Ir-Rh-RE alloy and preparation method thereof

Abstract

The invention discloses an Ir-Rh-RE alloy and a preparation method thereof, and belongs to the technical field of alloy preparation. According to the alloy, Ir serves as a matrix, Rh with the mass fraction being 25%-30% and RE with the mass fraction being 0.05%-0.5% are contained, and RE is one or two of La and Ce which are added in a compounded mode. The mechanical property of the iridium-based alloy is improved by utilizing a composite strengthening means of solid solution strengthening of the Rh element and precipitation strengthening and grain refinement strengthening of a trace RE element compound. By optimizing the preparation process, the Ir-Rh-RE alloy material with excellent comprehensive performance such as high-temperature mechanics, oxidation resistance and corrosion resistance can be obtained, and the highest performance of the Ir-Rh-RE alloy material reaches that the room-temperature tensile strength is 1220 MPa; the tensile strength at 1500 DEG C is 49.5 MPa; after 10h at 1500 DEG C, the endurance strength is 12.6 MPa; the creep life is 65.5 h at the temperature of 1500 DEG C and the pressure of 5 MPa; the creep rate is 0.06% / h at the temperature of 1500 DEG C and the pressure of 5 MPa; under a static atmospheric condition, the alloy weightlessness is 50 mg / cm < 2 > within 10 hours at 1500 DEG C. The Ir-Rh-RE alloy disclosed by the invention can be used as an airspace engine jet pipe, a crucible, a glass fiber bushing and other structural materials needing comprehensive properties such as high temperature, high strength, oxidation resistance and corrosion resistance.

Description

Technical Field

[0001] The invention relates to an Ir-Rh-RE alloy and a preparation method thereof, belonging to the technical field of alloy preparation. Background Art

[0002] At present, the first-generation aerospace engine nozzles at home and abroad generally use traditional niobium-hafnium high-temperature alloy materials (C103 alloy). Although the melting point of niobium alloy is high, its oxidation resistance is poor. Ceramic coatings such as silicide must be used for protection in high-temperature oxidation environments. Due to the limitation of material properties, the working temperature of high-temperature materials in the refractory metal / silicide material system cannot exceed 1300℃. With the rapid development of high technologies such as aerospace, there is an urgent need to develop second-generation aerospace engines. In recent years, aerospace developed countries or regions in the world have begun to apply iridium-based high-temperature alloys to the field of aerospace propulsion engine technology. For example, European EADS and German MMB have applied iridium-based alloy material nozzles to non-toxic propulsion, monopropellant and bipropellant engines. This type of engine has been selected as the propulsion system attitude control engine for CLUSTER scientific program satellites, ARTEMIS experimental communication satellites and SB300 satellites. Since the iridium-based alloy itself has extremely strong high-temperature oxidation resistance, the nozzle does not need coating protection, which greatly improves the stability of the nozzle product quality and the reliability of the engine operation. However, due to the need for technical confidentiality, foreign literature has not reported the specific composition of the iridium-based alloy used.

[0003] The high-temperature materials used in the nozzles of the second-generation aerospace engines work in an extremely harsh environment. They need to work stably for a long time at a high temperature of 1500-1600℃, and also need to have the ability to resist high-temperature erosion by strong oxidizing gases. Secondly, the engine working life is required to reach more than 10 hours, and the engine combustion chamber pressure can reach more than 1.5MPa. The nozzle works in a high-temperature, high-pressure and strong oxidizing corrosion environment for a long time. In order to ensure its long-term reliability, higher requirements are put forward for the high-temperature mechanical properties and oxidation resistance of the material. For example, the main technical requirements for nozzle materials for engines of spacecraft such as satellites and spacecraft are: high-temperature tensile strength at 1500℃ ≥40MPa; endurance strength at 1500℃, 10h ≥10MPa; creep life at 1500℃, 5MPa ≥50h; creep rate at 1500℃, 5MPa ≤0.15% / h; alloy weight loss at 1500℃, 10h ≤150mg / cm under static atmospheric conditions 2 At present, the performance of the best iridium-based alloys or composite materials is difficult to meet the comprehensive technical requirements of the above-mentioned aerospace high-temperature structural materials.

[0004] Iridium has a high melting point (2446℃), strong anti-oxidation, corrosion resistance and chemical stability. It does not require coating protection when used at high temperatures. It has become an indispensable high-temperature structural material in many special application environments, such as glass fiber industrial leak plates, experimental analysis and crystal growth vessel materials. Pure iridium has high strength but poor plasticity. As a structural material, it needs to be alloyed or composited to meet the requirements of use. The iridium matrix can be strengthened by a variety of strengthening mechanisms, such as solid solution strengthening, deformation strengthening, grain boundary strengthening, second phase strengthening, intermetallic compound strengthening, etc. For this reason, people have conducted long-term research on the strengthening theory and mechanism of iridium and developed a variety of strengthened iridium materials.

[0005] At present, there are many varieties of iridium-based alloy materials that are actually used, and the high-temperature materials involved are mainly divided into two categories, namely solid solution-strengthened alloys and dispersion-strengthened composite materials. Solid solution-strengthened alloys mainly include binary alloys such as Ir-Rh, Ir-Cu, Pt-Ir, Ir-Ni, and Ir-W, and ternary alloys such as Ir-Ni-W and Ir-Rh-Ru. Among them, the Pt-30Ir alloy has the highest high-temperature mechanical properties, such as the endurance strength at 1500℃ reaching 15MPa, but the processing performance of the alloy is poor, and it is difficult to process into parts with complex shapes such as nozzles and crucibles; although the processing performance of Ir-Rh alloys with low Rh content is good, the high-temperature mechanical properties do not meet the technical requirements for actual use. Among the existing Ir-Rh alloys, Ir-30Rh has the best mechanical properties, but its endurance strength at 1500℃ and 10h is only 8MPa. Further increasing Rh can increase its high-temperature mechanical properties, but the processing performance becomes very poor. Studies have found that adding a small amount of rare earth elements to pure Ir or Ir-Rh alloys with low Rh content can improve the high-temperature strength of the alloy.

[0006] Dispersion-strengthened iridium-based composite materials mainly include ODS, ZGS and DPH, which use dispersed oxide particles as the strengthening phase. Their high-temperature mechanical properties are generally higher than those of solid-solution iridium-based alloys with the same composition. For example, the endurance strength of DPH Ir-10Rh composite material at 1600℃ for 10h reaches 7.5MPa, which is twice that of Ir-10Rh alloy. Many applications require high-temperature structural parts to be welded with other metals, but after melting, the lighter oxide particles of dispersion-strengthened iridium-based composite materials float out of the melt, causing the strength of the weld to drop to the level of unstrengthened materials. In addition, the ductility of the material after dispersion strengthening is greatly reduced, the brittleness increases, resulting in processing difficulties, and easy cracking when stress is concentrated, which cannot meet the use requirements of aerospace engine nozzles and crucible materials.

[0007] In order to further improve the high-temperature mechanical properties of iridium-based alloys, people have been actively seeking and studying iridium-based high-temperature alloys with structures similar to γ / γ' precipitation-strengthened nickel-based high-temperature alloys in recent years. Ir can form a face-centered cubic (FCC) solid solution and L12-type ordered intermetallic compound Ir3X (X is Al or transition metal, L12 phase is also called γ' phase) with Al and transition metals (such as Zr, Hf, Nb, Ta, etc.), and FCC and γ' phase form an ideal high-temperature strengthening coherent structure. Researchers have found that Ir solid solutions can exist in equilibrium with L12 structure ordered phases in the study of Ir-Hf, Ir-Zr, Ir-Al, Ir-Al-Cr and Ir-Al-Cr-Ni alloy systems. However, so far, no reports have been found on the high-temperature mechanical, oxidation resistance and other technical performance parameters and practical applications of these precipitation-strengthened iridium-based alloy materials under study.

[0008] The main technical requirements for nozzle materials of engines of spacecraft such as satellites and spacecraft are: high temperature tensile strength at 1500℃ ≥40MPa; endurance strength at 1500℃, 10h ≥10MPa; creep life at 1500℃, 5MPa ≥50h; creep rate at 1500℃, 5MPa ≤0.15% / h; alloy weight loss at 1500℃, 10h ≤150mg / cm under static atmospheric conditions 2 At present, the performance of the best iridium-based alloys or composite materials is difficult to meet the comprehensive technical requirements of the above-mentioned aerospace high-temperature structural materials.

[0009] The present invention combines the composite strengthening mechanisms of iridium-based alloys such as solid solution strengthening, precipitation strengthening and grain refinement strengthening, and invents an Ir-Rh-RE high-temperature alloy structural material with comprehensive excellent properties such as high strength, oxidation resistance and corrosion resistance by adding trace amounts of rare earth elements to Ir-Rh with a high Rh content, so as to meet the needs of aerospace and other high-tech fields for high-performance high-temperature structural materials. Summary of the invention

[0010] In order to improve the performance of iridium-based alloys, one of the objects of the present invention is to provide an Ir-Rh-RE alloy, wherein the Ir-Rh-RE alloy comprises the following contents, calculated by mass percentage: 69% to 75% Ir, 25% to 30% Rh and 0.05% to 0.5% RE, wherein the total mass percentage of Ir, Rh and RE is 100%.

[0011] Preferably, the RE is one or both of La and Ce added in any proportion.

[0012] Another object of the present invention is to provide a method for preparing an Ir-Rh-RE alloy, comprising pre-alloying, smelting and casting, homogenizing heat treatment, hot forging, surface treatment and cold forging of the alloy, the specific steps of which are as follows:

[0013] (1) Pre-alloying: The prepared alloy raw materials are placed in an electric arc furnace and smelted to obtain pre-alloyed alloy ingots.

[0014] (2) Melting and casting: The pre-alloyed alloy ingot obtained in step (1) is placed in a crucible, and melted and cast under vacuum-argon filling conditions to obtain an alloy ingot.

[0015] (3) Homogenization heat treatment: The alloy ingot obtained in step (2) is placed in a vacuum furnace for homogenization heat treatment.

[0016] (4) Hot forging: The alloy ingot processed in step (3) is subjected to hot forging, wherein the hot forging includes rolling and stress relief annealing, to obtain an alloy bar.

[0017] (5) Surface treatment: The alloy rod obtained in step (4) is subjected to pickling and lathing in sequence for surface treatment to remove impurities and surface defects on the surface of the rod.

[0018] (6) Cold forging: The alloy bar treated in step (5) is subjected to cold forging to obtain a semi-hard alloy bar.

[0019] Preferably, the smelting conditions in step (1) are: carried out under vacuum and argon filling conditions, the vacuum degree in the arc melting furnace is not less than 0.01 Pa before filling with argon, and the ingot needs to be turned over for 3 to 4 times during melting.

[0020] Preferably, the crucible in step (2) is a zirconia crucible; the smelting and casting conditions are: vacuum degree not less than 0.01 Pa, smelting temperature of 1900-2000° C., casting using a water-cooled copper mold, and casting time of 10-20 seconds.

[0021] Preferably, the conditions for the homogenization heat treatment in step (3) are: vacuum degree not less than 0.01 Pa, heat treatment temperature 1200° C. to 1300° C., and time not less than 2 h.

[0022] Preferably, in step (4), the deformation of each rolling pass is controlled within 5%, and stress relief annealing is performed when the cumulative deformation reaches 30%, with the annealing temperature being 1200° C. to 1300° C. and the time being not less than 0.5 h.

[0023] The Ir-Rh-RE alloy prepared by the present invention can be applied to a new generation of aerospace engine nozzles, crucibles, glass fiber bushings and other structural materials that require high temperature, high strength, oxidation resistance and corrosion resistance.

[0024] Precious metals Ir and Rh can form various forms of intermetallic compounds (Ir5RE, Ir3RE) and rare earth oxides with La and Ce. Most Ir5RE compounds have a melting point higher than 1600℃ and a microhardness of 4600Mpa. Therefore, Ir5RE compounds have excellent stability and can effectively diffuse between phases, extending the precipitation strengthening effect to higher temperatures. These intermetallic compounds and oxide particles are dispersed in the crystals and grain boundaries of the Ir matrix, which refines the matrix grains, reduces the grain size, improves the strength and plasticity, and has a significant organizational refinement and strengthening effect on the Ir or Ir-Rh matrix, significantly improving the high-temperature strength performance of the material. Adding RE to form high-melting-point precipitation phases of Ir, RE and Ir:RE+(Ir.Rh) is difficult to decompose at high temperatures, pins the grain boundaries, hinders grain boundary migration and grain growth, and thus improves the high-temperature strength.

[0025] Beneficial effects of the present invention:

[0026] (1) The Ir-Rh-RE alloy material prepared by the present invention has comprehensive properties such as high strength, oxidation resistance and corrosion resistance, and its highest performance reaches: room temperature tensile strength 1220MPa, 1500℃ tensile strength 49.5MPa; 1500℃, 10h, endurance strength 12.6MPa; 1500℃, 5MPa, creep life 65.5h; 1500℃, 5MPa, creep rate 0.06% / h; under static atmospheric conditions, 1500℃, 10h alloy weight loss 50mg / cm 2 .

[0027] (2) The tensile strength of the classic Ir-30Rh alloy at 1500°C is 38 MPa; at 1500°C, 10 h, the endurance strength is 8.2 MPa. The optimal performance of the Ir-Rh-RE alloy of the present invention is significantly higher than that of the classic Ir-30Rh alloy.

[0028] (3) The present invention further improves the high-temperature mechanical properties of the alloy by adding trace rare earth elements La and Ce on the basis of high Rh content, while maintaining the alloy's good processing performance and high-temperature oxidation resistance. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described below by specific implementation methods. However, the following embodiments are only simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0030] The purity of the bulk or powdered Ir, Rh and La raw materials used in all the examples is ≥99.95%.

[0031] Example 1

[0032] A method for preparing an Ir-Rh-La alloy. In this embodiment, each pre-alloyed batch weighs 50 g, wherein the mass fraction of Rh is 25%, the mass fraction of La is 0.2%, and the balance is Ir. The specific preparation steps are as follows:

[0033] (1) Pre-alloying: The prepared alloy raw materials are placed in an arc furnace for melting and pre-alloying is performed under vacuum and argon filling conditions. The vacuum degree in the arc melting is 0.01 Pa before argon filling, and the melting is turned over 4 times.

[0034] (2) Melting and casting: The pre-alloyed alloy ingot obtained in step (1) is placed in a zirconia crucible and melted under vacuum-argon filling conditions. The vacuum degree in the melting furnace before argon filling is not less than 0.01 Pa. The melting temperature is 2000°C and cast in a water-cooled copper mold to obtain a cylindrical alloy ingot.

[0035] (3) Homogenization heat treatment: The alloy ingot obtained in step (2) is placed in a vacuum furnace for homogenization heat treatment at a vacuum degree of 0.01 Pa, a heat treatment temperature of 1220° C., and a time of 2.5 h.

[0036] (4) Hot forging: The alloy ingot processed in step (3) is subjected to hot forging, which includes rolling and stress relief annealing, wherein the deformation amount of each pass is controlled at 5%, and stress relief annealing is performed when the cumulative deformation amount reaches 30%, the annealing temperature is 1200° C., and the annealing time is 40 min, to obtain an alloy rod.

[0037] (5) Surface treatment: The alloy bar obtained in step (4) is subjected to surface treatment by pickling and turning the hot forged alloy bar.

[0038] (6) Cold forging: The alloy bar treated in step (5) is subjected to 26% cold forging deformation to finally obtain a semi-hard alloy bar.

[0039] The room temperature tensile strength of the Ir-25Rh-0.2La alloy prepared in this embodiment is 1120MPa, the tensile strength at 1500℃ is 40.6MPa; at 1500℃, 10h, the endurance strength is 10.1MPa; at 1500℃, 5MPa, the creep life is 50.2h; at 1500℃, 5MPa, the creep rate is 0.13% / h; under static atmospheric conditions, at 1500℃, 10h, the alloy loses 58mg / cm 2 .

[0040] Example 2

[0041] A method for preparing an Ir-Rh-La alloy. In this embodiment, each pre-alloyed batch weighs 50 g, wherein the mass fraction of Rh is 25%, the mass fraction of La is 0.5%, and the balance is Ir. The specific preparation steps are as follows:

[0042] (1) Pre-alloying: The prepared alloy raw materials are placed in an arc furnace for melting and pre-alloying is performed under vacuum and argon filling conditions. The vacuum degree in the arc melting is 0.01 Pa before argon filling, and the melting is turned over 4 times.

[0043] (2) Melting and casting: The pre-alloyed alloy ingot obtained in step (1) is placed in a zirconia crucible and melted under vacuum-argon filling conditions. The vacuum degree in the melting furnace before argon filling is not less than 0.01 Pa. The melting temperature is 2000°C and cast in a water-cooled copper mold to obtain a cylindrical alloy ingot.

[0044] (3) Homogenization heat treatment: The alloy ingot obtained in step (2) is placed in a vacuum furnace for homogenization heat treatment at a vacuum degree of 0.01 Pa, a heat treatment temperature of 1250° C., and a time of 3.0 h.

[0045] (4) Hot forging: The alloy ingot processed in step (3) is subjected to hot forging, which includes rolling and stress relief annealing, wherein the deformation amount of each pass is controlled at 5%, and stress relief annealing is performed when the cumulative deformation amount reaches 30%, the annealing temperature is 1200° C., and the annealing time is 40 min, to obtain an alloy rod.

[0046] (5) Surface treatment: The alloy bar obtained in step (4) is subjected to surface treatment by pickling and turning the hot forged alloy bar.

[0047] (6) Cold forging: The alloy bar treated in step (5) is subjected to 26% cold forging deformation to finally obtain a semi-hard alloy bar.

[0048] The room temperature tensile strength of the Ir-25Rh-0.5La alloy prepared in this embodiment is 1145MPa, the tensile strength at 1500℃ is 42.3MPa; at 1500℃, 10h, the endurance strength is 10.4MPa; at 1500℃, 5MPa, the creep life is 54.7h; at 1500℃, 5MPa, the creep rate is 0.12% / h; under static atmospheric conditions, at 1500℃, 10h, the alloy loses 53mg / cm 2 .

[0049] Example 3

[0050] A method for preparing an Ir-Rh-La alloy. In this embodiment, each pre-alloyed batch weighs 50 g, wherein the mass fraction of Rh is 25%, the mass fraction of La is 0.25%, the mass fraction of Ce is 0.25%, and the balance is Ir. The specific preparation steps are as follows:

[0051] (1) Pre-alloying: The prepared alloy raw materials are placed in an arc furnace for melting and pre-alloying is performed under vacuum and argon filling conditions. The vacuum degree in the arc furnace is not less than 0.01 Pa before filling with argon, and the melting is turned over 4 times.

[0052] (2) Melting and casting: The pre-alloyed alloy ingot obtained in step (1) is placed in a zirconia crucible and melted under vacuum-argon filling conditions. The vacuum degree in the melting furnace before argon filling is 0.01 Pa, the melting temperature is 2000°C, and the alloy is cast in a water-cooled copper mold to obtain a cylindrical alloy ingot.

[0053] (3) Homogenization heat treatment: The alloy ingot obtained in step (2) is placed in a vacuum furnace for homogenization heat treatment at a vacuum degree of 0.01 Pa, a heat treatment temperature of 1250° C., and a time of 3.0 h.

[0054] (4) Hot forging: The alloy ingot processed in step (3) is subjected to hot forging, which includes rolling and stress relief annealing, wherein the deformation amount of each pass is controlled at 5%, and stress relief annealing is performed when the cumulative deformation amount reaches 30%, the annealing temperature is 1200° C., and the annealing time is 40 min, to obtain an alloy rod.

[0055] (5) Surface treatment: The alloy bar obtained in step (4) is subjected to surface treatment by pickling and turning the hot forged alloy bar.

[0056] (6) Cold forging: The alloy bar treated in step (5) is subjected to 26% cold forging deformation to finally obtain a semi-hard alloy bar.

[0057] The room temperature tensile strength of the Ir-25Rh-0.25La-0.25Ce alloy prepared in this embodiment is 1150MPa, the tensile strength at 1500℃ is 43.4MPa; at 1500℃, 10h, the endurance strength is 10.5MPa; at 1500℃, 5MPa, the creep life is 55.6h; at 1500℃, 5MPa, the creep rate is 0.11% / h; under static atmospheric conditions, at 1500℃, 10h, the alloy loses 52mg / cm 2 .

[0058] Example 4

[0059] A method for preparing an Ir-Rh-La alloy. In this embodiment, each pre-alloyed batch weighs 50 g, wherein the mass fraction of Rh is 30%, the mass fraction of La is 0.2%, and the balance is Ir. The specific preparation steps are as follows:

[0060] (1) Pre-alloying: The prepared alloy raw materials are placed in an arc furnace for melting and pre-alloying is performed under vacuum and argon filling conditions. The vacuum degree in the arc melting is 0.01 Pa before argon filling, and the melting is turned over 4 times.

[0061] (2) Melting and casting: The pre-alloyed alloy ingot obtained in step (1) is placed in a zirconia crucible and melted under vacuum-argon filling conditions. The vacuum degree in the melting furnace before argon filling is 0.01 Pa, the melting temperature is 2000°C, and the alloy is cast in a water-cooled copper mold to obtain a cylindrical alloy ingot.

[0062] (3) Homogenization heat treatment: The alloy ingot obtained in step (2) is placed in a vacuum furnace for homogenization heat treatment, the vacuum degree is not less than 0.01 Pa, the heat treatment temperature is 1300°C, and the time is 3.0 h.

[0063] (4) Hot forging: The alloy ingot processed in step (3) is subjected to hot forging, which includes rolling and stress relief annealing, wherein the deformation amount of each pass is controlled at 5%, and stress relief annealing is performed when the cumulative deformation amount reaches 30%, the annealing temperature is 1300° C., and the annealing time is 50 min, to obtain an alloy rod.

[0064] (5) Surface treatment: The alloy bar obtained in step (4) is subjected to surface treatment by pickling and turning the hot forged alloy bar.

[0065] (6) Cold forging: The alloy bar treated in step (5) is subjected to 26% cold forging deformation to finally obtain a semi-hard alloy bar.

[0066] The room temperature tensile strength of the Ir-30Rh-0.2La alloy prepared in this embodiment is 1190MPa, the tensile strength at 1500℃ is 47.2MPa; the endurance strength at 1500℃, 10h is 12.0MPa; the creep life at 1500℃, 5MPa is 60.8h; the creep rate at 1500℃, 5MPa is 0.08% / h; under static atmospheric conditions, the alloy loses 53mg / cm2 at 1500℃, 10h 2 .

[0067] Example 5

[0068] A method for preparing an Ir-Rh-La alloy. In this embodiment, each pre-alloyed batch weighs 50 g, wherein the mass fraction of Rh is 30%, the mass fraction of La is 0.5%, and the balance is Ir. The specific preparation steps are as follows:

[0069] (1) Pre-alloying: Place the prepared alloy raw materials into an arc furnace for melting and pre-alloying under vacuum and argon filling conditions. The vacuum degree in the arc furnace is 0.01 Pa before filling with argon, and the melting is turned over 3 to 4 times.

[0070] (2) Melting and casting: The pre-alloyed alloy ingot obtained in step (1) is placed in a zirconia crucible and melted under vacuum-argon filling conditions. The vacuum degree in the melting furnace before argon filling is 0.01 Pa, the melting temperature is 2000°C, and the alloy is cast in a water-cooled copper mold to obtain a cylindrical alloy ingot.

[0071] (3) Homogenization heat treatment: The alloy ingot obtained in step (2) is placed in a vacuum furnace for homogenization heat treatment at a vacuum degree of 0.01 Pa, a heat treatment temperature of 1250° C., and a time of 3.0 h.

[0072] (4) Hot forging: The alloy ingot processed in step (3) is subjected to hot forging, which includes rolling and stress relief annealing, wherein the deformation amount of each pass is controlled at 5%, and stress relief annealing is performed when the cumulative deformation amount reaches 30%, the annealing temperature is 1200° C., and the annealing time is 40 min, to obtain an alloy rod.

[0073] (5) Surface treatment: The alloy bar obtained in step (4) is subjected to surface treatment by pickling and turning the hot forged alloy bar.

[0074] (6) Cold forging: The alloy bar treated in step (5) is subjected to 26% cold forging deformation to finally obtain a semi-hard alloy bar.

[0075] The room temperature tensile strength of the Ir-30Rh-0.5La alloy prepared in this embodiment is 1205MPa, the tensile strength at 1500℃ is 48.7MPa; the endurance strength at 1500℃, 10h is 12.4MPa; the creep life at 1500℃, 5MPa is 63.8h; the creep rate at 1500℃, 5MPa is 0.07% / h; under static atmospheric conditions, the alloy loses 54mg / cm2 at 1500℃, 10h 2 .

[0076] Example 6

[0077] A method for preparing an Ir-Rh-La alloy. In this embodiment, each pre-alloyed batch weighs 50 g, wherein the mass fraction of Rh is 30%, the mass fraction of La is 0.25%, the mass fraction of Ce is 0.25%, and the balance is Ir. The specific preparation steps are as follows:

[0078] (1) Pre-alloying: The prepared alloy raw materials are placed in an arc furnace for melting and pre-alloying is performed under vacuum and argon filling conditions. The vacuum degree in the arc melting is 0.01 Pa before argon filling, and the melting is turned over 4 times.

[0079] (2) Melting and casting: The pre-alloyed alloy ingot obtained in step (1) is placed in a zirconia crucible and melted under vacuum-argon filling conditions. The vacuum degree in the melting furnace before argon filling is 0.01 Pa, the melting temperature is 2000°C, and the alloy is cast in a water-cooled copper mold to obtain a cylindrical alloy ingot.

[0080] (3) Homogenization heat treatment: The alloy ingot obtained in step (2) is placed in a vacuum furnace for homogenization heat treatment at a vacuum degree of 0.01 Pa, a heat treatment temperature of 1250° C., and a time of 3.0 h.

[0081] (4) Hot forging: The alloy ingot processed in step (3) is subjected to hot forging, which includes rolling and stress relief annealing, wherein the deformation amount of each pass is controlled at 5%, and stress relief annealing is performed when the cumulative deformation amount reaches 30%, the annealing temperature is 1200° C., and the annealing time is 40 min, to obtain an alloy rod.

[0082] (5) Surface treatment: The alloy bar obtained in step (4) is subjected to surface treatment by pickling and turning the hot forged alloy bar.

[0083] (6) Cold forging: The alloy bar treated in step (5) is subjected to 26% cold forging deformation to finally obtain a semi-hard alloy bar.

[0084] The room temperature tensile strength of the Ir-30Rh-0.25La-0.25Ce alloy prepared in this embodiment is 1220MPa, the tensile strength at 1500℃ is 49.5MPa; the endurance strength at 1500℃, 10h is 12.6MPa; the creep life at 1500℃, 5MPa is 65.5h; the creep rate at 1500℃, 5MPa is 0.06% / h; under static atmospheric conditions, the alloy loses 50mg / cm2 at 1500℃, 10h 2 .

[0085] Comparative Example 1

[0086] For comparison, the only difference between this comparative example and Example 1 is that no rare earth element is added. Therefore, the mass fraction of Rh in the alloy prepared in this comparative example is 25%, and the balance is Ir. The preparation method is exactly the same as that of Example 1.

[0087] The room temperature tensile strength of the alloy prepared in this embodiment is 980MPa, the tensile strength at 1500℃ is 34.6MPa; at 1500℃, 10h, the endurance strength is 7.6MPa; at 1500℃, 5MPa, the creep life is 45.6h; at 1500℃, 5MPa, the creep rate is 0.25% / h; under static atmospheric conditions, at 1500℃, 10h, the alloy loses weight of 89mg / cm 2 .

[0088] Comparative Example 2

[0089] For comparison, the only difference between this comparative example and Example 1 is that the pre-alloying treatment in step (1) is not performed during the preparation process, and the alloy composition and other steps are exactly the same as those in Example 1.

[0090] The room temperature tensile strength of the alloy prepared in this embodiment is 767MPa, the tensile strength at 1500℃ is 25.7MPa; at 1500℃, 10h, the endurance strength is 4.9MPa; at 1500℃, 5MPa, the creep life is 30.7h; at 1500℃, 5MPa, the creep rate is 0.32% / h; under static atmospheric conditions, at 1500℃, 10h, the alloy loses 92mg / cm 2 .

[0091] Comparative Example 3

[0092] For comparison, the difference between this comparative example and Example 1 is that the temperature of the homogenization heat treatment in step (3) is 1400° C., and the remaining steps and alloy components are exactly the same as those in Example 1.

[0093] The room temperature tensile strength of the alloy prepared in this embodiment is 932MPa, the tensile strength at 1500℃ is 31.5MPa; at 1500℃, 10h, the endurance strength is 6.5MPa; at 1500℃, 5MPa, the creep life is 36.2h; at 1500℃, 5MPa, the creep rate is 0.24% / h; under static atmospheric conditions, at 1500℃, 10h, the alloy loses 82mg / cm 2 .

[0094] Comparative Example 4

[0095] For comparison, the difference between this comparative example and Example 1 is that the cold forging process in step (6) is not performed, and the remaining steps and alloy composition are exactly the same as those in Example 1.

[0096] The room temperature tensile strength of the alloy prepared in this embodiment is 875MPa, the tensile strength at 1500℃ is 32.9MPa; at 1500℃, 10h, the endurance strength is 6.8MPa; at 1500℃, 5MPa, the creep life is 37.9h; at 1500℃, 5MPa, the creep rate is 0.28% / h; under static atmospheric conditions, at 1500℃, 10h, the alloy loses 85mg / cm 2 .

[0097] Table 1 Test results of alloy properties prepared in Examples and Comparative Examples

[0098]

[0099] The highest performance of the Ir-Rh-RE alloy prepared by the present invention is as follows: room temperature tensile strength of 1220MPa; 1500℃ tensile strength of 46.5MPa; 1500℃, 10h, endurance strength of 12.6MPa; 1500℃, 5MPa, creep life of 65.5h; 1500℃, 5MPa, creep rate of 0.06% / h; under static atmospheric conditions, 1500℃, 10h alloy weight loss of 50mg / cm 2 , meeting the main technical requirements for nozzle materials of engines of space vehicles such as satellites and spacecraft.

Claims

1. An Ir-Rh-RE alloy, characterized in that: The Ir-Rh-RE alloy comprises the following substances in terms of mass percentage: 69% to 75% of Ir, 25% to 30% of Rh and 0.05% to 0.5% of RE, wherein the total mass percentage of Ir, Rh and RE is 100%.

2. The Ir-Rh-RE alloy according to claim 1, characterized in that: The RE is one of La and Ce or a combination of the two in any proportion.

3. The method for preparing the Ir-Rh-RE alloy according to claim 1, characterized in that: It includes alloy pre-alloying, smelting and casting, homogenization heat treatment, hot forging, surface treatment and cold forging. The specific steps are as follows: (1) Pre-alloying: placing the prepared alloy raw materials into an electric arc furnace for smelting to obtain pre-alloyed alloy ingots; (2) Melting and casting: placing the pre-alloyed alloy ingot obtained in step (1) into a crucible, melting it under vacuum-argon filling conditions, and then casting it to obtain an alloy ingot; (3) Homogenization heat treatment: placing the alloy ingot obtained in step (2) into a vacuum furnace for homogenization heat treatment; (4) hot forging: hot forging the alloy ingot processed in step (3), wherein the hot forging includes rolling and stress relief annealing to obtain an alloy bar; (5) Surface treatment: The alloy rod obtained in step (4) is subjected to pickling and lathing in sequence for surface treatment to remove impurities and surface defects on the surface of the rod; (6) Cold forging: The alloy bar treated in step (5) is subjected to cold forging to obtain a semi-hard alloy bar.

4. The method for preparing the Ir-Rh-RE alloy according to claim 3, characterized in that: The smelting conditions in step (1) are: carried out under vacuum and argon filling conditions, the vacuum degree in the arc melting furnace is not less than 0.01 Pa before filling with argon, and the ingot needs to be turned over for 3 to 4 times during melting.

5. The method for preparing the Ir-Rh-RE alloy according to claim 3, characterized in that: The crucible in step (2) is a zirconia crucible; the smelting conditions are: the vacuum degree is not less than 0.01 Pa, the smelting temperature is 1900-2000° C., the casting is performed using a water-cooled copper mold, and the casting time is 10-20S.

6. The method for preparing the Ir-Rh-RE alloy according to claim 3, characterized in that: The conditions of the homogenization heat treatment in step (3) are: vacuum degree not less than 0.01 Pa, heat treatment temperature 1200° C. to 1300° C., and time not less than 2 h.

7. The method for preparing the Ir-Rh-RE alloy according to claim 3, characterized in that: In step (4), the deformation of each rolling pass is controlled within 5%, and stress relief annealing is performed when the cumulative deformation reaches 30%. The annealing temperature is 1200° C. to 1300° C., and the time is not less than 0.5 h.

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