In-situ synthesized GdB2C2 / Al composite material, preparation method and application thereof

Abstract

The application belongs to the technical field of neutron shielding materials, and relates to an in-situ self-grown GdB2C2 / Al composite material and a preparation method and application thereof. The application discloses a preparation method of an in-situ self-grown GdB2C2 / Al composite material, which comprises the following steps: S1, mixing B4C powder and graphite powder to obtain mixed powder, and coating the mixed powder with aluminum foil to prepare a preform; S2, melting pure aluminum to obtain a metal melt; the temperature is increased to 900-1300 DEG C, an aluminum-gadolinium alloy is added to react, and the preform in S1 is added to react to obtain a reaction melt; S3, adding a refining agent to the reaction melt to stir; then, removing the slag on the surface of the reaction melt, and casting into a mold to form a GdB2C2 / Al composite material. The GdB2C2 / Al composite material is generated by in-situ reaction, so that the neutron absorption efficiency is higher.

Description

Technical Field

[0001] This invention belongs to the field of neutron shielding materials technology, and relates to an in-situ self-generated GdB2C2 / Al composite material, its preparation method and application. Background Technology

[0002] Compared to traditional energy sources, nuclear energy is considered an ideal next-generation energy source due to its safety, efficiency, and environmental friendliness. However, with the use of nuclear fuel, the nuclear reaction process generates a large number of strong radioactive neutrons and gamma rays, making the high-density storage and subsequent processing of spent fuel a critical challenge. To address this issue, developing efficient, lightweight, and high-performance neutron shielding materials for spent fuel storage is fundamental work. These materials need to possess high neutron absorption capacity and a good strength-ductility match. Neutron absorption efficiency is primarily determined by the neutron-absorbing elements and their content in the material. Naturally occurring boron (B) and gypsum (Gd) are ideal neutron-absorbing materials due to their large neutron absorption cross-sections; while aluminum (Al), as one of the most widely used metallic materials in current industry, exhibits excellent strength-ductility matching.

[0003] Traditional aluminum-based neutron shielding materials mainly consist of B4C / Al composites. However, a B4C content of over 30% is required to achieve good neutron absorption, which significantly reduces the composite's ductility and toughness. Replacing B4C with GdB2C2 particles, which have a higher neutron absorption cross-section, would greatly improve the material's overall performance. Currently, the preparation of B4C / Al composites primarily relies on powder metallurgy, but this method is not only inefficient but also costly. Therefore, developing a technology for efficiently preparing Al-based composites containing GdB2C2 particles is of great significance for improving the performance of neutron absorbing materials. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems in the existing technology by proposing an in-situ self-generated GdB2C2 / Al composite material, its preparation method, and its application.

[0005] One objective of this invention is achieved through the following technical solution:

[0006] A method for preparing an in-situ self-generated GdB2C2 / Al composite material, comprising:

[0007] S1. Mix B4C powder and graphite powder in a mass ratio of 1:(0.36~1.02) to obtain a mixed powder, and then wrap the mixed powder with aluminum foil to form a preform.

[0008] S2. Pure aluminum is smelted and completely melted to obtain a molten metal; the temperature is raised to 900~1300℃ and aluminum-gadolinium alloy is added to react, and then the preformed block in S1 is added to react to obtain a reactive melt;

[0009] S3. Add the refining agent to the reaction melt and stir; then remove the slag from the surface of the reaction melt and cast it into a mold to obtain the GdB2C2 / Al composite material.

[0010] Preferably, in step S1, the mass ratio of B4C powder to graphite powder is 1:(0.55~0.75).

[0011] In a further preferred embodiment, in step S1, the mass ratio of B4C powder to graphite powder is 1:0.65.

[0012] Preferably, the average particle size of the B4C powder is 0.1~5 μm, and the average particle size of the graphite powder is 100~1000 nm.

[0013] Preferably, in step S1, the mixed powder is wrapped in aluminum foil and then pressed into preforms using a hydraulic press.

[0014] Further optimization is to use a hydraulic press pressure of 5~10 MPa.

[0015] Preferably, in step S2, the molar ratio of gadolinium, boron and carbon in the reaction melt is 1:(1~3):(1~3).

[0016] Further optimization yields a molar ratio of gadolinium, boron, and carbon in the reaction melt of 1:2:2.

[0017] Preferably, in step S2, the mass percentage of gadolinium in the reaction melt is 0.1~4wt%.

[0018] Preferably, in step S2, the pure aluminum is pure aluminum ingot, and the content of impurity elements in the pure aluminum ingot is 0.1~0.4wt% by mass percentage, with the remainder being Al; the impurity elements include one or more of Si, Fe, and Cu.

[0019] Preferably, in step S2, pure aluminum is smelted at 700~800℃.

[0020] Further optimization involves smelting pure aluminum at 730~760℃.

[0021] Preferably, in step S2, the amount of aluminum-gadolinium alloy added is 0.1 to 58.0 wt% of the mass of pure aluminum.

[0022] Further optimization involves adding an aluminum-gadolinium alloy at a rate of 5 to 30.0 wt% of the mass of pure aluminum.

[0023] Preferably, in step S2, the content of Gd in the aluminum-gadolinium alloy is 1.0~30.0 wt% by mass, and the remainder is Al.

[0024] In a further preferred embodiment, in step S2, the content of Gd in the aluminum-gadolinium alloy is 10.0~30.0 wt% by mass, with the remainder being Al.

[0025] Preferably, in step S2, the amount of preform added is 0.1 to 20.0 wt% of the mass of pure aluminum.

[0026] Further optimization involves adding precast blocks at a rate of 0.5 to 5.0 wt% of the mass of pure aluminum.

[0027] Preferably, in step S2, pure aluminum is smelted and completely melted to obtain a molten metal; after heating to 900~1300℃, aluminum-gadolinium alloy is added to the molten metal until it is completely melted to obtain a first reaction melt, and then a preform is added and reacted for 15~150 minutes to obtain a second reaction melt.

[0028] Further preferred, in step S2, pure aluminum is smelted and completely melted to obtain a molten metal; after heating to 900~1300℃, aluminum-gadolinium alloy is added to the molten metal until it is completely melted to obtain a first reaction melt; then the preform is placed in a graphite bell jar, and the graphite bell jar is placed 10~100mm below the surface of the first reaction melt and stirred for 15~150min; throughout the reaction process, every 10~20min, the mixture is stirred with a graphite stirring rod at a speed of 60~120r / min for 1~5min to obtain a second reaction melt.

[0029] Preferably, in step S3, the amount of refining agent added is 0.1 to 0.5 wt% of the mass of the reaction melt.

[0030] Further optimization involves adding a refining agent at a rate of 0.1 to 0.2 wt% of the mass of the reaction melt.

[0031] Preferably, in step S3, the refining agent is placed in a graphite bell jar, and then the graphite bell jar is placed 10-100 mm below the surface of the reaction melt and stirred for 5-30 minutes, and then allowed to stand at 900-1300℃ for 1-30 minutes.

[0032] Preferably, in step S3, the casting mold is made of steel or graphite.

[0033] Preferably, in step S3, the in-situ self-generated GdB2C2 / Al composite material is an aluminum-based composite material containing GdB2C2 particles, and the mass percentage of GdB2C2 is 0.1~15wt%.

[0034] Preferably, the preparation method of the in-situ self-generated GdB2C2 / Al composite material further includes post-processing, which includes: extrusion molding and / or rolling deformation;

[0035] The extrusion ratio used in the extrusion molding process is greater than 10:1;

[0036] The deformation during rolling is greater than 30%.

[0037] Further preferably, the in-situ self-generated GdB2C2 / Al composite material undergoes post-processing, which includes: sequential extrusion molding and rolling deformation.

[0038] More preferably, the in-situ self-generated GdB2C2 / Al composite material is extruded into an extruded sheet at an extrusion ratio of (16~25):1; the extruded sheet is then rolled and deformed, with a deformation amount of 40~60%.

[0039] The second objective of this invention is achieved through the following technical solution:

[0040] An in-situ self-generated GdB2C2 / Al composite material was prepared by the method described above.

[0041] Preferably, the in-situ self-generated GdB2C2 / Al composite material is an aluminum-based composite material containing GdB2C2 particles.

[0042] Further preferably, the mass percentage of GdB2C2 is 0.1~15wt%.

[0043] Preferably, the neutron shielding performance of the GdB2C2 / Al composite material is ≥99.5%.

[0044] The third objective of this invention is achieved through the following technical solution:

[0045] Application of the above-mentioned in-situ self-generated GdB2C2 / Al composite material in neutron shielding materials and the nuclear industry.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] 1. This invention generates a GdB2C2 / Al composite material by in-situ reaction of Al-Gd alloy, B4C powder, and graphite powder in aluminum melt, which contains the neutron-absorbing nuclide GdB2C2 with a higher neutron absorption cross section, thereby having a higher neutron absorption efficiency;

[0048] 2. In the in-situ self-generated GdB2C2 / Al composite material of the present invention, the GdB2C2 ceramic phase has a layered structure. As a shielding material, it can store helium between layers and capture the defect aggregation caused by neutron irradiation, thereby improving the radiation resistance of the shielding material.

[0049] 3. The preparation method of the in-situ self-generated GdB2C2 / Al composite material of the present invention is simple, the process is convenient, the process is highly reliable, which greatly improves the production efficiency and provides a feasible solution for mass production.

[0050] 4. The smelting and casting process of the in-situ self-generated GdB2C2 / Al composite material preparation method of the present invention can be seamlessly connected with the extrusion and / or rolling processes, so as to realize the rapid preparation of profiles such as pipes and plates, while further optimizing the microstructure and properties of the material. Attached Figure Description

[0051] Figure 1 This shows the distribution of GdB2C2 in the Al matrix in the in-situ self-generated GdB2C2 / Al composite material of Example 1 of the present invention. Detailed Implementation

[0052] The technical solution of the present invention will be further described and illustrated below through specific embodiments. It should be understood that the specific embodiments described herein are only for the purpose of helping to understand the present invention and are not intended to limit the present invention.

[0053] Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used in the art, and the methods used in the embodiments are all conventional methods in the art.

[0054] In this paper, the preparation method of in-situ self-generated GdB2C2 / Al composite material includes:

[0055] S1. Mix B4C powder and graphite powder in a mass ratio of 1:0.65 to obtain a mixed powder, and then wrap the mixed powder with aluminum foil to form a preform.

[0056] S2. Pure aluminum is smelted at 700~800℃ until it is completely melted to obtain a molten metal; the temperature is raised to 900~1300℃, aluminum-gadolinium alloy is added to react, and then a pre-formed block is added to react to obtain a reactive melt;

[0057] The amount of aluminum-gadolinium alloy added is 0.1~58.0 wt% of the mass of pure aluminum; the content of Gd in the aluminum-gadolinium alloy is 10.0~30.0 wt%, and the remainder is Al;

[0058] The amount of precast blocks added is 0.1~20.0 wt% of the mass of pure aluminum;

[0059] The molar ratio of gadolinium, boron, and carbon in the reaction melt is 1:2:2;

[0060] S3. Add the refining agent to the reaction melt and stir; then remove the slag from the surface of the reaction melt and cast it into a mold to obtain the GdB2C2 / Al composite material.

[0061] In this article, the raw materials include:

[0062] Pure aluminum: Hebei Luohong Technology Co., Ltd., pure aluminum ingots with a purity of 99.8%, and the total weight ratio of other impurity elements such as Si, Fe, and Cu does not exceed 0.2%;

[0063] Al-Gd alloys: Hebei Luohong Technology Co., Ltd., Al-30Gd, Al-15Gd, Al-10Gd, where Al-30Gd indicates that the gadolinium content in the Al-Gd alloy is 30wt% by mass.

[0064] B4C powder: Zhongbo Technology (Weihai) Co., Ltd., ultrafine B4C powder, average particle size 1 μm;

[0065] Graphite powder: Qinhuangdao Yinuo High-tech Materials Development Co., Ltd., 99% pure graphite powder, average particle size 500 nm;

[0066] Refining agent: Shenzhen Ruibao Industrial Co., Ltd., RJ-1 type refining agent.

[0067] In this paper, the mass of the aluminum foil in the pre-compressed block is small and negligible.

[0068] In this paper, the test methods include: yield strength, tensile strength, and elongation were tested according to ASTM E8 / E8M-15a standard; neutron shielding efficiency was tested under the conditions of neutron energy of 0.025 eV and material thickness of 30 mm.

[0069] Example 1

[0070] The preparation method of the in-situ self-generated GdB2C2 / Al composite material in this embodiment includes the following steps:

[0071] S1. Mix 4.22g of B4C powder and 2.74g of graphite powder to obtain a mixed powder. After wrapping the mixed powder with aluminum foil, press it into a preform using a hydraulic press.

[0072] S2. 300g of pure aluminum was melted at 740℃. After the molten metal was completely melted, the temperature was raised to 1200℃, and 79.97g of Al-30Gd alloy was added to form the first reaction melt. Then, the preform was placed 50mm below the surface of the molten aluminum through a bell jar and allowed to react for 60min to obtain the second reaction melt. Throughout the process, the mixture was stirred for 1min at a speed of 60r / min every 15min. The molar ratio of gadolinium, boron and carbon in the second reaction melt was 1:2:2.

[0073] S3. Place 0.5g of refining agent into a graphite bell jar, then place the graphite bell jar 50mm below the surface of the second reaction melt and stir for 5 minutes. Let it stand for 5 minutes at a temperature of 1200℃. Then use a slag removal spoon to remove the slag from the surface of the melt and cast it into a steel or graphite mold to obtain the in-situ GdB2C2 / Al composite material.

[0074] In this embodiment, the mass of GdB2C2 in the in-situ self-generated GdB2C2 / Al composite material is 8 wt% of the total mass of the composite material.

[0075] according to Figure 1 As can be seen, in this embodiment, GdB2C2 particles were generated in situ in the aluminum-based material, and GdB2C2 / Al composite material was successfully prepared.

[0076] The properties of the in-situ self-generated GdB2C2 / Al composite material in this embodiment are shown in Table 1.

[0077] Example 2

[0078] The preparation method of the in-situ self-generated GdB2C2 / Al composite material in this embodiment includes:

[0079] S1. Proceed according to step S1 of Example 1, except that 1.34g of B4C powder and 0.87g of graphite powder are mixed to obtain a mixed powder and then made into a preform.

[0080] S2. Proceed according to step S2 of Example 1, except that the amount of Al-30Gd alloy added is 25.38g; the molar ratio of gadolinium, boron and carbon in the second reaction melt is 1:2:2.

[0081] S3. Proceed according to step S3 of Example 1.

[0082] In this embodiment, the mass of GdB2C2 in the in-situ self-generated GdB2C2 / Al composite material is 3wt% of the total mass of the composite material.

[0083] The properties of the in-situ self-generated GdB2C2 / Al composite material in this embodiment are shown in Table 1.

[0084] Example 3

[0085] The preparation method of the in-situ self-generated GdB2C2 / Al composite material in this embodiment includes:

[0086] S1. Proceed according to step S1 of Example 1, except that 3.62g of B4C powder and 2.36g of graphite powder are mixed to obtain a mixed powder and then made into a preform.

[0087] S2. Proceed according to step S2 of Example 1, except that the aluminum-gadolinium alloy is an Al-15Gd alloy and the amount added is 137.48g; the molar ratio of gadolinium, boron and carbon in the second reaction melt is 1:2:2.

[0088] S3. Proceed according to step S3 of Example 1.

[0089] In this embodiment, the mass of GdB2C2 in the in-situ self-generated GdB2C2 / Al composite material is 6 wt% of the total mass of the composite material.

[0090] The properties of the in-situ self-generated GdB2C2 / Al composite material in this embodiment are shown in Table 1.

[0091] Example 4

[0092] The preparation method of the in-situ self-generated GdB2C2 / Al composite material in this embodiment includes:

[0093] S1. Proceed according to step S1 of Example 1, except that 0.44g of B4C powder and 0.29g of graphite powder are mixed to obtain a mixed powder and then made into a preform.

[0094] S2. Proceed according to step S2 of Example 1, except that the aluminum-gadolinium alloy is an Al-10Gd alloy and the amount added is 25.27g; the molar ratio of gadolinium, boron and carbon in the second reaction melt is 1:2:2.

[0095] S3. Proceed according to step S3 of Example 1.

[0096] In this embodiment, the mass of GdB2C2 in the in-situ self-generated GdB2C2 / Al composite material is 1 wt% of the total mass of the composite material.

[0097] The properties of the in-situ self-generated GdB2C2 / Al composite material in this embodiment are shown in Table 1.

[0098] Example 5

[0099] The preparation method of the in-situ self-generated GdB2C2 / Al composite material in this embodiment includes the following steps:

[0100] S1. Proceed according to step S1 of Example 1, except that 2.39g of B4C powder and 1.56g of graphite powder are mixed to obtain a mixed powder and then made into a preform.

[0101] S2. Proceed according to step S2 of Example 1, except that the amount of Al-30Gd alloy added is 45.33g; the molar ratio of gadolinium, boron and carbon in the second reaction melt is 1:2:2.

[0102] S3. Proceed according to step S3 of Example 1.

[0103] In this embodiment, the mass of GdB2C2 in the in-situ self-generated GdB2C2 / Al composite material is 5.7 wt% of the total mass of the composite material.

[0104] The properties of the in-situ self-generated GdB2C2 / Al composite material in this embodiment are shown in Table 1.

[0105] Example 6

[0106] The preparation method of the in-situ self-generated GdB2C2 / Al composite material in this embodiment includes the following steps:

[0107] S1. Proceed according to step S1 of Example 1;

[0108] S2. 300g of pure aluminum is melted at 740℃. After the molten metal is completely melted, the temperature is raised to 1000℃, and 79.97g of Al-30Gd alloy is added to form the first reaction melt. Then, the preform is placed 50mm below the surface of the molten aluminum through a bell jar and allowed to react for 60min to obtain the second reaction melt. Throughout the process, the mixture is stirred for 1min at a speed of 60r / min every 15min.

[0109] S3. Proceed according to step S3 of Example 1.

[0110] In this embodiment, the mass of GdB2C2 in the in-situ self-generated GdB2C2 / Al composite material is 8 wt% of the total mass of the composite material.

[0111] The properties of the in-situ self-generated GdB2C2 / Al composite material in this embodiment are shown in Table 1.

[0112] Example 7

[0113] The preparation method of the in-situ self-generated GdB2C2 / Al composite material in this embodiment includes the following steps:

[0114] The in-situ self-generated GdB2C2 / Al composite material in Example 1 was post-processed: it was extruded into sheets using a vertical hydraulic press in Rugao, Nantong, with an extrusion ratio of 16:1.

[0115] The properties of the in-situ self-generated GdB2C2 / Al composite material plate in this embodiment are shown in Table 1.

[0116] Example 8

[0117] The preparation method of the in-situ self-generated GdB2C2 / Al composite material in this embodiment includes the following steps:

[0118] The in-situ self-generated GdB2C2 / Al composite material in Example 1 was post-processed: it was extruded into sheets using a vertical hydraulic press in Rugao, Nantong, with an extrusion ratio of 25:1.

[0119] The properties of the in-situ self-generated GdB2C2 / Al composite material plate in this embodiment are shown in Table 1.

[0120] Example 9

[0121] The preparation method of the in-situ self-generated GdB2C2 / Al composite material in this embodiment includes the following steps:

[0122] The in-situ self-generated GdB2C2 / Al composite material in Example 1 was post-processed: it was hot rolled into a sheet using a Wuxi Guancheng twin-roll mill in multiple passes, and the final deformation of the sheet after multiple passes was 40%.

[0123] The properties of the in-situ self-generated GdB2C2 / Al composite material plate in this embodiment are shown in Table 1.

[0124] Example 10

[0125] The preparation method of the in-situ self-generated GdB2C2 / Al composite material in this embodiment includes the following steps:

[0126] The in-situ self-generated GdB2C2 / Al composite material in Example 1 was post-processed: it was extruded into sheet using a vertical hydraulic press in Rugao, Nantong, with an extrusion ratio of 16:1; and then hot-rolled into sheet using a twin-roll mill in Guancheng, Wuxi, with a final deformation of 40%.

[0127] The properties of the in-situ self-generated GdB2C2 / Al composite material plate in this embodiment are shown in Table 1.

[0128] Example 11

[0129] The preparation method of the in-situ self-generated GdB2C2 / Al composite material in this embodiment includes:

[0130] The in-situ self-generated GdB2C2 / Al composite material in Example 1 was post-processed: it was extruded into sheet using a vertical hydraulic press in Rugao, Nantong, with an extrusion ratio of 25:1; and then hot-rolled into sheet using a twin-roll mill in Guancheng, Wuxi, with a final deformation of 40%.

[0131] The properties of the in-situ self-generated GdB2C2 / Al composite material plate in this embodiment are shown in Table 1.

[0132] Comparative Example 1

[0133] The preparation method of the aluminum-based composite material in this comparative example includes:

[0134] S1. Mix 4.22g of B4C powder and 2.74g of graphite powder to obtain a mixed powder, without making a pre-compressed block;

[0135] S2. Melt 300g of pure aluminum at 740℃. After the molten metal is completely melted, raise the temperature to 1200℃ and add 79.97g of Al-30Gd alloy to form the first reaction melt. Then add the mixed powder from S1 and react fully for 60min to obtain the second reaction melt. Throughout the process, stir with a graphite stirring rod at a speed of 60r / min for 1min every 15min.

[0136] S3. Proceed according to step S3 of Example 1.

[0137] The properties of the aluminum-based gadolinium boron carbon composite material in this comparative example are shown in Table 1.

[0138] Comparative Example 2

[0139] The preparation method of the aluminum-based composite material in this comparative example includes:

[0140] S1. Follow the steps of Example 1, except that 4.22g of B4C powder and 5g of graphite powder are mixed to obtain a mixed powder and then made into a preform.

[0141] S2. Proceed according to step S2 of Example 1;

[0142] S3. Proceed according to step S3 of Example 1.

[0143] The properties of the aluminum-based gadolinium boron carbon composite material in this comparative example are shown in Table 1.

[0144] Comparative Example 3

[0145] The preparation method of the aluminum-based composite material in this comparative example includes:

[0146] S1. Follow step S1 of Example 1, except that graphite powder is not added;

[0147] S2. Proceed according to step S2 of Example 1;

[0148] S3. Proceed according to step S3 of Example 1.

[0149] The properties of the aluminum-based gadolinium boron carbon composite material in this comparative example are shown in Table 1.

[0150] Comparative Example 4

[0151] The preparation method of the aluminum-based composite material in this comparative example includes:

[0152] S1. Proceed according to step S1 of Example 1;

[0153] S2. Proceed according to step S2 of Example 1; the difference is that the amount of Al-50Gd alloy added is 200g; the molar ratio of gadolinium, boron and carbon in the second reaction melt is 2.1:1:1;

[0154] S3. Proceed according to step S3 of Example 1.

[0155] The properties of the aluminum-based gadolinium boron carbon composite material in this comparative example are shown in Table 1.

[0156] Comparative Example 5

[0157] The preparation method of the aluminum-based composite material in this comparative example includes:

[0158] S1. Proceed according to step S1 of Example 1;

[0159] S2. Melt 300g of pure aluminum at 740℃. After the molten metal is completely melted, without raising the temperature, add 79.97g of Al-30Gd alloy to form the first reaction melt. Then, place the preformed block into the molten aluminum at 50mm below the surface through a bell jar and allow it to react fully for 60min to obtain the second reaction melt. Throughout the process, stir with a graphite stirring rod at a speed of 60r / min for 1min every 15min.

[0160] S3. Proceed according to step S3 of Example 1.

[0161] The properties of the aluminum-based gadolinium boron carbon composite material in this comparative example are shown in Table 1.

[0162] Comparative Example 6

[0163] The preparation method of the aluminum-based composite material in this comparative example includes:

[0164] S1. Proceed according to step S1 of Example 1;

[0165] S2. 300g of pure aluminum is melted at 740℃. After the molten metal is completely melted, the temperature is raised to 1500℃, and 79.97g of Al-30Gd alloy is added to form the first reaction melt. Then, the preform is placed 50mm below the surface of the molten aluminum through a bell jar and allowed to react for 60min to obtain the second reaction melt. Throughout the process, the mixture is stirred for 1min at a speed of 60r / min every 15min.

[0166] S3. Proceed according to step S3 of Example 1.

[0167] The properties of the aluminum-based gadolinium boron carbon composite material in this comparative example are shown in Table 1.

[0168]

[0169] As shown in the table above, the GdB2C2 / Al composite material prepared by the in-situ reaction described in this invention has both excellent mechanical properties and neutron shielding properties; and further heat deformation post-treatment can further improve the performance of the composite material.

[0170] In Comparative Example 1, because the B4C powder and C powder were not coated with aluminum foil and pre-pressed into preforms, most of the low-density powder floated on the surface of the molten aluminum. This made it difficult for them to fully react with the Gd element dissolved in the molten aluminum, and they also suffered severe burn-off, resulting in a significant decrease in the mechanical properties and neutron shielding performance of the composite material. In Comparative Example 2, the amount of graphite powder added was too high. Excessive free carbon reacted with aluminum to form the needle-like brittle phase Al4C3, inducing stress concentration, microcracks, and pores, thereby weakening the mechanical properties and neutron shielding performance of the composite material. Yes; In Comparative Example 3, no graphite powder was added, resulting in insufficient carbon source in the system, which led to a significant reduction in the amount of GdB2C2 phase generated and a decrease in neutron shielding performance; at the same time, the excess boron element existed in the form of free B4C particles and brittle AlB2 phase, which destroyed the uniformity of the structure and further degraded the material properties; in Comparative Example 4, after increasing the Gd content, the excess Gd in the system formed brittle intermetallic compounds (Al2Gd, Al3Gd) with aluminum, which weakened the interfacial bonding and matrix toughness, while the improvement in neutron absorption performance was limited;

[0171] In Comparative Example 5, the melt temperature was increased to 1500℃, which caused gadolinium to change from a dissolved state to a free state and suffer severe burn-off. At the same time, the activity of carbon was significantly increased, and brittle Al4C3 and AlB2 phases were easily formed, which inhibited the formation of GdB2C2, thus causing a significant decrease in the mechanical properties and neutron shielding performance of the composite material.

[0172] In Comparative Example 6, the melt temperature was not increased, resulting in insufficient reaction conditions for the aluminum melt. The dissolution of Gd and its reaction with B4C and C were limited, the formation of the GdB2C2 phase was incomplete and the content was low. The residual powder was removed with the slag, which ultimately significantly reduced the mechanical properties and neutron shielding performance of the composite material.

[0173] In summary, appropriate in-situ reaction temperature, precise control of the Gd, B, and C element ratios, and reasonable preform design are key to achieving high performance in GdB2C2 / Al composite materials.

[0174] All aspects, embodiments, and features of this invention should be considered illustrative in all respects and not limiting of the invention; the scope of the invention is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0175] In the preparation method of this invention, the order of the steps is not limited to the listed order. For those skilled in the art, variations in the order of the steps without creative effort are also within the scope of protection of this invention. Furthermore, two or more steps or actions can be performed simultaneously.

[0176] Finally, it should be noted that the specific embodiments described herein are merely illustrative examples of the invention and are not intended to limit the implementation of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them; it is neither necessary nor possible to exemplify all embodiments here. However, these obvious variations or modifications derived from the essential spirit of the invention still fall within the scope of protection of the invention, and interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A method for preparing an in-situ self-generated GdB2C2 / Al composite material, characterized in that, The preparation method includes the following steps: S1. Mix B4C powder and graphite powder in a mass ratio of 1:(0.36~1.02) to obtain a mixed powder, and then wrap the mixed powder with aluminum foil to form a preform. S2. Pure aluminum is smelted and completely melted to obtain a molten metal; the temperature is raised to 900~1300℃ and aluminum-gadolinium alloy is added to react, and then the preformed block in S1 is added to react to obtain a reactive melt; The molar ratio of gadolinium, boron, and carbon in the reaction melt is 1:(1~3):(1~3); S3. Add the refining agent to the reaction melt and stir; then remove the slag from the surface of the reaction melt and cast it into a mold to obtain the GdB2C2 / Al composite material.

2. The method for preparing in-situ self-generated GdB2C2 / Al composite material according to claim 1, characterized in that, In step S1, the mixed powder is wrapped in aluminum foil and then pressed into preforms using a hydraulic press.

3. The method for preparing in-situ self-generated GdB2C2 / Al composite material according to claim 1, characterized in that, In step S2, pure aluminum is smelted and completely melted to obtain a molten metal. After heating to 900~1300℃, aluminum-gadolinium alloy is added to the molten metal until it is completely melted to obtain a first reaction melt. Then, a preform is added and reacted for 15~150 minutes to obtain a second reaction melt.

4. The method for preparing the in-situ self-generated GdB2C2 / Al composite material according to claim 1, characterized in that, In step S2, the amount of aluminum-gadolinium alloy added is 0.1 to 58.0 wt% of the mass of pure aluminum.

5. The method for preparing in-situ self-generated GdB2C2 / Al composite material according to claim 1, characterized in that, In step S2, the amount of preform added is 0.1 to 20.0 wt% of the mass of pure aluminum.

6. The method for preparing the in-situ self-generated GdB2C2 / Al composite material according to claim 1, characterized in that, In step S3, the amount of refining agent added is 0.1~0.5 wt% of the mass of the reaction melt.

7. The method for preparing in-situ self-generated GdB2C2 / Al composite material according to claim 1, characterized in that, The preparation method of the in-situ self-generated GdB2C2 / Al composite material further includes post-processing, which includes: extrusion molding and / or rolling deformation; The extrusion ratio during extrusion molding is greater than 10:1; The deformation during rolling is greater than 30%.

8. An in-situ self-generated GdB2C2 / Al composite material, characterized in that, It is prepared by the method for preparing in-situ self-generated GdB2C2 / Al composite material as described in any one of claims 1 to 7; The in-situ self-generated GdB2C2 / Al composite material is an aluminum-based composite material containing GdB2C2 particles.

9. The in-situ self-generated GdB2C2 / Al composite material according to claim 8, characterized in that, The mass percentage of GdB2C2 in the in-situ self-generated GdB2C2 / Al composite material is 0.1~15wt%.

10. The application of an in-situ self-generated GdB2C2 / Al composite material in neutron shielding materials and the nuclear industry, characterized in that, The in-situ self-generated GdB2C2 / Al composite material is prepared by the preparation method of the in-situ self-generated GdB2C2 / Al composite material as described in any one of claims 1 to 7, or is the in-situ self-generated GdB2C2 / Al composite material as described in any one of claims 8 to 9.

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