Cu-si3n4-fe cocrnmn nanolaminate composite material and method of making

Abstract

The application discloses Cu-Si3N4-FeCoCrNiMn nanolayer composite material and a preparation method thereof, characterized by comprising a plurality of groups of sequentially compounded and stacked layer composite units, each group of layer composite units being sequentially compounded and stacked by a Cu film, a Si3N4 film and a FeCoCrNiMn film, and the thickness of the Cu film is 30-100 nm, the thickness of the Si3N4 film is 5-15 nm, and the thickness of the FeCoCrNiMn film is 20-60 nm; the Cu-Si3N4-FeCoCrNiMn nanolayer composite material combines the high thermal conductivity and electrical conductivity of Cu, the high hardness and high-temperature resistance of Si3N4 ceramic, and the excellent mechanical properties of FeCoCrNiMn high-entropy alloy, and realizes multi-scale synergistic reinforcement. The Cu layer serves as a plastic buffer phase, passivates crack propagation and relieves interface stress concentration, the Si3N4 layer can effectively pin dislocation motion and inhibit high-temperature grain boundary sliding, and the high-temperature stability and wear resistance of the material are significantly improved. Moreover, the nanolayer structure can control the average free path of dislocation, fully utilizes the thickness size effect, and improves the strength while maintaining good toughness.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, and in particular to Cu-Si3N4-FeCoCrNiMn nanolayered composite material and its preparation method. Background Technology

[0002] In the research and application of structural materials, achieving a synergistic improvement in both strength and ductility has always been a core objective. However, due to differences in the load-bearing mechanisms of materials during deformation, strength and ductility often exhibit a trade-off between strength and toughness. Traditional strengthening methods, such as grain refinement, solid solution strengthening, or precipitation hardening, while significantly improving material strength, are often accompanied by a significant decrease in plasticity and toughness, limiting their service capability under extreme conditions. Therefore, how to overcome this inherent limitation through microstructural design and develop advanced structural materials that combine high strength and high ductility has become an important development direction in the field of materials science.

[0003] As a typical face-centered cubic (FCC) high-entropy alloy, FeCoCrNiMn exhibits excellent low-temperature toughness, good ductility, and a strong-toughness balance, demonstrating good mechanical stability in extreme environments. This is attributed to its complex multi-component composition and high mixing entropy effect, which effectively delays crack initiation and propagation during plastic deformation. However, this high-entropy alloy also faces a series of problems that urgently need to be addressed: First, its room-temperature strength is relatively low (approximately 500 MPa), failing to meet the requirements of high-strength structural applications; second, under high-temperature conditions, the FCC structure is prone to grain boundary softening and diffusion-type creep deformation, leading to rapid deterioration of high-temperature mechanical properties; furthermore, the lack of a second-phase strengthening mechanism limits its wear resistance; and in terms of functionality, such as electrical conductivity, thermal conductivity, and radiation resistance, its single solid solution structure also results in insufficient performance. These problems severely restrict the application of FeCoCrNiMn high-entropy alloys in key fields such as aerospace, nuclear energy, and high-temperature equipment.

[0004] Nanolayered composite structures are considered an effective strategy for overcoming the strength-toughness tradeoff due to their controllable layer thickness and interfacial properties. By precisely controlling the layer thickness and interfacial structure, nanolayered materials can restrict and regulate dislocation movement, strengthening the material while preserving or even improving its ductility. For example, with a large layer thickness (tens to hundreds of nanometers), dislocations accumulate between layers, forming a Hall-Petch-like strengthening effect; while when the layer thickness drops below a critical value, the material exhibits an interface-dominated "interfacial barrier mechanism," causing the strength to stabilize and no longer decrease. Simultaneously, the dislocation storage and annihilation processes at the interface also help release local stress concentrations, improving plasticity. Studies on FeCoCrNiMn-based nanolayered composite structures show that these materials can significantly improve their strength by refining the layer thickness while retaining the plasticity of high-entropy alloys. However, nanolayered structures also face several challenges, such as interfacial reactions, insufficient thermal stability, and difficulties in matching the thermophysical properties of different components in multiphase systems, limiting their engineering applications. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a Cu-Si3N4-FeCoCrNiMn nanolayered composite material and its preparation method. By constructing an alternating nanolayered structure of Cu / Si3N4 / high-entropy alloy, it achieves high strength, high toughness, excellent high-temperature performance and multifunctional synergistic optimization, meeting the needs of aerospace, nuclear energy, microelectronics and other fields for high-performance composite materials.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: Cu-Si3N4-FeCoCrNiMn nanolayered composite material, comprising multiple sets of sequentially stacked layered composite units, each set of layered composite units being composed of Cu film, Si3N4 film and FeCoCrNiMn film sequentially stacked, wherein the thickness of Cu film is 30-100nm, the thickness of Si3N4 film is 5-15nm, and the thickness of FeCoCrNiMn film is 20-60nm.

[0007] Furthermore, the thickness of the Cu film is 50–70 nm, the thickness of the Si3N4 film is 6–10 nm, and the thickness of the FeCoCrNiMn film is 30–50 nm.

[0008] Furthermore, the thickness of the Cu film is 60 nm, the thickness of the Si3N4 film is 8 nm, and the thickness of the FeCoCrNiMn film is 40 nm.

[0009] Furthermore, the layered composite unit comprises 6 to 10 groups.

[0010] Furthermore, the layered composite unit comprises 7 groups.

[0011] The preparation method of Cu-Si3N4-FeCoCrNiMn nanolayered composite material includes the following specific steps:

[0012] (1) Fix Cu target, FeCoCrNiMn target and Si3N4 target on the target head of the magnetron sputtering instrument respectively;

[0013] (2) Reduce the pressure in the sputtering chamber of the magnetron sputtering instrument to 5×10 -4 Pa, while argon gas is introduced as the sputtering medium, and Cu target, FeCoCrNiMn target and Si3N4 target are pre-sputtered to remove the oxide layer or adsorbed impurities on the target surface.

[0014] (3) First, deposit a Cu thin film on the Si substrate, control the argon flow rate to 50 sccm, the sputtering pressure to 0.7-1.8 Pa, the power supply to 120 W, and the deposition time to 5 minutes, so that the Cu thin film deposition thickness reaches 30-100 nm.

[0015] (4) Then, Si3N4 film is deposited on Cu film, with argon flow rate of 50 sccm, sputtering pressure of 1.5 Pa, power supply of 90 W, and deposition time of 2 to 5 minutes, so that the deposition thickness of Si3N4 film is 5 to 15 nm.

[0016] (5) Finally, FeCoCrNiMn film was deposited on Si3N4 film. The argon flow rate was controlled to be 60 sccm, the sputtering pressure was 1.3 to 2.3 Pa, the power supply was 120 W, and the deposition time was 5 minutes, so that the deposition thickness of FeCoCrNiMn film reached 20 to 60 nm, thus obtaining a set of layered composite units.

[0017] (6) Then deposit a Cu film on the FeCoCrNiMn film of the layered composite unit, and repeat steps (3) to (5) 5 to 9 times to obtain Cu-Si3N4-FeCoCrNiMn nanolayered composite material.

[0018] Preferably, in step (1), the purity of the Cu target is 99.9999%, the purity of the FeCoCrNiMn target is 99.95%, and the purity of the Si3N4 target is 99.9%.

[0019] Preferably, in step (1), the Cu target and the FeCoCrNiMn target are respectively fixed on the first permanent magnet target head and the strong magnet target head connected to the DC power supply, and the Si3N4 target is fixed on the second permanent magnet target head connected to the radio frequency power supply.

[0020] Compared with existing technologies, the advantages of this invention are: the Cu-Si3N4-FeCoCrNiMn nanolayered composite material combines the high thermal / electrical conductivity of Cu, the high hardness and high-temperature resistance of Si3N4 ceramics, and the excellent mechanical properties of FeCoCrNiMn high-entropy alloys, achieving multi-scale synergistic reinforcement. Specifically, the Cu layer acts as a plastic buffer phase, passively inhibiting crack propagation and alleviating interfacial stress concentration, while the Si3N4 layer effectively pins dislocation movement and suppresses high-temperature grain boundary slip, significantly improving the material's high-temperature stability, wear resistance, hardness, and corrosion resistance. Furthermore, the nanolayered structure allows for the control of the dislocation mean free path, fully utilizing the thickness effect to maintain good toughness while improving strength. In addition, regarding functional properties, the introduction of the Cu layer provides an efficient electrical / thermal conduction pathway, while the insulation and radiation resistance of Si3N4 compensate for the shortcomings of high-entropy alloys in electromagnetic shielding and nuclear environments, thus achieving a multifunctional design for the material. Attached Figure Description

[0021] Figure 1 This is a cross-sectional schematic diagram of the Cu-Si3N4-FeCoCrNiMn nanolayered composite material of the present invention;

[0022] Figure 2 This is a comparison chart of the thermogravimetric analysis results of Cu-FeCoCrNiMn and Cu-Si3N4-FeCoCrNiMn nanolayered composite materials in this invention;

[0023] Figure 3 This is a comparison of the experimental results of high-speed steel, Cu-FeCoCrNiMn thin film deposited on high-speed steel, and Cu-Si3N4-FeCoCrNiMn thin film using potentiodynamic chemical etching method.

[0024] Figure 4 This is a comparison chart of the test results of Young's modulus and hardness of Cu-FeCoCrNiMn and Cu-Si3N4-FeCoCrNiMn nanolayered composite materials according to the present invention. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0026] Example 1: Cu-Si3N4-FeCoCrNiMn nanolayered composite material, comprising 7 sets of sequentially stacked layered composite units. Each set of layered composite units is composed of Cu film, Si3N4 film and FeCoCrNiMn film stacked sequentially, with the Cu film having a thickness of 60 nm, the Si3N4 film having a thickness of 8 nm and the FeCoCrNiMn film having a thickness of 40 nm.

[0027] In the first embodiment above, the thickness of the Cu film can be selected in the range of 30 to 100 nm, preferably in the range of 50 to 70 nm, and the optimal thickness is 60 nm. This ensures that the Cu film has good electrical and thermal conductivity while providing the necessary plastic deformation capability. The thickness of the Si3N4 film can be selected in the range of 5 to 15 nm, preferably in the range of 6 to 10 nm, and the optimal thickness is 8 nm. Strictly setting the thickness of the Si3N4 film can ensure the interface strengthening effect while avoiding the increase of brittleness. The thickness of the FeCoCrNiMn film can be selected in the range of 20 to 60 nm, preferably in the range of 30 to 50 nm, and the optimal thickness is 40 nm. Setting the thickness of the FeCoCrNiMn film can give full play to the toughening characteristics of the high-entropy alloy.

[0028] Furthermore, in the above-mentioned nano-layered composite material, the number of layers of composite units can be selected in the range of 6 to 10, preferably 7. Setting the number of layers of composite units can significantly improve the interface effect and mechanical properties of Cu-Si3N4-FeCoCrNiMn nano-layered composite material, realize the synergistic strengthening effect of nano-layered structure, and at the same time avoid the accumulation of interface defects, thus ensuring the compactness and stability of the material.

[0029] The Cu-Si3N4-FeCoCrNiMn nanolayered composite material was cut by FIB and observed by TEM. The results showed a nanolayered composite structure with uniformly alternating distributions of Cu, Si3N4, and FeCoCrNiMn phases and clear interfaces. Figure 1 As shown.

[0030] Example 2: A method for preparing Cu-Si3N4-FeCoCrNiMn nanolayered composite material, comprising the following specific steps:

[0031] (1) Fix Cu target, FeCoCrNiMn target and Si3N4 target on the target head of the magnetron sputtering instrument, wherein: the purity of Cu target is 99.9999%, the purity of FeCoCrNiMn target is 99.95%, and the purity of Si3N4 target is 99.9%; and fix Cu target and FeCoCrNiMn target on the first permanent magnet target head and strong magnet target head connected to DC power supply, respectively, and fix Si3N4 target on the second permanent magnet target head connected to RF power supply;

[0032] (2) Reduce the pressure in the sputtering chamber of the magnetron sputtering instrument to 5×10 -4 Pa, while argon gas is introduced as the sputtering medium, and Cu target, FeCoCrNiMn target and Si3N4 target are pre-sputtered to remove the oxide layer or adsorbed impurities on the target surface.

[0033] (3) First, deposit a Cu thin film on the Si substrate, control the argon flow rate to 50 sccm, the sputtering pressure to 0.7 Pa, the DC power supply to 120 W, and the deposition time to 5 minutes, so that the Cu thin film deposition thickness reaches 60 nm.

[0034] (4) Then, Si3N4 film was deposited on Cu film, with argon flow rate of 50 sccm, sputtering pressure of 1.5 Pa, RF power of 90 W and deposition time of 4 minutes, so that the deposition thickness of Si3N4 film was 8 nm.

[0035] (5) Finally, FeCoCrNiMn film was deposited on Si3N4 film. The argon flow rate was controlled at 60sccm, the sputtering pressure was 1.3Pa, the DC power was 120W, and the deposition time was 5 minutes, so that the deposition thickness of FeCoCrNiMn film reached 40nm, thus obtaining a set of layered composite units.

[0036] (6) Then deposit a Cu film on the FeCoCrNiMn film of the layered composite unit, and repeat steps (3) to (5) 6 times to obtain Cu-Si3N4-FeCoCrNiMn nanolayered composite material.

[0037] In the above embodiment 2, the magnetron sputtering instrument can be a three-target magnetron sputtering instrument, model TRP450.

[0038] The properties of the Cu-Si3N4-FeCoCrNiMn nanolayered composite material prepared by this method were verified as follows.

[0039] (I) Thermogravimetric analysis (TG curves) was performed on Cu-FeCoCrNiMn and Cu-Si3N4-FeCoCrNiMn nanolayered composite materials, respectively, as follows: Figure 2 As shown, the results indicate that the Cu-FeCoCrNiMn composite material begins to increase in mass at 622.7℃ and reaches mass equilibrium at 788.6℃. When the temperature rises to 839.2℃, the mass of the Cu-FeCoCrNiMn sample begins to decrease, and finally stabilizes at 918.4℃. This suggests that without the addition of interfacial materials, the Cu-FeCoCrNiMn composite material exhibits weak thermal stability under high-temperature conditions and displays significant oxidation and decomposition behavior.

[0040] Adding a Si3N4 interfacial layer between the Cu and FeCoCrNiMn films significantly improved the thermal stability of the Cu-Si3N4-FeCoCrNiMn nanolayered composite material. When the Si3N4 deposition time was 2 minutes, the critical temperature for mass increase in the Cu-Si3N4-FeCoCrNiMn composite material was delayed to 686℃, and the temperature at which mass began to decrease was delayed to 897℃, while the rate of mass increase was significantly reduced. This indicates that the Si3N4 interfacial layer can effectively delay the chemical reaction between Cu and FeCoCrNiMn and inhibit the oxidation process. When the Si3N4 deposition time was extended to 3 minutes, the critical temperature for mass increase was delayed to 691.6℃, and the critical temperature at which mass began to decrease was further delayed to 904.5℃, with the rate of mass increase further decreasing. Particularly when the deposition time was extended to 4 minutes, the mass of the Cu-Si3N4-FeCoCrNiMn composite material showed almost no significant change, indicating its superior thermal stability at high temperatures. Therefore, the Si3N4 interface layer plays a crucial role in suppressing the high-temperature oxidation behavior and improving the thermal stability of layered composite structures. Furthermore, the shielding effect of the Si3N4 interface material becomes increasingly significant with prolonged Si3N4 deposition time, effectively reducing the reaction between the Cu and FeCoCrNiMn layers. Its main mechanism lies in forming a physical and chemical barrier, preventing oxygen diffusion and direct reaction between Cu and FeCoCrNiMn under high-temperature conditions. In addition, the high melting point and low diffusion coefficient of the Si3N4 interface layer are also key factors contributing to its excellent thermal stability at high temperatures. These characteristics effectively reduce the activity of chemical reactions at the interface, thereby significantly improving the thermal performance of the layered composite structure. By optimizing the thickness of the Si3N4 layer, the thermal stability of the layered composite structure can be precisely controlled. However, the thickness of the interface layer needs to be appropriately controlled. Although a thicker Si3N4 layer can further improve thermal stability, excessively thick interface materials may have a potential impact on the mechanical properties and surface microstructure of the composite material.

[0041] (II) The corrosion resistance of Cu-Si3N4-FeCoCrNiMn nanolayered composite material was tested. Specifically, the high-speed steel (HSS), Cu-FeCoCrNiMn film deposited on HSS, and Cu-Si3N4-FeCoCrNiMn film with different Si3N4 deposition times were tested by potentiodynamic chemical corrosion method. The results are shown in Figure 3. Figure 3Figure (a) shows the Tafel curves for each material. As can be seen from the figure, the corrosion potential (Ecorr) of HSS is -0.6114 V, and the corrosion current density (Jcorr) is -5.73 A / cm², exhibiting lower stability and a slower dissolution rate. The corrosion potential of the Cu-FeCoCrNiMn film is significantly increased to -0.5226 V, indicating higher chemical stability in 3.5% NaCl solution. However, its corrosion current density is slightly higher than that of HSS, reflecting that while improving the surface passivation performance of the material, there may be enhanced local electrochemical reactions caused by surface defects or other factors, preventing an effective slowdown in the dissolution rate. Si3N4 can effectively improve the chemical stability of HSS in 3.5% NaCl solution. Figure 3 (b) The changes in corrosion potential (red curve) and corrosion current density (black curve) of different samples with Si3N4 deposition time show that, with the extension of Si3N4 deposition time, the corrosion potential (Ecorr) exhibits a trend of first decreasing and then increasing and tending to stabilize, reaching its lowest value at 2 min deposition, while significantly increasing at 4 min and 5 min. This indicates that the Si3N4 film may have incomplete coverage or defects in the early stage of deposition, but with the extension of deposition time, a dense and uniform protective layer gradually forms on the surface, improving the chemical stability of the material. At the same time, the corrosion current density (Jcorr) shows a trend of "first increasing and then decreasing", reaching its maximum value at 3 min, and then significantly decreasing at 4 min and 5 min. This indicates that the protective effect of the film is insufficient when the deposition time is short, leading to an accelerated material dissolution rate, while with the extension of deposition time, the formation of the passivation film effectively inhibits the corrosion reaction. Overall, the Cu-Si3N4-FeCoCrNiMn nanolayered composite material with Si3N4 film deposited for 4 min achieved a better balance in terms of potential and current density, significantly improving the corrosion resistance of Cu-FeCoCrNiMn film.

[0042] (III) The Young's modulus and hardness of Cu-FeCoCrNiMn and Cu-Si3N4-FeCoCrNiMn nanolayered composite materials were tested respectively, such as... Figure 4As shown, the Young's modulus (black curve) of the Cu-FeCoCrNiMn nanolayered composite material is approximately 64 GPa, and its hardness (red curve) is approximately 1.9 GPa. With the extension of Si3N4 deposition time, both the Young's modulus and hardness of the Cu-Si3N4-FeCoCrNiMn nanolayered composite material show a significant increasing trend. As the Si3N4 deposition time gradually increases from 2 minutes to 5 minutes, the Young's modulus significantly increases to 80 GPa, and the hardness also increases to 2.3 GPa. However, the Young's modulus tends to stabilize after the Si3N4 deposition time exceeds 3 minutes, with a relatively small change. This result indicates that the introduction of Si3N4 significantly improves the mechanical properties of the composite structure, and its reinforcing effect tends to saturate after a certain deposition time. The strengthening effect of Si3N4 is mainly reflected in its high hardness and dense structure. In the composite material, Si3N4 forms a thin film with high hardness and good toughness, significantly improving the surface rigidity of the material while effectively hindering dislocation propagation. This strengthening effect leads to a continuous increase in the Young's modulus and hardness of the nanolayered composite material with prolonged Si3N4 deposition time. Furthermore, the excellent bonding between Si3N4 and the matrix material at the interface forms a strongly constrained interface, further enhancing the material's resistance to deformation. These characteristics indicate that Si3N4 deposition plays a crucial role in optimizing the mechanical properties of nanolayered composite materials.

[0043] The scope of protection of this invention includes, but is not limited to, the above embodiments. The scope of protection is defined by the claims. Any substitutions, modifications, or improvements to this technology that are easily conceived by those skilled in the art fall within the scope of protection of this invention.

Claims

1. A Cu-Si3N4-FeCoCrNiMn nanolayered composite material, characterized in that... It includes multiple sets of layered composite units stacked sequentially. Each set of layered composite units is composed of Cu film, Si3N4 film and FeCoCrNiMn film stacked sequentially, with the thickness of Cu film being 50-70 nm, Si3N4 film being 6-10 nm and FeCoCrNiMn film being 30-50 nm.

2. The Cu-Si3N4-FeCoCrNiMn nanolayered composite material as described in claim 1, characterized in that: The thickness of the Cu film is 60 nm, the thickness of the Si3N4 film is 8 nm, and the thickness of the FeCoCrNiMn film is 40 nm.

3. The Cu-Si3N4-FeCoCrNiMn nanolayered composite material as described in claim 1, characterized in that: The layered composite unit comprises 6 to 10 groups.

4. The Cu-Si3N4-FeCoCrNiMn nanolayered composite material as described in claim 1 or 3, characterized in that: There are 7 groups of layered composite units.

5. A method for preparing Cu-Si3N4-FeCoCrNiMn nanolayered composite material, characterized by comprising the following specific steps: (1) Fix Cu target, FeCoCrNiMn target and Si3N4 target on the target head of the magnetron sputtering instrument respectively; (2) Reduce the pressure in the sputtering chamber of the magnetron sputtering instrument to 5×10 -4 Pa, while argon gas is introduced as the sputtering medium, and Cu target, FeCoCrNiMn target and Si3N4 target are pre-sputtered to remove oxide layer or adsorbed impurities on the target surface. (3) First, deposit a Cu thin film on the Si substrate, control the argon flow rate to 50 sccm, the sputtering pressure to 0.7-1.8 Pa, the power supply to 120 W, and the deposition time to 5 minutes, so that the Cu thin film deposition thickness reaches 30-100 nm. (4) Then, Si3N4 film is deposited on Cu film, with argon flow rate of 50 sccm, sputtering pressure of 1.5 Pa, power supply of 90 W, and deposition time of 2 to 5 minutes, so that the deposition thickness of Si3N4 film is 5 to 15 nm. (5) Finally, FeCoCrNiMn film was deposited on Si3N4 film. The argon flow rate was controlled to be 60 sccm, the sputtering pressure was 1.3 to 2.3 Pa, the power supply was 120 W, and the deposition time was 5 minutes, so that the deposition thickness of FeCoCrNiMn film reached 20 to 60 nm, thus obtaining a set of layered composite units. (6) Then deposit a Cu film on the FeCoCrNiMn film of the layered composite unit, and repeat steps (3) to (5) 5 to 9 times to obtain Cu-Si3N4-FeCoCrNiMn nanolayered composite material.

6. The method for preparing Cu-Si3N4-FeCoCrNiMn nanolayered composite material as described in claim 5, characterized in that: In step (1), the purity of the Cu target is 99.9999%, the purity of the FeCoCrNiMn target is 99.95%, and the purity of the Si3N4 target is 99.9%.

7. The method for preparing Cu-Si3N4-FeCoCrNiMn nanolayered composite material as described in claim 5, characterized in that: In step (1), the Cu target and the FeCoCrNiMn target are respectively fixed on the first permanent magnet target head and the strong magnet target head connected to the DC power supply, and the Si3N4 target is fixed on the second permanent magnet target head connected to the radio frequency power supply.

Images