Method for recording and observing corrosion behavior of magnesium alloy microstructure in situ

A microstructure and magnesium alloy technology, applied in the preparation of test samples, weather resistance/light resistance/corrosion resistance, measuring devices, etc., can solve the problems of complex operation and single means, achieve simple and reliable analysis, and avoid mirror contamination , The effect of simple sample preparation

Active Publication Date: 2015-06-03
GRIMAT ENG INST CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, there are only a few methods for in situ observation of microbattery reactions in magnesium alloys, such as stereo microscopes, scanning electron microscope

Method used

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  • Method for recording and observing corrosion behavior of magnesium alloy microstructure in situ
  • Method for recording and observing corrosion behavior of magnesium alloy microstructure in situ
  • Method for recording and observing corrosion behavior of magnesium alloy microstructure in situ

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] In situ observation and recording of microstructure corrosion behavior of EW75 magnesium alloy after solution treatment in NaCl solution:

[0031] (1) Sample preparation: Take a metallographic sample on the EW75 magnesium alloy material, after rough grinding and fine grinding with 240#, 800#, 2000#, 5000# sandpaper, polish; the polished observation surface is at 4% ( Volume %) After corroding the microstructure in the nitric acid alcohol solution, dry it with a hair dryer and set it aside.

[0032] (2) On the metallographic microscope stage, place a piece of cover glass with good light transmission, the size of the cover glass completely covers the microscope observation hole; place the sample processed in step (1) on the cover glass, adjust The lens has a clear metallographic structure; the thickness of the cover glass is 0.17±0.02mm, otherwise the light transmission is not good, which will affect the observation effect.

[0033] (3) Use a cotton swab to take 1×10 -4...

Embodiment 2

[0038] In situ observation and recording of extruded WE93 magnesium alloy in NaHSO 3 Corrosion behavior of microstructure in solution, the observation condition is: corrosion solution 1×10 -4 mol / L NaHSO 3 , the number of wipes on the observation surface is 8 times, the time interval x=1s, and other steps are the same as in Example 1.

[0039] image 3 It is a 500 times metallographic photograph of continuous observation of in-situ corrosion of WE93 magnesium alloy in extruded state for 1-6 seconds. from image 3 It can be seen that the corrosion is obvious in the area where the size of the second phase is larger. The larger the size of the second phase, the more obvious the effect of the potential difference between the matrix and the second phase, and the galvanic corrosion occurs on the interface between the matrix and the second phase. The larger the trend, the alloy corrosion produces H 2 Bubbles are formed. Due to the direct contact between the cover glass and the obs...

Embodiment 3

[0041] In-situ observation and recording of the microstructural corrosion behavior of aged AZ80 magnesium alloy in NaCl solution, the observation conditions are: corrosion solution 1×10 -5 mol / L NaCl, the number of wipes on the observation surface is 3 times, the time interval x=2s, other steps are the same as in Example 1.

[0042] Figure 4 The 200 times metallographic photographs of the AZ80 magnesium alloy in the aging state were continuously observed for in-situ corrosion for 2 to 12 seconds. from Figure 4 It can be seen that the second phase Mg of the aged AZ80 magnesium alloy 17 Al 12 Relatively thick, and to some extent connected into a network. The alloy undergoes galvanic corrosion due to the potential difference effect between the matrix and the second phase. In the place where the second phase is relatively sparse, the alloy corrodes preferentially, and as the corrosion progresses gradually, the corrosion area gradually expands to the surrounding area. This ...

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Abstract

The invention relates to a method for recording and observing the corrosion behavior of a magnesium alloy microstructure in situ, and belongs to the field of material corrosion analysis. The method comprises the following steps: firstly, sampling, taking a metallographic specimen from a to-be-analyzed magnesium alloy material, carrying out rough grinding, fine grinding, polishing and corroding for later use; putting a cover glass with good light transparency on a shelving unit of a metallographic microscope, wherein the cover glass can completely cover a microscope observation hole; putting a processed sample on the cover glass, and adjusting a lens so as to obtain a clear metallographic structure; dipping a cotton swab in a corrosion salt solution, wiping the observation surface of the specimen lightly for multiple times, and putting the specimen on the cover glass; observing and recording the corrosion behavior of the specimen by the microscope, and recording the crystal boundary, the crystal grain and the second phase corrosion status at each time interval by observing and recording the corrosion behavior of the specimen by the microscope. According to the invention, the sampling is simple, the cycle is short, and the analysis speed is high; the priority corrosion region can be determined accurately by comparing, observing and analyzing the corrosion behavior of the magnesium alloy microstructure, so that the corrosion mechanism of the material can be judged.

Description

technical field [0001] The invention relates to a method for in-situ observation and recording of magnesium alloy microstructure corrosion behavior, which belongs to the technical field of material corrosion analysis. technical background [0002] Magnesium alloy has the advantages of high specific strength, high specific stiffness, good shock absorption performance, and easy processing, and is widely used in aerospace, military industry, automobile and electronic products and other fields. However, due to the addition of alloying elements in magnesium alloys, the strong electropositive property of magnesium has a great impact on the solid solubility of alloying elements. Magnesium has a strong chemical affinity with alloying elements, which promotes the formation of intermetallic compounds. Because these intermetallic compounds have electrode potentials different from those of solid solutions, they form micro-batteries with solid solutions, resulting in galvanic corrosion, ...

Claims

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Application Information

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IPC IPC(8): G01N1/32G01N17/00
Inventor 张奎蒋全通李兴刚李永军马鸣龙石国梁袁家伟
Owner GRIMAT ENG INST CO LTD
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