A method for preparing nano Y-Hf-O composite oxide dispersion strengthened nickel-based superalloy by laser 3D printing

Abstract

The application belongs to the technical field of high-temperature alloy additive manufacturing, and more particularly relates to a method for preparing a nano Y-Hf-O composite oxide dispersion strengthened nickel-based high-temperature alloy by laser 3D printing. The method comprises the following steps: introducing Y and Hf elements into a mother alloy component, forming a nano Y-Hf-O composite oxide precursor on the surface of the alloy powder by using a gas atomization reaction synthesis process; and further controlling a laser powder bed fusion (LPBF) process to in-situ precipitate a fine, dispersed and excellent thermal stability Y-Hf-O nano strengthening phase in a non-equilibrium solidification process, effectively inhibiting the competitive reaction and coarsening behavior of the active elements such as Al, realizing the synergistic control of the size, distribution and content of the nano precipitated phase, and significantly improving the high-temperature creep performance of the ODS nickel-based alloy, which is suitable for efficient additive manufacturing of advanced nuclear energy systems and key components of the hot end of aerospace.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature alloy additive manufacturing technology, and more specifically relates to a method for preparing nano-Y-Hf-O composite oxide dispersion-strengthened nickel-based high-temperature alloys by laser 3D printing. Background Technology

[0002] Oxide dispersion strengthened (ODS) nickel-based superalloys, thanks to the intrinsic strength of the matrix and the pinning effect of nano-oxides, have broken through the traditional ODS steel's service limit of 650℃. They exhibit excellent high-temperature creep and radiation resistance properties, making them key candidate materials for hot-end components of advanced nuclear energy systems.

[0003] Laser Powder Bed Fusion (LPBF) technology offers a revolutionary path to overcome the bottlenecks of traditional powder metallurgy, such as long processes, high pollution, and geometric limitations, enabling efficient near-net-shape forming of complex ODS alloy components. Constructing fine, dispersed, and thermally stable nano-reinforcing phases is key to improving the radiation resistance and high-temperature creep resistance of additively manufactured ODS nickel-based alloys. Its role is mainly reflected in two aspects: first, by effectively pinning dislocations and grain boundaries, it significantly enhances the high-temperature strength of the alloy; second, the numerous phase interfaces between the oxide and the matrix can act as annihilation traps for irradiation defects, thereby reducing defect density, trapping helium atoms, and inhibiting the formation of helium bubbles.

[0004] Y₂O₃ is currently the most commonly used dispersed strengthening phase in ODS alloys. In ODS alloys prepared using traditional powder metallurgy processes such as ball milling and hot pressing sintering, the Y₂O₃ strengthening phase is relatively small. However, additive manufacturing processes have high requirements for powder sphericity and flowability. ODS alloy powders prepared by ball milling have irregular shapes, making it difficult to meet the powder spreading requirements of 3D printing. Furthermore, in existing technologies, the Y₂O₃ strengthening phase particles formed after LPBF forming of Y₂O₃-containing nickel-based alloy powders are typically large (~45 nm). More importantly, in Al-containing high-temperature alloy systems, Y₂O₃ readily reacts with active elements in the matrix (such as Al) to generate even coarser Y-Al-O type oxides, with sizes reaching up to 500 nm. This not only provides limited strengthening but may even degrade the alloy's mechanical properties and radiation resistance.

[0005] Therefore, how to obtain fine, dispersed, and thermally stable nano-oxide reinforcing phases in additive manufacturing of ODS nickel-based alloys, while suppressing their competitive reaction and coarsening with the matrix elements, is a technical problem that urgently needs to be solved in the current field. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing nano-Y-Hf-O composite oxide dispersion-strengthened nickel-based superalloys by laser 3D printing, in order to solve the problem that in the above-mentioned existing technology, the traditional Y2O3 strengthening phase in additive manufacturing ODS nickel-based alloys is large in size and easily reacts with Al elements in the alloy to form even coarser Y-Al-O phases, resulting in insufficient improvement in high-temperature creep of the alloy.

[0007] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of this invention is to provide a method for preparing nano-Y-Hf-O composite oxide dispersion-strengthened nickel-based superalloys by laser 3D printing, the steps of which include: Based on the composition of the target nickel-based superalloy, raw materials were prepared, and Hf and Y elements were added. After vacuum melting, the master alloy was obtained. After the master alloy is vacuum melted, it is subjected to gas atomization powdering treatment in an oxygen-containing atmosphere to obtain ODS alloy powder. The ODS alloy powder was subjected to a powder bed laser melting (LPBF) additive manufacturing process to obtain a deposited alloy. The deposited alloy was subjected to hot isostatic pressing and solution treatment to obtain the nano-Y-Hf-O composite oxide dispersion-strengthened nickel-based superalloy.

[0008] Furthermore, the target nickel-based superalloy includes GH3230 alloy.

[0009] Furthermore, the content of the Y element in the master alloy is 0.2~0.45 wt.%.

[0010] Furthermore, the mass ratio of the Hf element to the Y element is 1.5 to 2.5.

[0011] Furthermore, the Hf and Y elements are added in the form of a Ni-containing master alloy.

[0012] Optionally, the Ni-containing master alloy is a Ni-Y alloy and a Ni-Hf alloy, or a Ni-Y-Hf alloy.

[0013] Furthermore, the vacuum melting process is carried out at a temperature of 1450~1500℃ for 15 minutes.

[0014] Furthermore, the temperature of the vacuum melting is 1450~1500℃.

[0015] Furthermore, the oxygen-containing atmosphere is provided by a mixture of oxygen and argon.

[0016] Optionally, the oxygen content in the mixed gas is 1.5~3.5 vol.%.

[0017] Furthermore, the gas-liquid ratio of the gas atomization powder preparation process is 0.9~1.3 Nm. 3 / kg.

[0018] Furthermore, the ODS alloy powder has a particle size of 20~45 μm and an oxygen content of 0.1~0.3 wt.%.

[0019] Furthermore, the parameters of the powder bed laser melting (LPBF) additive manufacturing technology include: laser power 150~200 W, scanning speed 1200~1600 mm / s, scanning spacing 75~85 μm, and powder layer thickness 25~32 μm.

[0020] Furthermore, the parameters for the hot isostatic pressing treatment are: temperature 1150℃, pressure 150MPa, and holding time 3h.

[0021] Furthermore, the solution treatment temperature is 1180℃~1280℃, and the holding time is 0.5h-2h.

[0022] This invention introduces Y and Hf elements into the master alloy composition and uses a gas atomization reaction synthesis process to form a nanoscale Y-Hf-O composite oxide precursor on the surface of the alloy powder. Furthermore, by controlling the laser powder bed melting (LPBF) process, fine, dispersed Y-Hf-O nano-reinforcing phases with excellent thermal stability are precipitated in situ during non-equilibrium solidification, effectively suppressing their competitive reaction and coarsening behavior with active elements such as Al.

[0023] This invention achieves synergistic regulation of the size, distribution, and content of nano-precipitated phases through the design of Y-Hf-O composite oxides and the control of a two-stage (atomization powdering + laser forming) non-equilibrium metallurgical process, which significantly improves the high-temperature creep performance of ODS nickel-based alloys and is suitable for efficient additive manufacturing of key components in advanced nuclear energy systems and aerospace hot ends.

[0024] The second technical solution of the present invention provides a nano-Y-Hf-O composite oxide dispersion-strengthened nickel-based superalloy, wherein the nano-Y-Hf-O composite oxide dispersion-strengthened nickel-based superalloy is prepared by the above method.

[0025] The third technical solution of the present invention provides an application of the above-mentioned nano-Y-Hf-O composite oxide dispersion-strengthened nickel-based superalloy or the above-mentioned method in the preparation of nuclear energy system components and aerospace hot-end components.

[0026] The present invention discloses the following technical effects: This invention uses a highly thermally stable Y-Hf-O composite oxide to replace traditional Y2O3 as the nano-reinforcing phase. The formation energy of Y2Hf2O7 is lower than that of Y2O3 and Y-Al-O oxides, exhibiting higher thermodynamic stability and effectively preventing the formation of coarse Y-Al-O phases. In the ODS alloy prepared by the method described in this invention, the average size of the Y-Hf-O nano-reinforcing phase is 20~35 nm, and the number density is ≥10. 21 m -3 It is uniformly dispersed in the matrix, which significantly improves the high-temperature creep performance of the alloy.

[0027] This invention utilizes a gas atomization reaction synthesis process to control the oxygen content and gas-liquid ratio in the mixed gas, enabling Y and Hf to react with oxygen in situ. This generates a Y-Hf-O composite oxide precursor layer with a controllable thickness of 20-40 nm on the powder surface, providing a material basis for the uniform dispersion of nanophases during LPBF molding. At the same time, it avoids problems such as poor powder sphericity and impurity introduction in traditional mechanical alloying methods.

[0028] Compared with traditional ODS alloy preparation methods (mechanical alloying + hot extrusion), this invention adopts a technical route that combines gas atomization reaction synthesis with LPBF additive manufacturing, which can realize the integrated near-net-shape forming of complex-shaped ODS alloy parts, with high material utilization, shortened preparation cycle and significantly reduced production cost. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the preparation process of the nano-Y-Hf-O composite oxide dispersion-strengthened nickel-based superalloy of the present invention.

[0030] Figure 2 The cross-sectional area distribution of O element in the ODS alloy powder obtained in Example 1 is shown.

[0031] Figure 3 The results are STEM characterizations of the nano-oxides in the ODS alloy obtained in Example 1.

[0032] Figure 4 STEM image of the Ni5Y intermetallic compound in the nickel-based superalloy prepared in Comparative Example 2. Detailed Implementation

[0033] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0034] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0035] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0036] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0037] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0038] Unless otherwise specified, all raw materials and reagents involved in the specific embodiments of this invention are commercially available products.

[0039] Unless otherwise specified, room temperature and normal temperature in the specific embodiments of this invention refer to 20-30℃.

[0040] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0041] The exemplary alloy system of the target nickel-based superalloy in this invention, which uses GH3230 alloy, does not mean that the technical solution of this invention is limited to GH3230 alloy. Therefore, the selection of the target nickel-based superalloy in this invention is not limited to GH3230 alloy.

[0042] Figure 1 This is a schematic diagram of the preparation process of the nano-Y-Hf-O composite oxide dispersion-strengthened nickel-based superalloy of the present invention.

[0043] Example 1 The preparation steps of nano-Y-Hf-O composite oxide dispersion-strengthened nickel-based superalloys include: S1. Master alloy smelting: In a vacuum induction melting furnace, the GH3230 nickel-based superalloy base material was first melted, followed by the sequential addition of Ni-20Hf and Ni-30Y master alloys, with a designed addition amount of Y of 0.45 wt.% and a designed Hf / Y mass ratio of 1.8. After refining at 1500℃ for 15 min, the mixture was cast into a master alloy ingot (vacuum degree ≤0.1Pa, using the heating rate of conventional induction melting).

[0044] Inductively coupled plasma (ICP) compositional analysis revealed that the master alloy contained 0.41 wt.% Y, 0.78 wt.% Hf, with an Hf / Y mass ratio of 1.90 and an oxygen content of 45 ppm. Other major elements were within the standard chemical composition range, specifically: 20.42 wt% Cr, 14.58 wt% W, 2.17 wt% Mo, 1.68 wt% Fe, 2.89 wt% Co, 0.10 wt% C, 0.03 wt% La, 0.34 wt% Al, 0.51 wt% Si, 0.65 wt% Mn, with Ni as the balance.

[0045] S2, synthesis via gas atomization reaction: The master alloy was remelted under vacuum at a temperature between 1450 and 1500°C, and then atomized into powder using an argon-oxygen mixture containing 2.8 vol.% oxygen at a gas-liquid ratio of 1.1 Nm. 3 / kg.

[0046] After sieving, ODS alloy powder with a particle size range of 20~45μm was obtained, with an oxygen content of 0.22wt.%, a powder flowability of 15.3 s / 50g, and an average oxide layer thickness of about 32nm on the powder surface.

[0047] Figure 2 The cross-sectional O element distribution of the ODS alloy powder obtained in Example 1 is shown (the yellow area is the surface oxide layer).

[0048] S3, Additive Manufacturing: The ODS alloy powder prepared in step S2 was shaped using an LPBF process with a laser power of 175 W, a scanning speed of 1400 mm / s, a scanning spacing of 80 μm, and a powder layer thickness of 30 μm to obtain a deposited alloy with good density.

[0049] S4. Post-treatment: The deposited ODS alloy was subjected to hot isostatic pressing at 1150℃ and 150 MPa (conventional heating rate, between 5-10℃ / min) for 3 h. After cooling in the furnace, it was subjected to solution treatment at 1230℃ for 1 h to obtain a nano-Y-Hf-O composite oxide dispersion strengthened nickel-based superalloy (ODS-GH3230 alloy).

[0050] The alloy samples were characterized using scanning transmission electron microscopy (STEM). The results showed that a large number of dispersed nano-Y-Hf-O oxide particles precipitated within the alloy, with an average size of 28 nm and a number density as high as 3.1 × 10⁻⁶. 21 m -3 Thanks to the dispersion strengthening effect of this high-density fine nano-oxide, the ODS-GH3230 alloy prepared in Example 1 has a creep rupture life of about 350 h under test conditions of 950 °C and 300 MPa, which is 1.94 times that of the creep rupture life of GH3230 alloy under the same conditions (~180 h).

[0051] Figure 3 The results are STEM characterizations of the nano-oxides in the ODS alloy obtained in Example 1.

[0052] Example 2 The preparation steps of nano-Y-Hf-O composite oxide dispersion-strengthened nickel-based superalloys include: S1. Master alloy smelting: In a vacuum induction melting furnace, the GH3230 nickel-based superalloy base material is first melted, followed by the sequential addition of Ni-20Hf and Ni-30Y master alloys, with a designed addition amount of Y of 0.34 wt.% and a designed Hf / Y mass ratio of 2.0. After refining at 1500℃ for 15 min, it is cast into a master alloy ingot.

[0053] Inductively coupled plasma (ICP) compositional analysis revealed that the master alloy contained 0.29 wt.% Y, 0.64 wt.% Hf, with an Hf / Y mass ratio of 2.2 and an oxygen content of 42 ppm. Other major elements were within the standard chemical composition range, specifically: 21.18 wt% Cr, 13.95 wt% W, 2.46 wt% Mo, 1.92 wt% Fe, 2.74 wt% Co, 0.12 wt% C, 0.028 wt% La, 0.31 wt% Al, 0.49 wt% Si, 0.61 wt% Mn, with Ni as the balance.

[0054] S2, synthesis via gas atomization reaction: The master alloy was remelted under vacuum at a temperature between 1450 and 1500°C, and then atomized into powder using an argon-oxygen mixture containing 2.2 vol.% oxygen at a gas-liquid ratio of 1.0 Nm. 3 / kg.

[0055] After sieving, ODS alloy powder with a particle size range of 20~45μm was obtained, with an oxygen content of 0.18wt.%, a powder flowability of 16.8 s / 50g, and an average oxide layer thickness of about 25 nm on the powder surface.

[0056] S3, Additive Manufacturing: The ODS alloy powder prepared in step S2 was shaped using an LPBF process with a laser power of 170 W, a scanning speed of 1350 mm / s, a scanning spacing of 80 μm, and a powder layer thickness of 30 μm to obtain a deposited alloy with good density.

[0057] S4. Post-treatment: The deposited ODS alloy was subjected to hot isostatic pressing at 1150℃ and 150 MPa for 3 h. After cooling in the furnace, it was subjected to solution treatment at 1230℃ for 1 h to obtain a nano-Y-Hf-O composite oxide dispersion-strengthened nickel-based superalloy (ODS-GH3230 alloy).

[0058] The alloy samples were characterized using scanning transmission electron microscopy (STEM). The results showed that a large number of dispersed nano-Y-Hf-O oxide particles precipitated within the alloy, with an average size of 24 nm and a number density as high as 2.5 × 10⁻⁶. 21 m -3 Thanks to the dispersion strengthening effect of this high-density fine nano-oxide, the ODS-GH3230 alloy prepared in Example 2 has a creep rupture life of about 310 h under test conditions of 950 °C and 300 MPa, which is 1.72 times that of the creep rupture life of GH3230 alloy under the same conditions (~180 h).

[0059] Comparative Example 1 The difference from Example 1 is that the amount of Y added and the oxygen content of the atomized atmosphere are both lower.

[0060] S1. Master alloy smelting: In a vacuum induction melting furnace, the GH3230 nickel-based superalloy base material was first melted, followed by the sequential addition of Ni-20Hf and Ni-30Y master alloys, with a designed addition amount of Y of 0.18 wt.% and a designed Hf / Y mass ratio of 1.8. After refining at 1500℃ for 15 min, the mixture was cast into a master alloy ingot.

[0061] Inductively coupled plasma (ICP) composition analysis revealed that the Y content in the master alloy was 0.15 wt.%, the Hf content was 0.3 wt.%, the Hf / Y mass ratio was 2.0, and the oxygen content was 40 ppm.

[0062] S2, synthesis via gas atomization reaction: The master alloy was remelted under vacuum at a temperature between 1450 and 1500°C, and then atomized into powder using an argon-oxygen mixture containing 0.8 vol.% oxygen at a gas-liquid ratio of 1.1 Nm. 3 / kg.

[0063] After sieving, ODS alloy powder with a particle size range of 20~45μm was obtained. Its oxygen content was 0.09wt.%, the powder flowability was 14.9 s / 50g, and the oxide layer on the powder surface was extremely thin and discontinuous, with an average thickness of less than 5 nm.

[0064] S3, Additive manufacturing: Same as Example 1.

[0065] S4. Post-processing: Same as in Example 1.

[0066] STEM characterization results showed that sufficient nano-Y-Hf-O composite oxides failed to form inside the alloy. The creep rupture life of the obtained nickel-based superalloy under test conditions of 950℃ and 300MPa was only 195h, which was almost no improvement compared with the creep rupture life of GH3230 alloy (~180h) under the same conditions.

[0067] Comparative Example 2 The difference from Example 1 is that the amount of Y added is higher.

[0068] S1. Master alloy smelting: In a vacuum induction melting furnace, the GH3230 nickel-based superalloy base material is first melted, followed by the sequential addition of Ni-20Hf and Ni-30Y master alloys, with a designed addition amount of Y of 0.65 wt.% and a designed Hf / Y mass ratio of 1.8. After refining at 1500℃ for 15 min, it is cast into a master alloy ingot.

[0069] Inductively coupled plasma (ICP) composition analysis revealed that the Y content in the master alloy was 0.59 wt.%, the Hf content was 1.21 wt.%, the Hf / Y mass ratio was 2.05, and the oxygen content was 65 ppm.

[0070] S2, synthesis via gas atomization reaction: The master alloy was remelted under vacuum at a temperature between 1450 and 1500°C, and then atomized into powder using an argon-oxygen mixture containing 2.8 vol.% oxygen at a gas-liquid ratio of 1.1 Nm. 3 / kg.

[0071] After sieving, ODS alloy powder with a particle size range of 20~45μm was obtained, with an oxygen content of 0.35wt.%, a powder flowability of 17.1 s / 50g, and an average oxide layer thickness of about 50nm on the powder surface.

[0072] S3, Additive manufacturing: Same as Example 1.

[0073] S4. Post-processing: Same as in Example 1.

[0074] STEM characterization results showed that, in addition to the formation of some Y-Hf-O composite oxides, a large amount of Ni5Y intermetallic compounds precipitated within the alloy. These compounds, ranging in size from 150 to 400 nm, were distributed in bulk form along grain boundaries and subgrain boundaries. Energy dispersive spectroscopy (EDS) confirmed that the Ni / Y atomic ratio of these coarse precipitates was approximately 5:1, consistent with the stoichiometry of Ni5Y. Due to the low melting point of Ni5Y (approximately 1380 °C), it is prone to softening or dissolving under high-temperature service conditions. Furthermore, its poor coherence with the matrix provides favorable sites for crack initiation and propagation. In addition, the excessive addition of Y led to coarsening of the oxide particles (some Y-Hf-O particles exceeding 80 nm in size) and uneven distribution, resulting in a decrease in the number density to approximately 7.2 × 10⁻⁶. 20 m -3 The obtained nickel-based superalloy exhibited a creep rupture life of only 220 h under test conditions of 950℃ and 300 MPa, which is far lower than the levels of Examples 1 and 2.

[0075] Figure 4 The image shows a STEM image of the Ni5Y intermetallic compound in the nickel-based superalloy prepared in Comparative Example 2. As can be seen from the image, a large amount of Ni5Y intermetallic compound precipitates at the grain boundaries of the alloy when the Y content is 0.59 wt.%. (red arrows).

[0076] Comparative Example 3 The difference from Example 1 is that the amount of Y added is lower.

[0077] S1. Master alloy smelting: In a vacuum induction melting furnace, the GH3230 nickel-based superalloy base material was first melted, followed by the sequential addition of Ni-20Hf and Ni-30Y master alloys, with a designed addition amount of Y of 0.18 wt.% and a designed Hf / Y mass ratio of 1.8. After refining at 1500℃ for 15 min, the mixture was cast into a master alloy ingot.

[0078] Inductively coupled plasma (ICP) composition analysis revealed that the Y content in the master alloy was 0.16 wt.%, the Hf content was 0.29 wt.%, the Hf / Y mass ratio was 1.81, and the oxygen content was 40 ppm.

[0079] S2, synthesis via gas atomization reaction: The master alloy was remelted under vacuum at a temperature between 1450 and 1500°C, and then atomized into powder using an argon-oxygen mixture containing 2.8 vol.% oxygen at a gas-liquid ratio of 1.1 Nm. 3 / kg.

[0080] After sieving, ODS alloy powder with a particle size range of 20-45 μm was obtained, with an oxygen content of 0.21 wt.% and a powder flowability of 18.9 s / 50 g. Microscopic analysis showed that a Y-Hf-O oxide layer with a thickness of approximately 10 nm was formed on the powder surface, and Cr-rich oxides were also generated inside it.

[0081] S3, Additive manufacturing: Same as Example 1.

[0082] S4. Post-processing: Same as in Example 1.

[0083] STEM characterization results showed that sufficient nano-Y-Hf-O composite oxides were not formed inside the alloy; instead, micron-sized Cr-rich oxides were formed. The prepared ODS-GH3230 alloy had a creep rupture life of approximately 198 h under test conditions of 950 °C and 300 MPa, which was almost no improvement compared to the creep rupture life of GH3230 alloy (~180 h) under the same conditions.

[0084] Comparative Example 4 The difference from Example 1 is that the oxygen content in the atomized atmosphere is lower.

[0085] S1. Master alloy smelting: Same as in Example 1.

[0086] S2, synthesis via gas atomization reaction: The master alloy was remelted under vacuum at a temperature between 1450 and 1500°C, and then atomized into powder using an argon-oxygen mixture containing 0.8 vol.% oxygen at a gas-liquid ratio of 1.1 Nm. 3 / kg.

[0087] After sieving, ODS alloy powder with a particle size range of 20~45μm was obtained. Its oxygen content was 0.10wt.%, the powder flowability was 14.9 s / 50g, and the oxide layer on the powder surface was extremely thin and discontinuous, with an average thickness of less than 5 nm.

[0088] S3, Additive manufacturing: Same as Example 1.

[0089] S4. Post-processing: Same as in Example 1.

[0090] STEM characterization results showed that sufficient nano-Y-Hf-O composite oxides failed to form inside the alloy. The creep rupture life of the obtained nickel-based superalloy under test conditions of 950℃ and 300MPa was only 189h, which was almost no improvement compared with the creep rupture life of GH3230 alloy (~180h) under the same conditions.

[0091] Comparative Example 5 The difference from Example 1 is that the Hf element is not introduced.

[0092] S1. Master alloy smelting: In a vacuum induction melting furnace, the GH3230 nickel-based superalloy base material is first melted, and then the Ni-30Y master alloy is added, with the designed addition amount of Y being 0.45 wt.%. After refining at 1500℃ for 15 min, it is cast into a master alloy ingot.

[0093] Inductively coupled plasma (ICP) composition analysis revealed that the Y content in the master alloy was 0.42 wt.% and the oxygen content was 43 ppm.

[0094] S2, Gas atomization reaction synthesis: Same as Example 1.

[0095] After sieving, ODS alloy powder with a particle size range of 20~45μm was obtained, with an oxygen content of 0.25wt.% and a powder flowability of 15.7 s / 50g. A Y-Al-O and YO composite oxide layer was formed on the powder surface, and the interior contained Cr-rich oxides.

[0096] S3, Additive manufacturing: Same as Example 1.

[0097] S4. Post-processing: Same as in Example 1.

[0098] STEM characterization results showed that the alloy contained micron-sized coarse Y-Al-O and Cr-rich oxides, with only a small amount of nano-sized Y2O3 particles. The resulting nickel-based superalloy exhibited a creep rupture life of only 175 h under test conditions of 950 °C and 300 MPa, which was slightly lower than that of GH3230 alloy (~180 h) under the same conditions.

[0099] Comparative Example 6 Mechanical mixing: GH3230 nickel-based superalloy powder with a particle size of 15-53 μm was mixed with 100 nm Y2O3 and 100 nm HfO2 powders by high-energy ball milling, allowing the oxides to embed into the alloy grains. Inductively coupled plasma (ICP) composition analysis showed that the prepared powder contained 0.40 wt.% Y, 0.79 wt.% Hf, and an Hf / Y mass ratio of 1.975. All other major elements were within the standard chemical composition range.

[0100] After sieving, ODS alloy powder with a particle size range of 20~45μm was obtained, with an oxygen content of 0.10wt.%, a powder flowability of 21.3 s / 50g, and an irregular surface morphology.

[0101] The prepared ODS alloy powder was shaped using the LPBF process with a laser power of 175 W, a scanning speed of 1400 mm / s, a scanning spacing of 80 μm, and a powder layer thickness of 30 μm. Due to the poor powder spreading properties, the density of the deposited alloy was low, only 89.5%, which is far below the density requirement of conventional printing (>99.5%).

[0102] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0103] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing nano-Y-Hf-O composite oxide dispersion-strengthened nickel-based superalloys by laser 3D printing, characterized in that the steps include... include: Based on the composition of the target nickel-based superalloy, raw materials were prepared, and Hf and Y elements were added. After vacuum melting, the master alloy was obtained. After the master alloy is vacuum melted, it is subjected to gas atomization powdering treatment in an oxygen-containing atmosphere to obtain ODS alloy powder. The ODS alloy powder is formed by powder bed laser melting additive manufacturing to obtain a deposited alloy. The deposited alloy was subjected to hot isostatic pressing and solution treatment to obtain the nano-Y-Hf-O composite oxide dispersion-strengthened nickel-based superalloy.

2. The method as described in claim 1, characterized in that, The target nickel-based superalloy includes GH3230 alloy; And / or, the content of the Y element in the master alloy is 0.2~0.45 wt.%; And / or, the mass ratio of the Hf element to the Y element is 1.5 to 2.5; And / or, the Hf and Y elements are added in the form of a Ni-containing master alloy.

3. The method as described in claim 2, characterized in that, The Ni-containing master alloy is a Ni-Y alloy and a Ni-Hf alloy, or a Ni-Y-Hf alloy.

4. The method as described in claim 1, characterized in that, The vacuum melting process is carried out at a temperature of 1450~1500℃ for 15 minutes. And / or, the temperature of the vacuum melting is 1450~1500℃; And / or, the oxygen-containing atmosphere is provided by a mixture of oxygen and argon.

5. The method as described in claim 4, characterized in that, The oxygen content in the mixed gas is 1.5~3.5 vol.%.

6. The method as described in claim 1, characterized in that, The gas-liquid ratio of the gas atomization powder preparation process is 0.9~1.3 Nm. 3 / kg; And / or, the ODS alloy powder has a particle size of 20~45 μm and an oxygen content of 0.1~0.3 wt.%.

7. The method as described in claim 1, characterized in that, The parameters of the powder bed laser melting additive manufacturing technology include: laser power 150~200 W, scanning speed 1200~1600 mm / s, scanning spacing 75~85 μm, and powder layer thickness 25~32 μm.

8. The method as described in claim 1, characterized in that, The parameters for the hot isostatic pressing treatment are: temperature 1150℃, pressure 150MPa, and holding time 3h. And / or, the solution treatment temperature is 1180℃~1280℃, and the holding time is 0.5h-2h.

9. A nano-Y-Hf-O composite oxide dispersion-strengthened nickel-based superalloy, characterized in that, The nano-Y-Hf-O composite oxide dispersion-strengthened nickel-based superalloy is prepared by the method described in any one of claims 1-8.

10. The application of the nano-Y-Hf-O composite oxide dispersion-strengthened nickel-based superalloy of claim 9 or the method of any one of claims 1-8 in the preparation of nuclear energy system components and aerospace hot-end components.

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