A heat fatigue resistant high-entropy alloy with endogenous nanoparticle strengthening and a preparation method thereof

Abstract

The present application relates to high-entropy alloy preparation technical field, provide a kind of endogenous nano-particle strengthening's anti thermal fatigue high-entropy alloy and its preparation method.Endogenous nano-particle strengthening's anti thermal fatigue high-entropy alloy preparation method includes: under argon protection condition, chromium iron nitride powder, titanium powder and boron powder are mixed, then with aluminum powder is mixed after, after using thermal explosion method processing, obtain intermediate alloy, again intermediate alloy and Ni-Cr-Fe-Co-Al system high-entropy alloy melt is mixed and melts, stirring, after casting endogenous nano-particle strengthening's anti thermal fatigue high-entropy alloy is obtained.The endogenous nano-particle strengthening's anti thermal fatigue high-entropy alloy obtained by the present application uniformly disperses nano-particle, particle size is 26-140nm, after 2000-2800 times 10-700 DEG C cold thermal fatigue test, main crack is ≤297 microns, suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of high-entropy alloy preparation technology, specifically to a thermal fatigue-resistant high-entropy alloy reinforced with endogenous nanoparticles and its preparation method. Background Technology

[0002] High-entropy alloys, due to their multi-principal-element design, high strength, and good high-temperature microstructure stability, have broad application prospects in wear resistance, corrosion resistance, and extreme temperature service. Among them, Ni-Cr-Fe-Co-Al series high-entropy alloys have high strength, certain oxidation resistance, and good thermal stability. After 2000-2800 cycles at 10-700℃, the principal crack length of thermal fatigue is 0.8-1mm, making them suitable for the development of structural materials under alternating heating and cooling, large temperature gradients, and complex thermomechanical coupling environments. However, existing high-entropy alloys may still suffer from microstructure coarsening, insufficient phase interface stability, thermal stress concentration, and grain boundary fatigue crack initiation during repeated heating-cooling cycles, thus affecting their long-term thermal fatigue resistance. To improve the thermal fatigue resistance of high-entropy alloys, long-term high-temperature homogenization treatment and the addition of more than 20% high-cost alloying elements are usually employed to control the alloy microstructure. Homogenization treatment can improve elemental segregation in the as-cast microstructure, promote the precipitation or dissolution of the second phase, and regulate grain size, phase ratio, and residual stress state, thereby enhancing the microstructure stability and crack propagation resistance of the alloy during thermal cycling. However, traditional heat treatment methods are lengthy and energy-intensive, increasing equipment costs and energy consumption. For large castings or complex-shaped components, temperature gradients and uneven cooling are prone to occur during heat treatment, leading to residual stress redistribution and even inducing thermal cracks or deformation. Therefore, how to reduce the addition of high-cost metal elements, avoid prolonged high-temperature homogenization heat treatment, reduce the length of the main crack after thermal fatigue, improve the uniformity of the alloy microstructure, stabilize the phase interface and inhibit the accumulation of thermal cycling damage, and simultaneously improve the thermal fatigue resistance of high-entropy alloys, and develop high-entropy alloys that balance economic benefits and excellent performance, are currently urgent technical challenges to be solved. Summary of the Invention

[0003] To address the aforementioned technical challenges, this invention provides a high-entropy alloy reinforced with endogenous nanoparticles to resist thermal fatigue, the preparation method of which includes the following steps: (1) Under argon protection, chromium nitride powder, titanium powder and boron powder are mixed at a mass ratio of 9-29:31-79:2-11 for 3.5-7 hours at a speed of 32-91 rpm to obtain mixed powder 1; wherein the particle size of the chromium nitride powder is 177-891 micrometers, the particle size of the titanium powder is 78-123 micrometers, and the particle size of the boron powder is 5-17 micrometers; (2) Under argon protection, the mixed powder 1 obtained in step (1) is mixed with aluminum powder at a mass ratio of 178-268:53-89 for 78-189 hours to obtain mixed powder 2; the aluminum powder has a particle size of 76-234 micrometers. (3) Under argon protection, the mixed powder 2 obtained in step (2) is treated by thermal explosion to obtain alloy 1; the thermal explosion treatment is as follows: pressure is 0.033-0.87MPa, voltage is 792-913V, current is 366-817A, and temperature is 1287-1937℃. (4) At a temperature of 1400℃-1435℃, alloy 1 from step (3) is placed into a high-entropy alloy melt until alloy 1 is completely melted in the high-entropy alloy melt. After stirring and holding at the temperature for 7-15 minutes, it is cast to obtain a high-entropy alloy with endogenous nanoparticle reinforcement for thermal fatigue resistance. The composition of the high-entropy alloy melt, by mass percentage, is: nickel 36-41%, chromium 15-19%, iron 17-20%, cobalt 18-22%, and aluminum 8-10%. The mass ratio of alloy 1 in the high-entropy alloy melt is 0.1-0.4 wt.%:1. The high-entropy alloy with endogenous nanoparticle reinforcement for thermal fatigue resistance contains nano-ceramic particles with a particle size of 26-140nm. The mass ratio of nano-ceramic particles to the high-entropy alloy melt is 0.02-0.08. wt.%:1; The thermal fatigue main crack length of the endogenous nanoparticle-reinforced high-entropy alloy is ≤297 micrometers after 2000-3000 cycles at 10-700℃.

[0004] Furthermore, the particle size of the chromium nitride powder in step (1) is 191-813 micrometers, the particle size of the titanium powder is 81-122 micrometers, and the particle size of the boron powder is 6-17 micrometers.

[0005] Furthermore, the particle size of the aluminum powder in step (2) is 81-217 micrometers.

[0006] Furthermore, the thermal fatigue main crack length of the endogenous nanoparticle-reinforced high-entropy alloy described in step (4) after 2000-2800 cycles at 10-700℃ is 120-286 micrometers.

[0007] Compared with the prior art, the present invention has the following advantages: Existing high-entropy alloys achieve their thermal fatigue resistance by adding more than 20% cobalt or through prolonged high-temperature heat treatment. However, existing technologies achieve a main crack length of 0.8-1 mm after 2000-2800 cycles at 10-700℃. This invention, by reducing the cobalt content and incorporating low-cost nanoparticles (0.02-0.08 wt.%) uniformly dispersed in the alloy matrix, reduces raw material costs compared to existing technologies. It simplifies the process by eliminating prolonged high-temperature heat treatment, while simultaneously improving thermal fatigue resistance through multiple high-temperature cycles, achieving a main crack length ≤297 micrometers. A longer main crack indicates poorer thermal fatigue resistance; the main crack length achieved by this invention is significantly shorter than that obtained by existing technologies, thus demonstrating superior thermal fatigue resistance. This indicates that this invention achieves a significant improvement in the high-temperature thermal fatigue performance of high-entropy alloys through the synergistic regulation of the interaction between nanoparticles and elements, their proportions, and the process and process parameters. Attached Figure Description

[0008] Figure 1 The optical microstructure of the endogenous nanoparticle-reinforced high-entropy alloy 1, prepared in Example 1 of this invention, after 2100 thermal cycles at 13-697℃.

[0009] Figure 2 The optical microstructure of the endogenous nanoparticle-reinforced high-entropy alloy 2 prepared in Example 2 of this invention after 2200 thermal cycles at 12-689℃.

[0010] Figure 3 The optical microstructure of the endogenous nanoparticle-reinforced high-entropy alloy 3, prepared in Example 3 of this invention, after 2400 thermal cycles at 15-695℃.

[0011] Figure 4 This is an optical microstructure image of the high-entropy alloy 1 prepared in Comparative Example 1 of the present invention after 2050 thermal cycles. Detailed Implementation

[0012] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0013] The preparation method of the endogenous nanoparticle-reinforced high-entropy alloy 1, which is resistant to thermal fatigue, includes the following steps: (1) Under argon protection, chromium nitride powder, titanium powder and boron powder were mixed at a mass ratio of 13:51:4 for 4.5 hours to obtain mixed powder 1; the particle size of the chromium nitride powder was 276 micrometers, the particle size of the titanium powder was 87 micrometers, and the particle size of the boron powder was 6 micrometers. (2) Under argon protection, the mixed powder 1 obtained in step (1) and aluminum powder are mixed at a mass ratio of 197:67 for 123 hours to obtain mixed powder 2; the particle size of the aluminum powder is 134 micrometers. (3) Under argon protection, the mixed powder 2 obtained in step (2) is treated by thermal explosion to obtain alloy 1; the thermal explosion treatment is as follows: pressure is 0.26MPa, voltage is 830V, current is 567A and temperature is 1387℃. (4) At a temperature of 1415℃, alloy 1 from step (3) is placed into a high-entropy alloy melt until alloy 1 is completely melted in the high-entropy alloy melt. After stirring and holding at the temperature for 11 minutes, it is cast to obtain a high-entropy alloy 2 reinforced with endogenous nanoparticles to resist thermal fatigue. The composition of the high-entropy alloy melt by mass percentage is: nickel 37%, chromium 19%, iron 18%, cobalt 18%, and aluminum 8%. The mass ratio of alloy 1 in the high-entropy alloy melt is 0.15 wt.%:1. The high-entropy alloy 1 reinforced with endogenous nanoparticles to resist thermal fatigue contains nano-ceramic particles. The mass ratio of nanoparticles in the high-entropy alloy melt is 0.03 wt.%:1, and the particle size is 70 nm. The thermal fatigue crack size of the high-entropy alloy 1 reinforced with endogenous nanoparticles to resist thermal fatigue is 189 micrometers.

[0014] The optical microstructure of the endogenous nanoparticle-reinforced, thermally fatigue-resistant high-entropy alloy 1 in this embodiment after 2100 thermal cycles at 13-697℃ is as follows. Figure 1 As shown, the thermal fatigue main crack length of the endogenous nanoparticle-reinforced high-entropy alloy 1 is 189 micrometers. The effective synergy of the interaction, ratio, process and process parameters between the nanoparticles and the high-entropy alloy improves the thermal fatigue resistance. Example 2

[0015] The preparation method of the endogenous nanoparticle-reinforced high-entropy alloy 2, which is resistant to thermal fatigue, includes the following steps: (1) Under argon protection, chromium nitride powder, titanium powder and boron powder were mixed at a mass ratio of 14:56:6 for 5.5 hours to obtain mixed powder 1; the particle size of the chromium nitride powder was 285 micrometers, the particle size of the titanium powder was 93 micrometers, and the particle size of the boron powder was 7 micrometers. (2) Under argon protection, the mixed powder 1 obtained in step (1) is mixed with aluminum powder at a mass ratio of 189:71 for 133 hours to obtain mixed powder 2; the aluminum powder has a particle size of 144 micrometers. (3) Under argon protection, the mixed powder 2 obtained in step (2) is treated by thermal explosion to obtain alloy 1; the thermal explosion treatment is as follows: pressure is 0.28MPa, voltage is 855V, current is 592A, and temperature is 1766℃. (4) At a temperature of 1425℃, alloy 1 from step (3) is placed into a high-entropy alloy melt until alloy 1 is completely melted in the high-entropy alloy melt. After stirring and holding at the temperature for 9 minutes, it is cast to obtain a high-entropy alloy 2 reinforced with endogenous nanoparticles to resist thermal fatigue. The composition of the high-entropy alloy melt by mass percentage is: nickel 38%, chromium 18%, iron 19%, cobalt 18%, and aluminum 9%. The mass ratio of alloy 1 in the high-entropy alloy melt is 0.25 wt.%:1. The high-entropy alloy 2 reinforced with endogenous nanoparticles to resist thermal fatigue contains nano-ceramic particles. The mass ratio of nanoparticles in the high-entropy alloy melt is 0.06 wt.%:1, and the particle size is 61 nm. The thermal fatigue crack size of the high-entropy alloy 2 reinforced with endogenous nanoparticles to resist thermal fatigue is 212 micrometers.

[0016] The optical microstructure of the endogenous nanoparticle-reinforced, thermally fatigue-resistant high-entropy alloy 2 in this embodiment after 2200 cycles of thermal cycling at 12-689℃ is as follows. Figure 2 As shown, the thermal fatigue main crack length of the endogenous nanoparticle-reinforced high-entropy alloy 2 is 212 micrometers. The effective synergy of the interaction, ratio, process and process parameters between the nanoparticles and the high-entropy alloy improves the thermal fatigue resistance. Example 3

[0017] The preparation method of the endogenous nanoparticle-reinforced high-entropy alloy 3, which is resistant to thermal fatigue, includes the following steps: (1) Under argon protection, chromium nitride powder, titanium powder and boron powder were mixed at a mass ratio of 21:67:9 for 6.5 hours to obtain mixed powder 1; the particle size of the chromium nitride powder was 671 micrometers, the particle size of the titanium powder was 113 micrometers, and the particle size of the boron powder was 15 micrometers. (2) Under argon protection, the mixed powder 1 obtained in step (1) and aluminum powder are mixed at a mass ratio of 219:82 for 153 hours at a speed of 41 rpm to obtain mixed powder 2; the particle size of the aluminum powder is 157 micrometers. (3) Under argon protection, the mixed powder 2 obtained in step (2) is treated by thermal explosion to obtain alloy 1; the thermal explosion treatment is as follows: pressure is 0.71MPa, voltage is 805V, current is 422A, and temperature is 1841℃. (4) At a temperature of 1435℃, alloy 1 from step (3) is placed into a high-entropy alloy melt until alloy 1 is completely melted in the high-entropy alloy melt. After stirring and holding at the temperature for 14 minutes, it is cast to obtain a high-entropy alloy 3 with endogenous nanoparticle reinforcement for thermal fatigue resistance. The composition of the high-entropy alloy melt by mass percentage is: nickel 36%, chromium 17%, iron 20%, cobalt 18%, and aluminum 9%. The mass ratio of alloy 1 in the high-entropy alloy melt is 0.35 wt.%:1. The high-entropy alloy 3 with endogenous nanoparticle reinforcement for thermal fatigue resistance contains nano-ceramic particles. The mass ratio of nanoparticles in the high-entropy alloy melt is 0.05 wt.%:1, and the particle size is 89 nm. The thermal fatigue crack size of the high-entropy alloy 3 with endogenous nanoparticle reinforcement for thermal fatigue resistance is 286 micrometers.

[0018] The optical microstructure of the endogenous nanoparticle-reinforced, thermally fatigue-resistant high-entropy alloy 3 in this embodiment after 2400 cycles of thermal cycling at 15-695℃ is as follows. Figure 3 As shown, the thermal fatigue main crack length of the endogenous nanoparticle-reinforced high-entropy alloy 2 is 286 micrometers. The effective synergy of the interaction, ratio, process and process parameters between the nanoparticles and the high-entropy alloy improves the thermal fatigue resistance. Comparative Example 1

[0019] High-entropy alloy 1, its preparation method includes the following steps: (1) The high-entropy alloy was stirred and held at 1415℃ for 11 minutes before being cast to obtain a high-entropy alloy ingot; the high-entropy alloy melt composition by mass percentage was: nickel 38%, chromium 18%, iron 16%, cobalt 20%, and aluminum 8%; (2) The high-entropy alloy ingot was heated to 1160°C, homogenized for 16 hours, and then quenched to obtain high-entropy alloy 1.

[0020] The optical microstructure of high-entropy alloy 1 in this comparative example after 2000 cycles of thermal cycling at 13-697℃ is as follows: Figure 4 As shown, the length of the main thermal fatigue crack in high-entropy alloy 1 is 923 micrometers.

[0021] The difference between Embodiments 1-3 of the present invention and Comparative Example 1 is that: Compared to Comparative Example 1, the endogenous nanoparticle-reinforced high-entropy alloy 1 prepared in Example 1 contains 0.03 wt.% nanoparticles, but reduces the lengthy homogenization heat treatment and the addition of the costly Co element, thus significantly reducing the raw material cost of Example 1. The main crack length after 2100 cycles of thermal fatigue in Example 1 is 388% shorter than that after 2000 cycles in Comparative Example 1. Therefore, the thermal fatigue resistance of the endogenous nanoparticle-reinforced high-entropy alloy 1 in this example is superior to that of Comparative Example 1.

[0022] Compared to Comparative Example 1, the endogenous nanoparticle-reinforced high-entropy alloy 2 prepared in Example 2 contained 0.06 wt.% nanoparticles, but reduced the lengthy homogenization heat treatment and the addition of the costly Co element, thus significantly reducing the raw material cost of this invention. The main crack length after 2200 cycles of thermal fatigue in Example 2 was reduced by 335% compared to that after 2000 cycles in Comparative Example 1. Therefore, the thermal fatigue resistance of the endogenous nanoparticle-reinforced high-entropy alloy 2 in this example is superior to that of Comparative Example 1.

[0023] Compared to Comparative Example 1, the endogenous nanoparticle-reinforced high-entropy alloy 3 prepared in Example 3 incorporated 0.05 wt.% nanoparticles, but reduced the lengthy homogenization heat treatment and the addition of the costly Co element, thus significantly lowering the raw material cost of this invention. The main crack length after 2400 cycles of thermal fatigue in Example 3 was reduced by 323% compared to that after 2000 cycles in Comparative Example 1. Therefore, the thermal fatigue resistance of the endogenous nanoparticle-reinforced high-entropy alloy 3 in this example is superior to that of Comparative Example 1.

[0024] The components, proportions, and process parameters used in Examples 1-3 of this invention are all different. Compared with Comparative Example 1, the addition of high-cost cobalt is reduced, and high-temperature long-term heat treatment is not used. The main crack length is smaller even with more cycles of thermal fatigue testing. However, the effects obtained in all examples are significantly better than those obtained by existing technologies. Furthermore, the process parameters and performance differ in each example of this invention, indicating that the superior effects obtained by this invention are not determined by a single component, proportion, process, or process parameter, but are achieved through the synergistic regulation of components, proportions, processes, and process parameters. The optimal technical effect can only be achieved within the scope of claim 1 of this invention. Simultaneously, compared with existing technologies, this invention reduces the addition of precious metal elements, simplifies the process flow, and improves the thermal fatigue resistance of high-entropy alloys under alternating hot and cold conditions. Furthermore, the endogenous nanoparticle-reinforced high-entropy alloy for thermal fatigue resistance prepared by this invention contains uniformly distributed nanoparticles with a particle size of 26-140 nanometers.

[0025] In summary, compared with existing technologies, this invention reduces the amount of alloy added and eliminates the need for heat treatment, thus saving raw material costs and significantly reducing heat treatment temperature and processing time. As a result, the alloy obtained by this invention exhibits higher resistance to thermal fatigue and is easily mass-produced industrially. Furthermore, because this invention relates to the synergistic control of components, proportions, processes, and process parameters, it possesses high flexibility. In the future, it can be further optimized and customized to develop products with different performance characteristics according to specific needs, demonstrating broad market prospects and research value, thereby promoting the widespread application of high-performance, high-entropy alloys in aerospace, energy, and other high-end equipment fields. Moreover, the proportions and process parameters differ in each embodiment of this invention, resulting in different performance characteristics for each embodiment. This demonstrates that the optimal effect obtained by this invention is not determined by a specific component, proportion, process, or process parameter, but rather by the interaction between nanoparticles and components, and the synergistic control of proportions, processes, and process parameters. Furthermore, only within the scope of the claims of this invention can the significantly improved technical effects be achieved.

Claims

1. A high-entropy alloy reinforced with endogenous nanoparticles to resist thermal fatigue, characterized in that, Its preparation method includes the following steps: (1) Under argon protection, chromium nitride powder, titanium powder and boron powder are mixed at a mass ratio of 9-29:31-79:2-11 for 3.5-7 hours at a speed of 32-91 rpm to obtain mixed powder 1; wherein the particle size of the chromium nitride powder is 177-891 micrometers, the particle size of the titanium powder is 78-123 micrometers, and the particle size of the boron powder is 5-17 micrometers; (2) Under argon protection, the mixed powder 1 obtained in step (1) is mixed with aluminum powder at a mass ratio of 178-268:53-89 for 78-189 hours to obtain mixed powder 2; the aluminum powder has a particle size of 76-234 micrometers. (3) Under argon protection, the mixed powder 2 obtained in step (2) is treated by thermal explosion to obtain alloy 1; the thermal explosion treatment is as follows: pressure is 0.033-0.87MPa, voltage is 792-913V, current is 366-817A, and temperature is 1287-1937℃. (4) At a temperature of 1400℃-1435℃, alloy 1 from step (3) is placed into a high-entropy alloy melt until alloy 1 is completely melted in the high-entropy alloy melt. After stirring and holding at the temperature for 7-15 minutes, it is cast to obtain a high-entropy alloy with endogenous nanoparticle reinforcement for thermal fatigue resistance. The composition of the high-entropy alloy melt, by mass percentage, is: nickel 36-41%, chromium 15-19%, iron 17-20%, cobalt 18-22%, and aluminum 8-10%. The mass ratio of alloy 1 to the high-entropy alloy melt is 0.1-0.4 wt.%:

1. The high-entropy alloy with endogenous nanoparticle reinforcement for thermal fatigue resistance contains nano-ceramic particles with a particle size of 26-140nm. The mass ratio of nano-ceramic particles to the high-entropy alloy melt is 0.02-0.

08. wt.%:1; The thermal fatigue main crack length of the endogenous nanoparticle-reinforced high-entropy alloy is ≤297 micrometers after 2000-3000 cycles at 10-700℃.

2. The high-entropy alloy for thermal fatigue resistance reinforced by endogenous nanoparticles according to claim 1, characterized in that, The particle size of the chromium nitride powder in step (1) is 191-813 micrometers, the particle size of the titanium powder is 81-122 micrometers, and the particle size of the boron powder is 6-17 micrometers.

3. The high-entropy alloy for thermal fatigue resistance reinforced by endogenous nanoparticles according to claim 1, characterized in that, The aluminum powder particle size in step (2) is 81-217 micrometers.

4. The high-entropy alloy for thermal fatigue resistance reinforced by endogenous nanoparticles according to claim 1, characterized in that, The thermal fatigue main crack length of the endogenous nanoparticle-reinforced high-entropy alloy described in step (4) after 2000-2800 cycles at 10-700℃ is 120-286 micrometers.

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