Ti, Nb and C composite added high-strength and high-plasticity CoCrFeNi high-entropy alloy and preparation method thereof
By adding Ti and Nb to the CoCrFeNi high-entropy alloy and introducing C element to form TiC and NbC carbides, the problem of difficulty in balancing strength and plasticity in high-entropy alloys is solved, and a synergistic improvement in high strength and high plasticity is achieved. The prepared alloy exhibits excellent comprehensive performance.
Patent Information
- Application Number
- CN202511707815.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-20
- Publication Date
- 2026-02-06
AI Technical Summary
Existing high-entropy alloys cannot simultaneously possess both high strength and high ductility, thus failing to meet the performance requirements of certain applications.
Adding appropriate amounts of Ti and Nb elements and introducing C elements to the CoCrFeNi high-entropy alloy allows for the in-situ precipitation of TiC and NbC carbides, forming a hard second phase that hinders dislocation movement, thereby improving the alloy's strength while maintaining high plasticity.
The high-entropy alloy achieved a synergistic improvement in strength and plasticity. The prepared alloy maintained high tensile properties while significantly improving tensile strength and tensile strain, reaching 628.8 MPa and 52.72%, respectively, which is significantly better than the comparative example without the addition of Ti and Nb.
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Figure CN121472682A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of high-entropy alloy materials, specifically to a high-strength, high-plasticity CoCrFeNi high-entropy alloy with Ti, Nb, and C composite additives and its preparation method. Background Technology
[0002] High-entropy alloys, as a novel type of metallic material, have attracted widespread attention due to their unique microstructure and excellent comprehensive properties. High-entropy alloys are composed of five or more main elements, each with an atomic percentage between 5% and 35%. They typically consist of multiple main elements in the same or nearly identical molar ratios, as their high-entropy effect favors the formation of simple solid solution phases. High-entropy alloys possess excellent comprehensive properties, such as high strength, oxidation resistance, excellent corrosion resistance, and ductility, and have wide applications in numerous fields including biomedicine, defense industry, aerospace, energy, and nuclear power generation.
[0003] Heterogeneous alloys composed of alternating soft and hard phases often possess a good combination of strength and ductility. CoCrFeNi high-entropy alloys are typical FCC structures, exhibiting excellent plasticity but potentially lower-than-expected strength. Summary of the Invention
[0004] The purpose of this invention is to solve the problem that existing high-entropy alloys cannot simultaneously possess high strength and high ductility, and to provide a high-strength and high-ductility CoCrFeNi high-entropy alloy with composite addition of Ti, Nb, and C, and its preparation method.
[0005] To achieve a synergistic improvement in plasticity and strength, this invention adds appropriate proportions of Ti, Nb, and C elements to the alloy, with C in a fixed proportion. This promotes the in-situ precipitation of TiC and NbC carbides, primarily distributed between dendrites and grain boundaries. Simultaneously, the precipitated carbides, acting as a hard second phase, significantly hinder dislocation movement and refine the grains. Therefore, the strength of the alloy can be significantly improved with minimal sacrifice in plasticity. It is evident that the contents of Ti, Nb, and C elements have a significant impact on the evolution of the microstructure within high-entropy alloys, thereby allowing for the control of their properties.
[0006] A high-strength and high-plasticity CoCrFeNi high-entropy alloy with composite addition of Ti, Nb, and C comprises the following components by weight percentage: Co: 25.62%~25.88%, Cr: 22.61%~22.83%, Fe: 24.28%~24.52%, Ni: 25.52%~25.77%, Ti: 0%~1%, Nb: 0%~1.94%, C: 0.02%~0.03%; wherein the contents of Ti and Nb are not both 0%.
[0007] A method for preparing a high-strength, high-ductility CoCrFeNi high-entropy alloy with composite additions of Ti, Nb, and C is specifically carried out according to the following steps:
[0008] I. Weigh out Co, Cr, Fe, Ni, Ti, Nb, and C powders according to the following weight percentages: Co: 25.62%~25.88%, Cr: 22.61%~22.83%, Fe: 24.28%~24.52%, Ni: 25.52%~25.77%, Ti: 0%~1%, Nb: 0%~1.94%, C: 0.02%~0.03%; where the contents of Ti and Nb are not the same, the content is 0%.
[0009] 2. The raw materials are pickled and then loaded into a vacuum suspension melting furnace and evacuated. Argon gas is then used for scrubbing and as a protective gas during the melting and casting process.
[0010] III. Smelting:
[0011] ① Under the protection of argon atmosphere, first adjust the power of the vacuum suspension melting furnace to 100kW, and melt at 100kW for 5min~10min, then adjust to 150kW, and melt at 150kW for 5min~10min, then adjust to 200kW, and melt at 200kW for 5min~10min, and finally adjust to 150kW, and melt at 150kW for 10min~15min, and cool with the furnace to 100℃~150℃;
[0012] ② Repeat step 3.1 three to five times. The material needs to be turned over between the two melting processes. After melting, the material is cast to obtain a high-strength, high-plasticity CoCrFeNi high-entropy alloy with Ti, Nb, and C composite additives.
[0013] The beneficial effects of this invention are:
[0014] I. The high-strength, high-plasticity CoCrFeNi high-entropy alloy prepared by this invention, with composite addition of Ti, Nb, and C, exhibits a synergistic improvement in both plasticity and strength. The prepared Ti exhibits high tensile strength. 0.6 Nb 0.6 The high-entropy alloy material maintains a tensile strength of 628.8 MPa while its tensile strain remains at 52.72%. This is because: the equal ratio of Ti and Nb tends to form complex carbides, which are hard phases and dispersed, significantly improving strength through dislocation bypassing mechanisms with minimal loss of plasticity; in addition, while the precipitated carbides significantly improve the alloy strength, the alloy size of 162.25 μm and the relatively coarse grain size provide capacity for plastic deformation, achieving a synergistic improvement in plasticity and strength, and falling within the range of coordinated strong plasticity.
[0015] Second, the mechanical properties of the series of high-entropy alloys prepared by this invention are enhanced. Attached Figure Description
[0016] Figure 1 Preparation of Nb for Example 1 1.2 Tensile curves of high-entropy alloys;
[0017] Figure 2 Preparation of Nb for Example 1 1.2 IPF diagram of high-entropy alloys;
[0018] Figure 3 Preparation of Nb for Example 1 1.2 SEM images of high-entropy alloys;
[0019] Figure 4 Preparation of Ti for Example 2 0.3 Nb 0.9 Tensile curve of high-entropy alloy;
[0020] Figure 5 Preparation of Ti for Example 2 0.3 Nb 0.9 IPF diagram of high-entropy alloys;
[0021] Figure 6 Preparation of Ti for Example 2 0.3 Nb 0.9 SEM images of high-entropy alloys;
[0022] Figure 7 Preparation of Ti for Example 3 0.6 Nb 0.6 Tensile curve of high-entropy alloy;
[0023] Figure 8 Preparation of Ti for Example 3 0.6 Nb 0.6 IPF diagram of high-entropy alloys;
[0024] Figure 9 Preparation of Ti for Example 3 0.6 Nb 0.6 SEM images of high-entropy alloys;
[0025] Figure 10 Preparation of Ti for Example 4 0.9 Nb 0.3 Tensile curves of high-entropy alloys;
[0026] Figure 11 Preparation of Ti for Example 4 0.9 Nb 0.3 IPF diagram of high-entropy alloys;
[0027] Figure 12 Preparation of Ti for Example 4 0.9 Nb 0.3SEM images of high-entropy alloys;
[0028] Figure 13 Preparation of Ti in Example 5 1.2 Tensile curves of high-entropy alloys;
[0029] Figure 14 Preparation of Ti in Example 5 1.2 IPF diagram of high-entropy alloys;
[0030] Figure 15 Preparation of Ti in Example 5 1.2 SEM images of high-entropy alloys;
[0031] Figure 16 Tensile curves of the CoCrFeNiNb1 high-entropy alloy prepared for comparison.
[0032] Figure 17 The graph shows a comparison of the mechanical properties of the high-entropy alloys prepared in Examples 1-5 and the comparative examples. Detailed Implementation
[0033] Specific Implementation Method 1: This implementation method describes a high-strength, high-plasticity CoCrFeNi high-entropy alloy with composite addition of Ti, Nb, and C, comprising the following components by weight percentage: Co: 25.62%~25.88%, Cr: 22.61%~22.83%, Fe: 24.28%~24.52%, Ni: 25.52%~25.77%, Ti: 0%~1%, Nb: 0%~1.94%, C: 0.02%~0.03%; and the contents of Ti and Nb are not both 0%.
[0034] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the high-entropy alloy comprises the following components by weight percentage: Co: 25.62%, Cr: 22.61%, Fe: 24.29%, Ni: 25.53%, Nb: 1.92%, C: 0.03%. Other steps are the same as in Specific Implementation Method One.
[0035] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the high-entropy alloy comprises the following components by weight percentage: Co: 25.69%, Cr: 22.66%, Fe: 24.34%, Ni: 25.58%, Ti: 0.25%, Nb: 1.45%, C: 0.03%. Other steps are the same as in Specific Implementation Method One or Two.
[0036] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the high-entropy alloy comprises the following components by weight percentage: Co: 25.74%, Cr: 22.72%, Fe: 24.40%, Ni: 25.64%, Ti: 0.50%, Nb: 0.97%, C: 0.03%. Other steps are the same as in Specific Implementation Methods One to Three.
[0037] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the high-entropy alloy comprises the following components by weight percentage: Co: 25.81%, Cr: 22.77%, Fe: 24.45%, Ni: 25.71%, Ti: 0.75%, Nb: 0.48%, C: 0.03%. Other steps are the same as in Specific Implementation Methods One to Four.
[0038] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the high-entropy alloy comprises the following components by weight percentage: Co: 25.87%, Cr: 22.82%, Fe: 24.51%, Ni: 25.77%, Ti: 1.00%, C: 0.03%. Other steps are the same as in Specific Implementation Methods One to Five.
[0039] Specific Implementation Method Seven: This implementation method is a method for preparing a high-strength, high-plasticity CoCrFeNi high-entropy alloy with composite addition of Ti, Nb, and C, specifically completed according to the following steps:
[0040] I. Weigh out Co, Cr, Fe, Ni, Ti, Nb, and C powders according to the following weight percentages: Co: 25.62%~25.88%, Cr: 22.61%~22.83%, Fe: 24.28%~24.52%, Ni: 25.52%~25.77%, Ti: 0%~1%, Nb: 0%~1.94%, C: 0.02%~0.03%; where the contents of Ti and Nb are not the same, the content is 0%.
[0041] 2. The raw materials are pickled and then loaded into a vacuum suspension melting furnace and evacuated. Argon gas is then used for scrubbing and as a protective gas during the melting and casting process.
[0042] III. Smelting:
[0043] ① Under the protection of argon atmosphere, first adjust the power of the vacuum suspension melting furnace to 100kW, and melt at 100kW for 5min~10min, then adjust to 150kW, and melt at 150kW for 5min~10min, then adjust to 200kW, and melt at 200kW for 5min~10min, and finally adjust to 150kW, and melt at 150kW for 10min~15min, and cool with the furnace to 100℃~150℃;
[0044] ② Repeat step 3.1 three to five times. The material needs to be turned over between the two melting processes. After melting, the material is cast to obtain a high-strength, high-plasticity CoCrFeNi high-entropy alloy with Ti, Nb, and C composite additives.
[0045] Specific Implementation Method Eight: The difference between this implementation method and Specific Implementation Methods One to Seven is that the content of a single impurity in the raw material described in Step One is less than 0.03 wt.%, and the total amount of impurities is <0.10 wt.%. The other steps are the same as those in Specific Implementation Methods One to Seven.
[0046] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: in step two, hydrochloric acid with a mass fraction of 5% to 20% is used to acid wash the raw materials. The other steps are the same as in Specific Implementation Methods One to Eight.
[0047] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that: In step three①, under argon atmosphere protection, the power of the vacuum suspension melting furnace is first adjusted to 100kW, and melting is performed at 100kW for 5 minutes. Then, it is adjusted to 150kW, and melting is performed at 150kW for 5 minutes. Next, it is adjusted to 200kW, and melting is performed at 200kW for 5 minutes. Finally, it is adjusted to 150kW, and melting is performed at 150kW for 15 minutes, followed by furnace cooling to 100℃~150℃. In step three②, step three① is repeated five times. The material needs to be turned over between the two melting operations. After melting, it is cast to obtain a high-strength, high-plasticity CoCrFeNi high-entropy alloy with composite additions of Ti, Nb, and C. Other steps are the same as in Specific Implementation Methods One to Nine.
[0048] The beneficial effects of the present invention are verified using the following embodiments:
[0049] Example 1: A method for preparing a high-strength, high-plasticity CoCrFeNi high-entropy alloy with composite addition of Ti, Nb, and C, specifically completed according to the following steps:
[0050] I. Weigh out Co, Cr, Fe, Ni, Nb, and C powders according to the following weight percentages: Co: 25.62%, Cr: 22.61%, Fe: 24.29%, Ni: 25.53%, Nb: 1.92%, C: 0.03% to obtain the raw material;
[0051] The raw material described in step one contains less than 0.03 wt.% of a single impurity and less than 0.10 wt.% of a total impurity.
[0052] 2. The raw materials are pickled with 5% hydrochloric acid, then loaded into a vacuum suspension melting furnace and evacuated. Argon gas is then used for scrubbing and as a protective gas during the melting and casting process.
[0053] III. Smelting:
[0054] Under the protection of argon atmosphere, the power of the vacuum suspension melting furnace is first adjusted to 100kW and melted for 5 minutes at 100kW. Then it is adjusted to 150kW and melted for 5 minutes at 150kW. Next, it is adjusted to 200kW and melted for 5 minutes at 200kW. Finally, it is adjusted to 150kW and melted for 15 minutes at 150kW. The furnace is then cooled to 100℃.
[0055] ② Repeat step 3① 5 times. The material needs to be turned over between the two melting processes. After melting, it is cast into a plate to obtain (CoCrFeNi). 98.65 C 0.15 Nb 1.2 High-entropy alloys, denoted as Nb 1.2 .
[0056] Figure 1 Preparation of Nb for Example 1 1.2 Tensile curves of high-entropy alloys;
[0057] from Figure 1 Analysis shows that the alloy prepared by Example 1 exhibits superior comprehensive performance. The alloy has a yield strength of 289.5 MPa and a tensile strength of 619.4 MPa, while maintaining a tensile strain of 48.79%. The tensile curve is stable, and it has both good strength and plasticity.
[0058] Figure 2 Preparation of Nb for Example 1 1.2 IPF diagram of high-entropy alloys;
[0059] from Figure 2 Analysis shows that the alloy prepared in Example 1 has no obvious preferred orientation of grains. Its microstructure is composed of coarse equiaxed grains with an average grain size of 178.17 μm. This structure can withstand a large amount of plastic deformation, which is why it can maintain high strength while having a tensile strain of 48.79%.
[0060] Figure 3 Preparation of Nb for Example 1 1.2 SEM images of high-entropy alloys;
[0061] from Figure 3Analysis shows that the high-entropy alloy prepared in Example 1 exhibits a typical dendritic structure and a dispersed NbC phase in its SEM images. Combined with the tensile stress-strain curves, this indicates that the in-situ generated carbides have a significant impact on achieving a synergistic improvement in strength and plasticity.
[0062] Example 2: A method for preparing a high-strength, high-plasticity CoCrFeNi high-entropy alloy with composite addition of Ti, Nb, and C, specifically completed according to the following steps:
[0063] I. Weigh out Co, Cr, Fe, Ni, Ti, Nb, and C powders according to the following weight percentages: Co: 25.69%, Cr: 22.66%, Fe: 24.34%, Ni: 25.58%, Ti: 0.25%, Nb: 1.45%, C: 0.03% to obtain the raw material;
[0064] The raw material described in step one contains less than 0.03 wt.% of a single impurity and less than 0.10 wt.% of a total impurity.
[0065] 2. The raw materials are pickled with 5% hydrochloric acid, then loaded into a vacuum suspension melting furnace and evacuated. Argon gas is then used for scrubbing and as a protective gas during the melting and casting process.
[0066] III. Smelting:
[0067] Under the protection of argon atmosphere, the power of the vacuum suspension melting furnace is first adjusted to 100kW and melted for 5 minutes at 100kW. Then it is adjusted to 150kW and melted for 5 minutes at 150kW. Next, it is adjusted to 200kW and melted for 5 minutes at 200kW. Finally, it is adjusted to 150kW and melted for 15 minutes at 150kW. The furnace is then cooled to 100℃.
[0068] ② Repeat step 3① 5 times. The material needs to be turned over between the two melting processes. After melting, cast it into a plate to obtain (CoCrFeNi). 98.65 C 0.15 Ti 0.3 Nb 0.9 High-entropy alloys, denoted as Ti 0.3 Nb 0.9 .
[0069] Figure 4 Ti prepared in Example 2 0.3 Nb 0.9 Tensile curves of high-entropy alloys;
[0070] The alloy was prepared according to the procedure in Example 2, starting from... Figure 4Analysis shows that the alloy exhibits excellent mechanical properties, with a tensile strength of 553.6 MPa, a yield strength of 241.7 MPa, and a tensile strain of 49.45%. The stress-strain curve is continuous and stable, demonstrating superior plasticity and strength.
[0071] Figure 5 Preparation of Ti for Example 2 0.3 Nb 0.9 IPF diagram of high-entropy alloys;
[0072] from Figure 5 Analysis shows that the alloy prepared in Example 2 still exhibits no obvious preferred orientation in its grain orientation. With the addition of Ti and the reduction of Nb, the microstructure is still composed of coarse equiaxed crystals, and the grain size increases, with an average grain size of 340.08 μm. The extremely coarse equiaxed crystal structure provides a wide slip distance for dislocations and can maintain high plasticity (49.45%), but the strengthening effect of fine grains is weakened, and the improvement in strength is slightly lower than that of the other four examples (553.6 MPa).
[0073] Figure 6 Ti prepared in Example 2 0.3 Nb 0.9 SEM images of high-entropy alloys;
[0074] from Figure 6 Analysis shows that the alloy prepared in Example 2 exhibits a significant dendritic structure, with white composite carbide phases distributed between the dendrites. Combined with the IPF diagram, the coarse grains and carbide phases enhance strength, while the coarse dendrite regions improve extensive plastic deformation.
[0075] Example 3: A method for preparing a high-strength, high-ductility CoCrFeNi high-entropy alloy with composite addition of Ti, Nb, and C, specifically completed according to the following steps:
[0076] I. Weigh out Co, Cr, Fe, Ni, Ti, Nb, and C powders according to the following weight percentages: Co: 25.74%, Cr: 22.72%, Fe: 24.40%, Ni: 25.64%, Ti: 0.50%, Nb: 0.97%, C: 0.03% to obtain the raw material;
[0077] The raw material described in step one contains less than 0.03 wt.% of a single impurity and less than 0.10 wt.% of a total impurity.
[0078] 2. The raw materials are pickled with 5% hydrochloric acid, then loaded into a vacuum suspension melting furnace and evacuated. Argon gas is then used for scrubbing and as a protective gas during the melting and casting process.
[0079] III. Smelting:
[0080] Under the protection of argon atmosphere, the power of the vacuum suspension melting furnace is first adjusted to 100kW and melted for 5 minutes at 100kW. Then it is adjusted to 150kW and melted for 5 minutes at 150kW. Next, it is adjusted to 200kW and melted for 5 minutes at 200kW. Finally, it is adjusted to 150kW and melted for 15 minutes at 150kW. The furnace is then cooled to 100℃.
[0081] ② Repeat step 3① 5 times. The material needs to be turned over between the two melting processes. After melting, cast it into a plate to obtain (CoCrFeNi). 98.65 C 0.15 Ti 0.6 Nb 0.6 High-entropy alloys, denoted as Ti 0.6 Nb 0.6 .
[0082] Figure 7 Ti prepared in Example 3 0.6 Nb 0.6 Tensile curves of high-entropy alloys;
[0083] from Figure 7 Analysis shows that the alloy prepared in Example 3 has a yield strength of 271.8 MPa and a tensile strength of 628.8 MPa, which are the highest among the five examples. Importantly, it also maintains a tensile strain of 52.72%, combining high strength and high plasticity, making it the best in mechanical properties among the five examples.
[0084] Figure 8 Ti prepared in Example 3 0.6 Nb 0.6 IPF diagram of high-entropy alloys;
[0085] from Figure 8 Analysis shows that when the alloy is prepared according to the process in Example 3, the equiaxed crystal structure is most uniformly distributed when the ratio of Ti to Nb is the same, the average grain size reaches 162.25 μm, and the grain orientation shows no obvious preferred orientation. The uniform microstructure has better stress distribution and dislocation accumulation at grain boundaries, which is an important reason why it can maintain a tensile strength of 628.8 MPa while also having a tensile strain of 52.72%, and has the best comprehensive performance.
[0086] Figure 9 Ti prepared in Example 3 0.6 Nb 0.6 SEM images of high-entropy alloys;
[0087] from Figure 9Analysis shows that the alloy prepared in Example 3, with equal proportions of Ti and Nb added, still exhibits dendrites but becomes finer. Combined with the dispersed composite carbide phase, it achieves optimal synergistic improvement in plasticity and strength, and its overall performance is the best among the five examples.
[0088] Example 4: A method for preparing a high-strength, high-ductility CoCrFeNi high-entropy alloy with composite addition of Ti, Nb, and C, specifically completed according to the following steps:
[0089] I. Weigh out Co, Cr, Fe, Ni, Ti, Nb, and C powders according to the following weight percentages: Co: 25.81%, Cr: 22.77%, Fe: 24.45%, Ni: 25.71%, Ti: 0.75%, Nb: 0.48%, C: 0.03% to obtain the raw material;
[0090] The raw material described in step one contains less than 0.03 wt.% of a single impurity and less than 0.10 wt.% of a total impurity.
[0091] 2. The raw materials are pickled with 5% hydrochloric acid, then loaded into a vacuum suspension melting furnace and evacuated. Argon gas is then used for scrubbing and as a protective gas during the melting and casting process.
[0092] III. Smelting:
[0093] Under the protection of argon atmosphere, the power of the vacuum suspension melting furnace is first adjusted to 100kW and melted for 5 minutes at 100kW. Then it is adjusted to 150kW and melted for 5 minutes at 150kW. Next, it is adjusted to 200kW and melted for 5 minutes at 200kW. Finally, it is adjusted to 150kW and melted for 15 minutes at 150kW. The furnace is then cooled to 100℃.
[0094] ② Repeat step 3① 5 times. The material needs to be turned over between the two melting processes. After melting, cast it into a plate to obtain (CoCrFeNi). 98.65 C 0.15 Ti 0.9 Nb 0.3 High-entropy alloys, denoted as Ti 0.9 Nb 0.3 .
[0095] Figure 10 Ti prepared in Example 4 0.9 Nb 0.3 Tensile curves of high-entropy alloys;
[0096] Figure 10Analysis shows that the alloy prepared in Example 4 exhibits superior comprehensive performance. The alloy has a tensile strength of 625.4 MPa, a yield strength of 263.0 MPa, and maintains a tensile strain of 37.79%. The tensile curve changes continuously and stably, maintaining high strength while also having good plasticity. Its comprehensive performance is slightly lower than that of Example 3.
[0097] Figure 11 Ti prepared in Example 4 0.9 Nb 0.3 IPF diagram of high-entropy alloys;
[0098] Figure 11 Analysis shows that the alloy was prepared according to the process in Example 4. The microstructure of the alloy is a coarse equiaxed crystal structure with an average grain size of 144.10 μm. The grain orientation shows no obvious preferred orientation. While maintaining a tensile strength of 625.4 MPa, it has a tensile strain of 37.79% (lower than other examples). The overall performance is slightly lower than that of Example 3.
[0099] Figure 12 Ti prepared in Example 4 0.9 Nb 0.3 SEM images of high-entropy alloys;
[0100] Figure 12 Analysis shows that the microstructure of the alloy prepared in Example 4 did not change with the increase of Ti content and the decrease of Nb content. However, the carbide phase was mainly TiC, and local aggregation occurred in the region, which easily became stress concentration points and caused a decrease in plasticity.
[0101] Example 5: A method for preparing a high-strength, high-ductility CoCrFeNi high-entropy alloy with composite additions of Ti, Nb, and C, specifically comprising the following steps:
[0102] I. Weigh out Co, Cr, Fe, Ni, Ti, and C powders according to the following weight percentages: Co: 25.87%, Cr: 22.82%, Fe: 24.51%, Ni: 25.77%, Ti: 1.00%, C: 0.03% to obtain the raw material;
[0103] The raw material described in step one contains less than 0.03 wt.% of a single impurity and less than 0.10 wt.% of a total impurity.
[0104] 2. The raw materials are pickled with 5% hydrochloric acid, then loaded into a vacuum suspension melting furnace and evacuated. Argon gas is then used for scrubbing and as a protective gas during the melting and casting process.
[0105] III. Smelting:
[0106] Under the protection of argon atmosphere, the power of the vacuum suspension melting furnace is first adjusted to 100kW and melted for 5 minutes at 100kW. Then it is adjusted to 150kW and melted for 5 minutes at 150kW. Next, it is adjusted to 200kW and melted for 5 minutes at 200kW. Finally, it is adjusted to 150kW and melted for 15 minutes at 150kW. The furnace is then cooled to 100℃.
[0107] ② Repeat step 3① 5 times. The material needs to be turned over between the two melting processes. After melting, cast it into a plate to obtain (CoCrFeNi). 98.65 C 0.15 Ti 1.2 High-entropy alloys, denoted as Ti 1.2 .
[0108] Figure 13 Ti prepared in Example 5 1.2 Tensile curves of high-entropy alloys;
[0109] from Figure 13 Analysis shows that the alloy was prepared according to the preparation method in Example 5. The alloy yield strength reached 246.8 MPa, the tensile strength reached 572.8 MPa, and the tensile strain was 56.54%. However, the strength decreased and the plasticity was partially improved compared with the previous group of examples. The overall performance was slightly lower than that of Example 3.
[0110] Figure 14 Ti prepared in Example 5 1.2 IPF diagram of high-entropy alloys;
[0111] from Figure 14 Analysis shows that the alloy prepared in Example 5 has a disordered color and randomly distributed grains. Its microstructure exhibits a uniform and fine equiaxed crystal structure with an average grain size of 128.07 μm, which is the smallest among the five examples. Although the fine grains have limited ability to coordinate deformation during plastic deformation, the TiC precipitates in this example are few in number and dispersed, which has a mild effect on hindering dislocation movement. The fine and uniform grains promote the uniformity of strain distribution and delay necking. Therefore, this is an important reason why it maintains a tensile strength of 572.8 MPa while also having a tensile strain of 56.54% (the largest among the five examples).
[0112] Figure 15 Ti prepared in Example 5 1.2 SEM images of high-entropy alloys;
[0113] from Figure 15Analysis shows that the alloy preparation process follows the preparation method in Example 5. This invention example does not contain Nb element, the precipitate is mainly TiC, the quantity is reduced and the distribution is more dispersed, the strength strengthening effect is weakened. Combined with the IPF diagram, it has coarse grains and a small number of precipitates, corresponding to higher strength and the highest tensile strain.
[0114] Comparative Example: The preparation method of CoCrFeNiNb1 high-entropy alloy is carried out according to the following steps:
[0115] I. Weigh out Co, Cr, Fe, Ni, and Nb powders according to the following weight percentages: Co: 18.51%, Cr: 16.33%, Fe: 17.54%, Ni: 18.43%, Nb: 29.19% to obtain the raw material;
[0116] The raw material described in step one contains less than 0.03 wt.% of a single impurity and less than 0.10 wt.% of a total impurity.
[0117] 2. The raw materials are pickled with 5% hydrochloric acid, then loaded into a vacuum suspension melting furnace and evacuated. Argon gas is then used for scrubbing and as a protective gas during the melting and casting process.
[0118] III. Smelting:
[0119] Under the protection of argon atmosphere, the power of the vacuum suspension melting furnace is first adjusted to 100kW and melted for 5 minutes at 100kW. Then it is adjusted to 150kW and melted for 5 minutes at 150kW. Next, it is adjusted to 200kW and melted for 5 minutes at 200kW. Finally, it is adjusted to 150kW and melted for 15 minutes at 150kW. The furnace is then cooled to 100℃.
[0120] ② Repeat step 3① 5 times. The material needs to be turned over between the two melting processes. After melting, the material is cast into a plate to obtain CoCrFeNiNb1 high-entropy alloy.
[0121] Figure 16 Tensile curves of the CoCrFeNiNb1 high-entropy alloy prepared for comparison.
[0122] from Figure 16 Analysis shows that the strength and plasticity of the CoCrFeNiNb1 high-entropy alloy prepared in the comparative example are significantly inferior to those of the five examples. The yield strength reaches 214.1 MPa, the tensile strength only reaches 375.6 MPa, and the tensile strain is only 26.96%, making it difficult to achieve a synergistic improvement in strength and plasticity, resulting in poor overall performance.
[0123] Table 1 shows the tensile strain, yield strength, tensile strength, and average grain size values for each embodiment and comparative example;
[0124] Table 1
[0125]
[0126] Figure 17 Comparison of the mechanical properties of the high-entropy alloys prepared in Examples 1-5 and the comparative examples;
[0127] from Figure 17 Analysis shows that the high-strength and high-plasticity CoCrFeNi high-entropy alloys with Ti, Nb, and C composite additives prepared in Examples (1-5) have significant advantages in comprehensive performance compared with the comparative examples. The tensile strength of the five examples in this invention is greater than 550 MPa, which is 47.39% to 67.41% higher than that of the comparative example (375.6 MPa). At the same time, the tensile strain of the five examples is 40.17% to 109.68% higher than that of the comparative example, which far exceeds the performance of the comparative example. Among them, Example 3 has the highest tensile strength among the five examples while maintaining a high strain of 52.72%. Figure 17 The comparative data significantly demonstrate that high-entropy alloys with the composite addition of Ti, Nb, and C to CoCrFeNi can achieve a synergistic improvement in both high strength and high plasticity.
Claims
1. A high-strength, high-ductility CoCrFeNi high-entropy alloy with composite additions of Ti, Nb, and C, characterized in that... The high-entropy alloy comprises the following components by weight percentage: Co: 25.62%~25.88%, Cr: 22.61%~22.83%, Fe: 24.28%~24.52%, Ni: 25.52%~25.77%, Ti: 0%~1%, Nb: 0%~1.94%, C: 0.02%~0.03%; and the contents of Ti and Nb are not both 0%.
2. The high-strength, high-plasticity CoCrFeNi high-entropy alloy with Ti, Nb, and C composite additives according to claim 1, characterized in that... The high-entropy alloy comprises the following components by weight percentage: Co: 25.62%, Cr: 22.61%, Fe: 24.29%, Ni: 25.53%, Nb: 1.92%, C: 0.03%.
3. The high-strength, high-plasticity CoCrFeNi high-entropy alloy with Ti, Nb, and C composite additives according to claim 1, characterized in that... The high-entropy alloy comprises the following components by weight percentage: Co: 25.69%, Cr: 22.66%, Fe: 24.34%, Ni: 25.58%, Ti: 0.25%, Nb: 1.45%, C: 0.03%.
4. The high-strength, high-plasticity CoCrFeNi high-entropy alloy with Ti, Nb, and C composite additives according to claim 1, characterized in that... The high-entropy alloy comprises the following components by weight percentage: Co: 25.74%, Cr: 22.72%, Fe: 24.40%, Ni: 25.64%, Ti: 0.50%, Nb: 0.97%, C: 0.03%.
5. The high-strength, high-plasticity CoCrFeNi high-entropy alloy with Ti, Nb, and C composite additives according to claim 1, characterized in that... The high-entropy alloy comprises the following components by weight percentage: Co: 25.81%, Cr: 22.77%, Fe: 24.45%, Ni: 25.71%, Ti: 0.75%, Nb: 0.48%, C: 0.03%.
6. The high-strength, high-plasticity CoCrFeNi high-entropy alloy with Ti, Nb, and C composite additives according to claim 1, characterized in that... The high-entropy alloy comprises the following components by weight percentage: Co: 25.87%, Cr: 22.82%, Fe: 24.51%, Ni: 25.77%, Ti: 1.00%, C: 0.03%.
7. The method for preparing a high-strength, high-plasticity CoCrFeNi high-entropy alloy with composite addition of Ti, Nb, and C as described in claim 1, characterized in that... The preparation method is specifically carried out according to the following steps: I. Weigh out Co, Cr, Fe, Ni, Ti, Nb, and C powders according to the following weight percentages: Co: 25.62%~25.88%, Cr: 22.61%~22.83%, Fe: 24.28%~24.52%, Ni: 25.52%~25.77%, Ti: 0%~1%, Nb: 0%~1.94%, C: 0.02%~0.03%; where the contents of Ti and Nb are not the same, the content is 0%.
2. The raw materials are pickled and then loaded into a vacuum suspension melting furnace and evacuated. Argon gas is then used for scrubbing and as a protective gas during the melting and casting process. III. Smelting: ① Under the protection of argon atmosphere, first adjust the power of the vacuum suspension melting furnace to 100kW, and melt at 100kW for 5min~10min, then adjust to 150kW, and melt at 150kW for 5min~10min, then adjust to 200kW, and melt at 200kW for 5min~10min, and finally adjust to 150kW, and melt at 150kW for 10min~15min, and cool with the furnace to 100℃~150℃; ② Repeat step 3.1 three to five times. The material needs to be turned over between the two melting processes. After melting, the material is cast to obtain a high-strength, high-plasticity CoCrFeNi high-entropy alloy with Ti, Nb, and C composite additives.
8. The method for preparing a high-strength, high-plasticity CoCrFeNi high-entropy alloy with composite addition of Ti, Nb, and C according to claim 7, characterized in that... The content of a single impurity in the raw material mentioned in step one is less than 0.03 wt.%, and the total amount of impurities is less than 0.10 wt.%.
9. The method for preparing a high-strength, high-ductility CoCrFeNi high-entropy alloy with composite addition of Ti, Nb, and C according to claim 7, characterized in that... In step two, the raw materials are pickled using hydrochloric acid with a mass fraction of 5% to 20%.
10. The method for preparing a high-strength, high-ductility CoCrFeNi high-entropy alloy with composite addition of Ti, Nb, and C according to claim 7, characterized in that... In step 3①, under the protection of argon atmosphere, the power of the vacuum suspension melting furnace is first adjusted to 100kW, and melting is carried out at 100kW for 5 minutes. Then it is adjusted to 150kW, and melting is carried out at 150kW for 5 minutes. Then it is adjusted to 200kW, and melting is carried out at 200kW for 5 minutes. Finally, it is adjusted to 150kW, and melting is carried out at 150kW for 15 minutes. The furnace is then cooled to 100℃~150℃. In step 3②, step 3① is repeated 5 times. The material needs to be turned over between the two meltings. After the melting is completed, it is cast to obtain a high-strength and plastic high-entropy alloy of Ti, Nb and C composite additives.