Metallographic corrosive agent for high-magnesium aluminum alloy and metallographic preparation method

Abstract

The invention discloses a metallographic corrosive agent for a high-magnesium aluminum alloy and a metallographic preparation method, and relates to the technical field of metal material metallographic detection. The metallographic corrosive agent comprises a component A corrosive agent and a component B corrosive agent, the component A corrosive agent is composed of oxalic acid, nitric acid and water, and the component B corrosive agent is composed of HF, HCl, HNO3 and H2O. The problem that a traditional metallographic corrosive agent is poor in effect on the high-magnesium aluminum alloy, especially the high-magnesium aluminum alloy with the magnesium content exceeding 8% is solved, and the corrosive agent is simple in raw material, good in use safety, simple in corrosion process and short in corrosion time.

Description

Technical Field

[0001] The invention relates to the technical field of metallographic detection of metal materials, and in particular to a metallographic etching agent and a metallographic preparation method of a high-magnesium aluminum alloy. Background Art

[0002] High magnesium aluminum alloy, classified by aluminum alloy grade, belongs to 5 series aluminum alloy. The aluminum content generally accounts for 5wt% to 10wt%, and can reach up to 12wt%. The increase of magnesium content greatly reduces the density of the material. Therefore, this type of material has become a key material with great application potential in industries such as aerospace, automobile industry and electronic equipment. With the increase of magnesium content, the solid solution strengthening effect of the alloy increases, and the processing performance of the material deteriorates. With the development of new deformation processes such as high strain rate rolling, the processing performance of high magnesium aluminum alloy has gradually improved, and it has become a new type of structural material that has attracted widespread attention. However, high magnesium aluminum alloy shows complexity in microstructure. Its organizational characteristics are mainly reflected in the unique composition rich in magnesium. When the magnesium content in the alloy is higher than 3.5wt.%, β-Al3Mg2 phase will precipitate and distribute along subgrain boundaries and grain boundaries, resulting in a decrease in its corrosion resistance. At the same time, during the severe hot deformation process, the dynamic recrystallization mechanism induces the formation of a "double peak structure", which makes the metallographic observation of the alloy more difficult. Traditional aluminum alloy metallographic etchants, such as Keller reagent, have poor corrosion effects, unclear grain boundaries, and affect the observation effect. Chinese patent document CN116103656A discloses an etchant for displaying the macroscopic structure of aluminum alloy and its application. The etchant is a broad-spectrum etchant suitable for various grades of aluminum alloys, but the corrosion effect is still not ideal for 5 series aluminum alloys with a magnesium content of more than 8%. Summary of the invention

[0003] One of the purposes of the present invention is to provide a metallographic etching agent suitable for high-magnesium aluminum alloys.

[0004] In order to achieve the above object, the present invention adopts the following technical scheme: a metallographic etchant for high magnesium aluminum alloy, comprising a component A etchant and a component B etchant, wherein the component A etchant is composed of oxalic acid, nitric acid, and water (such as deionized water), and the component B etchant is composed of HF, HCl, HNO3, and H2O. The component B etchant is Keller reagent.

[0005] Furthermore, the volume fractions of oxalic acid, nitric acid and water in the component A corrosive agent are 0.5%-2%, 0.5%-2% and 96%-99% respectively.

[0006] Furthermore, the volume fractions of HF, HCl, HNO3, and H2O in the component B corrosive agent are 1%, 1.5%, 2.5%, and 95%, respectively.

[0007] Furthermore, the volume ratio of oxalic acid to nitric acid in the component A corrosive agent is 1:1.

[0008] Another object of the present invention is to provide a metallographic preparation method of a high-magnesium aluminum alloy, which uses the above-mentioned metallographic etchant and comprises the following steps: The high-magnesium aluminum alloy material to be corroded is corroded using component A corrosive agent and component B corrosive agent in sequence.

[0009] Furthermore, the corrosion time of the component A corrosive agent on the high-magnesium aluminum alloy material to be corroded does not exceed the corrosion time of the component B corrosive agent on the high-magnesium aluminum alloy material to be corroded.

[0010] Furthermore, the corrosion time of the component A corrosive agent on the high-magnesium aluminum alloy material to be corroded is 10S-30S.

[0011] Furthermore, the corrosion time of the component B corrosive agent on the high-magnesium aluminum alloy material to be corroded is 30S-60S.

[0012] Furthermore, the magnesium content in the high-magnesium aluminum alloy material to be corroded is 5wt%-12wt%.

[0013] Among them, the higher the magnesium content in the high-magnesium aluminum alloy material to be corroded, the longer the corrosion time.

[0014] Furthermore, the high-magnesium aluminum alloy material to be corroded is polished before corrosion, and the material is cleaned after each corrosion, wherein the cleaning process may be to put the material into deionized water for ultrasonic cleaning.

[0015] Among them, the corresponding relationship between the magnesium content in the high-magnesium aluminum alloy material to be corroded, the raw material ratio in the metallographic corrosive agent, and the corrosion time can be: a. When the magnesium content (wt%) in the high-magnesium aluminum alloy to be corroded is 5%, the metallographic corrosive agent includes component A corrosive agent (0.5% oxalic acid + 0.5% nitric acid + 99% water) and component B corrosive agent (1% HF + 1.5% HCl + 2.5% HNO3 + 95% H2O), and the corrosion time is: 10S for component A corrosive agent and 30S for component B corrosive agent.

[0016] b. When the magnesium content (wt%) in the high-magnesium aluminum alloy to be corroded is 8%, the metallographic corrosive agents include component A corrosive agent (1% oxalic acid + 1% nitric acid + 98% water) and component B corrosive agent (1% HF + 1.5% HCl + 2.5% HNO3 + 95% H2O), and the corrosion time is: 15S for component A corrosive agent and 45S for component B corrosive agent.

[0017] c. When the magnesium content (wt%) in the high-magnesium aluminum alloy to be corroded is 10%, the metallographic corrosive agent includes component A corrosive agent (1.5% oxalic acid + 1.5% nitric acid + 97% water) and component B corrosive agent (1% HF + 1.5% HCl + 2.5% HNO3 + 95% H2O), and the corrosion time is: 15S for component A corrosive agent and 50S for component B corrosive agent.

[0018] d. When the magnesium content (wt%) in the high-magnesium aluminum alloy to be corroded is 12%, the metallographic corrosive agents include component A corrosive agent (2% oxalic acid + 2% nitric acid + 96% water) and component B corrosive agent (1% HF + 1.5% HCl + 2.5% HNO3 + 95% H2O), and the corrosion time is: 20S for component A corrosive agent and 60S for component B corrosive agent.

[0019] The present invention overcomes the problem that traditional metallographic etching agents have poor effects on high-magnesium aluminum alloys, especially high-magnesium aluminum alloys with a magnesium content of more than 8%. In addition, the etching agent has simple raw materials, good safety in use, simple etching process and short etching time. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a picture of the structure of the magnesium-aluminum alloy after corrosion in Example 1; Figure 2 This is a picture of the structure of the magnesium-aluminum alloy after corrosion in Example 2; Figure 3 This is a picture of the structure of the magnesium-aluminum alloy after corrosion in Example 3; Figure 4 This is a microstructure picture of the magnesium-aluminum alloy after corrosion in Example 4; Figure 5 This is the microstructure picture of the magnesium-aluminum alloy after corrosion in Comparative Example 1; Figure 6 This is the microstructure picture of the magnesium-aluminum alloy after corrosion in Comparative Example 2; Figure 7 This is the microstructure picture of the magnesium-aluminum alloy after corrosion in Comparative Example 3; Figure 8 This is the microstructure picture of the magnesium-aluminum alloy after corrosion in Comparative Example 4; Fig. 9 This is a microstructure picture of the magnesium-aluminum alloy after corrosion in Comparative Example 5; Fig.10 This is the microstructure picture of the magnesium-aluminum alloy after corrosion in Comparative Example 6; Fig.11 This is the microstructure picture of the magnesium-aluminum alloy after corrosion in Comparative Example 7; Fig.12 This is a picture of the structure of the magnesium-aluminum alloy after corrosion in Comparative Example 8. DETAILED DESCRIPTION

[0021] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with the examples, and the contents mentioned in the examples are not limitations of the present invention. It should be noted in advance that the following examples were completed in the laboratory, and those skilled in the art should understand that the amounts of the components given in the examples only represent the ratio relationship between the components, rather than specific limitations.

[0022] Aiming at the problem that the existing aluminum alloy metallographic etchant has poor corrosion effect on high-magnesium aluminum alloy, the present invention provides a metallographic etchant suitable for high-magnesium aluminum alloy, which comprises a component A etchant and a component B etchant. The component A etchant is (0.5-2%) oxalic acid + (0.5-2%) nitric acid + (96-99%) deionized H2O; the component B etchant is Keller reagent, specifically 1% HF + 1.5% HCl + 2.5% HNO3 + 95% H2O. The above percentages are all volume fractions.

[0023] At the same time, the present invention also provides a metallographic preparation method of a high-magnesium aluminum alloy, and the specific steps are as follows: 1. Prepare the corrosive agent: Prepare component A corrosive agent and component B corrosive agent respectively according to the volume ratio.

[0024] 2. Polishing: Polish the high-magnesium aluminum alloy material to be corroded.

[0025] 3. Corrosion: 3.1, first put the material into component A corrosive agent, the corrosion time is 10-30S (the higher the magnesium content, the longer the corrosion time).

[0026] 3.2, Cleaning: Place the material in deionized water for ultrasonic cleaning.

[0027] 3.3, put the material into component B corrosive agent, the corrosion time is 30S-60S.

[0028] 3.4. Place the material in deionized water for ultrasonic cleaning and dry (such as by blowing dry), then observe.

[0029] The present invention combines component A etchant with component B etchant (Keller reagent) to obtain a metallographic etchant suitable for high-magnesium aluminum alloys, overcoming the problem that traditional metallographic etchants have poor effects on high-magnesium aluminum alloys, especially high-magnesium aluminum alloys with a magnesium content of more than 8%. In addition, the raw materials of the etchant are simple and the use safety is good. At the same time, the corrosion process is simple and the time is short. Example 1

[0030] The high-magnesium aluminum alloy material of this embodiment is a 5-series aluminum alloy, wherein the magnesium content (wt%) in the aluminum alloy is 5%.

[0031] The metallographic preparation method of the high magnesium aluminum alloy of this embodiment is as follows: 1. Prepare the corrosive agent: Prepare component A corrosive agent and component B corrosive agent according to the volume ratio. The prepared component A corrosive agent is 0.5% oxalic acid + 0.5% nitric acid + 99% deionized H2O; the prepared component B corrosive agent is 1% HF + 1.5% HCl + 2.5% HNO3 + 95% H2O. The above are all volume fractions.

[0032] 2. Polishing: Polish the high-magnesium aluminum alloy material to be corroded.

[0033] 3. Corrosion: 3.1. Place the material into component A corrosive agent for 10 seconds.

[0034] 3.2, put the material into deionized water for ultrasonic cleaning.

[0035] 3.3, put the material into component B corrosive agent, the corrosion time is 30S.

[0036] 3.4, put the material into deionized water for ultrasonic cleaning and blow dry.

[0037] The microstructure of the high magnesium aluminum alloy material of this embodiment after corrosion is as follows Figure 1 As shown, the observed results are: the crystal surface is clean, the grain boundary is clear, and the corrosion effect is good. Example 2

[0038] The high-magnesium aluminum alloy material of this embodiment is a 5-series aluminum alloy, wherein the magnesium content (wt%) in the aluminum alloy is 8%.

[0039] The metallographic preparation method of the high magnesium aluminum alloy of this embodiment is as follows: 1. Prepare the corrosive agent: Prepare component A corrosive agent and component B corrosive agent according to the volume ratio. The prepared component A corrosive agent is 1% oxalic acid + 1% nitric acid + 98% deionized H2O; the prepared component B corrosive agent is 1% HF + 1.5% HCl + 2.5% HNO3 + 95% H2O. The above are all volume fractions.

[0040] 2. Polishing: Polish the high-magnesium aluminum alloy material to be corroded.

[0041] 3. Corrosion: 3.1. Place the material into component A corrosive agent for 15 seconds.

[0042] 3.2, put the material into deionized water for ultrasonic cleaning.

[0043] 3.3, put the material into component B corrosive agent, the corrosion time is 45S.

[0044] 3.4, put the material into deionized water for ultrasonic cleaning and blow dry.

[0045] The microstructure of the high magnesium aluminum alloy material of this embodiment after corrosion is as follows Figure 2 As shown, the observed results are: the crystal surface is clean, the grain boundary is clear, and the corrosion effect is good. Example 3

[0046] The high-magnesium aluminum alloy material of this embodiment is a 5-series aluminum alloy, wherein the magnesium content (wt%) in the aluminum alloy is 10%.

[0047] The metallographic preparation method of the high magnesium aluminum alloy of this embodiment is as follows: 1. Prepare the corrosive agent: Prepare component A corrosive agent and component B corrosive agent according to the volume ratio. The prepared component A corrosive agent is 1.5% oxalic acid + 1.5% nitric acid + 97% deionized H2O; the prepared component B corrosive agent is 1% HF + 1.5% HCl + 2.5% HNO3 + 95% H2O. The above are all volume fractions.

[0048] 2. Polishing: Polish the high-magnesium aluminum alloy material to be corroded.

[0049] 3. Corrosion: 3.1. Place the material into component A corrosive agent for 15 seconds.

[0050] 3.2, put the material into deionized water for ultrasonic cleaning.

[0051] 3.3, put the material into component B corrosive agent, the corrosion time is 50S.

[0052] 3.4, put the material into deionized water for ultrasonic cleaning and blow dry.

[0053] The microstructure of the high magnesium aluminum alloy material of this embodiment after corrosion is as follows Figure 3 As shown, the observed results are: the crystal surface is clean, the grain boundary is clear, and the corrosion effect is good. Example 4

[0054] The high-magnesium aluminum alloy material of this embodiment is a 5-series aluminum alloy, wherein the magnesium content (wt%) in the aluminum alloy is 12%.

[0055] The metallographic preparation method of the high magnesium aluminum alloy of this embodiment is as follows: 1. Prepare the corrosive agent: Prepare component A corrosive agent and component B corrosive agent according to the volume ratio. The prepared component A corrosive agent is 2% oxalic acid + 2% nitric acid + 96% deionized H2O; the prepared component B corrosive agent is 1% HF + 1.5% HCl + 2.5% HNO3 + 95% H2O. The above are all volume fractions.

[0056] 2. Polishing: Polish the high-magnesium aluminum alloy material to be corroded.

[0057] 3. Corrosion: 3.1. Place the material into component A corrosive agent for 20 seconds.

[0058] 3.2, put the material into deionized water for ultrasonic cleaning.

[0059] 3.3, put the material into component B corrosive agent, the corrosion time is 60S.

[0060] 3.4, put the material into deionized water for ultrasonic cleaning and blow dry.

[0061] The microstructure of the high magnesium aluminum alloy material of this embodiment after corrosion is as follows Figure 4 As shown, the observed results are: the crystal surface is clean, the grain boundary is clear, and the corrosion effect is good. Comparative Example 1

[0062] The high-magnesium aluminum alloy material of this comparative example is a 5-series aluminum alloy, wherein the magnesium content (wt%) in the aluminum alloy is 5%.

[0063] The metallographic preparation method of the high magnesium aluminum alloy of this comparative example is as follows: 1. Prepare the corrosive agent: Prepare component A corrosive agent. The prepared component A corrosive agent is 0.5% oxalic acid + 0.5% nitric acid + 99% deionized H2O. The above are all volume fractions.

[0064] 2. Polishing: Polish the high-magnesium aluminum alloy material to be corroded.

[0065] 3. Corrosion: 3.1. Place the material into component A corrosive agent for 20 seconds.

[0066] 3.2, put the material into deionized water for ultrasonic cleaning and blow dry.

[0067] The microstructure of the high magnesium aluminum alloy material in this comparative example after corrosion is as follows Figure 5 As shown, the observed effect is: only part of the grain boundary is corroded and cannot be observed. Comparative Example 2

[0068] The high-magnesium aluminum alloy material of this comparative example is a 5-series aluminum alloy, wherein the magnesium content (wt%) in the aluminum alloy is 8%.

[0069] The metallographic preparation method of the high magnesium aluminum alloy of this comparative example is as follows: 1. Prepare the corrosive agent: Prepare the component B corrosive agent. The component B corrosive agent prepared is 1% HF + 1.5% HCl + 2.5% HNO3 + 95% H2O. The above are all volume fractions.

[0070] 2. Polishing: Polish the high-magnesium aluminum alloy material to be corroded.

[0071] 3. Corrosion: 3.1. Place the material into component B corrosive agent for 60 seconds.

[0072] 3.2, put the material into deionized water for ultrasonic cleaning and blow dry.

[0073] The microstructure of the high magnesium aluminum alloy material in this comparative example after corrosion is as follows Figure 6 As shown, the observed effect is: only part of the grain boundary is corroded and cannot be observed. Comparative Example 3

[0074] The high-magnesium aluminum alloy material of this comparative example is a 5-series aluminum alloy, wherein the magnesium content (wt%) in the aluminum alloy is 10%.

[0075] The metallographic preparation method of the high magnesium aluminum alloy of this comparative example is as follows: 1. Prepare the corrosive agent: Prepare the component B corrosive agent. The component B corrosive agent prepared is 1% HF + 1.5% HCl + 2.5% HNO3 + 95% H2O. The above are all volume fractions.

[0076] 2. Polishing: Polish the high-magnesium aluminum alloy material to be corroded.

[0077] 3. Corrosion: 3.1. Place the material into component B corrosive agent for 80 seconds.

[0078] 3.2, put the material into deionized water for ultrasonic cleaning and blow dry.

[0079] The microstructure of the high magnesium aluminum alloy material in this comparative example after corrosion is as follows Figure 7 As shown, the observed effect is: the crystal surface is severely corroded and cannot be observed. Comparative Example 4

[0080] The high-magnesium aluminum alloy material of this comparative example is a 5-series aluminum alloy, wherein the magnesium content (wt%) in the aluminum alloy is 12%.

[0081] The metallographic preparation method of the high magnesium aluminum alloy of this comparative example is as follows: 1. Prepare the corrosive agent: Prepare the component B corrosive agent. The component B corrosive agent prepared is 1% HF + 1.5% HCl + 2.5% HNO3 + 95% H2O. The above are all volume fractions.

[0082] 2. Polishing: Polish the high-magnesium aluminum alloy material to be corroded.

[0083] 3. Corrosion: 3.1. Place the material into component B corrosive agent for 50 seconds.

[0084] 3.2, put the material into deionized water for ultrasonic cleaning and blow dry.

[0085] The microstructure of the high magnesium aluminum alloy material in this comparative example after corrosion is as follows Figure 8 As shown, the observed effect is: only part of the grain boundary is corroded and cannot be observed. Comparative Example 5

[0086] The high-magnesium aluminum alloy material of this comparative example is a 5-series aluminum alloy, wherein the magnesium content (wt%) in the aluminum alloy is 5%.

[0087] The metallographic preparation method of the high magnesium aluminum alloy of this comparative example is as follows: 1. Prepare the corrosive agent: Prepare the component B corrosive agent. The component B corrosive agent prepared is 1% HF + 1.5% HCl + 2.5% HNO3 + 95% H2O. The above are all volume fractions.

[0088] 2. Polishing: Polish the high-magnesium aluminum alloy material to be corroded.

[0089] 3. Corrosion: 3.1. Place the material into component B corrosive agent for 30 seconds.

[0090] 3.2, put the material into deionized water for ultrasonic cleaning and blow dry.

[0091] The microstructure of the high magnesium aluminum alloy material in this comparative example after corrosion is as follows Fig. 9 As shown, the observed effect is: only part of the grain boundary is corroded and cannot be observed. Comparative Example 6

[0092] The high-magnesium aluminum alloy material of this comparative example is a 5-series aluminum alloy, wherein the magnesium content (wt%) in the aluminum alloy is 8%.

[0093] The metallographic preparation method of the high magnesium aluminum alloy of this comparative example is as follows: 1. Prepare the corrosive agent: Prepare component A corrosive agent and component B corrosive agent according to the volume ratio. The prepared component A corrosive agent is 1% oxalic acid + 1% nitric acid + 98% deionized H2O; the prepared component B corrosive agent is 1% HF + 1.5% HCl + 2.5% HNO3 + 95% H2O. The above are all volume fractions.

[0094] 2. Polishing: Polish the high-magnesium aluminum alloy material to be corroded.

[0095] 3. Corrosion: 3.1. Place the material into component A corrosive agent for 30 seconds.

[0096] 3.2, put the material into deionized water for ultrasonic cleaning.

[0097] 3.3, put the material into component B corrosive agent, the corrosion time is 50S.

[0098] 3.4, put the material into deionized water for ultrasonic cleaning and blow dry.

[0099] The microstructure of the high magnesium aluminum alloy material in this comparative example after corrosion is shown in the figure below. Fig.10 As shown, the observed effect is: the crystal surface is severely corroded and cannot be observed. Comparative Example 7

[0100] The high-magnesium aluminum alloy material of this comparative example is a 5-series aluminum alloy, wherein the magnesium content (wt%) in the aluminum alloy is 10%.

[0101] The metallographic preparation method of the high magnesium aluminum alloy of this comparative example is as follows: 1. Prepare the corrosive agent: Prepare component A corrosive agent and component B corrosive agent according to the volume ratio. The prepared component A corrosive agent is 1.5% oxalic acid + 1.5% nitric acid + 97% deionized H2O; the prepared component B corrosive agent is 1% HF + 1.5% HCl + 2.5% HNO3 + 95% H2O. The above are all volume fractions.

[0102] 2. Polishing: Polish the high-magnesium aluminum alloy material to be corroded.

[0103] 3. Corrosion: 3.1. Place the material into component A corrosive agent for 15 seconds.

[0104] 3.2, put the material into deionized water for ultrasonic cleaning.

[0105] 3.3, put the material into component B corrosive agent, the corrosion time is 30S.

[0106] 3.4, put the material into deionized water for ultrasonic cleaning and blow dry.

[0107] The microstructure of the high magnesium aluminum alloy material in this comparative example after corrosion is shown in the figure below. Fig.11 As shown, the observed effect is: only part of the grain boundary is corroded and cannot be observed. Comparative Example 8

[0108] The high-magnesium aluminum alloy material of this comparative example is a 5-series aluminum alloy, wherein the magnesium content (wt%) in the aluminum alloy is 12%.

[0109] The metallographic preparation method of the high magnesium aluminum alloy of this comparative example is as follows: 1. Prepare the corrosive agent: Prepare component A corrosive agent and component B corrosive agent according to the volume ratio. The prepared component A corrosive agent is 2% oxalic acid + 2% nitric acid + 96% deionized H2O; the prepared component B corrosive agent is 1% HF + 1.5% HCl + 2.5% HNO3 + 95% H2O. The above are all volume fractions.

[0110] 2. Polishing: Polish the high-magnesium aluminum alloy material to be corroded.

[0111] 3. Corrosion: 3.1. Place the material into component A corrosive agent for 10 seconds.

[0112] 3.2, put the material into deionized water for ultrasonic cleaning.

[0113] 3.3, put the material into component B corrosive agent, the corrosion time is 60S.

[0114] 3.4, put the material into deionized water for ultrasonic cleaning and blow dry.

[0115] The microstructure of the high magnesium aluminum alloy material in this comparative example after corrosion is as follows Fig.12 As shown, the observed effect is: only part of the grain boundary is corroded and cannot be observed.

[0116] By comparison, it can be seen that the magnesium-aluminum alloy materials after being corroded by the corrosive agents in Examples 1-4 can all be observed, and the observation effect is good, but the comparative examples 1-8 cannot be observed, so the effect achieved by Examples 1-4 is significantly better than that of the comparative examples 1-8. Among them, the combined use of the component A corrosive agent and the component B corrosive agent plays a key role, and the control of the raw material ratio of the component A corrosive agent and the control of the corrosion time of the component A corrosive agent and the component B corrosive agent also play an important role. In addition, the corrosion process of Examples 1-4 is very simple, the corrosion time is also very short, not exceeding 1 minute, and the corrosion efficiency is relatively high.

[0117] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention may also be implemented in other ways. Any obvious replacement without departing from the concept of the present technical solution is within the protection scope of the present invention.

[0118] Finally, it should be emphasized that in order to allow ordinary technicians in the field to more easily understand the improvements of the present invention over the prior art, some descriptions of the present invention have been simplified, and for the sake of clarity, some other elements are omitted in this application document. Those skilled in the art should realize that these omitted elements may also constitute the content of the present invention.

Claims

1. A metallographic etchant for high magnesium aluminum alloy, characterized in that: The invention comprises a component A corrosive agent and a component B corrosive agent, wherein the component A corrosive agent is composed of oxalic acid, nitric acid and water, and the component B corrosive agent is composed of HF, HCl, HNO3 and H2O.

2. The metallographic etching agent for high magnesium aluminum alloy according to claim 1, characterized in that: The volume fractions of oxalic acid, nitric acid and water in the component A corrosive agent are 0.5%-2%, 0.5%-2% and 96%-99% respectively.

3. The metallographic etching agent for high magnesium aluminum alloy according to claim 1, characterized in that: The volume fractions of HF, HCl, HNO3 and H2O in the component B corrosive agent are 1%, 1.5%, 2.5% and 95% respectively.

4. The metallographic etching agent for high magnesium aluminum alloy according to claim 1 or 2, characterized in that: The volume ratio of oxalic acid to nitric acid in the component A corrosive agent is 1:

1.

5. A metallographic preparation method of a high-magnesium aluminum alloy, characterized in that: Using the metallographic etching agent of the high magnesium aluminum alloy according to any one of claims 1 to 4 comprises the following steps: The high-magnesium aluminum alloy material to be corroded is corroded using component A corrosive agent and component B corrosive agent in sequence.

6. The metallographic preparation method of high magnesium aluminum alloy according to claim 5, characterized in that: The corrosion time of the component A corrosive agent on the high-magnesium aluminum alloy material to be corroded is not longer than the corrosion time of the component B corrosive agent on the high-magnesium aluminum alloy material to be corroded.

7. The metallographic preparation method of high magnesium aluminum alloy according to claim 5 or 6, characterized in that: The corrosion time of the component A corrosive agent on the high-magnesium aluminum alloy material to be corroded is 10S-30S.

8. The metallographic preparation method of high magnesium aluminum alloy according to claim 5 or 6, characterized in that: The corrosion time of the component B corrosive agent on the high-magnesium aluminum alloy material to be corroded is 30S-60S.

9. The metallographic preparation method of high magnesium aluminum alloy according to claim 5, characterized in that: The magnesium content in the high-magnesium aluminum alloy material to be corroded is 5wt%-12wt%.

10. The metallographic preparation method of high magnesium aluminum alloy according to claim 5, characterized in that: The high-magnesium aluminum alloy material to be corroded is polished before corrosion, and the material is cleaned after each corrosion.

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