size of less than or equal to 1 micrometer, and the corrosion resistance of the magnesium alloy is significantly improved, the self-corrosion current density of the magnesium alloy is reduced by three orders of magnitude compared with that before the micro-arc oxidation treatment, the self-corrosion current density is less than or equal to 3.588*10 ‑8 A cm ‑2 , and the corrosion resistance efficiency is greater than or equal to 1208%.

Description

Technical Field

[0001] This invention relates to the field of metal surface treatment technology, and in particular to a micro-arc oxidation treatment method for magnesium alloys containing LPSO phase. Background Technology

[0002] Magnesium alloys are alloys composed of magnesium as the base element and other elements added. Magnesium alloys have the characteristics of low density, high strength, high elastic modulus, good heat dissipation, good shock absorption, strong ability to withstand impact loads, excellent electrical and thermal conductivity, and good damping properties. They are widely used in portable devices and the automotive industry.

[0003] In recent years, it has been discovered that adding elements such as zinc, copper, or nickel to Mg-RE (Gd, Y, Tb, Dy, Ho, Tm) alloys can yield long-period stacked ordered structures (LPSO) with excellent properties. LPSO includes both compositional ordering and stacking fault ordering. LPSO significantly improves the alloy's plasticity, strength, creep resistance, and damping properties, attracting widespread attention. In recent years, with the development of automotive automation, aerospace, mobile communications, and the computer industry, high-strength and high-toughness magnesium alloys containing LPSO phases have attracted considerable interest.

[0004] However, magnesium alloys possess high chemical and electrochemical activity and extremely low standard electrode potential, making them highly susceptible to corrosion, which significantly limits their application range. Micro-arc oxidation technology is a surface treatment technique that has emerged in recent years. It utilizes the instantaneous high-temperature sintering effect generated by arc discharge to prepare a ceramic film. The resulting ceramic film has a smaller relative pore area compared to anodized films, typically consisting of a loose layer, a dense layer, and a transition layer. It is tightly bonded to the substrate and exhibits high wear resistance, corrosion resistance, high-temperature impact resistance, and excellent electrical insulation. The film obtained using this technology offers controllable thickness and superior corrosion and wear resistance, making it widely recognized as the most promising surface treatment technology for magnesium alloys.

[0005] Typically, micro-arc oxidation films exhibit a "volcano"-like morphology with accompanying microcracks. At the center of each "volcano" is a discharge channel from which molten material emerges. Upon contact with the electrolyte, this material is rapidly quenched, forming boundaries that separate the different "volcanoes." Furthermore, each "volcano" contains large pores extending deep into the film, due to the extremely strong discharge during the oxidation process. The formation of microcracks is caused by the internal stress generated when the molten material is quenched by the electrolyte. The morphology, structure, and composition of the micro-arc oxidation film are influenced by its electrical parameters, such as voltage or current, frequency, and duty cycle. As the voltage increases, the film thickness and adhesion initially increase and then decrease, while the film formation rate, porosity, and pore size continuously increase. Generally, the corrosion resistance of ceramic layers improves with increasing frequency and deteriorates with increasing duty cycle. The order of influence of process parameters on corrosion resistance from highest to lowest is: termination voltage, frequency, and duty cycle.

[0006] Currently, the electrical parameters for micro-arc oxidation of magnesium alloys are mostly selected in constant current mode, with a current density of 2-15 A / dm³. 2 The micro-arc oxidation processes are performed at frequencies of 100-500Hz, duty cycles of 10-50%, and durations of 5-40 minutes. A few also employ a dual-pulse constant-voltage mode with positive voltages of 250-550V and negative voltages of 0-100V, frequencies of 300-600Hz, duty cycles of 20-50%, and durations of 10-60 minutes. Most micro-arc oxidation temperatures are controlled between 20-40℃. The resulting micro-arc oxidation films have pore sizes of 2-15μm and porosities of 15-40%, exhibiting corrosion resistance that is up to two orders of magnitude higher than that of the substrate.

[0007] The electrolyte in micro-arc oxidation has a decisive influence on the composition, structure, and properties of the micro-arc oxidation ceramic layer of magnesium alloys. Traditionally, the most widely used systems are acidic and alkaline systems, but acidic systems are rarely used due to their polluting properties. Currently, research on electrolytes for magnesium alloy micro-arc oxidation focuses more on weakly alkaline electrolyte systems. The most common electrolytes mainly consist of single-solution systems such as aluminates, silicates, and phosphates, as well as mixed salt solutions such as phosphate-silicate and silicate-borate solutions. Simultaneously, stabilizing organic and inorganic reagents are added.

[0008] Chinese patent CN102560591A discloses "a micro-arc oxidation electrolyte and a micro-arc oxidation method", in which the electrolyte adopts a phosphate-silicate solution system; Chinese patent CN113026075A discloses "a micro-arc oxidation electrolyte for magnesium alloy anodes and a method for micro-arc oxidation of magnesium alloy anodes using the electrolyte", in which the electrolyte adopts a silicate-carbonate-borate solution system.

[0009] Chinese patent CN102851720A discloses "an aluminate electrolyte and its application in the preparation of magnesium alloy micro-arc oxidation film", in which the electrolyte adopts an aluminate single salt solution system.

[0010] Chinese patent CN102367584A discloses a "metal micro-arc oxidation electrolyte and a method for black ceramicizing the surface of metal micro-arc oxidation". In this patent, the electrolyte adopts a silicate single salt solution system.

[0011] Magnesium alloys containing the LPSO phase differ from commonly used AZ series magnesium alloys. When using existing micro-arc oxidation technology to treat magnesium alloys containing the LPSO phase, a large number of micro- and nano-sized second-phase LPSO phases are distributed on the surface, which has a certain impact on the micro-arc oxidation of magnesium alloys. Using traditional micro-arc oxidation methods and electrolytes for treatment results in slow arc initiation, or even no arc initiation, and failure to form a film through etching. Even if a film is formed, the micro-arc oxidation film has poor adhesion to the substrate, the film layer is not dense, and there are many defects such as microcracks and large pores, which limits the improvement of the corrosion resistance of magnesium alloys. Summary of the Invention

[0012] The purpose of this invention is to provide a micro-arc oxidation treatment method for magnesium alloys containing LPSO phase, solving the problems of arc failure, film formation failure, or non-dense film layers in existing micro-arc oxidation technologies when treating magnesium alloys containing LPSO phase. This method improves the structure of the micro-arc oxidation film on the magnesium alloy surface, obtaining a micro-arc oxidation film with low porosity, small pore size, smooth surface, and no microcracks. The porosity of the micro-arc oxidation film is ≤9%, the pore size is 140–1100 nm, and the average pore size is ≤1 μm. This significantly improves the corrosion resistance of the magnesium alloy, reducing the self-corrosion current density by three orders of magnitude compared to before micro-arc oxidation treatment, with a self-corrosion current density ≤3.588 × 10⁻⁶. -8 A cm -2 Corrosion resistance efficiency ≥1208%.

[0013] To achieve the above objectives, the technical solution of the present invention is as follows:

[0014] A micro-arc oxidation treatment method for magnesium alloys containing LPSO phase includes the following steps:

[0015] 1) Preprocessing

[0016] Grind the magnesium alloy surface to remove the oxide layer, and clean it to remove oil and other impurities.

[0017] 2) Micro-arc oxidation

[0018] The pretreated magnesium alloy is placed in a micro-arc oxidation electrolyte, with stainless steel as the cathode and magnesium alloy as the anode, and undergoes a two-step micro-arc oxidation process. The first step of the micro-arc oxidation process has a voltage of 180-200V and a processing time of 10-40s; the second step of the micro-arc oxidation process has a voltage of 350-400V and a processing time of 240-360s. The micro-arc oxidation electrolyte is mainly composed of silicates and / or their hydrates, phosphates and / or their hydrates, aluminates and / or their hydrates, a strong alkali, and water.

[0019] 3) Cleaning and drying

[0020] The magnesium alloy surface treated with micro-arc oxidation is cleaned and dried.

[0021] Preferably, in step 2), the concentration of the micro-arc oxidation electrolyte is: silicate and / or its hydrate: 3-12 g / L, phosphate and / or its hydrate: 3-12 g / L, aluminate and / or its hydrate: 3-12 g / L, and strong alkali: 1-3 g / L.

[0022] Preferably, in step 2), the micro-arc oxidation electrolyte further includes polyvinyl alcohol, wherein the concentration of polyvinyl alcohol is 0.1-0.5 g / L.

[0023] Preferably, in step 2), the strong base is sodium hydroxide or potassium hydroxide.

[0024] Preferably, in step 2), the micro-arc oxidation treatment temperature is 8–16°C.

[0025] Preferably, in step 2), the pulse duty cycle during the micro-arc oxidation process is 4.5–8.4%.

[0026] Preferably, in step 2), the pulse width during the micro-arc oxidation process is 90–140 μs and the frequency is 500–600 Hz.

[0027] Preferably, in step 3), the drying is air drying, and the preferred air drying temperature is 40-60°C.

[0028] The present invention also provides an electrolyte for micro-arc oxidation treatment of magnesium alloys containing LPSO phase. The micro-arc oxidation electrolyte is mainly composed of silicate and / or its hydrates, phosphate and / or its hydrates, aluminate and / or its hydrates, a strong alkali and water, wherein the concentration of silicate and / or its hydrates is 3-12 g / L, the concentration of phosphate and / or its hydrates is 3-12 g / L, the concentration of aluminate and / or its hydrates is 3-12 g / L, and the concentration of strong alkali is 1-3 g / L.

[0029] Preferably, the micro-arc oxidation electrolyte further includes polyvinyl alcohol, with a polyvinyl alcohol concentration of 0.1–0.5 g / L.

[0030] Preferably, the strong base is sodium hydroxide or potassium hydroxide.

[0031] This invention targets magnesium alloys containing LPSO phases with long-period stacked ordered structures and employs a two-step micro-arc oxidation method:

[0032] The first step of micro-arc oxidation treatment has a voltage of 180-200V and a treatment time of 10-40s. The oxidation pretreatment under low voltage can not only eliminate scratches, impurities and natural oxide layers generated by the pretreatment on the magnesium alloy surface, but also, during the low voltage and short time oxidation process, the LPSO phase and α-Mg boundary in the magnesium alloy matrix have a low defect potential, and the surrounding α-Mg partially dissolves, exposing the LPSO phase. This is beneficial for the LPSO phase to be embedded in the film during the next step of high voltage micro-arc oxidation.

[0033] The second step involves adjusting the voltage to 350–400V and the treatment time to 4–6 minutes. Under high voltage, an arc is ignited on the surface of the magnesium alloy substrate, generating a large amount of short-lived plasma discharge. Melting occurs at the interface between the magnesium alloy substrate and the electrolyte. The melt flows, then solidifies, diffuses, and sinters, densifying the MgO to form a partial ceramic phase. The LPSO phase exposed during the first step of the micro-arc oxidation process has a low potential and reacts violently. The ceramic phase rapidly forms a film that encapsulates the LPSO phase, thereby embedding the LPSO phase within the micro-arc oxidation film or connecting the micro-arc oxidation film and the substrate. This results in a dense micro-arc oxidation film structure and improves the corrosion resistance of the micro-arc oxidation film.

[0034] This invention configures a mixture of aluminate, silicate, and phosphate salts as the electrolyte for micro-arc oxidation. During micro-arc oxidation, the α-Mg matrix phase in the magnesium alloy has a lower electrode potential than the LPSO phase. The α-Mg matrix phase dissolves first by losing electrons, while the LPSO phase dissolves or remains undissolved later. The alkaline electrolyte contains a high concentration of OH-. - It provides oxygen, generating MgO and hydrogen gas. Simultaneously, SiO3 is present in the electrolyte. 2- PO4 3- and Al2O4 2- Driven by voltage, SiO3 moves towards the magnesium alloy matrix, which acts as the anode. 2- and PO4 3- The high charge-to-diameter ratio and rapid ion mass transfer rate of PO4 enable the micro-arc oxidation film to grow inwards, resulting in ion enrichment in the inner layer of the micro-arc oxidation film. 3- With Mg 2+ The formation of Mg3(PO4)2 with a very small solubility product results in structural stability and good thermal control, stabilizing the inner layer structure of the micro-arc oxidation film and SiO3. 2-It combines with the small amount of loose MgO generated in the first step of low-voltage micro-arc oxidation treatment and the partial non-ceramicized MgO in the second step of high-voltage micro-arc oxidation treatment to form Mg2SiO4, which can repair inner layer defects and make the inner layer of the micro-arc oxidation film more compact.

[0035] Al2O4 2- The small ratio of charge to ion diameter and the slow ion mass transfer rate cause the micro-arc oxidation film to grow outwards, with ions accumulating on the outer layer of the film. This is due to the SiO3... 2- and PO4 3- The participation of Al2O4 enables the rapid formation of the inner layer and results in a stable and dense structure. This reduces the intensity of the outer layer reaction, decreases the amount of hydrogen produced, reduces the pore size of the membrane, and... 2- With Mg 2+ The formation of MgAl2O4, which has good thermal conductivity, allows for rapid heat exchange with the low-temperature electrolyte. The pore size of the film is quenched before it can expand, which helps reduce the pore size and porosity of the micro-arc oxidation process. The synergistic effect of these three salts enables rapid film formation on the surface of magnesium alloys containing the LPSO phase, resulting in a stable, dense micro-arc oxidation film with small pore size and low porosity.

[0036] An electrolyte system consisting of aluminate, silicate, and phosphate salts, with SiO4 4- and PO4 3- This allows the micro-arc oxidation film to grow inwards, while Al2O4 2- The micro-arc oxidation film grows outward. This growth mode, combined with a two-step micro-arc oxidation process, allows a large number of exposed LPSO phases to be rapidly encapsulated and embedded in the micro-arc oxidation film by the components of the micro-arc oxidation film, rather than allowing the LPSO phases to detach from the substrate. This can further improve the film density.

[0037] The strong alkali in the electrolyte can provide a weakly alkaline environment, which accelerates the dissolution of the magnesium matrix and provides oxygen to facilitate the formation of MgO. Although polyvinyl alcohol does not participate in chemical reactions in the electrolyte, as an organic macromolecule, it can adsorb and precipitate suspended matter in the electrolytic cell, thus removing ash, ensuring the quality of the micro-arc oxidation film, reducing impurities, and improving the utilization rate of the electrolyte.

[0038] The micro-arc oxidation process is controlled at a relatively low temperature of 8-16℃, which is beneficial for the magnesium alloy matrix to be heated under high pressure and for the molten material flowing out from the discharge channel to be rapidly quenched when it comes into contact with the low-temperature electrolyte. This results in a small diffusion range and a smaller pore size.

[0039] In the micro-arc oxidation process of this invention, the pulse duty cycle is 4.5–8.4%. A higher duty cycle results in larger pore sizes in the film, while a lower duty cycle leads to an excessively high film formation rate and a less dense film. This invention employs a lower duty cycle, which not only ensures a dense film with excellent corrosion resistance but also improves the efficiency of micro-arc oxidation.

[0040] Using the electrolyte and two-step micro-arc oxidation process provided by this invention, magnesium alloys containing LPSO phase are subjected to micro-arc oxidation. The micro-arc oxidation film layer formed on the surface of the magnesium alloy has a dense structure, with pores that are almost nanoscale, a smooth surface, and no microcracks, thereby giving the magnesium alloy excellent corrosion resistance.

[0041] The beneficial effects of this invention are:

[0042] This invention targets magnesium alloys containing the LPSO phase. It employs an electrolyte system consisting of a mixture of aluminate, silicate, and phosphate salts, combined with a two-step micro-arc oxidation process. This controls the formation of the ceramic phase in the oxide film structure and embeds a large number of exposed LPSO phases into the micro-arc oxidation film, thereby obtaining a uniform, dense, clean, crack-free micro-arc oxidation film with small pore size and porosity, significantly improving the corrosion resistance of magnesium alloys.

[0043] The micro-arc oxidation film formed on the surface of magnesium alloy using the method described in this invention has a porosity ≤9%, a pore size of 140–1100 nm, and an average pore size ≤1 μm. This significantly improves the corrosion resistance of the magnesium alloy, reducing the self-corrosion current density by three orders of magnitude compared to before micro-arc oxidation treatment, to ≤3.588 × 10⁻⁶. -8 Acm -2 Corrosion resistance efficiency ≥1208%.

[0044] Traditional micro-arc oxidation treatment of magnesium alloys produces micro-arc oxidation films with pore sizes of 2-15 μm and porosity of 15-40%. The corrosion resistance is improved by up to two orders of magnitude compared to the magnesium alloy substrate before micro-arc oxidation treatment. Although the corrosion resistance is also improved to some extent, the improvement is far less than that of the present invention.

[0045] The micro-arc oxidation electrolyte used in this invention is inexpensive, environmentally friendly, and the overall process is simple and green, which can meet the needs of industrial development and mass production, thereby further expanding the application range of magnesium alloys.

[0046] The micro-arc magnesium oxide alloy products obtained by this invention can be used in aerospace, automotive, rail transportation, electronic communications and other fields. Attached Figure Description

[0047] Figure 1 This is a scanning electron microscope image of the magnesium alloy micro-arc oxidation film obtained in Example 1;

[0048] Figure 2 This is a scanning electron microscope image of the magnesium alloy micro-arc oxidation film obtained in Example 2;

[0049] Figure 3 This is a scanning electron microscope image of the magnesium alloy micro-arc oxidation film obtained in Example 3;

[0050] Figure 4 This is a scanning electron microscope image of the magnesium alloy micro-arc oxidation film obtained in Example 4;

[0051] Figure 5 The energy dispersive spectroscopy (EDS) spectrum of the magnesium alloy micro-arc oxidation film prepared in Example 1 is shown below.

[0052] Figure 6 The X-ray diffraction pattern of the magnesium alloy micro-arc oxidation film obtained in Example 1;

[0053] Figure 7 This is a scanning electron microscope (SEM) image of the cross-section of the magnesium alloy micro-arc oxide film obtained in Example 1;

[0054] Figure 8 The potential polarization curves are those of the magnesium alloy micro-arc oxide films prepared in Examples 1-4 and Comparative Example 1.

[0055] Figure 9 The potential polarization curves are for the magnesium alloy micro-arc oxide film layers prepared in Comparative Examples 2-4 and Comparative Example 1.

[0056] Figure 10 The images show the potential polarization curves of the magnesium alloy micro-arc oxide films prepared in Comparative Examples 5-7 and Comparative Example 1. Detailed Implementation

[0057] The present invention will be specifically described below by way of examples and comparative examples, but the scope of the present invention is not limited by these examples.

[0058] The composition of the micro-arc oxidation electrolyte in the embodiments and comparative examples of the present invention is shown in Table 1, and the manufacturing process in the embodiments and comparative examples of the present invention is shown in Table 2. The properties of the magnesium alloys obtained in the embodiments and comparative examples of the present invention are shown in Table 3.

[0059] Comparative Example 1 is a magnesium alloy containing LPSO phase after grinding and cleaning, without micro-arc oxidation treatment.

[0060] As shown in Table 3, the micro-arc oxidation film obtained by treating magnesium alloy with the micro-arc oxidation method described in this invention has small porosity and pore size, smooth surface, no microcracks, porosity ≤9%, micro-arc oxidation film pore size of 140~1100nm, average pore size ≤1μm, and corrosion resistance is significantly improved.

[0061] Figures 1-4The images are scanning electron microscope (SEM) images of the magnesium alloy micro-arc oxidation films in Examples 1-4 of this invention. As can be seen from the images, the LPSO-containing magnesium alloy micro-arc oxidation films prepared in Examples 1-4 have the "crater" morphology structure of traditional micro-arc oxidation films. The craters are very continuous and tightly interwoven, with no broken tip effect. The pores are small, mostly nanoscale pores, and are regularly distributed. The micro-arc oxidation pore size is 140-1100 nm.

[0062] Figure 5 This is the energy dispersive spectroscopy (EDS) analysis diagram of the magnesium alloy micro-arc oxidation film obtained in Example 1 of this invention;

[0063] Depend on Figure 5 It is known that the LPSO-containing magnesium alloy micro-arc oxidation film prepared in Example 1 contains Al, P, and Si elements, but the contents of Al, P, and Si elements vary. Surface testing revealed that Al content was the highest, while Si and P content were lower, indicating that aluminates, phosphates, and silicates all participated in the construction of the micro-arc oxidation film. However, aluminates grew outward and were mainly distributed in the outer layer, while phosphates and silicates grew inward and were mainly distributed in the inner layer. Furthermore, small amounts of LPSO phase constituent elements Gd, Y, and Zn were detected in the film, proving the presence of the LPSO phase in the micro-arc oxidation film and its contribution to film density.

[0064] Figure 6 The image shows the X-ray diffraction pattern of the magnesium alloy micro-arc oxidation film obtained in Example 1. The X-ray diffraction parameters were set as follows: test range 10–80°, scanning speed 4° / min.

[0065] Depend on Figure 6 It can be seen that in the crystal structure of the magnesium alloy micro-arc oxidation film containing LPSO phase obtained in Example 1, the main peak is the base magnesium alloy, and the secondary peak is the crystalline MgO in the micro-arc oxidation film. Mg2SiO4, Mg3(PO4)2 and MgAl2O4 are small in amount and mostly amorphous compounds, and therefore do not show obvious XRD diffraction peaks.

[0066] Figure 7 This is a scanning electron microscope (SEM) image of the cross-section of the magnesium alloy micro-arc oxide film obtained in Example 1. Figure 7 It can be seen that the membrane layer is tightly bonded to the substrate without gaps, the membrane layer is tightly stacked, the overall density is excellent, and the surface is smooth.

[0067] Figure 8 The potential polarization curves are those of the magnesium alloy micro-arc oxide films prepared in Examples 1-4 and Comparative Example 1.

[0068] Depend on Figure 8It can be seen that the corrosion resistance of magnesium alloys containing LPSO phase is significantly improved after treatment with the micro-arc oxidation method described in this invention. The self-corrosion current density is reduced by three orders of magnitude compared with the untreated magnesium alloy, specifically 3.094 × 10⁻⁶. -8 Acm -2 1.563×10 -8 A cm -2 3.588×10 -8 A cm -2 1.599×10 -8 A cm -2 .

[0069] Figure 9 The potential polarization curves are for the magnesium alloy micro-arc oxide film layers prepared in Comparative Examples 2-4 and Comparative Example 1. Figure 10 The images show the potential polarization curves of the magnesium alloy micro-arc oxide films prepared in Comparative Examples 5-7 and Comparative Example 1.

[0070] from Figure 9 , Figure 10 As shown in Table 3, when using traditional electrolytes for micro-arc oxidation treatment, the self-corrosion current density of magnesium alloy is reduced by up to two orders of magnitude compared to the magnesium alloy matrix before micro-arc oxidation treatment. However, the self-corrosion current density of magnesium alloy obtained by this invention is reduced by three orders of magnitude compared to the micro-arc oxidation treatment.

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Claims

1. A micro-arc oxidation treatment method for magnesium alloys containing LPSO phase, characterized in that, Includes the following steps: 1) Preprocessing Grind the magnesium alloy surface to remove the oxide layer, and clean it to remove oil and other impurities. 2) Micro-arc oxidation The pretreated magnesium alloy was placed in a micro-arc oxidation electrolyte, with stainless steel as the cathode and magnesium alloy as the anode, and a two-step micro-arc oxidation process was performed. The first step of the micro-arc oxidation process was performed with a voltage of 180~200V and a processing time of 10~40s; the second step of the micro-arc oxidation process was performed with a voltage of 350~400V and a processing time of 240~360s. The micro-arc oxidation electrolyte comprises silicates and / or their hydrates, phosphates and / or their hydrates, aluminates and / or their hydrates, a strong alkali, and water; the concentration of the micro-arc oxidation electrolyte is: silicates and / or their hydrates 3~12 g / L, phosphates and / or their hydrates 3~12 g / L, aluminates and / or their hydrates 3~12 g / L, and a strong alkali 1~3 g / L; The pulse duty cycle during the micro-arc oxidation process is 4.5~8.4%; 3) Cleaning and drying The magnesium alloy surface treated with micro-arc oxidation is cleaned and dried.

2. The micro-arc oxidation treatment method for magnesium alloys containing LPSO phase as described in claim 1, characterized in that, In step 2), the micro-arc oxidation electrolyte also includes polyvinyl alcohol, with a polyvinyl alcohol concentration of 0.1~0.5 g / L.

3. The micro-arc oxidation treatment method for magnesium alloys containing LPSO phase as described in claim 1 or 2, characterized in that, In step 2), the strong base is sodium hydroxide or potassium hydroxide.

4. The micro-arc oxidation treatment method for magnesium alloys containing LPSO phase as described in claim 1, characterized in that, In step 2), the micro-arc oxidation treatment temperature is 8~16℃.

5. The micro-arc oxidation treatment method for magnesium alloys containing LPSO phase as described in claim 1 or 4, characterized in that, In step 2), the pulse width during the micro-arc oxidation process is 90~140μs and the frequency is 500~600Hz.

6. The micro-arc oxidation treatment method for magnesium alloys containing LPSO phase as described in claim 1, characterized in that, In step 3), the drying is air drying.

7. The micro-arc oxidation treatment method for magnesium alloys containing LPSO phase as described in claim 6, characterized in that, In step 3), the air drying temperature is 40~60℃.

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