A multi-principal element alloy with interstitial atoms and a method of making the same

Abstract

The application relates to the technical field of alloy materials, and particularly discloses a multi-principal-element alloy added with interstitial atoms and a preparation method thereof. The multi-principal-element alloy added with interstitial atoms is characterized by being composed of a CoNiCrMo alloy base body with a weight of 99.7-99.9 wt% and 0.1-0.3 wt% of nitrogen elements; according to the atomic percentage of elements, the composition of the CoNiCrMo alloy base body is as follows: Co=33-37 at%; Ni=33-37 at%; Cr=18-22 at%; and Mo=7-11 at%. The application adopts the mode of interstitial atom solid solution strengthening and cold rolling deformation to improve the strength of the alloy, the interstitial N atoms stabilize the FCC phase structure, the strength of the alloy is improved while the good plasticity of the alloy is maintained, the strength of the alloy is further improved through cold rolling deformation, the alloy is balanced in strength and plasticity, and the practical application of the alloy in a low-temperature environment is facilitated.

Description

Technical Field

[0001] This application relates to the technical field of alloy materials, specifically to a multi-principal element alloy with interstitial atoms and its preparation method. Background Technology

[0002] Traditional alloy materials are mostly diluted solid solutions, generally consisting of a solute and a solvent. High-entropy alloys, however, are high-concentration solid solutions where the solute and solvent are indistinguishable. Due to this unique composition, high-entropy alloys exhibit a high mixing entropy effect, stabilizing the formation of solid solution phases, reducing the presence of intermetallic compound phases, and tending to form simple solid solution structures such as single-phase or multi-phase face-centered cubic (FCC), body-centered cubic (BCC), or hexagonal close-packed (HCP). The concept of multi-principal element alloys is developed based on the concept of high-entropy alloys.

[0003] CoNiCrMo medium-entropy alloys possess excellent mechanical properties, high solid solution strengthening effect, and good ductility; their toughness is better than most traditional alloys and high-entropy alloys. The FCC phase is generally considered to have excellent plasticity and toughness, but its strength and hardness are not as desirable.

[0004] Therefore, a new method is needed to prepare high-performance multi-principal-element alloys, achieving a balance between strength and plasticity to meet the requirements of alloys in extreme low-temperature environments such as fusion superconductivity and extraterrestrial exploration. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a multi-principal alloy with interstitial atoms and a method for its preparation.

[0006] In one aspect, this application provides a multi-principal alloy with added interstitial atoms, consisting of a CoNiCrMo alloy matrix of 99.7-99.9 wt% by weight and 0.1-0.3 wt% nitrogen element; Based on the atomic percentage of elements, the composition of the CoNiCrMo alloy matrix is: Co=33-37at; Ni=33-37at; Cr=18-22at; Mo=7-11at.

[0007] Preferably, the multi-principal alloy with added interstitial atoms is composed of 99.75-99.85 wt% CoNiCrMo alloy matrix and 0.15-0.25 wt% nitrogen element; the composition of the CoNiCrMo alloy matrix is: Co=34-36 at%; Ni=34-36 at%; Cr=19-21 at%; Mo=8-10 at%

[0008] Preferably, the multi-principal alloy with added interstitial atoms is composed of 99.75-99.85 wt% CoNiCrMo alloy matrix and 0.15-0.25 wt% nitrogen; the composition of the CoNiCrMo alloy matrix is: Co=34-36 at%; Ni=34-36 at%; Cr=19-21 at%; Mo=8-10 at%; P<0.001 at%; S<0.0015 at% . Secondly, this application provides a method for preparing the above-mentioned multi-principal alloy with added interstitial atoms, specifically including the following steps: S1: The ingredients are prepared according to the target composition ratio, and then placed in a vacuum pressure induction furnace and smelted under pressure of 10-20 bar in an inert gas atmosphere to obtain an alloy master ingot. The alloy ingot is then cast through a copper mold. S2: The alloy ingot is forged to obtain alloy flat steel; S3: After solution treatment of the alloy flat steel processed in step S2, a multi-principal element alloy in solid solution state is obtained; Alternatively, the alloy flat steel processed in step S2 can be subjected to solution treatment, hot rolling, heat treatment, cold rolling, and annealing in sequence to obtain a cold-rolled and annealed multi-principal alloy.

[0009] This application introduces a multi-principal element alloy with interstitial atoms, introducing a certain amount of nitrogen into a CoNiCrMo alloy to form an interstitial solid solution with the matrix. Through solution treatment or solution treatment combined with cold rolling, the alloy undergoes recrystallization, inducing twinning at low temperatures. The interstitial atoms stabilize the phase structure, and multiple dislocation mechanisms induce enhanced plasticity, resulting in a multi-strength effect that further improves the alloy's strength and ductility. During the experiments, the applicant found that a high nitrogen content significantly reduced the alloy's plasticity and toughness.

[0010] like Figure 1 The figure shows the thermodynamic phase diagram of a multi-principal element alloy with interstitial atoms added. Through analysis of... Figure 1 Analysis showed that when the solution temperature is selected at 1100-1200℃, nitrogen exists in the alloy in a solid solution state and Cr2N will not precipitate, which can ensure the stability of the single FCC phase. The alloy strengthening mechanism is solid solution strengthening.

[0011] Preferably, in step S2, the forging temperature is 950-1150℃.

[0012] Furthermore, in step S2, the forging temperature is 1000-1100℃.

[0013] Preferably, in step S3, the solution treatment specifically involves holding the solution at 1100-1200℃ for 50-70 minutes.

[0014] Further, in step S3, the solution treatment specifically involves holding the solution at 1120-1180℃ for 50-70 minutes.

[0015] Preferably, in step S3, the hot rolling process specifically involves: hot rolling reduction of 45-55%, multi-pass rolling, water cooling to room temperature, and obtaining a hot-rolled and cooled alloy plate.

[0016] Further, in step S3, the hot rolling process specifically involves: hot rolling reduction of 48-52%, multi-pass rolling, water cooling to room temperature, and obtaining a hot-rolled and cooled alloy plate.

[0017] Preferably, in step S3, the heat treatment specifically involves: holding at 1100-1200℃ for 0.5-2 hours, followed by water cooling to room temperature and pickling.

[0018] Further, in step S3, the heat treatment specifically involves: holding at 1120-1180℃ for 1-1.5 hours, followed by water cooling to room temperature and pickling.

[0019] Preferably, in step S3, the cold rolling process specifically involves a cold rolling reduction rate of 10-90% and multiple rolling passes.

[0020] Furthermore, in step S3, the cold rolling process specifically involves a cold rolling reduction rate of 30-60% and multiple rolling passes.

[0021] Preferably, in step S3, the annealing process specifically involves annealing at 800-900℃ for 2-20 minutes.

[0022] Further, in step S3, the annealing process specifically involves annealing the alloy plate sequentially at 800°C for 2-8 minutes, at 850°C for 2-8 minutes, and at 900°C for 2-8 minutes.

[0023] This application employs interstitial atom solid solution strengthening and cold rolling deformation to improve the strength of the alloy. By stabilizing the FCC phase structure through interstitial N atoms, the alloy's strength is improved while maintaining good plasticity. Furthermore, the strength of the alloy is further enhanced through cold rolling deformation, thus achieving a balance between strength and plasticity, which is beneficial for the practical application of the alloy in low-temperature environments.

[0024] In summary, the technical solution of this application has the following effects: This application introduces a multi-principal element alloy with interstitial atoms, introducing a certain amount of nitrogen into a CoNiCrMo alloy to form an interstitial solid solution with the matrix. Through solution treatment or solution treatment combined with cold rolling, the alloy undergoes recrystallization, inducing twinning at low temperatures. The interstitial atoms stabilize the phase structure, and multiple dislocation mechanisms induce enhanced plasticity, further improving the alloy's strength and ductility through multiple strengthening effects. This alloy preparation method is simple and contributes to promoting the application of multi-principal element alloys in low-temperature environments.

[0025] This invention relates to a multi-principal element alloy design with interstitial atoms and its preparation method, which solves the problem of insufficient low-temperature strength faced by CoNiCrMo alloy. Through multiple verifications and adjustments, the relationship between strength and plasticity is coordinated.

[0026] This invention also provides a reasonable combination of appropriate doping amount and processing technology, which can provide a relatively rich combination of performance control methods. In particular, by holding at a high temperature for a long time, the forged structure is partially or completely eliminated, and some precipitated phases dissolve to form a near single-phase structure. The alloy can regain a large space for performance control on the basis of higher performance level. Further strengthening can be achieved by combining deformation strengthening and precipitation strengthening to obtain a more reasonable strength and plasticity combination. Attached Figure Description

[0027] Figure 1 Thermodynamic phase diagram of the multi-principal alloy with interstitial atoms provided in this application.

[0028] Figure 2 Backscattered electron diffraction (EBSD) morphology of the microstructure of a solid-solution multi-principal-element alloy with interstitial atoms added in Example 1 of this application.

[0029] Figure 3 The tensile stress-strain curve is shown for the solid solution multi-principal element alloy with interstitial atoms prepared in Example 1 of this application.

[0030] Figure 4 The tensile stress-strain curve is shown for the cold-rolled annealed multi-principal alloy with interstitial atoms obtained in Example 2 of this application. Detailed Implementation

[0031] The present application will be further described in detail below with reference to embodiments, comparative examples and performance test results. These embodiments should not be construed as limiting the scope of protection claimed in this application. Example

[0032] Example 1 Example 1 provides a multi-principal element alloy with interstitial atoms and its preparation method.

[0033] The multi-principal alloy in this embodiment consists of a CoNiCrMo alloy matrix of 99.8 wt% and nitrogen of 0.2 wt%. The composition of the CoNiCrMo alloy matrix is: Co = 35 at%; Ni = 35 at%; Cr = 20 at%; Mo = 9 at%. The preparation method of the multi-principal element alloy in this embodiment includes the following steps: S1: Ingredient Preparation and Melting Calculate and weigh 50 kg of elemental raw materials of Co, Ni, Cr and Mo according to the target component ratio, and set aside for later use.

[0034] The uniformly mixed alloy elements and nitrogen element are placed in a vacuum induction furnace and smelted under an inert gas atmosphere at a pressure of 1500 kPa to obtain an alloy master ingot. The master ingot is then cast in a copper mold to obtain an alloy casting.

[0035] S2: Forging in blanks The alloy ingot was forged into a flat steel with a thickness of 15mm at a final forging temperature of 1050℃. Samples were taken to test the uniformity of the composition, and the chemical composition met the alloy design standards.

[0036] S3: Solution treatment The forged alloy flat steel was held in a heat treatment furnace at 1180℃ for 60 minutes, and then water-cooled to room temperature to obtain a solid solution multi-principal element alloy.

[0037] S4: Perform mechanical property testing on the obtained multi-principal element alloy. The alloy plate was cut into tensile specimens using an electrical discharge wire cutter, and the tensile mechanical properties of the alloy were tested using a universal mechanical testing machine at temperatures of 298K, 77K, and 4.2K.

[0038] Properties at 4.2K: tensile strength is 1720MPa, yield strength is 968MPa, and plasticity is 68%.

[0039] Properties at 77K: tensile strength 1500MPa, yield strength 794MPa, plasticity 65.5%.

[0040] Properties at 298K: tensile strength 947MPa, yield strength 437MPa, plasticity 57.5%.

[0041] Example 2 Example 2 provides a multi-principal element alloy with interstitial atoms and its preparation method.

[0042] The multi-principal alloy in this embodiment consists of a CoNiCrMo alloy matrix of 99.8 wt% and nitrogen of 0.2 wt%. The composition of the CoNiCrMo alloy matrix is: Co = 35 at%; Ni = 35 at%; Cr = 20 at%; Mo = 9 at%. The preparation method of the multi-principal element alloy in this embodiment includes the following steps: S1: Ingredient Preparation and Melting Calculate and weigh 50 kg of elemental raw materials of Co, Ni, Cr and Mo according to the target component ratio, and set aside for later use.

[0043] The uniformly mixed alloy elements and nitrogen element are placed in a vacuum induction furnace and smelted under an inert gas atmosphere at a pressure of 1500 kPa to obtain an alloy master ingot, which is then cast in a copper mold to obtain an alloy ingot. S2: Forging in blanks The alloy ingot was forged into a flat steel with a thickness of 15mm at a final forging temperature of 1050℃. Samples were taken to test the uniformity of the composition, and the chemical composition met the alloy design standards.

[0044] S3: Solution treatment, hot rolling, heat treatment, cold rolling, annealing Solution treatment: The forged alloy flat steel is held in a heat treatment furnace at 1180℃ for 60 minutes; Hot rolling: The alloy flat steel after the heat preservation is completed is immediately hot rolled. The alloy flat steel is rolled in multiple passes, and the final alloy thickness is rolled from 15mm to 7.5mm. Then it is water cooled to room temperature to obtain the hot rolled and cooled alloy plate. Heat treatment: The alloy plate is held in a heat treatment furnace at 1180℃ for 1 hour, then cooled to room temperature with water. The alloy plate is then immersed in a 20% hydrochloric acid solution for pickling to remove the oxide layer on the alloy surface caused by hot rolling.

[0045] Cold rolling: The alloy plate after removing the oxide layer is cold rolled, and the thickness of the alloy plate is rolled from 7.5mm to 3mm through multiple rolling passes to obtain alloy cold-rolled plate.

[0046] Annealing: The alloy cold-rolled sheet with a thickness of 3 mm is annealed. The alloy sheet is annealed at 900℃ for 5 min, 1000℃ for 5 min, and 1100℃ for 5 min in sequence, and then water-cooled to room temperature to obtain a cold-rolled annealed multi-principal element alloy.

[0047] S4: Perform mechanical property testing on the obtained multi-principal element alloy. The alloy plate was cut into tensile specimens using an electrical discharge wire cutter, and the tensile mechanical properties of the alloy were tested using a universal mechanical testing machine at a temperature of 77K.

[0048] The alloy exhibits a tensile strength of 1640 MPa, a low-temperature yield strength of 1158 MPa, and a plasticity of 31.5% after annealing at 900℃ for 5 min at 77 K. The alloy exhibits a tensile strength of 1562 MPa, a low-temperature yield strength of 1101 MPa, and a plasticity of 25.5% after annealing at 1000℃ for 5 min at 77 K. The alloy exhibits a tensile strength of 1601 MPa, a low-temperature yield strength of 965 MPa, and a plasticity of 36.5% after annealing at 1100℃ for 5 min at 77K.

[0049] Example 3 Example 3 provides a multi-principal element alloy with interstitial atoms and its preparation method.

[0050] The difference between Example 3 and Example 1 is that the multi-principal element alloy is composed of a CoNiCrMo alloy matrix of 99.7 wt% by weight and 0.3 wt% nitrogen element; the composition of the CoNiCrMo alloy matrix is: Co=35 at%; Ni=35 at%; Cr=20 at%; Mo=9 at%.

[0051] The alloy plate was cut into tensile specimens using an electrical discharge wire cutter, and the tensile mechanical properties of the alloy were tested using a universal mechanical testing machine at temperatures of 77K and 298K.

[0052] The properties of the multi-principal alloy in Example 3 at 77K are as follows: tensile strength of 1539MPa, yield strength of 857MPa, and plasticity of 61%.

[0053] The properties of the multi-principal element alloy in Example 3 at 298K are: tensile strength 995MPa, yield strength 493MPa, and plasticity 50%. The above embodiments are identical to Embodiment 1 in all other parameters.

[0054] Performance testing Figure 2 This is a backscattered electron diffraction (EBSD) pattern of the microstructure of the solid solution-state multi-principal-element alloy with interstitial atoms added in Example 1 of this application. Analysis of the EBSD pattern shows that the alloys prepared in Example 1 all exhibit a single FCC phase characteristic and equiaxed grains.

[0055] Figure 3 The image shows the tensile stress-strain curve of the solid solution multi-principal element alloy with interstitial atoms prepared in Example 1. Figure 4 This is the tensile stress-strain curve of the cold-rolled annealed multi-principal element alloy with added interstitial atoms obtained in Example 2. Figure 3 , Figure 4Analysis shows that the alloys obtained by solution treatment and cold rolling possess excellent low-temperature mechanical properties. By introducing a certain amount of nitrogen into the CoNiCrMo alloy, an interstitial solid solution is formed with the matrix. Through the solution treatment and cold rolling processes, the alloy undergoes recrystallization, which can induce twinning under low-temperature conditions. Through the interstitial atom-stabilized phase structure, multiple dislocation mechanisms induce plasticity enhancement, and the multiple strengthening effects further improve the strength and plasticity of the alloy.

[0056] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A multi-principal element alloy with added interstitial atoms, characterized in that, It consists of a CoNiCrMo alloy matrix of 99.7-99.9 wt% by weight and 0.1-0.3 wt% nitrogen. Based on the atomic percentage of each element, the composition of the CoNiCrMo alloy matrix is: Co = 33-37 at%; Ni = 33-37 at%; Cr = 18-22 at%; Mo = 7-11 at%; Furthermore, the preparation method of the multi-principal element alloy with added interstitial atoms specifically includes the following steps in sequence: S1: Prepare the ingredients according to the target composition ratio, then place them in a vacuum pressure induction furnace and melt them under pressure of 10-20 bar in an inert gas atmosphere to obtain an alloy master ingot. After casting in a copper mold, an alloy ingot is obtained. S2: The alloy ingot is forged at 950-1150℃ to obtain alloy flat steel; S3: After the alloy flat steel treated in step S2 is subjected to solution treatment at 1100-1200℃ for 50-70 minutes, a solution-treated multi-principal-element alloy is obtained. Alternatively, the alloy flat steel processed in step S2 can be subjected to solution treatment, hot rolling, heat treatment, cold rolling, and annealing in sequence to obtain a cold-rolled and annealed multi-principal element alloy. The hot rolling process specifically involves: hot rolling reduction of 45-55%, multi-pass rolling, and water cooling to room temperature to obtain a hot-rolled and cooled alloy plate. The heat treatment specifically involves: holding at 1100-1200℃ for 0.5-2 hours, followed by water cooling to room temperature and pickling. The cold rolling process specifically involves: cold rolling reduction of 10-90%, multi-pass rolling. The annealing process specifically involves: annealing at 800-900℃ for 2-20 minutes.

2. The multi-principal element alloy with interstitial atoms according to claim 1, characterized in that, It is composed of 99.75-99.85 wt% CoNiCrMo alloy matrix and 0.15-0.25 wt% nitrogen element; the composition of the CoNiCrMo alloy matrix is: Co=34-36 at; Ni=34-36 at; Cr=19-21 at; Mo=8-10 at.

3. The multi-principal element alloy with interstitial atoms according to claim 1, characterized in that, It is composed of a CoNiCrMo alloy matrix of 99.75-99.85 wt% by weight and 0.15-0.25 wt% nitrogen; the composition of the CoNiCrMo alloy matrix is: Co=34-36 at%; Ni=34-36 at%; Cr=19-21 at%; Mo=8-10 at%; P<0.001 at%; S<0.0015 at%

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