A highly wear and corrosion resistant multi-principal element alloy and a method of making the same

Abstract

This invention discloses a highly wear-resistant and corrosion-resistant multi-principal element alloy and its preparation method, belonging to the field of metallic material preparation technology. It includes four main alloying elements (Al, Cr, Fe, and Ni) and a dopant element (Mn). The chemical composition of the multi-principal element alloy satisfies the general formula Al... a Cr b Fe c Ni d Mn e Where a is the atomic percentage of Al, b is the atomic percentage of Cr, c is the atomic percentage of Fe, d is the atomic percentage of Ni, and e is the atomic percentage of Mn, with the sum of the atomic percentages of each element being 100%. This invention regulates the phase, microstructure, and elemental distribution of the alloy through Mn doping, resulting in an alloy that possesses high hardness, excellent corrosion resistance, and corrosion wear resistance, as well as good plastic processing performance. The supporting preparation method is simple, with controllable parameters and readily available raw materials, making it suitable for large-scale industrial production. It can be widely used in key structural components of marine engineering equipment and other equipment operating under harsh corrosion-wear coupling conditions.

Description

Technical Field

[0001] This invention belongs to the field of metal material preparation technology, specifically relating to a highly wear-resistant and corrosion-resistant multi-principal-element alloy and its preparation method. Background Technology

[0002] As marine engineering equipment and facilities expand into deep-sea areas, material failure caused by the combined effects of corrosion and wear is becoming increasingly prominent, posing a significant challenge to equipment reliability, service life, and operational safety. Key structural components such as ships, offshore industrial platforms, seawater pipeline systems, and propulsion systems operate long-term in harsh marine environments, facing the interaction of seawater corrosion and mechanical wear (erosion and abrasion). High-speed flowing seawater and abrasive particles such as sediment and air bubbles can damage the passivation film or protective layer on the material surface, exposing fresh substrate and accelerating electrochemical corrosion. Simultaneously, surface roughening, porosity, or product layers caused by corrosion further exacerbate mechanical wear. This synergistic corrosion-wear effect creates a vicious cycle, with a destructive impact far exceeding that of single corrosion or single wear, leading to a significant reduction in material service life.

[0003] Currently, key components used in marine environments rely heavily on traditional alloy systems, such as austenitic stainless steel, duplex stainless steel, copper-nickel alloys, and nickel-based and cobalt-based alloys. While these materials each possess advantages in a single property (corrosion resistance or wear resistance), their limitations become increasingly apparent under long-term, harsh corrosion-wear coupling conditions. The core issue lies in the difficulty of simultaneously achieving both corrosion resistance and wear resistance: on the one hand, highly corrosion-resistant materials often have low hardness and insufficient wear resistance, such as conventional austenitic stainless steel, which has a hardness of only around 190 HV; on the other hand, high-hardness wear-resistant materials, such as some high-carbon alloy steels or hard-phase reinforced coatings, have poor corrosion resistance, especially resistance to pitting corrosion, crevice corrosion, and other localized corrosion, failing to meet the long-term service requirements of marine environments.

[0004] In recent years, high-entropy alloys (HEAs), also known as multi-principal element alloys (MPEAs), have been considered as candidate materials for solving the problem of corrosion-wear synergistic failure due to their unique compositional design concept, exhibiting characteristics of high strength, high hardness, and excellent corrosion resistance. Studies have shown that multi-principal element alloys with Al, Cr, Fe, and Ni as the main components possess basic corrosion resistance and toughness, making them a potential development system for marine engineering materials. By rationally adding alloying elements, their pitting corrosion resistance can be further improved, while wear resistance can be enhanced through solid solution strengthening and second-phase strengthening effects. However, existing AlCrFeNi-based multi-principal element alloys are mostly optimized for single properties (such as corrosion resistance or toughness). Research on compositional design and microstructure control for marine corrosion-wear coupling conditions is still insufficient, making it difficult to simultaneously achieve excellent corrosion resistance, wear resistance, and the ability to resist corrosion and wear synergistic effects, thus failing to meet the long-life and high-reliability service requirements of deep-sea equipment.

[0005] In summary, developing a multi-principal element alloy based on AlCrFeNi for marine corrosion-wear coupling conditions, achieving both high corrosion resistance and high wear resistance through elemental modification, along with a corresponding industrial preparation method, has significant scientific value and engineering application implications. Summary of the Invention

[0006] The purpose of this invention is to provide a highly wear-resistant and corrosion-resistant multi-principal-element alloy and its preparation method, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, firstly, this invention provides a highly wear-resistant and corrosion-resistant multi-principal element alloy, comprising four main alloying elements (Al, Cr, Fe, and Ni) and a dopant element (Mn), with a chemical composition satisfying the general formula Al. a Cr b Fe c Ni d Mn e , where a is the atomic percentage of Al, b is the atomic percentage of Cr, c is the atomic percentage of Fe, d is the atomic percentage of Ni, and e is the atomic percentage of Mn; The atomic percentages of the four main alloying elements satisfy the following conditions: 21.05 ≤ a ≤ 25, 21.05 ≤ b ≤ 25, 21.05 ≤ c ≤ 25, 21.05 ≤ d ≤ 25. The atomic percentage of the dopant element Mn satisfies the following condition: 0 < e ≤ 15.79. The sum of the atomic percentages of all elements is 100%.

[0008] Furthermore, in order to balance the thermodynamic stability, matrix-to-precipitate ratio, wear resistance and corrosion resistance of the alloy, the alloy composition is optimized. The atomic percentage of each element in the general formula is preferably: 21≤a≤22.5, 21≤b≤22.5, 21≤c≤22.5, 21≤d≤22.5, 10≤e≤11.5.

[0009] Furthermore, the matrix of the multi-principal alloy is a body-centered cubic structure, with spherical nanoscale AlNi hard phases dispersed in the matrix. The alloy contains tangled dislocation structures, and through the synergistic effect of grain refinement strengthening, solid solution strengthening, and second phase strengthening, the hardness, wear resistance, and corrosion resistance of the alloy are simultaneously improved.

[0010] Furthermore, the hardness of the multi-principal alloy is 430HV~520HV. In a 3.5wt% NaCl aqueous solution, the passivation current density, measured using linear sweep voltammetry, is 2.01×10⁻⁷ A / cm²~1.50×10⁻⁶ A / cm². Under electrochemical conditions of 3.5wt% NaCl aqueous solution and an open-circuit potential of +0.1V, a wear rate was measured by continuous reciprocating friction for 30 minutes using a 6.35mm diameter alumina ball at a frequency of 5Hz and a load of 10N. .

[0011] Secondly, the present invention also provides a method for preparing a highly wear-resistant and corrosion-resistant multi-principal-element alloy, comprising the following steps: a) Ingredients: According to general formula Al a Cr b Fe c Ni d Mn e According to the atomic percentage ratio, weigh out the elemental raw materials of Al, Cr, Fe, Ni and Mn, and mix them to obtain the raw materials to be smelted; b) Primary melting: The raw materials to be melted are placed in an inert atmosphere for melting, heat preservation, and cooling to obtain a preliminary alloy ingot; c) Secondary melting: The preliminary alloy ingot is placed in an inert atmosphere for melting, holding and cooling to obtain the final alloy ingot.

[0012] Furthermore, the Al, Cr, Fe, Ni, and Mn elemental raw materials mentioned in step a) are all industrial-grade high-purity raw materials with a purity of ≥99.9% to ensure the purity of the alloy composition and reduce the adverse effects of impurities on performance.

[0013] Furthermore, the melting in steps b) and c) is carried out using induction melting. The specific process is as follows: the corresponding material is placed in an induction melting furnace, vacuumed, and then filled with inert gas to 0.05~0.1 MPa. The vacuuming and filling with inert gas are repeated three times before melting is started. The material is completely melted at 1800℃~2000℃ and held for 5~10 min. Then it is transferred to a mold and cooled naturally for 2 h. Through two repeated melting processes, the alloy elements are ensured to be evenly distributed and compositional segregation is avoided.

[0014] Furthermore, the inert gas is argon to prevent the alloying elements from being oxidized and burned off during the smelting process.

[0015] Furthermore, the preparation method also includes a forming step: the final alloy ingot is formed and processed by an electric arc melting copper mold suction casting process to obtain a multi-principal element alloy product; The specific process of electric arc melting copper mold suction casting is as follows: the final alloy ingot is placed in the suction casting position of the electric arc melting water-cooled copper plate, after vacuuming, inert gas is filled to 0.05~0.1 MPa, and the vacuuming and inert gas filling are repeated three times to completely melt the alloy ingot and perform suction casting operation.

[0016] Furthermore, the multi-principal alloy products are bars, plates, or irregularly shaped structural parts, which can meet the processing and forming requirements of different key components of marine engineering equipment.

[0017] Compared with the prior art, the beneficial effects of the present invention are: This invention innovates the composition by using Al, Cr, Fe, and Ni as the main alloying elements and introducing Mn for doping modification. By controlling the proportion of Mn added, the phase composition, microstructure, and element distribution of the alloy are optimized. While ensuring the corrosion resistance of the alloy matrix, the hardness and wear resistance of the alloy are significantly improved, solving the core problem of the difficulty in achieving both corrosion resistance and wear resistance in traditional materials. Compared with the AlCrFeNi quaternary comparative alloy without Mn doping, the alloy of this invention has a hardness increase of 11%~20.6%, a passivation current density decrease of more than 70%, and a wear rate decrease of 77.6%~83%, exhibiting excellent damage resistance under marine corrosion-wear coupling conditions. The multi-principal alloy of this invention forms a composite structure of body-centered cubic matrix and dispersed spherical nanoscale AlNi hard phase through composition design. Combining the synergistic effects of solid solution strengthening, fine grain strengthening and second phase strengthening, it achieves high hardness while retaining good plastic processing ability. It can be prepared into structural parts with complex shapes through conventional processing technology, which can meet the forming requirements of different parts of marine engineering equipment. The preparation method of this invention adopts a conventional induction melting + secondary remelting process, combined with arc melting copper mold suction casting. The process steps are simple, the parameter window is wide, the equipment requirements are low, and there is no need for complex subsequent heat treatment processes. The raw materials used are all conventional industrial-grade high-purity metals, which are readily available and cost-controllable. It is suitable for industrial mass production and has good engineering application prospects. Attached Figure Description

[0018] Figure 1 The XRD pattern of the multi-principal element alloy of Example 1 of the present invention is shown below. Figure 2 This is a schematic diagram of the polarization curve of the multi-principal element alloy in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the hardness of the multi-principal element alloy in Embodiment 1 of the present invention; Figure 4 The image shows a three-dimensional corrosion and friction image of a multi-principal alloy according to Embodiment 1 of the present invention. Figure 5This is a transmission electron microscope bright-field image of the multi-principal alloy of Embodiment 1 of the present invention. Detailed Implementation

[0019] The present invention will be further described below with reference to embodiments.

[0020] The following embodiments are used to illustrate the present invention. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Experimental methods in the following embodiments without specific conditions were performed according to conventional experimental conditions in the art; the raw materials, reagents, and testing consumables used in the embodiments, unless otherwise specified, were all purchased commercially.

[0021] All alloys in the embodiments and comparative examples of this invention were prepared using a uniform process and a uniform performance testing method to ensure the comparability of the test results, as detailed below: 1. Preparation process: Batching → Primary induction melting → Secondary induction melting → Arc melting and copper mold casting; 2. Hardness test: A Vickers hardness tester was used, with a load of 500gf and a holding time of 15s. Five points were tested on each sample and the average value was taken. 3. Corrosion resistance test: A three-electrode electrochemical workstation was used. The test medium was 3.5wt% NaCl aqueous solution. The reference electrode was a saturated calomel electrode, the auxiliary electrode was a platinum sheet, and the working electrode was the alloy sample to be tested. The potentiodynamic polarization curve was tested at a scan rate of 0.5mV / s to obtain the passivation current density. 4. Corrosion and wear test: A tribological tester was used with an electrochemical workstation. The test medium was a 3.5wt% NaCl aqueous solution. The friction pair consisted of alumina balls with a diameter of 6.35mm. The load was 10N, the reciprocating frequency was 5Hz, the friction stroke was 5mm, and the test time was 30min. During the test, an anodic polarization potential of +0.1V relative to the open circuit potential was applied. After the test, the depth of the wear pits was measured using a laser confocal microscope, and the wear rate was calculated.

[0022] Example 1 The highly wear-resistant and corrosion-resistant multi-principal element alloy of this embodiment has the chemical composition formula Al. 22.22 Cr 22.22 Fe 22.22 Ni 22.22 Mn 11.11 (at.%), the preparation method includes the following steps: 1. Batching: Weigh out Al, Cr, Fe, Ni, and Mn elemental raw materials with a purity ≥ 99.9% according to the atomic percentage ratio of the above components, and mix them evenly to obtain the raw materials to be smelted; 2. First melting: Place the raw material to be melted in an induction melting furnace, evacuate and then fill with argon to 0.08MPa. Repeat the evacuation and filling with argon three times before starting the melting process. The material is completely melted at 1900℃ and held for 10 minutes. Then it is transferred to a metal mold and allowed to cool naturally for 2 hours to obtain a preliminary alloy ingot. 3. Secondary melting: The preliminary alloy ingot is placed in the induction melting furnace again and remelted, held at the same temperature and cooled using the same process parameters as the first melting to obtain a final alloy ingot with uniform composition. 4. Molding and processing: The final alloy ingot is placed in the suction casting position of the electric arc melting water-cooled copper plate. After vacuuming, argon gas is introduced to 0.08MPa. The vacuuming and argon gas introduction are repeated three times to completely melt the alloy ingot and perform suction casting to obtain plate and bar samples of the required specifications.

[0023] The alloy prepared in this embodiment was characterized and its properties were tested. The results are as follows: 1. XRD pattern ( Figure 1 The results show that the alloy matrix has a typical body-centered cubic structure with no harmful impurity phases formed. 2. TEM bright-field image ( Figure 5 The data shows that spherical nanoscale AlNi hard phases are dispersed in the alloy matrix, and there are a large number of intertwined dislocation structures inside the matrix. 3. Hardness test results ( Figure 3 The data shows that the average hardness of the alloy is 520 HV; 4. Potentiodynamic polarization curves ( Figure 2 The results showed that the alloy exhibited a significant passivation effect in a 3.5 wt% NaCl aqueous solution, with a passivation current density of 0.20 μA / cm² (i.e., 2.0 × 10⁻⁷ A / cm²). 5. Corrosion and wear test results show that the wear depth of the alloy is 4.3 μm, and the wear rate is... The three-dimensional morphology of the wear pits is shown in Figure 4 .

[0024] Example 2 The highly wear-resistant and corrosion-resistant multi-principal element alloy of this embodiment has the chemical composition formula Al. 23.53 Cr 23.53 Fe 23.53 Ni 23.53 Mn 5.88 The preparation method, process parameters and testing methods are exactly the same as those in Example 1.

[0025] Performance test results: The average hardness of the alloy is 511.3 HV, the passivation current density is 1.02 μA / cm², and the wear rate is...

[0026] Example 3 The highly wear-resistant and corrosion-resistant multi-principal element alloy of this embodiment has the chemical composition formula Al. 21.05 Cr 21.05 Fe 21.05 Ni 21.05 Mn 15.79 (at.%), the preparation method, process parameters and testing methods are exactly the same as those in Example 1.

[0027] Performance test results: The average hardness of the alloy is 480.2 HV, the passivation current density is 1.50 μA / cm², and the wear rate is... .

[0028] Comparative Example The multi-principal element alloy in this comparative example has the chemical composition formula Al. 25 Cr 25 Fe 25 Ni 25 (at.%), containing only four elements: Al, Cr, Fe, and Ni, without the addition of the dopant element Mn, and the preparation method, process parameters, and testing methods are exactly the same as those in Example 1.

[0029] Performance test results: The average hardness of the alloy is 431.2 HV, the passivation current density is 5.01 μA / cm², and the wear rate is...

[0030] The performance data of each embodiment and comparative example are summarized in Table 1.

[0031] Table 1. Performance test results of alloys from the examples and comparative examples.

[0032] The test results show that the multi-principal element alloy of this invention, with Al, Cr, Fe, and Ni as the main alloying elements and modified by Mn doping, has significantly improved hardness, corrosion resistance, and anti-corrosion and wear performance compared to the quaternary comparative alloy without Mn doping. It has excellent service performance under the harsh working conditions of marine corrosion-wear coupling and fully meets the usage requirements of key structural components of high-end marine engineering equipment.

[0033] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A highly wear-resistant and corrosion-resistant multi-principal element alloy, comprising four main alloying elements Al, Cr, Fe, and Ni, and a dopant element Mn, characterized in that, The chemical composition of the multi-principal element alloy satisfies the general formula Al a Cr b Fe c Ni d Mn e , where a is the atomic percentage of Al, b is the atomic percentage of Cr, c is the atomic percentage of Fe, d is the atomic percentage of Ni, and e is the atomic percentage of Mn; The atomic percentages corresponding to the four main alloying elements satisfy: 21.05 ≤ a ≤ 25, 21.05 ≤ b ≤ 25, 21.05 ≤ c ≤ 25, 21.05 ≤ d ≤ 25, and the atomic percentage corresponding to the doping element Mn satisfies: 0 < e ≤ 15.

79. The sum of the atomic percentages of all elements is 100%.

2. The highly wear-resistant and corrosion-resistant multi-principal-element alloy according to claim 1, characterized in that: To balance the thermodynamic stability of the alloy, the ratio of the matrix to the precipitated phase, corrosion resistance and wear resistance, the atomic percentages of the elements in the general formula are: 21 ≤ a ≤ 22.5, 21 ≤ b ≤ 22.5, 21 ≤ c ≤ 22.5, 21 ≤ d ≤ 22.5, 10 ≤ e ≤ 11.

5.

3. The highly wear-resistant and corrosion-resistant multi-principal-element alloy according to claim 1, characterized in that: The matrix of the multi-principal element alloy is a body-centered cubic structure, and spherical nano-sized AlNi hard phases are dispersedly distributed in the matrix.

4. The highly wear-resistant and corrosion-resistant multi-principal element alloy according to claim 1, characterized in that: The hardness of the multi-principal alloy is 430 HV~520 HV. In a 3.5 wt% NaCl aqueous solution, the passivation current density, measured using linear sweep voltammetry, is 2.01 × 10⁻⁷ A / cm²~1.50 × 10⁻⁶ A / cm². Under electrochemical conditions of 3.5 wt% NaCl aqueous solution and an open-circuit potential of +0.1 V, a 6.35 mm diameter alumina ball was used for continuous reciprocating friction for 30 min at a frequency of 5 Hz and a load of 10 N. The measured wear rate was... .

5. A method for preparing a highly wear-resistant and corrosion-resistant multi-principal-element alloy, characterized in that, Applied to the highly wear-resistant and corrosion-resistant multi-principal element alloy according to any one of claims 1-4, the following steps are further included: a) Ingredients: According to general formula Al a Cr b Fe c Ni d Mn e According to the atomic percentage ratio, weigh out the elemental raw materials of Al, Cr, Fe, Ni and Mn, and mix them to obtain the raw materials to be smelted; b) Primary melting: Placing the raw materials to be melted under an inert atmosphere for melting, heat preservation, and cooling treatments to obtain a preliminary alloy ingot; c) Secondary melting: Placing the preliminary alloy ingot under an inert atmosphere for melting, heat preservation, and cooling treatments again to obtain a final alloy ingot.

6. The method for preparing a highly wear-resistant and corrosion-resistant multi-principal element alloy according to claim 5, characterized in that, In step a), the elemental Al, Cr, Fe, Ni, and Mn raw materials are all industrial-grade high-purity raw materials with a purity ≥ 99.9%.

7. The method for preparing a highly wear-resistant and corrosion-resistant multi-principal element alloy according to claim 5, characterized in that, The melting in steps b) and c) both uses induction melting. The specific process is: placing the corresponding materials in an induction melting furnace, evacuating and then filling with an inert gas to 0.05 - 0.1 MPa, repeating the evacuation and filling with an inert gas three times and then starting melting, completely melting at 1800 °C - 2000 °C and heat preserving for 5 - 10 min, and then transferring to a mold for natural cooling for 2 h.

8. The method for preparing a highly wear-resistant and corrosion-resistant multi-principal element alloy according to claim 7, characterized in that, The inert gas is argon.

9. The method for preparing a highly wear-resistant and corrosion-resistant multi-principal element alloy according to claim 5, characterized in that, The preparation method further includes a forming step: forming and processing the final alloy ingot by an arc melting copper mold suction casting process to obtain a multi-principal element alloy product; The arc melting copper mold suction casting process is specifically: placing the final alloy ingot in the suction casting position of an arc melting water-cooled copper disk, evacuating and then filling with an inert gas to 0.05 - 0.1 MPa, repeating the evacuation and filling with an inert gas three times, and then completely melting the alloy ingot and performing the suction casting operation.

10. The method for preparing a highly wear-resistant and corrosion-resistant multi-principal-element alloy according to claim 9, characterized in that, The multi-principal element alloy product is a bar, a plate, or a special-shaped structural part.

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