An oxide and gamma apos; preparation method of reinforced nickel-based alloy

Abstract

The invention discloses a preparation method of an oxide and gamma'reinforced nickel-based alloy, and belongs to the technical field of alloy materials. The method comprises the steps that pre-alloyed powder (13%-14% of Cr, 3%-4% of Al, 5%-6% of Ti and the balance Ni) and 0.8%-1.0% of Y2O3 powder are subjected to ball milling under argon protection, and mechanical alloyed powder is obtained; selective laser melting (SLM) is adopted for preparation, the laser power ranges from 280 W to 320 W, the scanning speed ranges from 1600 mm / s to 2000 mm / s, the scanning distance ranges from 0.04 mm to 0.08 mm, the layer thickness ranges from 20 micrometers to 40 micrometers, the scanning rotation angle ranges from 65 degrees to 69 degrees, and the oxide and gamma'reinforced nickel base alloy is obtained. Uniform dispersion of nano Y2O3 is realized through mechanical alloying, and a dual strengthening mechanism of oxide dispersion strengthening and gamma'phase precipitation strengthening is realized in combination with optimized selective laser melting process parameters. The prepared nickel-based alloy is low in porosity (1.36-1.68%), the tensile strength reaches 257-276 MPa at the temperature of 800 DEG C, the excellent high-temperature mechanical property is shown, and the nickel-based alloy is suitable for additive manufacturing of high-temperature structural parts in the fields of aerospace and the like.

Description

Technical Field

[0001] This invention belongs to the field of alloy materials technology, specifically relating to a method for preparing oxide and γ'-reinforced nickel-based alloys, and more particularly to a method for preparing high-performance nickel-based alloys with a dual strengthening mechanism by introducing nano-Y2O3 powder through mechanical alloying and combining it with selective laser melting. Background Technology

[0002] Nickel-based superalloys are widely used in high-temperature structural components in aerospace, gas turbines, and nuclear energy fields due to their excellent high-temperature strength, oxidation resistance, and creep resistance. To meet increasingly demanding service conditions, various strengthening mechanisms are needed to improve the overall performance of nickel-based alloys.

[0003] γ' phase precipitation strengthening is one of the most important strengthening mechanisms in nickel-based superalloys. By adding Al and Ti elements to the alloy, fine, dispersed γ' phases can precipitate in the matrix, effectively hindering dislocation movement and significantly improving the alloy's high-temperature strength and creep resistance. Oxide dispersion strengthening is another effective strengthening method. It introduces nanoscale oxide particles to form stable, dispersed phases at grain boundaries and within grains. These oxide particles exhibit excellent thermal stability at high temperatures, effectively pinning dislocations and grain boundaries, and preventing grain growth and dislocation climb. Among these, Y₂O₃ is widely used due to its high thermal stability and good dispersion effect.

[0004] Mechanical alloying is an important technique for preparing oxide dispersion-strengthened alloys. High-energy ball milling can uniformly disperse nano-oxide particles in alloy powder, preventing particle agglomeration. Selective laser melting, as an advanced additive manufacturing technology, offers advantages such as high forming accuracy, high material utilization, and the ability to manufacture complex structures, and has attracted widespread attention in the aerospace field.

[0005] However, existing technologies have the following shortcomings: First, traditional oxide dispersion strengthened nickel-based alloy preparation methods mainly employ mechanical alloying combined with hot extrusion or hot isostatic pressing processes, which have drawbacks such as long processing cycles, high costs, and difficulty in preparing complex shaped components.

[0006] Second, selective laser melting (SLM) technology faces challenges in preparing nickel-based superalloys, including high porosity, inhomogeneous microstructure, and large fluctuations in mechanical properties. This is particularly true for oxide dispersion-strengthened nickel-based alloys, where the presence of oxide particles makes the SLM formability and densification process more complex, resulting in limited research and insufficient optimization of process parameters.

[0007] Third, existing research mostly focuses on nickel-based alloys with a single strengthening mechanism. Research on dual-strengthened nickel-based alloys, particularly those using selective laser melting (SLM) to prepare such alloys, is still relatively scarce. How to achieve a synergistic strengthening effect of γ' phase and oxide particles through alloy composition design and process parameter optimization, thereby obtaining excellent high-temperature mechanical properties while maintaining low porosity, is a key technical problem that urgently needs to be solved.

[0008] Therefore, it is necessary to develop a new preparation method that uses mechanical alloying technology to uniformly disperse nano-Y2O3 powder in nickel-based pre-alloyed powder containing Al and Ti, and combines optimized selective laser melting process parameters to achieve a dual strengthening mechanism of oxide dispersion strengthening and γ' phase precipitation strengthening, thereby preparing a nickel-based alloy with low porosity and excellent high-temperature performance to meet the needs of aerospace and other fields for high-performance heat-resistant materials. Summary of the Invention

[0009] In view of the above-mentioned problems in the existing technology, the purpose of this invention is to provide a method for preparing oxide and γ'-strengthened nickel-based alloys. This method achieves the synergistic effect of dual strengthening mechanisms by organically combining mechanical alloying and selective laser melting technology, thereby obtaining excellent high-temperature mechanical properties while ensuring low porosity.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is a method for preparing an oxide and γ'-reinforced nickel-based alloy, comprising the following steps: Pre-alloyed powder and Y₂O₃ powder were ball-milled under argon protection to obtain mechanically alloyed powder. The pre-alloyed powder, by mass percentage, consisted of: Cr 13-14%, Al 3-4%, Ti 5-6%, with the balance being Ni. The amount of Y₂O₃ powder added was 0.8-1.0% of the mass of the pre-alloyed powder. The mechanically alloyed powder was prepared by selective laser melting to obtain oxides and γ'-reinforced nickel-based alloys. The selective laser melting power was 280-320W, the scanning speed was 1600-2000mm / s, the scanning spacing was 0.04-0.08mm, the layer thickness was 20-40μm, and the scanning rotation angle was 65-69°.

[0011] The technical concept of this invention is as follows: First, by designing the alloy composition, appropriate amounts of Al and Ti elements are introduced into the pre-alloyed powder to provide the necessary alloying element basis for the subsequent precipitation of the γ' phase. These elements form a supersaturated solid solution under the rapid cooling conditions during selective laser melting, and then precipitate a fine and uniform γ' strengthening phase under thermal cycling.

[0012] Secondly, mechanical alloying technology is employed to uniformly disperse nano-Y2O3 powder on the surface and within the pre-alloyed powder. The high-energy ball milling process causes mechanical embedding and partial dissolution of oxide particles, avoiding the agglomeration problem common in traditional methods. An argon protective atmosphere effectively prevents powder oxidation, ensuring powder quality. Adding an appropriate amount of process control agent prevents excessive cold welding of the powder, ensuring optimal ball milling results.

[0013] Furthermore, by optimizing the selective laser melting process parameters, a reasonable match is established between laser energy input, scanning speed, and scanning strategy. Appropriate laser power and scanning speed ensure sufficient powder melting and rapid solidification, reducing the formation of porosity defects. Reasonable scanning spacing and layer thickness guarantee good bonding between adjacent melt channels and layers. Specific scanning rotation angles optimize thermal stress distribution and improve microstructure uniformity.

[0014] The technical problems solved by this invention include: First, it solves the problem of the difficulty in fabricating complex components using oxide dispersion strengthened nickel-based alloys. By combining mechanical alloying with selective laser melting technology, direct forming of complex-shaped components is achieved.

[0015] Secondly, the problem of high porosity in the preparation of oxide dispersion-strengthened alloys by selective laser melting was solved. By optimizing the combination of process parameters, especially the reasonable matching of laser power, scanning speed, and scanning spacing, the porosity of the formed parts was effectively reduced.

[0016] Third, the synergistic effect of dual strengthening mechanisms—γ' phase precipitation strengthening and oxide dispersion strengthening—was achieved. Nano-Y2O3 particles are uniformly dispersed in the matrix, pinning dislocations at grain boundaries and within grains, thus improving high-temperature stability. Simultaneously, the precipitated γ' phase hinders dislocation movement. The synergistic effect of these two strengthening mechanisms significantly enhances the high-temperature mechanical properties of the alloy. Attached Figure Description

[0017] Figure 1 Nickel-based alloy samples prepared for embodiments of the present invention; Figure 2 These are measured images of the nickel-based alloy samples prepared in Examples 1 and 2 of this invention after high-temperature tensile testing. Figure 3 This is a schematic diagram showing the dimensions of the nickel-based alloy samples prepared in Examples 1 and 2 of the present invention; Detailed Implementation

[0018] This invention provides a method for preparing oxide and γ'-reinforced nickel-based alloys, comprising the following steps: Pre-alloyed powder and Y2O3 powder were ball-milled under argon protection to obtain mechanically alloyed powder; the composition of the pre-alloyed powder, by mass percentage, was: Cr 13-14%, Al 3-4%, Ti 5-6%, with the balance being Ni; the amount of Y2O3 powder added was 0.8-1.0% of the mass of the pre-alloyed powder. The mechanically alloyed powder was prepared by selective laser melting to obtain oxides and γ'-reinforced nickel-based alloys.

[0019] Using the aforementioned mechanically alloyed powder, selective laser melting (SLM) is employed to uniformly disperse nano-Y₂O₃ powder within the pre-alloyed powder through a mechanical alloying process. By controlling the process parameters during SLM, uniform dispersion of the oxide and precipitation of the γ' phase are achieved, forming a dual strengthening mechanism of oxide dispersion strengthening and γ' phase precipitation strengthening. This results in excellent high-temperature mechanical properties of the nickel-based alloy under low porosity conditions. The method provided by this invention effectively avoids the drawbacks of traditional methods, such as complex processing, high cost, and low efficiency, offering a new technical solution for preparing large-size, high-precision, and complex components made of dual-strengthened nickel-based alloys.

[0020] In this invention, pre-alloyed powder and Y2O3 powder are ball-milled under argon protection to obtain mechanically alloyed powder; the pre-alloyed powder has the following composition by mass percentage: Cr 13-14%, Al 3-4%, Ti 5-6%, with the balance being Ni.

[0021] In this invention, the purity of the Y₂O₃ powder is above 99%. In this invention, the particle size of the pre-alloyed powder is less than 75 μm; the particle size of the Y₂O₃ powder is less than 50 nm.

[0022] In this invention, the mass ratio of the pre-alloyed powder to the Y2O3 powder is 100:0.8-1.0.

[0023] In this invention, the pre-alloyed powder is prepared according to the following method: A master alloy was prepared by adding 13-14% Cr, 3-4% Al, 5-6% Ti and the balance Ni. After vacuum induction melting, the alloy was atomized to obtain a pre-alloyed powder.

[0024] During ball milling, a process control agent is added to prevent excessive cold welding of the powder; the process control agent is 4-5% ethanol by mass. In this invention, the preferred mass ratio of raw material to grinding balls is 1:22-1:26. In this invention, the ball milling time is 34-38 hours; the ball milling speed is 300-400 rpm; and the ball milling atmosphere is argon.

[0025] After obtaining the mechanically alloyed powder, this invention uses selective laser melting to prepare oxides and γ'-reinforced nickel-based alloys. This invention comprehensively considers the rational combination of process parameters such as laser power, scanning speed, scanning spacing, and scanning rotation angle to ensure that the prepared nickel-based alloys exhibit excellent room-temperature and high-temperature mechanical properties under low porosity conditions.

[0026] In this invention, the specific implementation steps for preparing oxides and γ'-reinforced nickel-based alloys using selective laser melting are as follows: 1. Prepare mechanically alloyed powder by ball milling using appropriate process parameters, and screen powders within a certain particle size range; 2. Use modeling software to create a 3D model of the sample; 3. Input the 3D model into the selected area laser melting equipment, and the file is converted into a processing path according to the layer thickness.

[0027] 4. Selective laser melting equipment melts powder layer by layer to form three-dimensional samples. In this invention, the selected area laser melting power is 280-320W, the scanning speed is 1600-2000mm / s, the scanning interval is 0.04-0.08mm, the layer thickness is 20-40μm, the scanning rotation angle is 65-69°, and the layer thickness is 20-40μm. In a specific embodiment of this invention, the laser power is 300W, the scanning speed is 1800mm / s, the scanning interval is 0.06mm, the scanning rotation angle is 67°, and the layer thickness is 30μm.

[0028] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, of an oxide and γ'-reinforced nickel-based alloy and its preparation method provided by the present invention, should not be construed as limiting the scope of protection of the present invention.

[0029] Example 1 Selective laser melting (SLM) for the preparation of oxide and γ'-strengthened nickel-based alloys Using pre-alloyed powder containing 13-14% Cr, 3-4% Al, 5-6% Ti, and the balance Ni as raw material, Y2O3 (particle size <50nm) accounting for 0.9% of the mass of the pre-alloyed powder and ethanol accounting for 4.5% of the mass as process control agents were placed in a planetary ball mill and ball-milled for 36 hours at 350 rpm under argon protection. The ball-to-powder ratio (mass of grinding balls to mass of powder) was 24:1, and the powder was passed through a 200-mesh sieve to obtain mechanically alloyed powder with a particle size <75μm.

[0030] The process parameters for selective laser melting are: laser power 300W, scanning speed 1800mm / s, scanning spacing 0.06mm, scanning rotation angle 67°, and layer thickness 30μm. Selective laser melting stops when the workpiece reaches a certain size. Figure 1 As shown, Figure 1 This is a diagram of a nickel-based alloy sample prepared in Example 1 of the present invention. The sample is a tensile sample, and the tensile direction of the sample is perpendicular to the forming direction, as shown below. Figure 3 As shown, Figure 3 This is a schematic diagram showing the dimensions of the nickel-based alloy tensile specimen prepared in Example 1 of the present invention.

[0031] The microstructure and mechanical properties of the nickel-based alloy sample prepared in Example 1 were tested. The results showed that the alloy porosity was 1.68%, and the tensile test conditions were: strain rate of 0.001 s⁻ 1 The tensile strength at 800℃ is 257MPa, as shown in Table 1. Table 1 is a performance comparison table of the nickel-based alloys prepared in Example 1 and Comparative Example 1 of the present invention. It can be seen from Table 1 that Example 1 is superior to the corresponding index of the nickel-based alloy of Comparative Example 1 with the same composition prepared by SLM.

[0032] Table 1. Porosity and performance test results of nickel-based alloys prepared in Examples 1, 2 and Comparative Example 1 of this invention. sample Porosity (%) Tensile strength at 800℃ (MPa) Comparative Example 1 6.14 175 Example 1 1.68 257 Example 2 1.36 276 Example 2 Selective laser melting (SLM) for the preparation of oxide and γ'-strengthened nickel-based alloys Using pre-alloyed powder containing 13-14% Cr, 3-4% Al, 5-6% Ti, and the balance Ni as raw material, Y2O3 (particle size <50nm) accounting for 0.9% of the mass of the pre-alloyed powder and ethanol accounting for 4.5% of the mass as process control agents were placed in a planetary ball mill and ball-milled for 36 hours at 350 rpm under argon protection. The ball-to-powder ratio (mass of grinding balls to mass of powder) was 24:1, and the powder was passed through a 200-mesh sieve to obtain mechanically alloyed powder with a particle size <75μm.

[0033] The process parameters for selective laser melting are: laser power 300W, scanning speed 1800mm / s, scanning spacing 0.06mm, scanning rotation angle 67°, and layer thickness 30μm. Selective laser melting stops when the workpiece reaches a certain size. Figure 1 As shown, Figure 1 This is a diagram of a nickel-based alloy sample prepared in Example 2 of the present invention. The sample is a tensile sample, and the tensile direction of the sample is perpendicular to the forming direction, as shown below. Figure 3 As shown, Figure 3 This is a schematic diagram showing the dimensions of the nickel-based alloy tensile specimen prepared in Example 2 of the present invention.

[0034] The microstructure and mechanical properties of the nickel-based alloy sample prepared in Example 2 were tested. The results showed that the alloy porosity was 1.36%, and the tensile test conditions were: strain rate of 0.001 s⁻ 1 The tensile strength at 800℃ is 276MPa, as shown in Table 1. Table 1 is a performance comparison table of the nickel-based alloys prepared in Example 2 and Comparative Example 1 of the present invention. It can be seen from Table 1 that Example 2 is superior to the corresponding index of the nickel-based alloy of Comparative Example 1 with the same composition prepared by SLM.

[0035] Comparative Example 1 Selective laser melting (SLM) for the preparation of oxide and γ'-strengthened nickel-based alloys Using pre-alloyed powder containing 13-14% Cr, 3-4% Al, 5-6% Ti, and the balance Ni as raw material, Y2O3 (particle size <50nm) accounting for 0.9% of the mass of the pre-alloyed powder and ethanol accounting for 4.5% of the mass as process control agents were placed in a planetary ball mill and ball-milled for 36 hours at 350 rpm under argon protection. The ball-to-powder ratio (mass of grinding balls to mass of powder) was 24:1, and the powder was passed through a 200-mesh sieve to obtain mechanically alloyed powder with a particle size <75μm.

[0036] The selective laser melting (SLM) process parameters are: laser power 270W, scanning speed 2000mm / s, scanning spacing 0.08mm, scanning rotation angle 0°, and layer thickness 30μm. SLM stops when the workpiece reaches a certain size. The specimen is a tensile specimen, with the tensile direction perpendicular to the forming direction, such as... Figure 3 As shown, Figure 3 This is a schematic diagram showing the dimensions of the nickel-based alloy tensile specimen prepared in Comparative Example 1 of this invention.

[0037] This invention tests the microstructure and mechanical properties of the nickel-based alloy sample prepared in Comparative Example 1. The alloy porosity is 6.14%, and the tensile test conditions are: strain rate of 0.001 s⁻ 1 The tensile strength at 800℃ is 175MPa, as shown in Table 1. Table 1 is a performance comparison table of nickel-based alloys prepared in Examples 1 and 2 and Comparative Example 1 of the present invention. It can be seen from Table 1 that Examples 1 and 2 are superior to the corresponding indicators of Comparative Example 1, which is a nickel-based alloy of the same composition prepared by SLM.

[0038] As can be seen from the above embodiments, the present invention provides a method for preparing oxide and γ'-reinforced nickel-based alloys, comprising the following steps: ball milling pre-alloyed powder with 0.8-1.0% Y2O3 powder under argon protection to obtain mechanically alloyed powder; the pre-alloyed powder, by mass percentage, has the following composition: Cr 13-14%, Al 3-4%, Ti 5-6%, with the balance being Ni; the mechanically alloyed powder is prepared by selective laser melting to obtain oxide and γ'-reinforced nickel-based alloys; the power of the selective laser melting is 280-320W, the scanning speed is 1600-2000mm / s, the scanning spacing is 0.04-0.08mm, the layer thickness is 20-40μm, and the scanning rotation angle is 65-69°. This invention employs selective laser melting (SLM) using mechanically alloyed powders with the aforementioned composition. By controlling the process parameters during SLM, uniform dispersion of oxides and precipitation of the γ' phase are achieved, forming a dual strengthening mechanism of oxide dispersion strengthening and γ' phase precipitation strengthening. This results in nickel-based alloys exhibiting excellent high-temperature mechanical properties under low porosity conditions. Experimental results show that the alloy porosity is 1.36-1.68%, and the strain rate is 0.001 s⁻. 1 The alloy exhibits excellent high-temperature mechanical properties with a tensile strength of 257-276 MPa at 800℃.

[0039] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an oxide and γ'-reinforced nickel-based alloy, comprising the following steps: Pre-alloyed powder and Y₂O₃ powder were ball-milled under argon protection to obtain mechanically alloyed powder. The pre-alloyed powder, by mass percentage, consisted of: Cr 13-14%, Al 3-4%, Ti 5-6%, with the balance being Ni; the amount of Y₂O₃ powder added was 0.8-1.0% of the mass of the pre-alloyed powder. The mechanically alloyed powder was prepared by selective laser melting to obtain oxides and γ'-reinforced nickel-based alloys; the power of the selective laser melting was 280-320W, the scanning speed was 1600-2000mm / s, the scanning spacing was 0.04-0.08mm, the layer thickness was 20-40μm, and the scanning rotation angle was 65-69°.

2. The method according to claim 1, characterized in that, The pre-alloyed powder is prepared by the following method: a master alloy is prepared by 13-14% Cr, 3-4% Al, 5-6% Ti and the balance Ni, and then atomized to obtain the pre-alloyed powder.

3. The method according to claim 1, characterized in that, The pre-alloyed powder has a particle size of less than 75 μm; the Y2O3 powder has a particle size of less than 50 nm.

4. The method according to claim 1, characterized in that, A process control agent, which is 4-5% by mass of ethanol, is added before ball milling.

5. The method according to claim 1, characterized in that, The ball milling time is 34-38 hours; the ball milling speed is 300-400 rpm; and the ball-to-material ratio is 22:1-26:1.

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