Y-containing nickel-based alloy with high-temperature stable NbC precipitated phase for molten salt reactor and preparation method of Y-containing nickel-based alloy

Abstract

The invention provides a Y-containing nickel-based alloy with high-temperature stable NbC precipitated phase for a molten salt reactor and a preparation method of the Y-containing nickel-based alloy, and belongs to the technical field of alloy preparation. The alloy comprises the following raw materials in percentage by mass: 0.02 to 0.08 percent of C, 0 to 0.5 percent of Al, 0 to 0.5 percent of Fe, 0 to 0.3 percent of Ti, 5.0 to 7.0 percent of Cr, 19 to 28 percent of W, 0 to 0.1 percent of Zr, 1t of Si and the balance of Al. 0.5%, Mn: lt; the component A is 0.8%, the component B is 2.0-4.5%, the component C is 0.02-0.1%, and the component B is 0.8%. 10 ppm, Plt; 10 ppm, Nlt; 10 ppm, Blt; 10 ppm, and the balance being Ni. The Nb element forms an NbC carbide in the alloy, and the added Y is extremely easy to enter the NbC in a solid solution manner to replace the Nb element in the NbC, so that the stability of the NbC at a high temperature is improved, and the size and the number of NbC precipitated phases are hardly changed even after solid solution aging treatment and 850 DEG C long-term thermal exposure.

Description

Technical Field

[0001] The invention relates to the technical field of alloy preparation, and in particular to a Y-containing nickel-based alloy with a high-temperature stable NbC precipitation phase for a molten salt reactor and a preparation method thereof. Background Art

[0002] In the fourth-generation nuclear reactor molten salt reactor, the commonly used HastelloyN alloy has a serious helium embrittlement problem. The impurity boron in the alloy and the matrix nickel atoms form helium bubbles through transmutation reaction, which gather on the grain boundaries and seriously deteriorate the mechanical properties of the alloy after irradiation. Researchers can significantly improve the above helium embrittlement problem by adding Nb to introduce fine MC-type carbides in the alloy structure to absorb helium bubbles. However, this series of alloys has the problem that MC (NbC) carbides are unstable at high temperatures.

[0003] When Oak Ridge National Laboratory first studied Nb-modified Hastelloy N alloy, it was found that the NbC precipitate phase began to lose stability and coarsen above 650°C. See the paper MCCOY JR H E. Status of materials development for molten salt reactors [R]. ORNL / TM / 5920, Oak Ridge National Lab., Tenn. (USA), 1978.

[0004] The paper (WANG JY, ZHU YC, CHEN WB, LIU RD, LI XK, WANG YW, ZHU QC, LIANG JP, LI CW, JIANG L, LI Z J. Realizing strength-ductility combination of Ni-12Mo-7Cr-2Nb based superalloy via nano-sized MC carbides at stacking faults and grain boundaries[J]. Materials Science and Engineering: A, 2024, 916: 147303.) shows that after aging at 750℃ for 100h, the Nb-modified GH3535 alloy showed significant instability coarsening of NbC.

[0005] Patent CN115786771A discloses a high-strength, corrosion-resistant, deformable high-temperature alloy for molten salt reactors and a preparation method thereof. The chemical composition of the alloy by mass percentage is: 6.0-8.0% Cr, 26.0-28.0% W, 0.1-0.4% Si, 0.025-0.08% C, 0-0.6% Fe, 0-0.6% Mn, 0-1.0% Mo, 0-0.2% Ti, 0-0.1% Zr, 0.5-4% Nb, and the balance is Ni. The alloy has high-temperature strength and high-temperature oxidation resistance, but poor tensile strength and elongation.

[0006] Patent CN115992326A discloses a Cr-free nickel-based alloy for high-temperature molten salt environment and its preparation method. The chemical composition of the alloy is: 2.0-4.0% Nb, 26.0-28.0% W, 0.2-0.4% Si, 0.025-0.08% C, 0-0.6% Mn, and the balance is Ni. Although it has high tensile strength, its high-temperature elongation is relatively low and its stability is insufficient.

[0007] Therefore, improving the stability of NbC at high temperatures, especially above 800°C, has become an important scientific difficulty at present. Summary of the invention

[0008] In view of this, the purpose of the present invention is to provide a Y-containing nickel-based alloy with a high-temperature stable NbC precipitation phase for a molten salt reactor, so as to improve the stability of the NbC precipitation phase.

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] A Y-containing nickel-based alloy with a NbC precipitation phase and high temperature stability for a molten salt reactor, comprising the following raw materials in percentage by mass:

[0011] C: 0.02~0.08%, Al: 0~0.5%, Fe: 0~0.5%, Ti: 0~0.3%, Cr: 5.0~7.0%, W: 19~28%, Zr: 0~0.1%, Si: <0.5%, Mn: <0.8%, Nb: 2.0~4.5%, Y: 0.02~0.1%, S<10ppm, P<10ppm, N<10ppm, B<10ppm, the balance is Ni.

[0012] Preferably, the alloy is composed of the following raw materials in percentage by mass:

[0013] C: 0.02~0.08%, Al: 0~0.3%, Fe: 0~0.3%, Ti: 0~0.3%, Cr: 5.8~7.0%, W: 19~26%, Zr: 0~0.1%, Si: <0.5%, Mn: <0.8%, Nb: 2.0~4.5%, Y: 0.02~0.1%, S<10ppm, P<10ppm, N<10ppm, B<10ppm, the balance is Ni.

[0014] Another object of the present invention is to provide a method for preparing a Y-containing nickel-based alloy with a high temperature stable NbC precipitation phase for a molten salt reactor, comprising the following steps:

[0015] (1) Casting: Using vacuum induction furnace for casting to obtain alloy ingots that meet the element ratio requirements;

[0016] (2) homogenization treatment: homogenizing the alloy ingot at 1100° C.-1250° C. for 2-30 hours;

[0017] (3) Forging: The alloy ingot after homogenization treatment is heated to 1100°C-1250°C for forging, and then cooled to room temperature to obtain a slab;

[0018] (4) Hot rolling: the slab is heated to 1100°C-1250°C, kept at this temperature for 0.5-5h for hot rolling, and cooled to room temperature to obtain a hot-rolled plate;

[0019] (5) Solution aging treatment: The hot-rolled plate is heated to 1100° C.-1300° C., kept at this temperature, and cooled to room temperature to obtain a Y-containing nickel-based alloy with a NbC precipitation phase having a high temperature stability for the molten salt reactor.

[0020] Preferably, the specific method of vacuum induction furnace casting in step (1) is:

[0021] The alloy raw materials are prepared according to the element ratio, and then added into a vacuum induction furnace for smelting to obtain alloy liquid, which is then cast to obtain alloy ingots.

[0022] More preferably, the smelting temperature is 1500°C-1550°C; the smelting time is 1h-2h; and the smelting vacuum degree is 10Pa-30Pa.

[0023] Preferably, the forging in step (3) is to forge the alloy ingot to a thickness of 30 to 50 mm;

[0024] The cooling method in step (3) is air cooling or water cooling.

[0025] Preferably, the hot rolling in step (4) is performed 5-10 times, and the deformation in each time is not less than 20%.

[0026] Preferably, the thickness of the hot-rolled plate in step (4) is 7 mm to 13 mm;

[0027] The cooling method in step (4) is air cooling or water cooling.

[0028] Preferably, the insulation time in step (5) is 10 min-60 min.

[0029] Preferably, the cooling method in step (5) is air cooling or water cooling.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention provides a Y-containing nickel-based alloy with a high-temperature stable NbC precipitation phase for a molten salt reactor, wherein the alloy contains Nb elements, and NbC carbides are formed in the alloy. The present invention also adds Y, which is extremely easy to solid-dissolve into NbC, replacing the Nb element in NbC, thereby improving the stability of NbC. The stability of the NbC precipitation phase in the alloy prepared by the present invention is greatly improved, because a fine and dispersed NbC precipitation phase is formed by adding an appropriate amount of Nb, and its stability at high temperature is improved by a trace amount of Y, even after solution aging treatment and long-term heat exposure at 850°C, the size and quantity of the NbC precipitation phase hardly change. In addition to being able to resist helium embrittlement, the stability of NbC also effectively hinders dislocation movement, giving the alloy excellent high-temperature mechanical properties. Under 850°C tensile conditions, the alloy has a yield strength of ≥190MPa, a tensile strength of ≥400MPa, and an elongation after fracture of ≥30%.

[0032] Adding 5.8-7.0% of chromium (Cr) to the alloy of the present invention can ensure the alloy's resistance to molten salt corrosion in a high-temperature environment while giving the alloy a certain anti-oxidation property.

[0033] C element is the main element that forms carbides in alloys.

[0034] The addition of trace elements such as Ti, Al, Mn, Zr, and Si can purify the grain boundaries and improve the smelting quality of the alloy.

[0035] The W element improves the comprehensive properties of the alloy through the solid solution strengthening mechanism.

[0036] The Fe element may be introduced into the alloy as an impurity of the raw materials.

[0037] The following first-principles calculation method is used to theoretically explain the mechanism by which Y can improve the stability of NbC. First, the original NbC configuration is optimized to obtain the most stable NbC configuration. The lattice constant of the optimized NbC configuration is The experimental value obtained by neutron diffraction Then, a NbC supercell of 216 atoms (3×3×3) was constructed and doped with Y atoms. The equilibrium lattice constants and total energies of different structures were obtained during the structural optimization process. In order to study the trend of preferential occupation of doped Y atoms in NbC carbides, the occupation energy ΔEoc was defined as shown in formula (1):

[0038] ΔE oc =E Nb107YC108 -E Nb108C108 -E Y +E Nb (1)

[0039] Where Y refers to the doped Y atom, E Nb107YC108 and E Nb108C108 represent the total energy of NbC structure before and after Y doping; E Y and E Nb Represents the single state of the doped Y element and the total energy of the replaced Nb atoms. The more negative the occupation energy is, the more stable the NbC system is and the easier it is for the doping element to be doped into NbC. The calculated ΔE oc =-0.369eV, indicating that the Y element is easily doped into NbC carbide and replaces Nb atoms, and the stability of Y-doped NbC is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The SEM microstructure of the Y-containing nickel-based alloy with NbC precipitation phase and high temperature stability for molten salt reactor prepared in Examples 1 to 6;

[0041] Figure 2 The NbC (MC type) precipitation phase morphology and precipitation phase EDS line scan image of the alloy in Example 1;

[0042] Figure 3 The morphology of the precipitated phase of the high temperature stable Y-containing nickel-based alloy for molten salt reactor prepared in Examples 1 to 6 after exposure to 850° C. for 500 hours;

[0043] Figure 4 This is the element line distribution diagram of the precipitated phase of the alloy of Example 6 after 850°C-500h thermal exposure;

[0044] Figure 5 The morphology of the precipitated phase of the high temperature stable Y-containing nickel-based alloy for molten salt reactor prepared in Examples 1-2 after exposure to 850°C for 1000h;

[0045] Figure 6 The SEM microstructure of the nickel-based alloy prepared in Comparative Examples 5 to 7;

[0046] Figure 7The SEM microstructure of the nickel-based alloy prepared in Comparative Examples 5 to 7 after exposure to 750° C. for 500 h;

[0047] Figure 8 The SEM microstructure of the nickel-based alloy prepared in Comparative Examples 5 to 7 after exposure to 850° C. for 500 h;

[0048] Fig. 9 This is the SEM-EDS morphology of the nickel-based alloy prepared in Comparative Example 8 after exposure to 850°C for 500h. DETAILED DESCRIPTION

[0049] The present invention provides a Y-containing nickel-based alloy with a high-temperature stable NbC precipitation phase for a molten salt reactor, which is composed of the following raw materials in percentage by mass:

[0050] C: 0.02~0.08%, Al: 0~0.5%, Fe: 0~0.5%, Ti: 0~0.3%, Cr: 5.0~7.0%, W: 19~28%, Zr: 0~0.1%, Si: <0.5%, Mn: <0.8%, Nb: 2.0~4.5%, Y: 0.02~0.1%, S<10ppm, P<10ppm, N<10ppm, B<10ppm, the balance is Ni.

[0051] In a specific embodiment of the present invention, the alloy is composed of the following raw materials in percentage by mass:

[0052] C: 0.02~0.08%, Al: 0~0.3%, Fe: 0~0.3%, Ti: 0~0.3%, Cr: 5.8~7.0%, W: 19~26%, Zr: 0~0.1%, Si: <0.5%, Mn: <0.8%, Nb: 2.0~4.5%, Y: 0.02~0.1%, S<10ppm, P<10ppm, N<10ppm, B<10ppm, the balance is Ni.

[0053] The alloy of the present invention contains Nb element, and NbC carbide is formed in the alloy. Y is also added in the present invention, and Y is extremely easy to be dissolved into NbC, replacing the Nb element in NbC, thereby improving the stability of NbC. In addition to being able to resist helium embrittlement, the stability of NbC also effectively hinders dislocation movement, giving the alloy excellent high-temperature mechanical properties, including yield strength, tensile strength and elongation after fracture.

[0054] In a specific embodiment of the present invention, in order to further improve the stability of NbC under high temperature long-term aging, the alloy is composed of the following raw materials in percentage by mass:

[0055] C: 0.035~0.04%, Al: 0.22~0.26%, Fe: 0~0.3%, Ti: 0.2~0.3%, Cr: 5.8~6.0%, W: 19~20%, Zr: 0~0.04% , Si: <0.5%, Mn: <0.8%, Nb: 2.0~4.5%, Y: 0.02~0.1%, S<10ppm, P<10ppm, N<10ppm, B<10ppm, the balance is Ni.

[0056] In a specific embodiment of the present invention, in order to further improve the elongation of the alloy, the alloy is composed of the following raw materials in mass percentage:

[0057] C: 0.035~0.04%, Al: 0.22~0.26%, Ti: 0.25~0.26%, Cr: 5.8~5.9%, W: 19~20%, Zr: 0.03~0.04%, Si: 0. 3~0.5%, Mn: 0.6~0.7%, Nb: 2.0~4.5%, Y: 0.02~0.09%, S<10ppm, P<10ppm, N<10ppm, B<10ppm, the balance is Ni.

[0058] In a specific embodiment of the present invention, in order to further improve the tensile strength and yield strength of the alloy, the alloy is composed of the following raw materials in percentage by mass:

[0059] C: 0.05~0.055%, Fe: 0~0.3%, Ti: 0~0.03%, Cr: 6.0~7.0%, W: 25~26%, Si: <0.5%, Mn: 0. 5~0.6%, Nb: 2.0~3.5%, Y: 0.04~0.045%, S<10ppm, P<10ppm, N<10ppm, B<10ppm, the balance is Ni.

[0060] The method for preparing the Y-containing nickel-based alloy with a high temperature stable NbC precipitation phase for the molten salt reactor of the present invention comprises the following steps:

[0061] (1) preparing alloy raw materials according to the element ratio, then adding them into a vacuum induction furnace for smelting to obtain alloy liquid, and then casting to obtain an alloy ingot that meets the element ratio requirements; the smelting temperature is 1500° C.-1550° C.; the smelting time is 1h-2h; the smelting vacuum degree is 10Pa-30Pa;

[0062] (2) homogenization treatment: homogenizing the alloy ingot at 1100° C.-1250° C. for 2-30 hours;

[0063] (3) Forging: The alloy ingot after homogenization treatment is heated to 1100°C-1250°C for forging, and then air-cooled to room temperature to obtain a slab with a thickness of 30 mm to 50 mm;

[0064] (4) Hot rolling: the slab is heated to 1100°C-1250°C, kept at this temperature for 0.5-5h for hot rolling, and air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 7mm-13mm; the hot rolling is performed 5-10 times, and the deformation of each time is not less than 20%;

[0065] (5) Solution aging treatment: The hot-rolled plate is heated to 1100° C.-1300° C., kept at this temperature for 10 min-60 min, and air-cooled to room temperature to obtain a Y-containing nickel-based alloy with a NbC precipitation phase having a high temperature stability for the molten salt reactor.

[0066] The present invention will be further described below in conjunction with the embodiments.

[0067] Example 1

[0068] A Y-containing nickel-based alloy with a NbC precipitation phase and high temperature stability for a molten salt reactor, comprising the following raw materials in percentage by mass:

[0069] C: 0.036%, Al: 0.23%, Ti: 0.26%, Cr: 5.83%, W: 19.61%, Zr: 0.035%, Si: 0.4%, M n: 0.68%, Nb: 2.12%, Y: 0.028%, S<10ppm, P<10ppm, N<10ppm, B<10ppm, the balance is Ni.

[0070] The preparation method of the Y-containing nickel-based alloy with a NbC precipitation phase and high temperature stability for the molten salt reactor comprises the following steps:

[0071] (1) preparing alloy raw materials according to the element ratio, then adding them into a vacuum induction furnace for smelting to obtain alloy liquid, and then casting to obtain an alloy ingot that meets the element ratio requirements; the smelting temperature is 1550° C.; the smelting time is 2 hours; the smelting vacuum degree is 10 Pa;

[0072] (2) homogenization treatment: the alloy ingot is subjected to homogenization treatment at 1230° C. for 3 h;

[0073] (3) Forging: The alloy ingot after homogenization treatment is heated to 1200°C for forging, and then air-cooled to room temperature to obtain a slab with a thickness of 40 mm;

[0074] (4) Hot rolling: the slab is heated to 1200°C, kept at this temperature for 1 hour for hot rolling, and air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 10 mm; the hot rolling is performed 6 times, and the deformation of each time is not less than 20%;

[0075] (5) Solution aging treatment: The hot-rolled plate is heated to 1200°C and kept at this temperature for 30 minutes to obtain a Y-containing nickel-based alloy with a NbC precipitation phase having a high temperature stability for the molten salt pile.

[0076] Embodiment 2-8

[0077] The element composition of the alloy was changed, and a Y-containing nickel-based alloy with a NbC precipitation phase and high temperature stability for a molten salt reactor was prepared according to the method of Example 1.

[0078] Comparative Examples 1 to 7

[0079] The element composition of the alloy was changed and the nickel-based alloy for molten salt reactor was prepared according to the method of Example 1.

[0080] Comparative Example 8

[0081] The element composition of the alloy was changed and a nickel-based alloy for molten salt reactor was prepared according to the method of Example 1, wherein the smelting temperature, homogenization temperature, forging temperature and solution treatment temperature were all 20° C. lower than those in Example 1.

[0082] The element compositions (mass percentage / %) of the alloys in Examples 1 to 8 and Comparative Examples 1 to 8 are shown in Table 1.

[0083] Table 1

[0084]

[0085]

[0086] The following tests were performed on the alloys prepared in Examples 1 to 8 and Comparative Examples 1 to 8:

[0087] 1. The SEM microstructure of the high temperature stable Y-containing nickel-based alloy with NbC precipitation phase prepared in Examples 1 to 6 for molten salt reactor is as follows: Figure 1 .in, Figure 1 (a) is Example 1, Figure 1 (b) is Example 2, Figure 1 (c) is Example 3, Figure 1 (d) is Example 4, Figure 1 (e) is Example 5, Figure 1 (f) is Example 6.

[0088] from Figure 1 It can be seen that the NbC precipitation phase of the Y-containing nickel-based alloys for molten salt reactors prepared in Examples 1 to 6 is stable after the NbC is subjected to solution treatment at 1200° C. for 0.5 h.

[0089] The morphology and EDS line scan of the NbC (MC type) precipitation phase of the alloy in Example 1 are as follows: Figure 2 .in Figure 2 (a) is the morphology of NbC (MC type) precipitation phase. Figure 2 (b) is the EDS line scan of the precipitated phase, indicating that Y is enriched in NbC.

[0090] 2. The Y-containing nickel-based alloy with NbC precipitation phase and high temperature stability for molten salt reactor prepared in Examples 1 to 6 was exposed to 850° C. for 500 h, and the morphology of the precipitation phase of the alloy after heat exposure was as follows: Figure 3 .in, Figure 3 (a) is Example 1, Figure 3 (b) is Example 2, Figure 3 (c) is Example 3, Figure 3 (d) is Example 4, Figure 3 (e) is Example 5, Figure 3 (f) is Example 6.

[0091] from Figure 3 It can be seen that after being thermally exposed at 850°C for 500 h, the NbC precipitated phases of the alloys of Examples 1 to 6 all exist stably.

[0092] The element line distribution diagram of the precipitation phase of the alloy of Example 6 after 850℃-500h thermal exposure is as follows: Figure 4 ,from Figure 4 It can be seen that Y is enriched in NbC.

[0093] 3. The Y-containing nickel-based alloy with NbC precipitation phase and high temperature stability for molten salt reactor prepared in Examples 1 and 2 was exposed to 850°C for 1000 hours to obtain the precipitation phase morphology of the alloy after heat exposure as shown in FIG. Figure 5 .in, Figure 5 (a) is Example 1, Figure 5 (b) is Example 2.

[0094] from Figure 5 It can be seen that after being thermally exposed at 850°C for 1000 h, the NbC precipitated phases of the alloys of Examples 1 to 2 are all stably present.

[0095] 4. The SEM microstructures of the nickel-based alloys prepared in Comparative Examples 5 to 7 are as follows: Figure 6 .in, Figure 6 (a) is Comparative Example 5, Figure 6 (b) is Comparative Example 6, Figure 6 (c) is Comparative Example 7.

[0096] from Figure 6 It can be seen that the nickel-based alloys prepared in Comparative Examples 5 to 7 do not have any precipitated phase after being solution treated at 1200° C. for 0.5 h.

[0097] 5. The nickel-based alloys prepared in Comparative Examples 5 to 7 were exposed to 750° C. for 500 h, and the SEM microstructure of the alloys after heat exposure was obtained as follows: Figure 7 .in, Figure 7 (a) and (b) are comparative examples 5, Figure 7 (c) and (d) are comparative examples 6, Figure 7 (e) and (f) are comparative examples 7.

[0098] from Figure 7 It can be seen that after thermal exposure at 750°C for 500h, the alloys of Comparative Examples 5 to 7 have NbC precipitation phase.

[0099] 6. The nickel-based alloys prepared in Comparative Examples 5 to 7 were exposed to 850° C. for 500 h, and the SEM microstructure of the alloys after heat exposure was obtained as follows: Figure 8 .in, Figure 8 (a) and (b) are comparative examples 5, Figure 8 (c) and (d) are comparative examples 6, Figure 8 (e) and (f) are comparative examples 7.

[0100] from Figure 8 It can be seen that after thermal exposure at 850°C for 500h, there is no NbC precipitation phase in Comparative Examples 5 and 6 without Y, and there is NbC in Comparative Example 7 without Y and with a high Nb content, but the amount is small.

[0101] 7. The nickel-based alloy prepared in Comparative Example 8 was exposed to 850°C for 500h, and the SEM-EDS morphology of the alloy after thermal exposure was obtained as follows: Fig. 9 .

[0102] from Fig. 9 It can be seen that the microstructure and composition distribution of Comparative Example 8 after heat exposure at 850°C for 500h, the carbides in the figure are all M6C, indicating that Nb has entered the Mo-rich M6C and there is no NbC.

[0103] The exposure time was changed, and the alloys prepared in Examples 1 to 6 and Comparative Examples 5 to 8 were recorded after the solid solution treatment (solution treatment at 1200° C. for 0.5 h in step (5)), as well as whether they contained NbC phase at different temperatures and exposure times. The results are shown in Table 2. In Table 2, √ represents the presence of NbC, and × represents the absence of NbC.

[0104] Table 2

[0105]

[0106]

[0107] As can be seen from Table 2, the stability of NbC in the alloy with Y added at 850°C for long-term aging is better than that without Y, where Comparative Example 8 is a Hastelloy N alloy with Nb added. Comparative Example 7 proves that Nb is a prerequisite for the precipitation of MC-type carbides, and NbC will not precipitate without Nb.

[0108] 8. The mechanical properties of the alloys prepared in Examples 1 to 5, 7 to 8 and Comparative Examples 1 to 7 under 850° C. tensile conditions (using GB / T 228.2-2015) were tested. The results are shown in Table 3:

[0109] Table 3

[0110]

[0111] It can be seen from Table 3 that the mechanical properties of the Y-containing alloy with a W content of 20% are equivalent to those of the alloy with a W content of 26% without Y, while the mechanical properties of the Y-containing alloy with a W content of 26% are much better than those without Y.

[0112] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A Y-containing nickel-based alloy with a high temperature stable NbC precipitation phase for molten salt reactor, characterized in that: The following raw materials are included in the following mass percentages: C: 0.02~0.08%, Al: 0~0.5%, Fe: 0~0.5%, Ti: 0~0.3%, Cr: 5.0~7.0%, W: 19~28%, Zr: 0~0.1%, Si: <0.5%, Mn: <0.8%, Nb: 2.0~4.5%, Y: 0.02~0.1%, S<10ppm, P<10ppm, N<10ppm, B<10ppm, the balance is Ni.

2. The Y-containing nickel-based alloy with a high temperature stable NbC precipitation phase for molten salt reactor according to claim 1, characterized in that: The alloy is composed of the following raw materials in percentage by mass: C: 0.02~0.08%, Al: 0~0.3%, Fe: 0~0.3%, Ti: 0~0.3%, Cr: 5.8~7.0%, W: 19~26%, Zr: 0~0.1%, Si: <0.5%, Mn: <0.8%, Nb: 2.0~4.5%, Y: 0.02~0.1%, S<10ppm, P<10ppm, N<10ppm, B<10ppm, the balance is Ni.

3. The method for preparing a Y-containing nickel-based alloy with a high temperature stable NbC precipitation phase for a molten salt reactor according to any one of claims 1 or 2, characterized in that: The following steps are involved: (1) Casting: Using vacuum induction furnace for casting to obtain alloy ingots that meet the element ratio requirements; (2) homogenization treatment: homogenizing the alloy ingot at 1100° C.-1250° C. for 2-30 hours; (3) Forging: The alloy ingot after homogenization treatment is heated to 1100°C-1250°C for forging, and then cooled to room temperature to obtain a slab; (4) Hot rolling: the slab is heated to 1100°C-1250°C, kept at this temperature for 0.5-5h for hot rolling, and cooled to room temperature to obtain a hot-rolled plate; (5) Solution aging treatment: The hot-rolled plate is heated to 1100° C.-1300° C., kept at this temperature, and cooled to room temperature to obtain a Y-containing nickel-based alloy with a NbC precipitation phase having a high temperature stability for the molten salt reactor.

4. The method for preparing the Y-containing nickel-based alloy with a high temperature stable NbC precipitation phase for molten salt reactor according to claim 3, characterized in that: The specific method of vacuum induction furnace casting in step (1) is: The alloy raw materials are prepared according to the element ratio, and then added into a vacuum induction furnace for smelting to obtain alloy liquid, which is then cast to obtain alloy ingots.

5. The method for preparing the Y-containing nickel-based alloy with a high temperature stable NbC precipitation phase for molten salt reactor according to claim 4, characterized in that: The smelting temperature is 1500° C.-1550° C.; the smelting time is 1 h-2 h; and the smelting vacuum degree is 10 Pa-30 Pa.

6. The method for preparing the Y-containing nickel-based alloy with a high temperature stable NbC precipitation phase for molten salt reactor according to claim 3, characterized in that: The forging in step (3) is to forge the alloy ingot to a thickness of 30 to 50 mm; The cooling method in step (3) is air cooling or water cooling.

7. The method for preparing the Y-containing nickel-based alloy with a high temperature stable NbC precipitation phase for molten salt reactor according to claim 3, characterized in that: The hot rolling in step (4) is performed 5 to 10 times, and the deformation in each time is not less than 20%.

8. The method for preparing the Y-containing nickel-based alloy with a high temperature stable NbC precipitation phase for molten salt reactor according to claim 3, characterized in that: The thickness of the hot-rolled plate in step (4) is 7 mm to 13 mm; The cooling method in step (4) is air cooling or water cooling.

9. The method for preparing the Y-containing nickel-based alloy with a high temperature stable NbC precipitation phase for molten salt reactor according to claim 3, characterized in that: The insulation time in step (5) is 10 min to 60 min.

10. The method for preparing the Y-containing nickel-based alloy with a high temperature stable NbC precipitation phase for molten salt reactor according to claim 3, characterized in that: The cooling method in step (5) is air cooling or water cooling.

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