Ultrahigh-temperature multi-element iridium alloy material and preparation method thereof

Abstract

The invention discloses an ultrahigh-temperature multi-element iridium alloy material and a preparation method thereof, and belongs to the technical field of alloy materials. The iridium alloy material comprises the following elements in percentage by mass: 53 to 58.5 percent of Ir, 40 percent of Ta, 0.5 to 2 percent of Y and 1 to 5 percent of Re. The preparation method of the iridium alloy material comprises the following steps: weighing Ir, Ta, Y and Re metal powder in proportion and uniformly mixing; blank pre-pressing treatment is conducted on the evenly-mixed metal powder, the metal powder is die-cast into a block, and a pressed blank is obtained; the pressed blank is smelted through an electric arc smelting method, and an iridium alloy crude product is obtained after smelting is finished; and the smelting is repeated for more than 7 times, so that the pressed blank is uniformly smelted, the content of each component reaches the standard, and the iridium alloy material is prepared. According to the iridium alloy material, through the synergistic effect of multiple elements and the preparation technology, the triple effects of structural distortion strengthening, high-temperature stability and oxidation film integrity are achieved. And due to the high mixed entropy, a similar high-entropy alloy structure is formed, the high-temperature oxidation resistance is remarkably improved, and the alloy is suitable for various ultra-high-temperature environments.

Description

Technical Field

[0001] This invention relates to a multi-element iridium alloy material for ultra-high temperature applications and its preparation method, belonging to the field of alloy material technology. Background Technology

[0002] With the rapid development of modern technology and industry, there is an urgent need for materials that are resistant to high temperatures, oxidation, and corrosion. Iridium alloys, with their crystal structure similar to nickel-based alloys, are considered ideal materials for the next generation of superalloys. Researchers have already conducted in-depth studies on iridium alloys: adding rhodium (Rh) to iridium (Ir) has shown that the addition of rhodium increases the high-temperature stability of the alloy. In iridium-rhodium alloys with 30-50% rhodium content, the weight loss rate is only half that of pure iridium. Although the weight loss rate of the aforementioned iridium-rhodium alloys is better than that of pure iridium, the alloy begins to lose weight after 10 hours of oxidation in an atmospheric atmosphere at 1550℃, resulting in a short overall service life. Furthermore, domestic research on multi-element iridium alloys is relatively limited, with existing studies mainly focusing on the addition of trace elements. Molten iridium has poor flow properties and a low element diffusion rate, making it prone to segregation of alloying elements in the iridium matrix. Moreover, multi-element iridium alloys exhibit complex intermediate phase formation. The iridium alloy material preparation method of the present invention enables Ta, Y, and Re to effectively combine with iridium. While significantly reducing the iridium content, it ensures that the alloy has an ultra-high melting point similar to that of pure iridium and has better oxidation resistance than pure iridium material, thereby enhancing the ultra-high temperature service life of the material. Summary of the Invention

[0003] One of the objectives of this invention is to provide a multi-element iridium alloy material for ultra-high temperature applications, wherein the elemental composition of the iridium alloy material, by mass fraction, is: 53~58.5% Ir, 40% Ta, 0.5~2% Y, and 1~5% Re.

[0004] Another objective of this invention is to provide a method for preparing a multi-element iridium alloy material for ultra-high temperature applications, specifically comprising the following steps: (1) Weigh out Ir, Ta, Y and Re powders by mass percentage and mix them evenly.

[0005] (2) The uniformly mixed metal powder is pre-pressed into a block shape to obtain a pressed blank.

[0006] (3) The pressed blank is smelted, and the crude product of iridium alloy material is obtained after the smelting is completed.

[0007] (4) Repeat step (3) above more than 7 times to make the pressed blank completely melted and uniform, and the content of each component meets the standard, so as to prepare iridium alloy material.

[0008] Preferably, in step (3), the pressing of the blank is carried out by electric arc melting. The specific method is as follows: the melting device (such as a melting furnace) is evacuated to ≤9×10 -4 Pa; Inert gas (such as high-purity argon with a purity of 99.99%) is introduced into the melting device until the gauge pressure inside the furnace is -0.05MPa; an electric arc is generated by the electrodes, and the current is ≥420A. The high temperature generated by the electric arc is used to melt the pressed blank.

[0009] Preferably, in step (4), step (3) is repeated more than 7 times, each time for 3 minutes. After melting is completed, the sample is cooled to room temperature to obtain iridium alloy material.

[0010] Mechanism of the invention: In this invention, the combined use of four metals—Ir, Ta, Y, and Re—in conjunction with the alloy preparation process of this invention generates a multi-element and process interaction, resulting in a synergistic triple effect of structural distortion enhancement, high-temperature stability, and oxide film integrity. The preparation process of this invention increases the mixing entropy of the material by mixing multiple alloying elements, forming a near-high-entropy alloy structure. Compared to single pure metals like Ir or Ir-Ta binary alloys, this structure more easily forms a stable body-centered cubic (BCC) phase. The synergistic effect of the multiple metals and the preparation process in this invention endows the iridium alloy material with stable high-temperature oxidation resistance and improves the oxide film structure, enabling the iridium alloy material to suppress crack formation under high-temperature cyclic oxidation conditions and protect the integrity of the entire oxide film.

[0011] The beneficial effects of this invention are: (1) The iridium alloy material prepared by the process of this invention has excellent high-temperature oxidation resistance. When the iridium alloy material prepared by this invention and pure metallic iridium were oxidized at 1500℃ for 12 hours, it was found that the pure metallic iridium began to lose weight after 12 hours, while the iridium alloy material of this invention remained in the state of oxidation and weight gain. Characterization was performed by SEM, and the specific characterization results are as follows: Figure 10 As shown, the iridium alloy material retains a continuous and dense oxide layer after cyclic oxidation at 1500℃ for 12 hours, with no obvious cracks observed.

[0012] (2) This invention uses a cyclic melting process and optimized Ir, Ta, Y and Re ratio to significantly reduce the amount of iridium by adding a large amount of tantalum, while ensuring that the alloy has an ultra-high melting point similar to pure iridium and better oxidation resistance than pure iridium material, thereby greatly improving the durability of the material in extreme high temperature environments. Attached Figure Description

[0013] Figure 1 The image shows the non-equilibrium solidification simulation of the iridium alloy material prepared in Example 1 in Thermo-Calc software.

[0014] Figure 2 The image shows the non-equilibrium solidification simulation of the iridium alloy material prepared in Example 2 in Thermo-Calc software.

[0015] Figure 3 The image shows the non-equilibrium solidification simulation of the iridium alloy material prepared in Example 3 in Thermo-Calc software.

[0016] Figure 4 The image shows the non-equilibrium solidification simulation of the iridium alloy material prepared in Example 4 in Thermo-Calc software.

[0017] Figure 5 The image shows the non-equilibrium solidification simulation of the iridium alloy material prepared in Example 5 in Thermo-Calc software.

[0018] Figure 6 The image shows the non-equilibrium solidification simulation of the iridium alloy material prepared in Example 6 in Thermo-Calc software.

[0019] Figure 7 The image shows the non-equilibrium solidification simulation of the iridium alloy material prepared in Example 7 in Thermo-Calc software.

[0020] Figure 8 The image shows the non-equilibrium solidification simulation of the iridium alloy material prepared in Example 8 in Thermo-Calc software.

[0021] Figure 9 The image shows the non-equilibrium solidification simulation of the iridium alloy material prepared in Example 9 in Thermo-Calc software.

[0022] Figure 10 This is a SEM characterization image of the oxide film on the surface of the iridium alloy material with a dense structure prepared in this invention.

[0023] Figure 11 SEM characterization image of the porous iridium alloy oxide film prepared for Comparative Example 2.

[0024] Figure 12 SEM characterization image of the oxide film of the iridium alloy material with localized cracks prepared for Comparative Example 3.

[0025] Figure 13 The image shows the non-equilibrium solidification simulation of the iridium alloy material prepared in Comparative Example 4 in Thermo-Calc software. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0027] The alloy compositions of the embodiments and comparative examples of the present invention are shown in Table 1.

[0028] Table 1 Example 1 This embodiment prepares iridium alloy material according to the following method: (1) Weigh the following raw materials by mass percentage: 58.5% Ir, 40% Ta, 0.5% Y, and 1% Re, and then mix the metal powder evenly.

[0029] (2) The uniformly mixed metal powder is pre-pressed into a block shape to obtain a pressed blank.

[0030] (3) Evacuate the smelting furnace to a vacuum level of ≤9×10. -4 Pa; High-purity argon gas with a purity of 99.99% is introduced into the melting furnace until the gauge pressure inside the furnace is -0.05MPa. An electric arc is generated by the electrodes, and the current is ≥420A. The high temperature generated by the electric arc is used to melt the pressed blank. After the melting is completed, the crude product of iridium alloy material is obtained.

[0031] (4) Repeat the above steps more than 7 times, each time for 3 minutes. If the molten metal in the pressing process flows smoothly, turn on the electromagnetic stirring to make the pressing process completely melted and uniform, and the content of each component reaches the standard (i.e., the mass percentage of Ir reaches 58.5%, the mass percentage of Ta reaches 40%, the mass percentage of Y reaches 0.5%, and the mass percentage of Re reaches 1%), and iridium alloy material is prepared.

[0032] The high-temperature resistance of the iridium alloy material prepared in this embodiment was tested using an ultra-high temperature cyclic oxidation experiment, specifically including the following steps: (1) Cut the alloy button ingot after melting and cut the sample size to 2mm×3mm×6mm.

[0033] (2) Use vernier calipers to measure the actual size of the cut sample block and calculate the surface area of ​​the sample.

[0034] (3) Measure the original mass of the sample.

[0035] (4) Heat the tubular resistance furnace to 1500°C in an atmospheric atmosphere, place the polished sample inside, and conduct a cyclic oxidation experiment.

[0036] (5) Measure the oxidation mass of the samples after 10 min, 30 min, 1 h, 2 h, 4 h, 6 h, 8 h, 10 h, 12 h, 15 h, 19 h and 24 h of cyclic oxidation.

[0037] (6) Subtract the original mass of the sample from the oxidized mass of the sample and then divide by the sample surface area to obtain the oxidized weight gain per unit area. The high temperature resistance of the sample can be judged based on the oxidized weight gain per unit area.

[0038] Tests showed that the iridium alloy material prepared in this embodiment, under the premise of adding a large amount of Ta to significantly reduce the amount of iridium, will first oxidize and increase in weight during the test. Moreover, because the iridium alloy material has a composite oxide layer composed of yttrium oxide and tantalum oxide, it can greatly reduce the inward diffusion of oxygen. No oxide film rupture was observed after 12 hours of oxidation. The test results indicate that the iridium alloy material prepared in this embodiment has excellent high-temperature oxidation resistance.

[0039] Example 2 This embodiment uses the same method as Example 1 to prepare iridium alloy material, the difference being: as shown in Table 1, the Ir content in this embodiment is 57% and the Re content is 2.5%.

[0040] The iridium alloy material prepared in this embodiment was subjected to high-temperature resistance testing in the same manner as in Example 1. The test results showed that the iridium alloy material prepared in this embodiment oxidized and gained weight during the test, even with the addition of a large amount of Ta to significantly reduce the amount of iridium. Furthermore, the composite oxide layer composed of yttrium oxide and tantalum oxide greatly reduced the inward diffusion of oxygen. No oxide film rupture was observed even after 12 hours of oxidation. The test results indicate that the iridium alloy material prepared in this embodiment has excellent high-temperature oxidation resistance.

[0041] Example 3 This embodiment uses the same method as Example 1 to prepare iridium alloy material, the difference being: as shown in Table 1, the Ir content in this embodiment is 54.5% and the Re content is 5%.

[0042] The iridium alloy material prepared in this embodiment was subjected to high-temperature resistance testing in the same manner as in Example 1. The test results showed that the iridium alloy material prepared in this embodiment oxidized and gained weight during the test, even with the addition of a large amount of Ta to significantly reduce the amount of iridium. Furthermore, the composite oxide layer composed of yttrium oxide and tantalum oxide greatly reduced the inward diffusion of oxygen. No oxide film rupture was observed even after 12 hours of oxidation. The test results indicate that the iridium alloy material prepared in this embodiment has excellent high-temperature oxidation resistance.

[0043] Example 4 This embodiment uses the same method as Example 1 to prepare iridium alloy material, the difference being: as shown in Table 1, the Ir content in this embodiment is 57.5% and the Y content is 1.5%.

[0044] The iridium alloy material prepared in this embodiment was subjected to high-temperature resistance testing in the same manner as in Example 1. The test results showed that the iridium alloy material prepared in this embodiment oxidized and gained weight during the test, even with the addition of a large amount of Ta to significantly reduce the amount of iridium. Furthermore, the composite oxide layer composed of yttrium oxide and tantalum oxide greatly reduced the inward diffusion of oxygen. No oxide film rupture was observed even after 12 hours of oxidation. The test results indicate that the iridium alloy material prepared in this embodiment has excellent high-temperature oxidation resistance.

[0045] Example 5 This embodiment uses the same method as Example 1 to prepare iridium alloy material, the difference being: as shown in Table 1, in this embodiment the Ir content is 56%, the Y content is 1.5%, and the Re content is 2.5%.

[0046] The iridium alloy material prepared in this embodiment was subjected to high-temperature resistance testing in the same manner as in Example 1. The test results showed that the iridium alloy material prepared in this embodiment oxidized and gained weight during the test, even with the addition of a large amount of Ta to significantly reduce the amount of iridium. Furthermore, the composite oxide layer composed of yttrium oxide and tantalum oxide greatly reduced the inward diffusion of oxygen. No oxide film rupture was observed even after 12 hours of oxidation. The test results indicate that the iridium alloy material prepared in this embodiment has excellent high-temperature oxidation resistance.

[0047] Example 6 This embodiment uses the same method as Example 1 to prepare iridium alloy material, the difference being: as shown in Table 1, in this embodiment the Ir content is 53.5%, the Y content is 1.5%, and the Re content is 5%.

[0048] The iridium alloy material prepared in this embodiment was subjected to high-temperature resistance testing in the same manner as in Example 1. The test results showed that the iridium alloy material prepared in this embodiment oxidized and gained weight during the test, even with the addition of a large amount of Ta to significantly reduce the amount of iridium. Furthermore, the composite oxide layer composed of yttrium oxide and tantalum oxide greatly reduced the inward diffusion of oxygen. No oxide film rupture was observed even after 12 hours of oxidation. The test results indicate that the iridium alloy material prepared in this embodiment has excellent high-temperature oxidation resistance.

[0049] Example 7 This embodiment uses the same method as Example 1 to prepare iridium alloy material, the difference being: as shown in Table 1, the Ir content in this embodiment is 57% and the Y content is 2%.

[0050] The iridium alloy material prepared in this embodiment was subjected to high-temperature resistance testing in the same manner as in Example 1. The test results showed that the iridium alloy material prepared in this embodiment oxidized and gained weight during the test, even with the addition of a large amount of Ta to significantly reduce the amount of iridium. Furthermore, the composite oxide layer composed of yttrium oxide and tantalum oxide greatly reduced the inward diffusion of oxygen. No oxide film rupture was observed even after 12 hours of oxidation. The test results indicate that the iridium alloy material prepared in this embodiment has excellent high-temperature oxidation resistance.

[0051] Example 8 This embodiment uses the same method as Example 1 to prepare iridium alloy material, the difference being: as shown in Table 1, in this embodiment the Ir content is 55.5%, the Y content is 2%, and the Re content is 2.5%.

[0052] The iridium alloy material prepared in this embodiment was subjected to high-temperature resistance testing in the same manner as in Example 1. The test results showed that the iridium alloy material prepared in this embodiment oxidized and gained weight during the test, even with the addition of a large amount of Ta to significantly reduce the amount of iridium. Furthermore, the composite oxide layer composed of yttrium oxide and tantalum oxide greatly reduced the inward diffusion of oxygen. No oxide film rupture was observed even after 12 hours of oxidation. The test results indicate that the iridium alloy material prepared in this embodiment has excellent high-temperature oxidation resistance.

[0053] Example 9 This embodiment uses the same method as Example 1 to prepare iridium alloy material, the difference being: as shown in Table 1, in this embodiment the Ir content is 53%, the Y content is 2%, and the Re content is 5%.

[0054] The iridium alloy material prepared in this embodiment was subjected to high-temperature resistance testing in the same manner as in Example 1. The test results showed that the iridium alloy material prepared in this embodiment oxidized and gained weight during the test, even with the addition of a large amount of Ta to significantly reduce the amount of iridium. Furthermore, the composite oxide layer composed of yttrium oxide and tantalum oxide greatly reduced the inward diffusion of oxygen. No oxide film rupture was observed even after 12 hours of oxidation. The test results indicate that the iridium alloy material prepared in this embodiment has excellent high-temperature oxidation resistance.

[0055] Comparative Example 1 uses the same method as Example 1 to prepare pure metallic iridium material, except that, as shown in Table 1, the Ir content in this comparative example is 100%.

[0056] The high-temperature resistance of the pure metallic iridium material prepared in this comparative example was tested by an ultra-high temperature cyclic oxidation experiment. The specific test method was the same as that in Example 1. The test results showed that the pure metallic iridium material in Comparative Example 1 would undergo an oxidation reaction to generate iridium oxide at a temperature of 600℃. The iridium oxide would volatilize at a temperature of about 1100℃. That is, the pure metallic iridium material would lose weight at the beginning in an environment of 1500℃, and its high-temperature oxidation stability was poor.

[0057] Comparative Example 2 used the same method as Example 1 to prepare iridium alloy materials, except that, as shown in Table 1, the Ir content in this comparative example was 55%, the Y content was 0%, and the Re content was 5%.

[0058] The high-temperature resistance of the iridium alloy material prepared in this comparative example was tested using an ultra-high temperature cyclic oxidation experiment. The specific testing method was the same as in Example 1. The test results showed that the iridium alloy material in Comparative Example 2 had poor high-temperature oxidation stability. This is because its oxide film is mainly composed of tantalum oxide and iridium oxide. Due to the volatilization of iridium oxide, the main material of the oxide film is tantalum oxide, and the surface of the oxide film is sieve-like (e.g., Figure 11 As shown in the figure, oxygen diffuses inwards unimpeded.

[0059] Comparative Example 3 prepared iridium alloy material using the same method as Example 1, except that, as shown in Table 1, the Ir content in this comparative example was 58%, the Y content was 2%, and the Re content was 0%.

[0060] The high-temperature resistance of the iridium alloy material prepared in this comparative example was tested using an ultra-high temperature cyclic oxidation experiment. The specific testing method was the same as in Example 1. The test results showed that the iridium alloy material in Comparative Example 3 had poor high-temperature oxidation stability, and local cracks appeared on its surface after 6 hours of oxidation (e.g., Figure 12 As shown in the figure, although the local oxide film is intact, oxygen can still penetrate deep into the alloy from the crack location.

[0061] Comparative Example 4 prepared iridium alloy material using the same method as Example 1, except that, as shown in Table 1, the Ir content in this comparative example was 85% and the Ta content was 15%.

[0062] The iridium alloy material prepared in this comparative example was analyzed using non-equilibrium solidification simulation. The analysis showed that the material properties of Comparative Example 4 (e.g.) Figure 13 (as shown) and Example 1 (as shown) Figure 1 The liquidus temperatures of the alloy materials prepared (as shown) are all higher than the cyclic oxidation test temperature of 1500℃. Furthermore, combined with the scanning electron microscope images of the iridium alloy materials after the cyclic oxidation performance test of Comparative Example 4 and Example 1, it can be concluded that the iridium alloy materials prepared in Comparative Example 4 (i.e., the mainstream research on low Ta content iridium alloys at home and abroad) and Example 1 have similar high-temperature oxidation resistance.

[0063] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A multi-element iridium alloy material for ultra-high temperature applications, characterized in that: The elemental composition of the iridium alloy material, by mass percentage, is: 53-58.5% Ir, 40% Ta, 0.5-2% Y, and 1-5% Re.

2. The preparation method of the ultra-high temperature multi-element iridium alloy material according to claim 1, characterized in that, Specifically, the following steps are included: (1) Weigh out Ir, Ta, Y and Re powders by mass percentage and mix them evenly; (2) The uniformly mixed metal powder is pre-pressed into a block shape to obtain a pressed blank; (3) The pressed blank is smelted, and the crude product of iridium alloy material is obtained after the smelting is completed; (4) Repeat step (3) more than 7 times to ensure that the pressed blank is completely melted and uniform, and that the content of each component meets the standard, so as to obtain iridium alloy material.

3. The method for preparing ultra-high temperature multi-element iridium alloy material according to claim 2, characterized in that, In step (3), the electric arc melting method is used for the pressing of the billet. The specific method is as follows: the melting device is evacuated to ≤9×10 -4 Pa; Inert gas is introduced into the melting device until the gauge pressure inside the device is -0.05MPa. An electric arc is generated by the electrodes, and the current is ≥420A. The high temperature generated by the electric arc is used to melt the pressed billet.

4. The method for preparing ultra-high temperature multi-element iridium alloy material according to claim 2, characterized in that, In step (4), step (3) is repeated more than 7 times, with each session lasting 3 minutes. After melting is completed, the sample is cooled to room temperature to obtain iridium alloy material.

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