Lanthanum-manganese alloy material with high density and low oxygen content, preparation method and film

Abstract

The invention provides a high-density low-oxygen-content lanthanum-manganese alloy material, a preparation method and a film, and belongs to the technical field of functional materials. The high-density and low-oxygen-content lanthanum-manganese alloy material comprises lanthanum hydride and manganese, and the lanthanum-manganese alloy material is obtained at least based on prefabricated densification sintering and densification sintering of a mixture of lanthanum hydride and manganese. The lanthanum-manganese alloy material with high density and low oxygen content according to the embodiment of the invention has high density and low oxygen content.

Description

Technical Field

[0001] This invention relates to the field of functional materials technology, and in particular to a high-density, low-oxygen-content lanthanum-manganese alloy material, its preparation method, and a thin film. Background Technology

[0002] In the field of advanced functional materials, lanthanum manganese (LaMn) alloy targets are key basic materials for the preparation of high-performance functional thin films, and are widely used in cutting-edge technologies such as spintronic devices, superconducting power systems, controlled nuclear fusion devices, solid oxide fuel cells, and catalytic materials. With the rapid development of information technology and the new energy industry, the market's performance requirements for LaMn-based thin films are constantly increasing, which in turn raises the standards for the quality of targets.

[0003] The preparation of LaMn alloy sputtering targets currently faces three major technical bottlenecks: First, insufficient density. Traditional powder metallurgy processes struggle to achieve complete densification, leaving residual pores and microscopic defects within the target, leading to poor film uniformity and unstable performance during sputtering. Second, difficulty in effectively controlling oxygen content. Lanthanum (La), as a rare earth element, exhibits extremely high chemical reactivity, readily reacting with oxygen during preparation and subsequent processing to generate oxide impurities such as La2O3, severely degrading the electrical and magnetic properties of the film. Third, difficulty in ensuring compositional uniformity. Manganese (Mn) is prone to volatilization during high-temperature sintering or melting, causing the actual composition to deviate from the designed ratio, thus affecting the functional consistency and reliability of the prepared film.

[0004] Currently, although mechanical alloying combined with hot pressing sintering can be used to prepare LaMn alloy targets, it is still difficult to avoid serious oxygen contamination and low density. Traditional melting-casting methods, on the other hand, easily lead to Mn segregation and volatilization, making it difficult to achieve compositional uniformity control. These inherent defects significantly limit the application of LaMn alloy targets in high-end functional devices, especially in the preparation of perovskite-structured LaMn targets. 1-x Sr x When producing high-performance functional thin films such as MnO3 (LSMO), the oxygen content and density of the target material directly determine the key performance indicators of the film, such as magnetoresistance, conductivity, and electrocatalytic activity. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a high-density, low-oxygen-content lanthanum-manganese alloy material, solving the problems of low density and high oxygen content in existing target materials.

[0006] To address the aforementioned problems, the first aspect of this invention provides a high-density, low-oxygen-content lanthanum-manganese alloy material, comprising: the raw materials of the lanthanum-manganese alloy target include lanthanum hydride and manganese, and the lanthanum-manganese alloy material is obtained at least based on a mixture of lanthanum hydride and manganese through pre-densification sintering and densification sintering.

[0007] According to one embodiment of the present invention, the raw material comprises 60%-75% lanthanum hydride and 25%-40% manganese by mass percentage.

[0008] According to one embodiment of the present invention, the lanthanum hydride is introduced in powder form, wherein the lanthanum hydride powder has a purity greater than 99.9% and a particle size D. 50 The particle size is 25~45 μm, and / or the manganese is introduced in powder form, and the purity of the manganese powder is greater than 99.9%, with a particle size D. 50 The size is 15~25 μm.

[0009] According to one embodiment of the present invention, the density of the target material is not less than 98.5% and the oxygen content is not more than 1200 ppm.

[0010] Secondly, the present invention also provides a method for preparing a high-density, low-oxygen-content lanthanum-manganese alloy material, comprising:

[0011] Raw material mixing: Lanthanum hydride and manganese are mixed in a protective atmosphere or vacuum environment to obtain a mixed powder;

[0012] Molding: The mixed powder is pressed into shape to obtain a green body;

[0013] Pre-densification sintering: The green blank is sintered under a controlled atmosphere to decompose and pre-alloy the LaH3, resulting in a pre-densification blank.

[0014] Densification sintering: The pre-densified blank is sintered using hot isostatic pressing or vacuum hot pressing to obtain the lanthanum-manganese alloy material.

[0015] According to one embodiment of the present invention, the raw material comprises 60%-75% lanthanum hydride and 25%-40% manganese by mass percentage.

[0016] According to one embodiment of the present invention, in the step of mixing the raw materials, a low-energy ball milling method is used for mixing. The raw materials and anhydrous ethanol are subjected to low-energy ball milling under vacuum conditions. The ball milling speed is 45~100 r / min and the ball-to-material ratio is (1~3):1.

[0017] According to one embodiment of the present invention, prior to the molding step, the method further includes:

[0018] Granulation: Add a binder to the mixed powder and perform spray granulation, while controlling the oxygen content during the granulation process to be below 3%.

[0019] According to one embodiment of the present invention, the pre-densification sintering is carried out in a nitrogen atmosphere with an oxygen content of less than 1000 ppm. The sintering process includes heating the blank in a stepped manner from 701°C to 1081°C and holding it at that temperature for 12 to 24 hours to allow LaH3 to decompose fully.

[0020] According to one embodiment of the present invention, the densification sintering adopts the hot isostatic pressing process, the sintering temperature is 520~600℃, the pressure is 120~160 MPa, and the pre-made densified blank is covered with Ti plate before sintering.

[0021] According to one embodiment of the present invention, the densification sintering is performed using a vacuum hot pressing process, with a sintering temperature of 560~620℃, a pressure of 35~60 MPa, and a vacuum degree of less than 10 MPa. -2 Pa.

[0022] Thirdly, the present invention also provides a thin film comprising the lanthanum-manganese alloy material described in the first aspect embodiment, or the lanthanum-manganese alloy material prepared by the preparation method of the second aspect embodiment.

[0023] Due to the above technical solution, the present invention has at least the following beneficial effects:

[0024] The high-density, low-oxygen-content lanthanum-manganese alloy material according to embodiments of the present invention uses LaH3 as the La source. When heated, LaH3 decomposes, generating not only highly reactive fresh La atoms but also simultaneously releasing reducing gas H2. This H2 effectively reduces the naturally formed oxide layer on the surface of Mn powder. This eliminates oxygen impurities at the source, thereby achieving a low-oxygen content in the lanthanum-manganese alloy material. Furthermore, the double-sintering process effectively improves the material's density.

[0025] Furthermore, the preparation method of high-density, low-oxygen-content lanthanum-manganese alloy material according to embodiments of the present invention achieves in-situ reduction by optimizing raw materials and proportions, purifying oxygen content, achieving low oxygen content, and improving the forming and sintering process, thus realizing complete densification and ultra-low oxygen content of the target material. Thin films prepared based on this target material possess superior electrical properties, such as resistivity, and magnetic properties, such as magnetoresistance, due to the high purity, density, and accurate composition of the parent material, meeting the requirements of high-end device applications. This provides key material support for the development of spintronic devices, new energy materials, and catalysis. It has particularly broad application prospects in next-generation magnetic memories, solid oxide fuel cells, and environmental pollution control. This technological breakthrough not only fills the gap in the domestic field of high-performance rare earth alloy target material preparation but will also promote the technological upgrading and innovative development of related industrial chains. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating the preparation method of a high-density, low-oxygen-content lanthanum-manganese alloy material according to an embodiment of the present invention.

[0027] Figure 2 This is another flowchart of the preparation method of the high-density, low-oxygen-content lanthanum-manganese alloy material according to an embodiment of the present invention;

[0028] Figure 3 This is an alloy phase diagram of the lanthanum-manganese alloy material according to an embodiment of the present invention. Detailed Implementation

[0029] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] As described in the background above, in existing technologies, alloy materials suffer from several drawbacks. La (La) is highly chemically reactive and easily oxidizes to form La₂O₃, leading to increased oxygen content. Mn (Mn) is also prone to volatilization at high temperatures, causing component segregation. Furthermore, deficiencies in the preparation process result in insufficient material density and internal porosity, affecting film uniformity and performance. This limits the application of LaMn targets in high-end devices.

[0031] Based on the above-mentioned technical problems, the present invention provides a method for preparing a high-density, low-oxygen-content lanthanum-manganese alloy material. Through raw material selection, process optimization and sintering control, the high density and low oxygen content of the target material are achieved.

[0032] The preparation method of the high-density, low-oxygen-content lanthanum-manganese alloy material of the present invention will be described below with reference to specific embodiments.

[0033] refer to Figure 1 , Figure 1 A flowchart illustrating a method for preparing a high-density, low-oxygen-content lanthanum-manganese alloy material according to an embodiment of the present invention is shown.

[0034] like Figure 1 As shown, the preparation methods for high-density, low-oxygen-content lanthanum-manganese alloy materials include S110-S140.

[0035] S110 involves mixing lanthanum hydride and manganese under a protective atmosphere or vacuum to obtain a mixed powder.

[0036] In embodiments of the present invention, LaH3 powder and Mn powder are selected as raw materials. Since LaH3 decomposes at high temperature to produce H2, it can reduce the surface-oxidized Mn powder particles and purify the powder. The sintered material thus has the characteristics of high density, uniform microstructure, fine grains, low oxygen content, and easy processing.

[0037] The chemical reaction equation corresponding to this reaction is as follows:

[0038]

[0039]

[0040]

[0041] In some embodiments, the mass percentage of the raw materials can be 60% to 75% of lanthanum hydride, for example, 63%, 65%, 68%, 70%, or 73%, and the mass percentage of manganese can be 25% to 40%, for example, 28%, 30%, 33%, 35%, or 38%. This ratio range is designed based on the lanthanum-manganese alloy phase diagram to ensure that the final alloy forms the target intermetallic compound, such as LaMn2, rather than a simple mixture, thereby obtaining the desired electrical and magnetic properties. Simultaneously, this ratio ensures sufficient lanthanum hydride decomposition to generate a sufficient concentration of hydrogen gas to reduce all oxides on the surface of the manganese powder, which is a key ratio design for achieving ultra-low oxygen content. If the lanthanum hydride ratio is too low, the reducing atmosphere will be insufficient, and the oxygen content will be difficult to control; if it is too high, the alloy composition will deviate from the design value, affecting performance.

[0042] In some embodiments, the protective gas may be nitrogen.

[0043] S120 is used to press the mixed powder into a shape to obtain a green body.

[0044] In an embodiment of the present invention, the pressing can be performed by cold isostatic pressing, with a pressing pressure between 140-200 MPa and a holding time between 600-900 s. The density of the pressed green body is approximately 56%-62%, providing geometry and initial density for subsequent sintering.

[0045] S130 is used to sinter the green blank under a controlled atmosphere, causing LaH3 to decompose and initially alloy, resulting in a pre-densified blank.

[0046] In embodiments of the present invention, the pre-densification sintering can be carried out in a nitrogen atmosphere, providing a safe reaction environment for the decomposition of LaH3 and the reduction of Mn by H2, and minimizing the risk of oxidation.

[0047] In some embodiments, the N2 flow rate inside the furnace can be controlled between 200 L / min and 600 L / min, the furnace pressure can be between 50 and 200 Pa, and the oxygen content inside the furnace can be <1000 ppm. These parameters ensure the safety of the reaction conditions.

[0048] In one embodiment of the present invention, a stepped heating sintering method can be adopted, wherein the stepped heating method can be divided into four stages: First stage, the heating rate corresponding to 0-120 ℃ is 0.4 ℃ / min - 0.6 ℃ / min, and the holding time is 3-6 h. Second stage, the heating rate corresponding to 120-300 ℃ is 0.1 ℃ / min - 0.3 ℃ / min, and the holding time is 6-12 h. Third stage, the heating rate corresponding to 300-701 ℃ is 0.1 ℃ / min - 0.3 ℃ / min, and the holding time is 6-12 h. Fourth stage, the heating rate corresponding to 701-1081 ℃ is 0.1 ℃ / min - 0.3 ℃ / min, and the holding time is 12-24 h.

[0049] Next, the blank is cooled to room temperature in the furnace. The density of the pre-densified blank produced by the above process is between 75% and 85%, and its pores are interconnected open-cell structures, which prepares it for the subsequent densification process.

[0050] S140 is obtained by sintering a pre-densified blank using hot isostatic pressing or vacuum hot pressing processes to obtain lanthanum-manganese alloy materials.

[0051] Hot isostatic pressing (HIP) is a densification sintering process that can significantly improve the mechanical properties and reliability of materials by closing the pores and homogenizing the microstructure under high temperature and isotropic high pressure gas, such as inert gas.

[0052] In some embodiments, during the hot isostatic pressing process, a Ti plate can be used to clad the preform. The reason for using titanium (Ti) for cladding is that Ti is an oxygen-loving metal, which can absorb oxygen from the product during sintering, thereby reducing the oxygen content of the product.

[0053] In addition, the sintering temperature in the hot isostatic pressing (HIP) process can be controlled between 520-600 ℃, and the sintering pressure can be controlled between 120-160 MPa. The blank after HIP can achieve a density of over 99%, with equiaxed grains, a grain size ≤100μm, and an oxygen content ≤1200 ppm.

[0054] In another embodiment of the present invention, densification sintering can also be performed by vacuum hot pressing on the pre-densified blank. This vacuum hot pressing process may include the following steps: placing the pre-made blank into a graphite mold and setting the sintering temperature, which can be controlled within the range of 560-620 °C; the sintering pressure can be 35-60 MPa; and the vacuum degree <10⁻² Pa. The blank after vacuum hot pressing can achieve a density of over 98.5%, with equiaxed grains, a grain size ≤120 μm, and an oxygen content ≤1000 ppm.

[0055] Finally, the blank sintered by HIP or vacuum hot pressing is transformed into a high-density, low-oxygen-content lanthanum-manganese alloy material, which can be further processed into the required product size by various machines.

[0056] In some embodiments of the present invention, in order to prepare a more ideal high-density, low-oxygen-content lanthanum-manganese alloy material, the above steps can be further improved, as described below. Figure 2 To explain.

[0057] refer to Figure 2 , Figure 2 Another flowchart of the preparation method of the high-density, low-oxygen-content lanthanum-manganese alloy material according to an embodiment of the present invention is shown.

[0058] like Figure 2 As shown, the flowchart includes S210-S260.

[0059] S210: Weigh lanthanum hydride powder, manganese powder, and main and auxiliary materials according to the specified proportions. This step corresponds to... Figure 1 S110 in the above. The proportion of raw materials can be obtained according to the proportion described in S110 above.

[0060] Among them, the main and auxiliary materials can be raw materials for ball milling, such as ball milling media and grinding balls.

[0061] S220, ball milling and granulation. This refers to the ball milling and granulation of well-balanced raw materials.

[0062] This step can be further divided into two steps: ball milling and granulation.

[0063] The ball milling process will be explained first below.

[0064] For example, LaH3 powder with a mass percentage of 60%-75% (purity ≥3N, D) 50 =25-45μm) and 25%-40% Mn powder (purity ≥3N, D 50 =15-25μm) is added to the vacuum drum ball mill jar, and anhydrous ethanol is added as the ball milling medium to grind the raw material. Using anhydrous ethanol as the ball milling medium and carrying out the process under vacuum conditions further creates an inert environment and effectively prevents oxygen pollution during the ball milling process.

[0065] In some embodiments, the weight of the milling media can be 50%-100% of the powder weight. For example, the total weight of LaH3 powder and Mn powder can be 1 kg, and the corresponding anhydrous ethanol can be 0.5 kg or 1 kg. This ratio is more conducive to the grinding of raw materials, ensuring that the particle size of the ground raw materials is controlled within the required range and remains uniform and fine.

[0066] In some embodiments, a low-energy ball milling method is employed, wherein the vacuum degree in the vacuum drum ball mill jar is controlled below 500 Pa. The ball-to-material ratio (1-3) in the ball milling parameters is 1, the ball milling speed is 45 r / min-100 r / min, the ball milling time is 6-12 h, and the loading amount is 1 / 3 to 2 / 3 of the ball mill jar volume. Compared with traditional high-energy ball milling, this low-energy ball milling achieves uniform powder mixing while minimizing oxidation and impurity introduction caused by high temperatures from violent collisions and fresh surfaces.

[0067] In some embodiments, high-hardness zirconium balls can be used as grinding balls. Using high-hardness zirconium balls directly controls the contamination of metal impurities from the grinding media at the source, ensuring the purity of the final target material. The grinding balls are supplied in three sizes: φ3mm, φ6mm, and φ10mm, in a ratio of (3~5):(2~5):(2~4). This ball ratio allows for a denser packing and a more rational spatial distribution within the grinding jar. The large balls provide the primary impact energy for breaking up larger soft agglomerates, the medium balls transfer energy and facilitate secondary collisions, and the small balls fill the gaps between the large balls. Their large number provides a large grinding contact area, achieving fine grinding and high homogenization of the powder.

[0068] In some embodiments, the vacuum tank liner can be made of polytetrafluoroethylene (PTFE) or polyurethane. These polymeric materials possess wear resistance and excellent chemical stability, and will not react with the raw material powder. Compared to metal tanks, using this material as a liner avoids direct contact and collision between the powder and the metal tank wall, thereby preventing the introduction of metallic impurities from the tank.

[0069] Next, we will continue to discuss the granulation process in S220.

[0070] 1) The slurry obtained after ball milling is prepared into a precursor slurry with uniform composition, good stability, and suitable for spray granulation by low-speed stirring and the addition of a specific binder.

[0071] In some embodiments, the ball-milled slurry can be introduced into a stirring device, with the stirring speed controlled between 12 r / min and 20 r / min, and the stirring time exceeding 20 min. This low-speed stirring method is employed because the powder particles in the ball-milled slurry may undergo slight sedimentation or form soft agglomerates in the ethanol medium due to gravity or van der Waals forces. High-speed stirring generates strong shear forces, which may disrupt the initially homogeneous mixture and even redistribute trace impurities from zirconium ball wear. Low-speed stirring provides gentle, low-shear energy, allowing the powder particles to redisperse uniformly in the ethanol medium, ensuring absolute consistency of composition throughout the slurry.

[0072] In some embodiments, during the granulation process, one or both of the following are added as binders: acrylic resin and N,N'-methylenebisacrylamide (MBAM) system (2%-6%), which can be completely decomposed under a nitrogen atmosphere, followed by ball milling granulation. This binder is then completely and without residue decomposed into gaseous products such as CO2, H2O, and N2 in the nitrogen atmosphere during the subsequent pre-densification sintering stage, and is subsequently discharged, which helps to achieve the requirements of low oxygen and low impurity content in the target material.

[0073] In some embodiments, the granulation equipment can be a closed-loop centrifugal spray granulation tower with the following granulation parameters: inlet temperature 140-200 ℃, outlet temperature 70-120 ℃, centrifugal disc speed 12000 r / min-20000 r / min, tower pressure 1-3 kPa, and tower oxygen content <3%. The powder produced by the above granulation process has the following parameters: particle size 45-90 mesh, spherical morphology, flowability 25-50 s / 50g, moisture content ≤0.2wt%, and loose density 2.2-2.6 g / cm³. 3By employing precisely controlled low-oxygen conditions and detailed process parameters, the mixed slurry is transformed into granulated powder with ideal spherical morphology, specific particle size, excellent flowability, high bulk density, and extremely low moisture content. This intermediate product ensures that subsequent pressing molding yields green bodies with uniform density and no defects, thus providing the fundamental material guarantee for the final sintering preparation of high-density, low-oxygen-content, and uniformly composed and microstructure LaMn alloy targets.

[0074] S230, CIP molding. This refers to cold isostatic pressing. This step corresponds to... Figure 1 The cold isostatic pressing process in S120 is described in detail above.

[0075] S240, pre-densification sintering. This step corresponds to... Figure 1 S130 in the above text. Specifically, refer to the description of the pre-densification sintering process in S120 above.

[0076] S250, HIP / vacuum hot pressing. This step corresponds to... Figure 1 S140 in the above text can be specifically referred to as the description of HIP or vacuum hot pressing in S140 above.

[0077] S260, CNC machining.

[0078] That is, Computer Numerical Control Machining (CNC).

[0079] The sintered blank, or sintered body (a high-density, low-oxygen lanthanum-manganese alloy), has achieved the required material properties, but its dimensions, shape, and surface finish have not yet met the stringent standards for commercial sputtering targets. CNC machining can use computer-controlled machine tools, such as lathes and milling machines, to precisely cut the sintered body. This ensures that the final dimensional tolerances, flatness, parallelism, and surface roughness of the target fully meet the requirements of the customer and the equipment used, such as the sputtering machine.

[0080] Furthermore, the present invention also provides a thin film, which can be described above. Figure 1 or Figure 2 The material was prepared as described. It possesses the same properties as high-density, low-oxygen lanthanum-manganese alloys, exhibiting high density and low oxygen content.

[0081] The high-density, low-oxygen-content lanthanum-manganese alloy material (hereinafter referred to as lanthanum-manganese alloy material) of the present invention will be described in detail below with reference to specific embodiments.

[0082] Example 1

[0083] 1) Take 60% by weight of LaH3 powder (purity ≥3N, D) 50 =25-45μm), 40% Mn powder (purity ≥3N, D 50 =15-25μm) was added to a vacuum drum ball mill jar, along with anhydrous ethanol (50% by weight of the powder), and the jar was evacuated to below 500 Pa.

[0084] 2) The mixture from step 1 was ball-milled. The ball-milling parameters were as follows: ball-to-material ratio 1:1, ball milling speed 45 r / min, ball milling time 6 h, and loading volume 1 / 3 of the ball mill jar volume. High-hardness zirconium balls were selected, and the grinding balls were a mixture of three sizes (φ3 mm, φ6 mm, and φ10 mm) in a ratio of 3:2:4.

[0085] 3) Granulation. The ball-milled slurry is introduced into a mixing device at a mixing speed of 12 r / min for at least 20 min. Acrylic resin binder is added, followed by ball milling and granulation. The granulation equipment is a closed-loop centrifugal spray granulation tower with the following parameters: inlet air temperature 140 ℃, outlet air temperature 70 ℃, centrifugal disc speed 12000 r / min, tower pressure 1 kPa, and oxygen content <3%. The powder produced by this granulation process has the following parameters: particle size 45-90 mesh, spherical morphology, flowability 25-50 s / 50g, moisture content ≤0.2wt%, and loose density 2.2-2.6 g / cm³. 3 .

[0086] 4) The granulated powder is subjected to cold isostatic pressing. The pressing pressure is 140 MPa and the holding time is 900 s; the density of the pressed green body is between 56% and 62%.

[0087] 5) The formed green blanks undergo pre-densification treatment; the sintering parameters are: N2 flow rate 200 L / min, furnace pressure 200 Pa, and furnace oxygen content <1000 ppm; stepped heating: in the first stage, the heating rate is 0.4℃ / min within 0-120℃, and the holding time is 3 h; in the 120-300℃ range, the heating rate is 0.3℃ / min, and the holding time is 6 h; in the 300-701℃ range, the heating rate is 0.1℃ / min, and the holding time is 12 h; in the 701-1081℃ range, the heating rate is 0.1℃ / min, and the holding time is 24 h; then the blanks are cooled to room temperature in the furnace. The density of the pre-densified blanks after the above process is between 75% and 85%, and its pores are interconnected open-cell structures.

[0088] 6) The pre-densified blank is then subjected to vacuum hot pressing densification. The pre-densified blank is placed in a graphite mold, and the sintering temperature is set to 620 ℃, the sintering pressure to 60 MPa, and the vacuum degree to <10 Pa. After sintering and cooling, lanthanum manganese alloy material S1 is obtained.

[0089] The S1 sample obtained through the above steps has a density of over 98.5%, and the grains are also equiaxed, with a grain size ≤120μm and an oxygen content ≤1000ppm.

[0090] refer to Figure 3 , Figure 3 A metallographic image of the lanthanum-manganese alloy material S1 according to an embodiment of the present invention is shown.

[0091] like Figure 3 As shown, this phase diagram reveals the equilibrium phase composition of the La-Mn binary system under different compositions and temperatures. The horizontal axis of the phase diagram represents the compositional variation of the alloy from pure lanthanum to pure manganese, while the vertical axis corresponds to the temperature gradient. Figure 3 As can be seen, eutectic and segregated crystal reactions occur in the system at temperatures of 701℃ and 1081℃, with the eutectic containing approximately 17% (at) Mn. In other words, 701℃ is the solidus line of the alloy system, and 1081℃ is the liquidus line. Therefore, in this embodiment of the invention, setting the first pre-sintering temperature (pre-density sintering temperature) from 701℃ to 1081℃ allows the system to be sintered between the solid and liquid phases. This increases the decomposition rate of LaH3 and enhances the density of the first pre-sintered blank, preparing it for the next process.

[0092] Example 2

[0093] 1) Take 75% by weight of LaH3 powder (purity ≥3N, D) 50 =25-45μm), 25% Mn powder (purity ≥3N, D 50 =15-25μm) was added to a vacuum drum ball mill jar, along with anhydrous ethanol (100% by weight of the powder), and the jar was evacuated to below 500Pa.

[0094] 2) The mixture from step 1 was ball-milled. The ball-milling parameters were as follows: ball-to-material ratio 3:1, ball milling speed 100 r / min, ball milling time 6 h, and loading volume 2 / 3 of the ball mill jar volume. High-hardness zirconium balls were selected, and the grinding balls were a mixture of three sizes (φ3mm, φ6mm, and φ10mm) in a ratio of 5:5:2.

[0095] 3) Granulation. The ball-milled slurry is introduced into a mixing device at a mixing speed of 20 r / min for at least 20 minutes. The binder, MBAM, is then added, followed by ball milling and granulation. The granulation equipment is a closed-loop centrifugal spray granulation tower with the following parameters: inlet air temperature 200℃, outlet air temperature 120℃, centrifugal disc speed 20000 r / min, tower pressure 3 kPa, and oxygen content <3%. The powder produced through this granulation process has the following parameters: particle size 45-90 mesh, spherical morphology, flowability 25-50 s / 50g, moisture content ≤0.2 wt%, and loose density 2.2-2.6 g / cm³. 3 .

[0096] 4) The granulated powder is subjected to cold isostatic pressing. The pressing pressure is 200 MPa and the holding time is 600 s; the density of the pressed green body can reach 60%.

[0097] 5) The formed green blanks undergo pre-densification treatment; the sintering parameters are: N2 flow rate 200 L / min, furnace pressure 200 Pa, and furnace oxygen content <1000 ppm; stepped heating: in the first stage, the heating rate is 0.6℃ / min within 0-120℃, and the holding time is 6 h; in the 120-300℃ range, the heating rate is 0.1℃ / min, and the holding time is 12 h; in the 300-701℃ range, the heating rate is 0.3℃ / min, and the holding time is 6 h; in the 701-1081℃ range, the heating rate is 0.3℃ / min, and the holding time is 12 h; then the blanks are cooled to room temperature in the furnace. The pre-densified blanks produced by the above process achieve a density of 80%, and their pores are interconnected open-cell structures.

[0098] 6) The pre-densified blank is densified by HIP. The pre-densified blank is covered with a Ti plate, sintered at 520℃ and 160MPa, and then cooled to obtain lanthanum manganese alloy material S2.

[0099] The S2 material obtained through the above steps has a density of over 99%, equiaxed grains, grain size ≤100μm, and oxygen content ≤1200ppm.

[0100] Example 3

[0101] 1) Take 70% by weight of LaH3 powder (purity ≥3N, D) 50 =25-45μm), 30% Mn powder (purity ≥3N, D 50 =15-25μm) was added to a vacuum drum ball mill jar, along with anhydrous ethanol (50% by weight of the powder), and the jar was evacuated to below 500Pa.

[0102] 2) The mixture from step 1 was ball-milled. The ball-milling parameters were as follows: ball-to-material ratio 2:1, ball milling speed 80 r / min, ball milling time 10 h, and loading volume 1 / 3 of the ball mill jar volume. High-hardness zirconium balls were selected, and the grinding balls were a mixture of three sizes (φ3mm, φ6mm, and φ10mm) in a ratio of 3:4:3.

[0103] 3) Granulation.

[0104] The ball-milled slurry is introduced into a mixing device at a mixing speed of 16 r / min for at least 20 minutes. Acrylic resin as a binder is then added, followed by ball milling and granulation. The granulation equipment is a closed-loop centrifugal spray granulation tower with the following parameters: inlet air temperature 180℃, outlet air temperature 100℃, centrifugal disc speed 15000 r / min, tower pressure 2 kPa, and oxygen content <3%. The resulting powder, produced through this granulation process, has the following parameters: particle size 45-90 mesh, spherical morphology, flowability 25-50 s / 50g, moisture content ≤0.2 wt%, and loose density 2.2-2.6 g / cm³. 3 .

[0105] 4) The granulated powder is subjected to cold isostatic pressing. The pressing pressure is 160 MPa and the holding time is 800 s. The density of the pressed green body is between 56% and 62%.

[0106] 5) Perform pre-densification treatment on the formed green blank.

[0107] The sintering parameters were as follows: N2 flow rate 400 L / min, furnace pressure 100 Pa, and furnace oxygen content <1000 ppm. The temperature was increased in stages: in the first stage, the heating rate was 0.5 °C / min from 0 to 120 °C, held for 5 hours; in the second stage, the heating rate was 0.2 °C / min from 120 to 300 °C, held for 8 hours; in the third stage, the heating rate was 0.2 °C / min from 300 to 701 °C, held for 9 hours; and in the fourth stage, the heating rate was 0.2 °C / min from 701 to 1081 °C, held for 24 hours. The furnace was then cooled to room temperature. The pre-densified blank produced using the above process had a density between 75% and 85%, and its pores were interconnected open-cell structures.

[0108] 6) Vacuum hot pressing is used to densify the pre-densified blank.

[0109] The preformed blank is placed into a graphite mold, the sintering temperature is set to 600℃, the sintering pressure is 60MPa, and the vacuum degree is <10Pa. After sintering and cooling, lanthanum manganese alloy material S1 is obtained.

[0110] The S1 sample obtained through the above steps has a density of over 98.0%, and the grains are also equiaxed, with a grain size ≤120μm and an oxygen content ≤1000ppm.

[0111] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A lanthanum-manganese alloy material having a high density and a low oxygen content, characterized by comprising: The lanthanum-manganese alloy material is prepared by the following steps: The raw material of the lanthanum-manganese alloy material comprises lanthanum hydride and manganese, and the lanthanum-manganese alloy material is obtained based on pre-densification sintering and densification sintering of a mixture of the lanthanum hydride and the manganese.

2. The lanthanum-manganese alloy material according to claim 1, characterized by The raw material comprises 60-75% of lanthanum hydride and 25-40% of manganese by mass percentage.

3. The lanthanum-manganese alloy material according to claim 1, characterized by said lanthanum hydride is introduced in the form of a powder, the purity of said lanthanum hydride powder being greater than 99.9%, the particle size D 50 25 to 45 μm, and / or said manganese is introduced in the form of a powder, the purity of said manganese powder being greater than 99.9%, the particle size D 50 15 to 25 μm.

4. The lanthanum-manganese alloy material according to claim 1 or 2, characterized by, The lanthanum-manganese alloy material has a density of not less than 98.5% and an oxygen content of not more than 1200 ppm.

5. A method of producing a lanthanum-manganese alloy material having a high density and a low oxygen content, characterized by, The method comprises the following steps: Raw material mixing: mixing lanthanum hydride and manganese in a protective atmosphere or a vacuum environment to obtain a mixed powder; Molding: pressing the mixed powder to obtain a green body; Pre-densification sintering: sintering the green body in a controllable atmosphere to decompose LaH3 and preliminarily alloy, thereby obtaining a pre-densification blank; Densification sintering: sintering the pre-densification blank by hot isostatic pressing or vacuum hot pressing to obtain the lanthanum-manganese alloy material.

6. The preparation method according to claim 5, characterized in that, The raw material comprises 60-75% of lanthanum hydride and 25-40% of manganese by mass percentage.

7. The preparation method according to claim 5, characterized in that, In the raw material mixing step, the raw material is mixed by low-energy ball milling under vacuum conditions with anhydrous ethanol, the ball milling rotation speed is 45-100 r / min, and the ball-to-material ratio is (1-3):

1.

8. The preparation method according to claim 5, characterized in that, The pre-densification sintering is performed in a nitrogen atmosphere with an oxygen content of less than 1000 ppm, and the sintering procedure comprises a stepwise heating mode of the blank, heating from 701 ℃ to 1081 ℃ and maintaining for 12-24 h, so as to fully decompose LaH3.

9. The preparation method according to claim 5, characterized in that, The densification sintering is performed by the hot isostatic pressing process, the sintering temperature is 520-600 ℃, the pressure is 120-160 MPa, and the pre-densification blank is coated with a titanium plate before sintering; or The densification sintering adopts vacuum hot pressing process, the sintering temperature is 560~620℃, the pressure is 35~60 MPa, and the vacuum degree is less than 10 -2 Pa.

10. A film, characterized by, The lanthanum-manganese alloy material prepared by the method of any one of claims 5-11.

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