Fe 59 Ni 30 Al 11 Medium-entropy alloy and preparation method thereof

Abstract

The application discloses a kind of Fe 59 Ni 30 Al 11 Ternary alloy and its preparation method belong to ternary entropy alloy material technical field.The method is first deformed by 60%~90% cold rolling to explore the influence of different deformation on the mechanical properties of alloy;Then the alloy under 90% deformation is kept at 600 DEG C and 700 DEG C for 1h and water quenching to control the distribution of Ni-Al phase and the precipitation of fine strengthening particles.Among them, the alloy performance is optimal after 600 DEG C x 1h aging treatment, and the room temperature tensile strength is as high as 1845 MPa under the condition of retaining 17.2% maximum deformation, which is about 358% higher than that of original cast state.The application realizes the fragmentation and deformation of Ni-Al phase and the accurate control of precipitated particles by the synergistic process of "gradient deformation amount cold rolling + quenching heat treatment", and makes the strength greatly improve under the premise of only losing a small amount of deformation, and the excellent comprehensive mechanical properties can be applied to key structure fields such as aerospace, rocket shell, high-performance shaft and pipe, high-strength fastener, etc.

Description

Technical Field

[0002] This invention relates to the field of ternary medium-entropy alloy materials technology, specifically to a Fe-Ni-Al ternary medium-entropy alloy and its hot working method. Background Technology

[0004] With the continuous advancement of science and technology, humanity's demand for space exploration is increasing daily. In high-tech fields, such as aerospace, rocket casings, high-performance shafts and pipes, and high-strength fasteners, the requirements for materials are becoming increasingly stringent. The materials needed in these fields not only require high strength but also excellent ductility to ensure reliability and safety. Therefore, structural metallic materials that combine high strength and excellent ductility are core to the long-life and high-reliability design in critical service fields such as aerospace and energy.

[0005] Among them, Fe-Ni-Al ternary alloys have been regarded as precipitation-strengthened medium-entropy alloys in recent years due to their wide compositional window, low cost, and good thermal stability. In this system, an ordered L12-Ni3Al phase precipitates in a face-centered cubic (FCC) γ matrix. Aging at 500-700℃ can form coherent nanoparticles of 50-500 nm in volume fraction (10-40%). The combined use of dislocation cut-through and bypass mechanisms increases the yield strength from 200 MPa to 800 MPa while maintaining an elongation of ≥20%. Further increasing the Al content (≥10 at.%) or decreasing the Ni / Fe ratio can induce the simultaneous precipitation of the B2-NiAl phase, forming an FCC+L12+B2 three-phase structure. The high hardness and semi-coherence of the B2 particles with the matrix provide additional Orowan strengthening and hinder grain boundary migration, allowing the alloy to maintain a strength of over 500 MPa at 600℃. However, existing processes mostly employ single isothermal aging, resulting in a wide distribution of precipitated phase sizes and significant grain coarsening, which limits the strength-ductility balance. Furthermore, they lack methods for synergistic control of the L12 / B2 dual-phase ratio, spatial distribution, and grain refinement, making it difficult to meet the requirements of 1 GPa-level strength and 15% uniform elongation. Therefore, developing a new process that precisely controls the kinetics of dual-phase precipitation and recrystallization through deformation-aging coupling, gradient temperature fields, or multi-step aging is crucial to overcoming the performance bottlenecks of Fe-Ni-Al alloys.

[0006] Therefore, by controlling the deformation amount and heat treatment temperature and time, we have developed a Fe-Ni-Al ternary alloy that exhibits both excellent plasticity and ultra-high tensile strength. 59 Ni 30 Al l1 Ternary alloys and their preparation methods provide a new paradigm for the development of low-cost, high-performance alloys. Summary of the Invention

[0008] 1. The technical problem to be solved by the present invention

[0009] To address the issue that existing Fe-Ni-Al ternary alloys fall far short of meeting the strength requirements for high-performance structural components, this invention provides a hot working method that uses gradient cold rolling deformation and heat treatment to synergistically regulate phase distribution and enhance particle precipitation behavior, thereby significantly improving the room temperature strength of the alloy while retaining most of its plasticity.

[0010] 2. The technical solution of the present invention

[0011] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0012] A Fe 59 Ni 30 Al 11 Hot working methods for medium-entropy alloys include:

[0013] (1) Cold rolling deformation: The alloy is subjected to multiple uniform cold rolling deformations at room temperature, with the total deformation amount controlled at 60%, 70%, 80%, and 90%. This step aims to analyze the influence of different deformation amounts on the alloy properties, while breaking the as-cast structure, introducing high-density dislocations and deformation bands, and further breaking the grains, while providing abundant nucleation sites for the subsequent precipitation of strengthening precipitates.

[0014] (2) Aging treatment: The cold-rolled alloy was subjected to aging treatment at two different temperatures of 600℃ and 700℃ for 1 hour each, followed by water quenching. This step utilizes the difference in atomic diffusion ability at different temperatures to systematically study and optimize the precipitation kinetics of fine precipitate particles in the matrix phase, thereby achieving precise control over the number and distribution of precipitate particles.

[0015] This process introduces a large number of nucleation sites through large deformation cold rolling, and controls the precipitation size and distribution of precipitated particles through different temperature aging systems.

[0016] 3. Beneficial effects of the present invention

[0017] Compared with the closest existing technology, the present invention achieves the following significant improvement in the mechanical properties of the alloy through a composite process of cold rolling deformation and heat treatment:

[0018] (1) Significantly improved strength: After 90% large deformation cold rolling, the room temperature tensile strength of the sample treated with 600℃ reached 1845 MPa, which is about 358% higher than that of the cast state, and retains 17.2% of the maximum deformation.

[0019] (2) Strong controllability of structure: By controlling the amount of cold rolling deformation and aging temperature, the size, distribution and volume fraction of Ni-Al precipitates and fine reinforcing particles can be effectively controlled, thereby achieving customization of mechanical properties;

[0020] (3) Low cost and excellent performance: The alloy obtained by this process has excellent comprehensive performance, and the raw materials are inexpensive. The preparation process is simple and easy to implement, and has the potential for industrial production. Attached Figure Description

[0022] Figure 1 Room temperature tensile stress-strain curves of the alloys in the examples and comparative examples;

[0023] Figure 2 Comparative Example 1: SEM tissue images and EDS surface scan results;

[0024] Figure 3 SEM tissue images of Examples 1-2 and Comparative Examples 2-5;

[0025] Figure 4 SEM tissue images of Comparative Examples 1-2 and Example 2, and EDS surface scan results of Example 2. Detailed Implementation

[0027] The present invention will be further described below with reference to embodiments and comparative examples, but the scope of protection of the present invention is not limited thereto.

[0028] Unless otherwise specified, the experimental methods used in this invention are conventional methods. Unless otherwise specified, all materials and reagents used in this invention are commercially available.

[0029] Example 1 (Optimal Process)

[0030] (1) Alloy smelting: according to Fe 59 Ni 30 Al 11 The composition consists of high-purity (≥99.0%) metal raw materials, which are melted in a non-consumable vacuum electric arc furnace under argon protection and repeatedly turned and remelted more than 5 times to obtain a casting with uniform composition.

[0031] (2) High deformation cold rolling: A 10 mm × 10 mm × 10 mm sample is cut from the ingot and cold rolled in a single direction on a rolling mill. Multiple passes are performed in a single direction on the cold rolling mill. The deformation amount is controlled at about 5% each time until the total deformation amount reaches 90%.

[0032] (3) The deformed sample was processed into a dog bone-shaped tensile specimen (gauge length 1 mm × 3 mm × 10 mm), and then water-quenched after being kept at 600℃ for 1 hour. It was recorded as CR90-600.

[0033] Example 2

[0034] The process is the same as in Example 1, except that the heat treatment temperature in step (3) is changed to 700℃, which is recorded as CR90-700.

[0035] Comparative Example 1 (cast state)

[0036] Tensile specimens are machined directly from the as-cast alloy and denoted as AC.

[0037] Comparative Examples 2-5

[0038] The process is the same as in Example 1, but the heat treatment in step (3) is omitted, and the total cold rolling deformation is changed to 90%, 80%, 70%, and 60%, which are recorded as CR90, CR80, CR70, and CR60 respectively.

[0039] Mechanical property testing and microstructure characterization

[0040] 1. The tensile properties of the medium-entropy alloys prepared in Examples 1-2 and Comparative Examples 1-5 were determined under load at room temperature.

[0041] Test method: Cut the smelted sample into 1mm×3mm×10mm (dog bone shape), and perform a tensile test on the sample in a universal testing machine at a loading rate of 1mm / min.

[0042] When testing the strength and plasticity of Examples 1-2 and Comparative Examples 1-5, the following results were obtained:

[0043] A. For the alloys prepared in Examples 1-2 and Comparative Examples 1-5, the specimen size for testing their strength and plasticity was 1mm × 3mm × 10mm (dog bone shape), and the test results are as follows: Figure 1 As shown in the figure. From the figure, it can be seen that: Example 1 has a strength of 1845 MPa and a deformation amount of 17.2%; Example 2 has a strength of 1577 MPa and a deformation amount of 19.4%; Comparative Example 2 has a strength of 1412 MPa and a deformation amount of 8.83%; Comparative Example 3 has a strength of 1312 MPa and a deformation amount of 8.97%; Comparative Example 4 has a strength of 1248 MPa and a deformation amount of 6.32%; Comparative Example 5 has a strength of 1160 MPa and a deformation amount of 6.59%; and Comparative Example 1 has a strength of 403 MPa and a deformation amount of 39.13%. Comparing Comparative Examples 1-5, it can be seen that: with the increase of deformation amount, Fe... 59 Ni 30 Al 11The yield strength and tensile strength of medium-entropy alloys both show an upward trend.

[0044] 2. Characterization of Fe prepared in Examples 1-2 and Comparative Examples 1-5 59 Ni 30 Al 11 Microstructure of medium-entropy alloys:

[0045] Determination method: Fe prepared in Comparative Examples 1-5 and Examples 1-2 59 Ni 30 Al 11 The microstructure of the medium-entropy alloy samples was characterized using scanning electron microscopy (SEM). Before characterization, the samples were first ground with 400-grit sandpaper along the same direction until the scratches became uniform. Then, 1000-grit sandpaper was used, and the samples were ground again after rotating 90°. This process was repeated with 1500, 2000, and 3000-grit sandpaper. Finally, the samples were polished with W1.5 diamond polishing paste until the surface was smooth and free of scratches. Finally, Keller's reagent (1 ml HF + 2.5 ml HNO3 + 1.5 ml HCl + 95 ml H2O) was used for etching for 2 min.

[0046] B. For the alloy prepared in Comparative Example 1, its metallographic microstructure was characterized, and its microstructure and energy dispersive spectroscopy (EDS) spectra are as follows: Figure 2 As shown, the precipitated phase is distributed in a bamboo-like pattern within the matrix phase, and through... Figure 2 The distribution of elements in the precipitate clearly shows that the precipitate is a Ni-Al rich phase.

[0047] C. For the alloys prepared in Examples 1-2 and Comparative Examples 2-5, their metallographic microstructure was characterized, and the microstructure is as follows: Figure 3 As shown, cold rolling deformation causes deformation and breakage of the precipitated phases. The deformation + heat treatment process effectively promotes the precipitation of reinforcing particles. Figure 3 (e~f) We can see a large number of fine precipitate particles.

[0048] D. To more clearly observe the precipitation behavior of the precipitated particles, we will observe their morphology under high magnification using SEM for Comparative Examples 1-2 and Example 2, such as... Figure 4 As shown, we can clearly see that the precipitates in the cast sample exhibit a complete bamboo-like morphology, while the precipitates after 90% cold rolling show deformation and breakage, and as... Figure 4 As shown in (c), a large number of fine precipitate particles appeared in the sample after rolling deformation and heat treatment.

[0049] Table 1: Tensile property test results of alloys in each embodiment and comparative example

[0050] CR90-600 (Example 1) 90 600 1845 17.20 CR90-700 (Example 2) 90 700 1577 19.40 AC (Comparative Example 1) 0 - 403 39.13 CR90 (Comparative Example 2) 90 - 1412 8.83 CR80 (Comparative Example 3) 80 - 1312 8.97 CR70 (Comparative Example 4) 70 - 1248 6.32 CR60 (Comparative Example 5) 60 - 1160 6.59

[0051] Results Analysis

[0052] As shown in Table 1, the optimal embodiment 1 (CR90-600) of the present invention achieved the best comprehensive mechanical properties, with its tensile strength σ at room temperature being the highest. UTS = 1845 MPa, and retains an excellent elongation of 17.2%.

[0053] Compared to Example 2 (CR90-700), the tensile strength of the alloy increased with decreasing heat treatment temperature, demonstrating that the heat treatment temperature after cold rolling deformation has a significant impact on Fe. 59 Ni 30 Al 11 The ultimate tensile strength of medium-entropy alloys is very important, and it is also one of the key steps in achieving high strength in this invention.

[0054] Compared with Comparative Examples 2-5 (CR60-90), the strength of the alloy showed a stable upward trend with the increase of deformation, which indicates that rolling deformation plays a key role in improving the performance of the alloy.

[0055] Compared to Comparative Example 1 (AC), the hot working process of "90% large deformation cold rolling followed by 600 °C aging" resulted in the precipitation of a large number of fine-sized precipitate particles in the alloy, which is Fe 59 Ni 30 Al 11 The key to achieving a significant increase in the ultimate tensile strength of medium-entropy alloys lies in the combination of cold rolling deformation and heat treatment. This demonstrates that the combination of cold rolling deformation and heat treatment can effectively promote the precipitation of reinforcing particles, thereby significantly improving tensile strength while retaining excellent plasticity. It combines excellent strength and plasticity, successfully breaking the strength-ductility trade-off and providing an effective strategy for the development of low-cost high-performance alloys.

[0056] In summary, this invention successfully designed a Fe alloy with excellent comprehensive mechanical properties through synergistic modification via cold rolling deformation and heat treatment. 59 Ni 30 Al 11 Medium-entropy alloy. The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A Fe 59 Ni 30 Al 11 The hot working method for medium-entropy alloys is characterized by, Includes the following steps: (1) Regarding the Fe 59 Ni 30 Al 11 The medium entropy alloy is cold rolled at room temperature with a total deformation of 60% to 90%; (2) The alloy obtained in step (1) is heat-treated at 600 to 700°C, and then cooled to room temperature after holding at the temperature.

2. The hot working method according to claim 1, characterized in that: The cold rolling deformation described in step (1) is carried out in multiple passes, with each deformation amount being 3% to 8%, and the rolling direction remains unchanged.

3. The hot working method according to claim 1, characterized in that: The cooling method described in step (2) is water quenching.

4. Fe prepared by the heat treatment method according to any one of claims 1-3 59 Ni 30 Al 11 Medium entropy alloy.

5. The Fe according to claim 4 59 Ni 30 Al 11 Applications of medium-entropy alloys in the manufacture of aerospace structural components, rocket shells, high-performance shafts and tubes, or high-strength fasteners.

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