A high-entropy alloy resistant to pollution and corrosion, a preparation method and application thereof

Abstract

The application belongs to the technical field of high-entropy alloys, and particularly relates to a high-entropy alloy resistant to pollution and corrosion, a preparation method and application thereof, and a high-entropy alloy component for a ship comprising the high-entropy alloy resistant to pollution and corrosion. The high-entropy alloy with strong corrosion resistance is successfully prepared by taking various metal powders as raw materials and through a vacuum arc melting method. The obtained high-entropy alloy has excellent pollution resistance and corrosion resistance in 3.5% NaCl solution and sulfuric acid reducing bacteria (SRB) solution. The application enriches the high-entropy alloy material system, has the advantages of simplicity, wide application range, etc., and has great application potential in the field of ships and ocean engineering.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high-entropy alloys, and particularly relates to a high-entropy alloy resistant to pollution and corrosion, a preparation method and application thereof, and a high-entropy alloy component for a ship comprising the high-entropy alloy resistant to pollution and corrosion. BACKGROUND

[0002] High-entropy alloys (HEAs) are a kind of new materials that have developed rapidly in recent years. Since 2004, Yeh et al. proposed that HEAs have excellent properties such as low-temperature toughness, thermal stability, wear resistance, and corrosion resistance, and these excellent properties are generally considered to be due to the interaction of four effects, namely, high-entropy effect, lattice distortion effect, slow diffusion effect, and cocktail effect. The design of traditional alloys is based on one or two main elements, but the attention of HEAs is focused on the intermediate region of the phase diagram. Four or more alloying elements are mixed in equal proportions or near equal proportions. According to the requirements of the alloy performance, by selectively adding certain alloying elements and controlling the proportion of alloying elements, the crystal structure and phase composition of the alloy can be changed, so as to form a single-phase solid solution under the action of high mixing configuration entropy.

[0003] At present, a variety of high-entropy alloy systems have been found, such as CrMnFeCoNi, AlCoCrFeNi, and CoCrCuFeNi high-entropy alloy systems with equal molar ratio or close to equal molar ratio, and Fe 40 Mn 40 Co 10 Cr 10 , Al5Nbo 24 Ti 40 V5Zr 26 and Fe 41 Mn 25 Ni 24 Co8Cr2 high-entropy alloy systems with non-equal molar ratio. High-entropy alloys are easy to form simple solid solutions rather than intermetallic compounds or other complex ordered phases such as body-centered cubic (BCC), face-centered cubic (FCC), and hexagonal close-packed structures due to their high configuration entropy. CrMnFeCoNi alloy composed of face-centered cubic (FCC) has high fracture toughness, and AlCoCrFeNi alloy composed of body-centered cubic (BCC) has high strength.

[0004] However, the above high-entropy alloy system has poor corrosion resistance in the extreme marine environment of high humidity, high salt fog, and marine microorganisms under the coupling of multiple physical fields. For example, the CrMnFeCoNi high-entropy alloy with a face-centered cubic (FCC) structure has excellent ultra-low temperature strength and toughness, but after testing, it is found that the high-entropy alloy has poor corrosion resistance after being immersed in 0.1 mol / L sulfuric acid solution for 30 days. It is found that the main components of the passivation film of the high-entropy alloy are the hydroxides of Cr, Fe and Ni and the oxides of Mn and Co, and there are Cr-poor regions and Fe-rich regions in the passivation film of the high-entropy alloy. The formation of the hydroxide and the appearance of the Cr-poor region are the main reasons for the decrease in the corrosion resistance of the high-entropy alloy.

[0005] Therefore, it is necessary to develop a high-entropy alloy with stronger fouling resistance and corrosion resistance in the extreme marine environment. SUMMARY

[0006] In order to overcome the shortcomings of the prior art, the present application provides a fouling-resistant and corrosion-resistant high-entropy alloy, a preparation method and application thereof, and a high-entropy alloy component for ships comprising the fouling-resistant and corrosion-resistant high-entropy alloy.

[0007] To achieve the above-mentioned purpose, the solution adopted by the present application is as follows:

[0008] In a first aspect, the present application provides a fouling-resistant and corrosion-resistant high-entropy alloy, the chemical formula of which is FeNiCoCrW x Al y wherein x and y are both between 0.05 and 0.75.

[0009] Preferably, the high-entropy alloy further comprises unavoidable C and O impurities, and the total content of impurities is ≤0.05%.

[0010] Preferably, the corrosion rate of the high-entropy alloy in a 3.5% NaCl solution is not more than 10 x 10 -3 mm / y, and the corrosion rate in a sulfate-reducing bacteria (SRB) solution is not more than 10 x 10 -3 mm / y.

[0011] In a second aspect, the present application also provides a preparation method of the fouling-resistant and corrosion-resistant high-entropy alloy as described above, comprising the following steps: uniformly mixing metal powders according to the metered proportion, placing them in a vacuum arc melting furnace for melting, and performing heat treatment after the melting is completed.

[0012] Preferably, the metal powders comprise Fe powder, Ni powder, Co powder, W powder and Al powder, the particle size of each metal powder is 5-200 μm, and the mass purity of each metal powder is greater than 99%.

[0013] Preferably, the step of uniformly mixing the metal powders is placing each metal powder raw material in a ball mill jar, using ZrO2 as the ball mill beads, rotating the ball mill jar at 60-180 rpm, and mixing the raw materials into a uniform powder for 10-100 hours.

[0014] Preferably, the specific parameters for the melting in the vacuum arc melting furnace in the step are: a vacuum degree less than 300 Pa, a reaction temperature of 1400-1700 DEG C, a heating rate of 5-25 DEG C, and melting three to four times to achieve uniform sample melting.

[0015] Preferably, the heat treatment after the melting in the step is cooling to 980-1150 DEG C, holding for 2 hours, and then rapidly air cooling or water cooling.

[0016] In a third aspect, the application also provides a use of the anti-fouling and corrosion-resistant high-entropy alloy as described above in the field of ships and ocean engineering.

[0017] In a fourth aspect, the application also provides a high-entropy alloy component for a ship, comprising the anti-fouling and corrosion-resistant high-entropy alloy as described above.

[0018] The application introduces W into Al x CoCrFeNi system, and a bulk high-entropy amorphous alloy is prepared by vacuum arc melting and rapid cooling after melting, the atomic arrangement of which presents long-range disorder and short-range order, and the alloy is macroscopically isotropic and amorphous, and does not have defects such as dislocations and grain boundaries, has super-high fracture toughness and excellent corrosion resistance, etc. x Al y The high-entropy amorphous alloy has a simple structure and uniform composition, can eliminate element differentiation and potential difference between different regions, reduce the probability of pitting corrosion, and delay the corrosion rate, and the amorphous structure can further improve the macroscopic strength and wear resistance of the alloy.

[0019] The FeNiCoCrW x Al yThe high-entropy alloy with refractory metal W as a main element can not only improve the high-temperature strength of the alloy, but also significantly improve the wear resistance and cutting property. In addition, the protective elements such as Al and Cr which can be oxidized to form a dense oxide layer film can be added to the alloy system to improve the corrosion resistance of the alloy material. The bulk high-entropy alloy obtained by vacuum arc melting and rapid cooling after melting can be amorphized, the element differentiation and potential difference in different regions in the material can be eliminated, and the corrosion resistance can be enhanced, so that the strength of the high-entropy alloy obtained by the application is improved. In addition, the rapid cooling process used in the preparation of the high-entropy alloy can delay the diffusion of alloy elements, avoid segregation and composition fluctuation, and obtain more uniform microstructure and composition distribution, and further enhance the high-temperature corrosion resistance.

[0020] Compared with the prior art, the application has the beneficial effects that:

[0021] The application uses multiple metal powders as raw materials, and successfully prepares a high-entropy alloy with good stain resistance and corrosion resistance by a vacuum arc melting method. The high-entropy alloy obtained by the application has excellent stain resistance and corrosion resistance in 3.5% NaCl solution and sulfate-reducing bacteria (SRB) solution. The application enriches the high-entropy alloy material system, has the advantages of simplicity, wide application range, etc., and has great application potential in the field of shipbuilding and ocean engineering. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The polarization curve of the high-entropy alloy prepared in Example 1, Example 2, Example 3, Example 4 and Comparative Example 1 in 3.5% NaCl solution.

[0023] Figure 2 The scanning electron microscope observation graph of the high-entropy alloy prepared in Example 1 soaked in 3.5% NaCl solution for 24 days.

[0024] Figure 3 The scanning electron microscope observation graph of the high-entropy alloy prepared in Example 1 soaked in sulfate-reducing bacteria (SRB) solution for 24 days. DETAILED DESCRIPTION

[0025] The technical solutions of the application are further described below in combination with specific embodiments, but the protection scope of the application is not limited to these embodiments. Any changes or equivalent replacements without departing from the concept of the application are included in the protection scope of the application.

[0026] Examples 1-4:

[0027] The embodiment provides a stain-resistant and corrosion-resistant high-entropy alloy, and the chemical formula of the high-entropy alloy is FeNiCoCrW x Al yThe high-entropy amorphous alloy provided by the embodiment also includes inevitable C and O impurities, and the total content of the impurities is less than or equal to 0.05%.

[0028] The preparation of the high-entropy alloy provided by the embodiment is performed according to the following steps.

[0029] (1) Each metal powder component (Fe, Ni, Co, Cr, W, Al) with the atomic percentage composition shown in Table 1 is dosed;

[0030] (2) Each metal powder is placed into a ball jar mill, ZrO2 balls are used as grinding beads, and the powder is mixed on the ball jar mill at a speed of 60-180 revolutions per minute (for example, 120 revolutions per minute) for 10-100 hours (for example, 24 hours) to obtain a uniform mixed powder; the mass ratio of the raw material to the grinding beads is 1:0.2;

[0031] (3) The powder obtained in step (2) is placed in a graphite mold, and is subjected to melting in a vacuum furnace with a vacuum degree less than 300 Pa at a temperature of 1400-1700 ℃ (for example, 1600 ℃), and the sample is turned over three times to ensure uniform melting;

[0032] (4) The bulk sample obtained in step (3) is heat treated at a temperature of 980-1150 ℃ (for example, 1150 ℃) for 2 hours, and then is water quenched.

[0033] Comparative Example 1

[0034] The comparative example provides a CoCrFeMnNi high-entropy alloy with a face-centered cubic (FCC) structure, and the chemical formula of the high-entropy alloy is CoCrFeMnNi, which also includes inevitable C and O impurities, and the total content of the impurities is less than or equal to 0.05%.

[0035] The preparation of the high-entropy alloy provided by the comparative example is performed according to the following steps.

[0036] (1) Each metal powder component (Co, Cr, Fe, Mn, Ni) with the atomic percentage composition shown in Table 1 is dosed;

[0037] (2) Each metal powder is placed into a ball jar mill, ZrO2 balls are used as grinding beads, and the powder is mixed on the ball jar mill at a speed of 60-180 revolutions per minute (for example, 120 revolutions per minute) for 10-100 hours (for example, 24 hours) to obtain a uniform mixed powder; the mass ratio of the raw material to the grinding beads is 1:0.2;

[0038] (3) The powder obtained in step (2) is placed in a graphite mold, and is subjected to melting in a vacuum furnace with a vacuum degree less than 300 Pa at a temperature of 1400-1700 ℃ (for example, 1600 ℃),

[0039] (4) The block sample obtained in step (3) is heat treated at 980-1150°C (for example, 1150°C) for 2 hours, and then water quenched.

[0040] Performance test:

[0041] 1. Corrosion performance test: The prepared high-entropy alloy sample is placed in a 3.5% NaCl solution, and the sample size is 10x10x1 mm. The potentiodynamic polarization test is carried out in an electrochemical workstation, and the corrosion rate is calculated by the corrosion current of the test result. The calculation formula is as follows:

[0042]

[0043] wherein K corr is the corrosion rate (mm / y), i corr is the corrosion current density (μA / cm2), k is a constant (=3.272 mm / (μA-cm-year)), EW is the equivalent weight of the electrode (g), and ρ is the density of the sample.

[0044] 2. Anti-fouling performance test: The prepared high-entropy alloy sample with a size of 10x10x1 mm is immersed in a sulfate-reducing bacteria (SRB) solution for 24 days. After removing the surface biofilm and corrosion products, the corrosion rate is calculated by weight loss. The calculation formula is as follows.

[0045]

[0046] wherein V corr is the sample corrosion rate (mm / y), Δm is the weight loss (g), ρ is the sample density (g / cm3), A is the exposed sample area (cm2), and t is the test time (h).

[0047] 3. Corrosion morphology observation: The prepared high-entropy alloy sample is immersed in a 3.5% NaCl solution and a sulfate-reducing bacteria (SRB) solution for 24 days. The morphology of the sample before and after corrosion is observed under a scanning electron microscope, and the corrosion pits are photographed.

[0048] Table 1: The atomic % of each metal of the raw material powder of Examples 1-4 and Comparative Example 1 and the performance table of the obtained high-entropy alloy

[0049]

[0050] Figure 2 The high-entropy alloy FeNiCoCrW 0.7 Al 0.2The scanning electron microscope observation figure of the sample immersed in the 3.5% NaCl solution for 24 days can be observed to have only the scratch left by the mechanical processing on the surface of the sample, and no obvious corrosion trace.

[0051] Figure 3 The high-entropy alloy FeNiCoCrW obtained in Example 1 0.7 Al 0.2 The scanning electron microscope observation figure of the sample immersed in the sulfuric acid reducing bacteria (SRB) solution for 24 days can be observed to have the bacteria attached to the surface of the sample to form a biofilm structure, and the micro corrosion pits appear.

[0052] Application of the embodiment:

[0053] The embodiment also provides application of the anti-fouling and anti-corrosion high-entropy alloy in the field of ship and marine engineering.

[0054] In the underwater area of the ship and marine engineering, the area is subjected to the immersion of seawater and the attack of marine organisms for a long time, and higher requirements are put forward for the chloride corrosion resistance and anti-fouling performance of the material. The application can be well applied to the main hull plate area below the keel of the ship, the outer surface of the rudder blade, the propeller and other positions, as well as the submarine pipeline, the pile leg of the offshore drilling platform, the underwater robot and other marine engineering application scenarios.

[0055] The above only describes the preferred embodiments of the application, and it should be noted that, for ordinary skilled persons in the art, some improvements and refinements can be made without departing from the principles of the application, and these improvements and refinements should also be regarded as the protection scope of the application.

Claims

1. A high-entropy alloy that is resistant to dirt and corrosion, characterized in that, The chemical formula of the high-entropy alloy is FeNiCoCrW. x Al y Where x and y are both between 0.05 and 0.75; The corrosion rate of the high-entropy alloy in 3.5% NaCl solution does not exceed 10 × 10⁻⁶. -3 mm / y, the corrosion rate in sulfuric acid-reducing bacteria solution does not exceed 10 × 10 -3 mm / y; The high-entropy alloy is an amorphous high-entropy alloy.

2. The method for preparing the high-entropy alloy resistant to contamination and corrosion as described in claim 1, characterized in that, The process includes the following steps: uniformly mixing metal powders according to the metering ratio, melting them in a vacuum arc melting furnace, and then performing heat treatment after melting. The metal powders include Fe powder, Ni powder, Co powder, W powder, and Al powder, with each metal powder having a particle size of 5-200 μm and a purity greater than 99%. The uniform mixing of the metal powders involves placing each metal powder raw material in a ball mill jar, using ZrO2 as the milling beads, rotating the ball mill jar at a speed of 60-180 rpm, and mixing for 10-100 hours to form a uniform powder. The melting parameters in the vacuum arc melting furnace are: vacuum degree less than 300 Pa, reaction temperature 1400-1700 ℃, melting three to four times until the sample is uniformly melted; The heat treatment involves cooling the temperature to 980-1150℃ after melting and holding it at that temperature for 2 hours, followed by rapid air cooling or water cooling.

3. The preparation method according to claim 2, characterized in that, After the heat treatment is completed, a CNC wire cutting machine is used to process the metal sheet.

4. The application of the high-entropy alloy with antifouling and corrosion resistance as described in claim 1 in the field of shipbuilding and marine engineering.

5. A high-entropy alloy component for ships, characterized in that, Including the high-entropy alloy that is resistant to dirt and corrosion as described in claim 1.

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