Silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical property as well as preparation method and application of silver-zirconium-copper

Abstract

The invention discloses silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical property as well as a preparation method and application of the silver-zirconium-copper. The alloy comprises the following components in percentage by mass: 2.7-3.5% of Ag, 0.4-0.6% of Zr, 0.2-0.5% of Cr, 0.15-0.45% of Nb and the balance of Cu. The total mass fraction of Cr and Nb is less than or equal to 1%; a base body of the silver zirconium copper contains a Cr2Nb phase. Meanwhile, the preparation process comprises the steps of burdening, powder preparation through a vacuum melting argon atomization method, vacuum hot pressing sintering and multi-stage deformation aging treatment. The nano Cr2Nb particles are used for pinning grain boundaries and cooperate with a matrix to improve the high-temperature strength of the alloy, so that the alloy has good thermal stability, and meanwhile, the alloy cannot be dissolved in the matrix to strongly damage the thermal conductivity by controlling the total addition amount of the alloy, so that the high thermal conductivity of silver-zirconium-copper is maintained, and meanwhile, the high-temperature mechanical property can be further improved.

Description

Technical Field

[0001] The invention belongs to the field of metallurgy and relates to silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties and a preparation method thereof. Background Art

[0002] The gas temperature of a high-thrust rocket engine can reach 3000°C. Under the action of the high-temperature gas jet, the combustion chamber pressure can exceed 200 atmospheres. Liquid hydrogen and liquid oxygen are burned in a certain mixture ratio in the combustion chamber to provide power for the engine. Generally, ultra-low temperature coolant is introduced by milling grooves in the inner wall of the combustion chamber to take away the heat and prevent the inner wall from failing due to overheating. This requires that the inner wall material must have high thermal conductivity and high high-temperature strength to prevent the cooling channel at the throat of the combustion chamber from plastic deformation or even cracking due to thermal stress and alternating loads. Due to the inverted relationship between the thermal conductivity and high-temperature mechanical properties of copper alloys, the thermal conductivity is generally reduced while the high-temperature mechanical properties of the alloy are improved. How to further improve the high-temperature mechanical properties of silver-zirconium copper without significantly reducing the excellent thermal conductivity of the inner wall material of the combustion chamber is a difficult problem that needs to be solved urgently.

[0003] The mainstream preparation method of silver-zirconium-copper alloy is vacuum melting casting + heat treatment + forging (CN 104232978B). However, the traditional preparation method cannot fundamentally refine the coarse Zr-rich phase in the alloy, reduce the probability of crack initiation of the alloy under high-temperature alternating loads, and optimize the high-temperature mechanical properties of the alloy. In addition, as aerospace vehicles have higher and higher requirements for load and reuse capabilities, the high-temperature mechanical properties of existing silver-zirconium-copper alloys also need to be further improved. Due to the essential "inverted" relationship between the thermal conductivity and high-temperature mechanical properties of copper alloys, while improving the high-temperature mechanical properties of the alloy, the thermal conductivity will generally be reduced. How to further improve the high-temperature mechanical properties of silver-zirconium-copper alloys without significantly reducing the excellent thermal conductivity of the inner wall material of the combustion chamber is a goal that researchers in this field have always pursued. Summary of the invention

[0004] In order to solve the problem that the thermal conductivity and high temperature mechanical properties of copper alloys in the prior art have an essentially "inverted" relationship, and cannot have both high thermal conductivity and excellent high temperature mechanical properties, the first object of the present invention is to provide a silver-zirconium-copper with high thermal conductivity and excellent high temperature mechanical properties. 2 Nb pinning relative to the grain boundaries improves the high-temperature strength of the alloy, giving it good thermal stability. At the same time, by controlling its total amount of addition, it will not dissolve in the matrix and strongly damage the thermal conductivity, thereby maintaining high thermal conductivity of silver-zirconium-copper and further improving high-temperature mechanical properties.

[0005] The second object of the present invention is to provide a preparation method of silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties. This method effectively reduces the melting temperature by using a Cr-Nb master alloy, and at the same time combines the rapid solidification of the high-temperature liquid silver-zirconium-copper liquid during the gas atomization process, significantly increasing the solid solubility of Cr and Nb elements in the alloy and precipitating fine and dispersed Cr 2 Nb phases.

[0006] The third object of the present invention is to provide an application of silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties. The materials of the present invention have high thermal conductivity and excellent high-temperature mechanical properties, and are particularly suitable for preparing the inner lining materials of aero-engine combustion chambers to extend their service life.

[0007] To achieve the above technical objects, the present invention provides a silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties, including by mass fraction: Ag 2.7-3.5%, Zr 0.4-0.6%, Cr 0.2%-0.5%, Nb 0.15%-0.45%, and the balance is Cu; and the total mass fraction of Cr and Nb is less than or equal to 1%; the matrix of the silver-zirconium-copper contains Cr 2 Nb phases.

[0008] The key of the present invention lies in optimizing alloy elements, adding a small amount of Cr and Nb to form Cr 2 Nb phases in the silver-zirconium-copper matrix, and the Cr 2 Nb phases exist in the form of nano Cr 2 Nb particles, which can pin the grain boundaries, improve the high-temperature strength of the alloy, and endow it with good thermal stability. In addition, the continuous Ag precipitation phase and Cu 4 AgZr existing simultaneously in the alloy of the present invention have a synergistic effect with the Cr 2 Nb phases. Specifically, the continuous Ag precipitation phase in the matrix of the present invention is granular with a size less than 30 nm and is densely distributed within the grains. The continuous Ag precipitation phase and the Cu matrix are in a coherent relationship, which can accumulate dislocations during the plastic deformation process and strengthen the matrix. The addition of Zr can slow down the diffusion rate of Ag atoms in the Cu matrix, promote the uniform precipitation of the continuous Ag precipitation phase in the matrix during the aging treatment of the alloy, and inhibit the formation of the discontinuous Ag precipitation phase. And the Cu 4 AgZr phase can pin dislocations and grain boundaries, hinder the movement of dislocations and the migration of grain boundaries, and improve the room-temperature strength of the alloy. At the same time, it is also very stable at high temperatures, can hinder the movement of grain boundaries in a high-temperature environment, thereby inhibiting grain coarsening, and improving the high-temperature strength of the alloy. And the Cr 2 Nb phase has better thermal stability than the Cu 4 AgZr phase. When a small amount of Cr and Nb are added, due to the extremely strong affinity between these two elements, they will combine to form Cr2 The Nb phase does not dissolve in the matrix, which has little impact on the thermal conductivity of the alloy. Therefore, the silver-zirconium-copper alloy of the present invention can maintain a high thermal conductivity while further improving the high-temperature mechanical properties.

[0009] The addition amounts of Ag and Zr in the alloy matrix of the present invention also need to be controlled. In the matrix of a conventional silver-zirconium-copper alloy, Ag can increase the recrystallization temperature of the copper alloy and exists in the form of continuous and discontinuous precipitation phases. However, the diffusion rate of Ag atoms will accelerate at high temperatures, resulting in the discontinuous precipitation of Ag. The strengthening effect of the discontinuous precipitation phase is not as good as that of the continuous precipitation phase. Slightly increasing the content of Ag will not significantly improve the high-temperature mechanical properties of the alloy. Zr hardly dissolves in copper at room temperature. If the Zr content in the alloy is increased to a certain extent, the impact on the thermal conductivity of the alloy will not be great, while Cu 4 The volume fraction of the AgZr phase will increase significantly, and macroscopic segregation will occur. A large number of coarse precipitation phases will instead cause a decrease in the strength and plasticity of the alloy. Therefore, the present invention uses a combination of a relatively high silver content and a relatively low Zr content.

[0010] At the same time, the total mass fraction of Cr and Nb has a direct impact on the thermal conductivity of the alloy matrix. The inventor found that only when the total mass fraction of Cr and Nb is less than or equal to 1%, can it be ensured that the matrix of silver-zirconium-copper contains sufficient Cr 2 Nb phase without the precipitation of Cr and Nb phases dissolving in the matrix and strongly damaging the thermal conductivity. Thus, silver-zirconium-copper with both high thermal conductivity and excellent high-temperature mechanical properties is obtained. An excessive addition amount will reduce the thermal conductivity of the alloy to a certain extent and will also lead to a decrease in the plasticity of the alloy, which is not conducive to subsequent deformation processing. Further preferably, Ag is 2.7 - 3.5%, Zr is 0.4 - 0.6%, Cr is 0.3% - 0.4%, Nb is 0.25% - 0.35%, and the balance is Cu.

[0011] As a preferred solution, when the ratio of the mass fraction of Cr to the mass fraction of Nb is 1.1 - 1.35, Cr and Nb completely exist as Cr 2 Nb in the silver-zirconium-copper matrix. Within the ratio range of the present invention, it can further ensure the content of the Cr 2 Nb phase in the alloy matrix, improve the high-temperature strength of the alloy, and avoid the formation of other miscellaneous phases.

[0012] As a preferred solution, the 2 size of the Nb phase is 50 - 100 nm.

[0013] As a preferred solution, there are also continuous Ag precipitation phases with a size of 5 - 20 nm and Cu 4 AgZr phases with a size of 200 - 500 nm in the matrix of the silver-zirconium-copper. In the present invention, Cr 2The Nb particles belong to the thermally stable phase, and their sizes are between the continuous Ag precipitation phase and the Cu 4 AgZr phase. The size distributions of the three phases are beneficial to strengthening the alloy with a second phase having multiple gradient sizes.

[0014] The present invention also provides a preparation method of silver-zirconium-copper having high thermal conductivity and excellent high-temperature mechanical properties. The method is to weigh raw materials according to the designed silver-zirconium-copper ratio; pure copper, pure silver, Cr-Nb master alloy and Cu-Zr master alloy are made into pre-alloyed powder by vacuum melting and gas atomization; the pre-alloyed powder is subjected to vacuum hot pressing sintering and multi-stage deformation aging treatment to obtain the product.

[0015] The preparation method of the present invention can further synergistically improve the comprehensive properties of the alloy within the range of the alloy components adopted. Specifically: the present invention first controls the total mass fraction of Cr and Nb to be below 1 wt%, so that Cr and Nb fully react to form the intermetallic compound Cr 2 Nb, avoiding the precipitation of Cr and Nb phases from affecting the thermal conductivity of the alloy; at the same time, the use of Cr-Nb master alloy effectively reduces the melting temperature, solves the problem of undissolved particles due to the large melting point differences of the three alloying elements of Cu, Cr and Nb, and enhances the uniformity of the alloy composition; then the powder is made by vacuum melting and argon gas atomization method. The prepared pure metals and master alloys are heated and melted in a high-frequency induction device, the argon gas atomization pressure is adjusted, the argon gas valve is opened, and the ceramic plug rod in the crucible is raised to make the melt start to atomize and break along the liquid guiding tube, prompting the high-temperature liquid silver-zirconium-copper liquid to solidify rapidly, greatly increasing the solid solubility of Cr and Nb elements in the alloy, forming a supersaturated solid solution, and precipitating fine and dispersed Cr 2 Nb phase, while reducing segregation. For Cu-Ag-Zr, under the condition of rapid solidification, the solid solubility of Zr in copper can be increased by nearly ten times, and Ag can be infinitely solid-soluble. This is beneficial to the formation of a supersaturated solid solution of Zr and Ag in the copper matrix, and decomposes into fine and dispersed second-phase particles during subsequent heat treatment or hot deformation processes, which can not only strengthen the matrix but also improve the thermal conductivity of the alloy; finally, the alloy formed by vacuum hot pressing sintering is subjected to cold rolling treatment and aging heat treatment to generate a dispersed high-temperature resistant phase Cr 2 Nb phase, further improving the alloy properties and obtaining silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties.

[0016] Furthermore, the pure copper adopted in the present invention is high-purity electrolytic copper (purity greater than 99.9%), the pure silver is with a purity greater than 99.9%, the Cr-Nb master alloy is Cr-47 wt% Nb, and the Cu-Zr master alloy is Cu-50 wt% Zr.

[0017] As a preferred solution, the process of vacuum melting and gas atomization powder making is as follows: the prepared raw materials are melted in a crucible, the melting temperature is controlled at 1200 - 1500 °C, and heat preservation is carried out for 30 - 60 min; after melting is completed, the ceramic stopper rod in the crucible is lifted to cause the melt to be atomized and broken along the liquid guiding tube, promoting the rapid solidification of the high-temperature liquid silver zirconium copper liquid, and collecting the pre-alloy powder after it is completely cooled. Through the rapid solidification process during the atomization after melting in the present invention, not only can the solid solubility of Cr and Nb elements in the alloy be greatly increased to form a supersaturated solid solution, but also fine and dispersed Cr 2 Nb phases can be precipitated to reduce segregation.

[0018] As a preferred solution, the medium for gas atomization powder making is argon, and the pressure is 3 - 4 Mpa. With the increase of the atomization air pressure, the average particle size of the powder decreases, thereby increasing the yield of fine powder. At the same time, the smaller the powder particle size, the faster the solidification rate, and the solid solution atoms have not had time to precipitate before the small particle powder has completed solidification, which is beneficial to increasing the solid solubility of elements in the alloy.

[0019] As a preferred solution, the particle size of the pre-alloy powder is less than 74 μm; the oxygen content is less than 0.0028%. The present invention uses vacuum degassing and densification to prevent the oxidation of the pre-alloy powder.

[0020] As a preferred solution, the conditions for vacuum hot pressing sintering are: the vacuum degree is 10 -3 -10 -5 Pa, the mold size is Φ20 - 40 mm, the pressure is 5 - 20 MPa, the hot pressing temperature is 830 - 850 °C, the pressurizing process is synchronized with the heating process, and the pressure maintaining and heat preservation time is 1.5 - 2 h.

[0021] As a preferred solution, the multi-stage deformation aging treatment includes 3 - 6 times of single-pass cold rolling, and the total deformation amount is 80% - 95%; an aging treatment is carried out after each single-pass cold rolling, the temperature of any aging treatment is 350 - 500 °C, and the time of any aging treatment is 15 - 60 min. After the copper alloy of the present invention is cold rolled, the original grains are broken to form small grains, and at the same time, the network precipitation phase formed after sintering treatment becomes nano-scale particulate Cu 4 AgZr phases, which are distributed in a band along the rolling direction, and cold rolling improves the uniformity of the alloy structure. At the same time, during the aging process, the precipitation of the second phase is further promoted, pinning the interface, inhibiting grain growth, and being able to eliminate the internal stress and dislocations generated during the cold rolling process, improving its thermal conductivity, so that it can be subjected to the next cold rolling treatment.

[0022] When the total deformation amount is large enough, the large-particle second phase and grains can be broken more uniformly. If a large deformation amount of cold rolling is carried out at one time, the huge rolling force will cause a small number of Cu 4Cracks occur on the surface of the AgZr phase. Due to the narrow crack width, while Cu 4 The size of the AgZr phase is relatively large, and the relatively soft copper matrix has not had time to fill the holes caused by the cracks during the cold rolling deformation process. The generation of holes will cause fatal damage to the mechanical properties of the alloy, especially the high-temperature mechanical properties. However, within the range of the number of single-pass cold rolling and the total deformation amount of the present invention, the above contradictions can be solved. In addition, the aging treatment temperature of the present invention should not be too high, otherwise it will promote grain growth.

[0023] Finally, the present invention also provides an application of silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties. It is used to prepare the inner lining material of the combustion chamber of an aeroengine. The thermal conductivity can reach up to 324 W / (m·K), and the tensile strength and yield strength can reach up to 267 MPa and 181 Mpa respectively during high-temperature tension at 500 °C.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The silver-zirconium-copper material provided by the present invention, by optimizing the types and contents of elements, uses in-situ generated nano Cr 2 Nb particles to pin the grain boundaries, improving the high-temperature strength of the alloy, making it have good thermal stability. At the same time, by controlling the total mass fraction of Cr and Nb to be less than or equal to 1%, it will not dissolve in the matrix strongly and damage the thermal conductivity, so that the silver-zirconium-copper can maintain high thermal conductivity while further improving the high-temperature mechanical properties.

[0026] (2) The preparation method provided by the present invention effectively reduces the melting temperature by using a Cr-Nb master alloy. At the same time, combined with the rapid solidification of the high-temperature liquid silver-zirconium-copper liquid during the gas atomization process, the solid solubility of Cr and Nb elements in the alloy is significantly increased, and fine and dispersed Cr 2 Nb phases are precipitated. Combined with the vacuum hot pressing sintering method and multi-stage cold rolling and aging heat treatment, dispersed high-temperature resistant Cr 2 Nb phases are generated, further improving the alloy properties, and obtaining silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties.

[0027] (3) The preparation method of the present invention has a simple process and has the potential for industrial production.

[0028] (3) The silver-zirconium-copper material obtained by the present invention has a thermal conductivity of up to 324 W / (m·K), and the tensile strength and yield strength can reach up to 267 MPa and 181 Mpa respectively during high-temperature tension at 500 °C, and is particularly suitable for preparing the inner lining material of the combustion chamber of an aeroengine. Description of the Drawings

[0029] Figure 1STEM-HAADF images and elemental surface distribution maps of the silver-zirconium-copper alloy prepared in Example 4 of the present invention.

[0030] The results from Figure 1 show that the elemental surface distributions of Cr and Nb in the silver-zirconium-copper alloy of the present invention completely overlap, indicating that there is no separate Cr or Nb present, and all Cr and Nb combine to form Cr 2 Nb phase.

[0031] Figure 2 Distribution map of Cu 4 AgZr phase in the silver-zirconium-copper alloy prepared in Example 4 of the present invention.

[0032] Figure 3 Distribution map of continuous Ag precipitation phase in the silver-zirconium-copper alloy prepared in Example 4 of the present invention. Detailed implementation manners

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] Example 1

[0035] For the silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties in this example, by mass fraction, its alloy components are: Ag: 3%, Zr: 0.4%, Cr: 0.2%, Nb: 0.15%, and the balance is Cu. Among them, the raw materials are high-purity electrolytic copper (purity greater than 99.9%), high-purity silver (purity greater than 99.9%), Cu-50% Zr (mass fraction, the same below) master alloy, and Cr-47% Nb master alloy.

[0036] The preparation method of the silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties in this example includes the following steps:

[0037] Powder preparation by vacuum melting and argon atomization: The prepared pure metals and master alloys are put into a melting crucible together, and argon is filled to the standard atmospheric pressure as the protective gas. The high-frequency induction device is turned on for heating. After all the alloys in the crucible are melted, the melt temperature is adjusted to 1350 °C and held for 30 min. The argon atomization pressure is adjusted to 3.5 MPa, and the argon valve is opened. After melting is completed, the ceramic stopper rod in the crucible is lifted to atomize and break the melt along the liquid guide tube, promoting the rapid solidification of the high-temperature liquid silver-zirconium-copper liquid. After the pre-alloy powder in the collector is completely cooled, the powder is collected. To prevent powder oxidation, the fine powder is immediately vacuum-packed after passing through a 200-mesh sieve and stored in a vacuum drying oven.

[0038] Vacuum hot pressing sintering: The vacuum is pumped to 1.0×10 -4 Pa, the mold size is Φ20 mm, the pressure is 5 MPa, the hot pressing temperature is 830 °C, the pressurization process is synchronized with the heating process, and the pressure holding and heat preservation time is 2 hours.

[0039] Multi-stage deformation aging treatment: After unidirectional cold rolling by 20%, it is held at 350 °C for 60 min. Secondly, after cold rolling by 50%, it is held at 400 °C for 40 min. Cold rolling by 50% is repeated and held at 400 °C for 40 min. Finally, cold rolling by 50% is aged at 350 °C for 15 min, and the total deformation amount is 90%.

[0040] The size of the second phase of the copper alloy prepared in this example is as follows: Cr 2 The size of the Nb phase is 50 - 80 nm, the size of the continuous Ag precipitation phase is 5 - 20 nm, and the size of the Cu 4 AgZr phase is 200 - 400 nm. The thermal conductivity reaches 318 W / (m·K). When high-temperature tensile testing is carried out at 500 °C, the tensile strength and yield strength are 245 MPa and 162 MPa respectively, and the elongation after fracture is 32%.

[0041] Example 2

[0042] For the silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties prepared in this example, by mass fraction, its alloy components are: Ag: 3%, Zr: 0.5%, Cr: 0.25%, Nb: 0.2%, and the balance is Cu. Among them, the raw materials are high-purity electrolytic copper (purity greater than 99.9%), high-purity silver (purity greater than 99.9%), Cu-50% Zr (mass fraction, the same below) master alloy, and Cr-47% Nb master alloy.

[0043] The preparation method and conditions of the silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties in this example are the same as those in Example 1.

[0044] The size of the second phase of the copper alloy prepared in this example is as follows: Cr 2The size of the Nb phase is 50 - 80 nm, the size of the continuous Ag precipitation phase is 5 - 20 nm, and Cu 4 The size of the AgZr phase is 200 - 400 nm. The thermal conductivity reaches 324 W / (m·K). When high-temperature tensile testing is carried out at 500 °C, the tensile strength and yield strength are 256 MPa and 170 MPa respectively, and the elongation after fracture is 29%.

[0045] Example 3

[0046] For the silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties in this example, by mass fraction, its alloy components are: Ag: 3%, Zr: 0.6%, Cr: 0.3%, Nb: 0.25%, and the balance is Cu. Among them, the raw materials are high-purity electrolytic copper (purity greater than 99.9%), high-purity silver (purity greater than 99.9%), Cu-50% Zr (mass fraction, the same below) master alloy, and Cr-47% Nb master alloy.

[0047] The preparation method and conditions of the silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties in this example are the same as those in Example 1.

[0048] The size of the second phase of the copper alloy prepared in this example is as follows: Cr 2 The size of the Nb phase is 50 - 80 nm, the size of the continuous Ag precipitation phase is 5 - 20 nm, and Cu 4 The size of the AgZr phase is 200 - 450 nm. The thermal conductivity reaches 321 W / (m·K). When high-temperature tensile testing is carried out at 500 °C, the tensile strength and yield strength are 260 MPa and 173 MPa respectively, and the elongation after fracture is 27%.

[0049] Example 4

[0050] For the silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties in this example, by mass fraction, its alloy components are: Ag: 3%, Zr: 0.5%, Cr: 0.4%, Nb: 0.35%, and the balance is Cu. Among them, the raw materials are high-purity electrolytic copper (purity greater than 99.9%), high-purity silver (purity greater than 99.9%), Cu-50% Zr (mass fraction, the same below) master alloy, and Cr-47% Nb master alloy.

[0051] The preparation method and conditions of the silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties in this example are the same as those in Example 1.

[0052] The size of the second phase of the copper alloy prepared in this example is as follows: Cr 2 The size of the Nb phase is 50 - 90 nm, the size of the continuous Ag precipitation phase is 5 - 20 nm, and Cu 4The size of the AgZr phase is 200 - 400 nm. The thermal conductivity reaches 324 W / (m·K). When subjected to high-temperature tensile testing at 500 °C, the tensile strength and yield strength are 267 MPa and 181 MPa respectively, and the elongation after fracture is 28%.

[0053] Example 5

[0054] For the silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties in this example, by mass fraction, its alloy components are: Ag: 3%, Zr: 0.5%, Cr: 0.4%, Nb: 0.35%, and the balance is Cu. Among them, the raw materials are high-purity electrolytic copper (purity greater than 99.9%), high-purity silver (purity greater than 99.9%), Cu-50% Zr (mass fraction, the same below) master alloy, and Cr-47% Nb master alloy.

[0055] The preparation method of the silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties in this example includes the following steps:

[0056] Powder preparation by vacuum melting and argon atomization: Put the prepared pure metals and master alloys together into the melting crucible, fill argon to standard atmospheric pressure as the protective gas, turn on the high-frequency induction device for heating. After all the alloys in the crucible are melted, adjust the melt temperature to 1300 °C and keep it for 40 min. Adjust the argon atomization pressure to 4 MPa and open the argon valve. After the pre-alloy powder in the collector is completely cooled, collect the powder. To prevent powder oxidation, after the powder is sieved through 200 meshes, immediately vacuum-pack the fine powder and store it in a vacuum drying oven.

[0057] Vacuum hot pressing and sintering: Vacuum pump to 1.0×10 -4 Pa. The mold size is Φ25 mm, the pressure is 10 MPa, the hot pressing temperature is 840 °C. The pressurization process is synchronized with the heating process, and the pressure-holding and heat-holding time is 2 hours.

[0058] Multi-stage deformation and aging treatment: After unidirectional cold rolling by 20%, keep it at 350 °C for 20 min. Secondly, after cold rolling by 25%, keep it at 450 °C for 30 min. Thirdly, cold roll by 50% and keep it at 400 °C for 20 min. Subsequently, after cold rolling by 30%, keep it at 400 °C for 40 min. Finally, cold roll by 50% and age at 350 °C for 15 min. The total deformation is 90%.

[0059] The size of the second phase of the copper alloy prepared in this example is as follows: Cr 2 The size of the Nb phase is 50 - 100 nm, the size of the continuous Ag precipitation phase is 5 - 20 nm, Cu 4The size of the AgZr phase is 200 - 500 nm. The thermal conductivity reaches 316 W / (m·K). When subjected to high-temperature tensile testing at 500 °C, the tensile strength and yield strength are 263 MPa and 178 MPa respectively, and the elongation after fracture is 34%.

[0060] Example 6

[0061] For the silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties in this example, by mass fraction, its alloy components are: Ag: 3%, Zr: 0.5%, Cr: 0.4%, Nb: 0.35%, and the balance is Cu. Among them, the raw materials are high-purity electrolytic copper (purity greater than 99.9%), high-purity silver (purity greater than 99.9%), Cu-50% Zr (mass fraction, the same below) master alloy, and Cr-47% Nb master alloy.

[0062] The preparation method of the silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties in this example includes the following steps:

[0063] Powder preparation by vacuum melting and argon atomization: Put the prepared pure metals and master alloys together into the melting crucible, fill argon to standard atmospheric pressure as the protective gas, turn on the high-frequency induction device for heating. After all the alloy in the crucible is melted, adjust the melt temperature to 1400 °C and hold for 30 min. Adjust the argon atomization pressure to 3.5 MPa and open the argon valve. After the pre-alloy powder in the collector is completely cooled, collect the powder. To prevent powder oxidation, after the powder is sieved through a 200-mesh sieve, immediately vacuum-pack the fine powder and store it in a vacuum drying oven.

[0064] Vacuum hot pressing and sintering: Vacuum pump to 1.0×10 -3 Pa, the die size is Φ25 mm, the pressure is 15 MPa, the hot pressing temperature is 850 °C, the pressurization process is synchronized with the heating process, and the pressure holding and heat preservation time is 1.5 hours.

[0065] Multi-stage deformation and aging treatment: After unidirectional cold rolling by 20%, hold at 350 °C for 20 min, then cold roll by 25% and hold at 350 °C for 30 min, then cold roll by 50% and hold at 400 °C for 20 min, then cold roll by 30% and hold at 400 °C for 40 min, and finally cold roll by 50% and age at 350 °C for 15 min. The total deformation is 90%.

[0066] The size of the second phase of the copper alloy prepared in this example is as follows: Cr 2 The size of the Nb phase is 50 - 90 nm, the size of the continuous Ag precipitation phase is 5 - 20 nm, and Cu 4The size of the AgZr phase is 200 - 400 nm. The thermal conductivity reaches 309 W / (m·K). When subjected to high-temperature tensile testing at 500 °C, the tensile strength and yield strength are 259 MPa and 163 MPa respectively, and the elongation after fracture is 35%.

[0067] Example 7

[0068] The silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties in this example, by mass fraction, has the following alloy components: Ag: 3%, Zr: 0.5%, Cr: 0.4%, Nb: 0.35%, and the balance is Cu. The raw materials are high-purity electrolytic copper (purity greater than 99.9%), high-purity silver (purity greater than 99.9%), Cu-50% Zr (mass fraction, the same below) master alloy, and Cr-47% Nb master alloy.

[0069] The preparation method of the silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties in this example includes the following steps:

[0070] Powder preparation by vacuum melting and argon atomization: Put the prepared pure metals and master alloys together into a melting crucible, fill argon to standard atmospheric pressure as the protective gas, turn on the high-frequency induction device for heating. After all the alloy in the crucible is melted, adjust the melt temperature to 1300 °C and hold for 60 min. Adjust the argon atomization pressure to 3.5 MPa and open the argon valve. After the pre-alloy powder in the collector is completely cooled, collect the powder. To prevent powder oxidation, after the powder is sieved through a 200-mesh sieve, immediately vacuum-pack the fine powder and store it in a vacuum drying oven.

[0071] Vacuum hot pressing and sintering: Vacuum pump to 1.0×10 -5 Pa, the mold size is Φ20 mm, the maximum pressure is 15 MPa, the hot pressing temperature is 830 °C, the pressure application process is synchronized with the heating process, and the pressure holding and heat preservation time is 2 hours.

[0072] Multi-stage deformation and aging treatment: After unidirectional cold rolling by 20%, hold at 350 °C for 20 min, then cold roll by 25% and hold at 350 °C for 30 min, then cold roll by 50% and hold at 400 °C for 20 min, and finally cold roll by 50% and hold at 400 °C for 40 min. The total deformation is 85%.

[0073] The size of the second phase of the copper alloy prepared in this example is as follows: Cr 2 The size of the Nb phase is 50 - 80 nm, the size of the continuous Ag precipitation phase is 5 - 20 nm, and the Cu 4 The size of the AgZr phase is 200 - 400 nm. The thermal conductivity reaches 313 W / (m·K). When subjected to high-temperature tensile testing at 500 °C, the tensile strength and yield strength are 251 MPa and 152 MPa respectively, and the elongation after fracture is 37%.

[0074] Comparative Example 1

[0075] The difference between this comparative example and Example 4 is only that the alloy composition is changed to: Ag: 3%, Zr: 0.5%, Cr: 0.4%, and the balance is Cu, and the other conditions and steps are the same.

[0076] The thermal conductivity of the obtained copper alloy reaches 297 W / (m·K). When high-temperature tensile testing is carried out at 500 °C, the tensile strength and yield strength are 243 MPa and 169 MPa respectively, and the elongation after fracture is 34%.

[0077] Comparative Example 2

[0078] The difference between this comparative example and Example 4 is only that the alloy composition is changed to: Ag: 3%, Zr: 0.5%, Nb: 0.35%, and the balance is Cu, and the other conditions and steps are the same.

[0079] The thermal conductivity of the obtained copper alloy reaches 281 W / (m·K). When high-temperature tensile testing is carried out at 500 °C, the tensile strength and yield strength are 250 MPa and 172 MPa respectively, and the elongation after fracture is 32%.

[0080] Comparative Example 3

[0081] For the silver-zirconium-copper of this comparative example with high thermal conductivity and excellent high-temperature mechanical properties, by mass fraction, its alloy composition is: Ag: 3%, Zr: 0.5%, and the balance is Cu. Among them, the raw materials are high-purity electrolytic copper (purity greater than 99.9%), high-purity silver (purity greater than 99.9%), and Cu-50% Zr (mass fraction, the same below) master alloy.

[0082] The preparation method and conditions of the silver-zirconium-copper of this comparative example with high thermal conductivity and excellent high-temperature mechanical properties are the same as those of Example 1.

[0083] The thermal conductivity of the copper alloy prepared in this comparative example reaches 326 W / (m·K). When high-temperature tensile testing is carried out at 500 °C, the tensile strength and yield strength are 216 MPa and 153 MPa respectively, and the elongation after fracture is 43%.

[0084] Comparative Example 4

[0085] For the silver-zirconium-copper of this comparative example with high thermal conductivity and excellent high-temperature mechanical properties, by mass fraction, its alloy composition is: Ag: 3%, Zr: 0.5%, Cr: 0.4%, Nb: 0.35%, and the balance is Cu. Among them, the raw materials are high-purity electrolytic copper (purity greater than 99.9%), high-purity silver (purity greater than 99.9%), Cu-50% Zr (mass fraction, the same below) master alloy, and Cr-47% Nb master alloy.

[0086] The preparation method of silver zirconium copper with high thermal conductivity and excellent high-temperature mechanical properties in this comparative example includes the following steps:

[0087] Powder preparation by vacuum melting and argon atomization: Put the prepared pure metals and master alloys together into a melting crucible, fill it with argon to standard atmospheric pressure as the protective gas, turn on the high-frequency induction device for heating. After all the alloys in the crucible are melted, adjust the melt temperature to 1350 °C and keep it for 30 min. Adjust the argon atomization pressure to 3.5 MPa, open the argon valve. After melting is completed, raise the ceramic stopper rod in the crucible to make the melt break atomically along the liquid guide tube, promoting the rapid solidification of the high-temperature liquid silver zirconium copper. After the pre-alloy powder in the collector is completely cooled, collect the powder. To prevent powder oxidation, after the powder is sieved through a 200-mesh sieve, immediately vacuum-pack the fine powder and store it in a vacuum drying oven.

[0088] Vacuum hot pressing sintering: Vacuum pump to 1.0×10 -4 Pa, the mold size is Φ20 mm, the pressure is 5 MPa, the hot pressing temperature is 830 °C, the pressurization process is synchronized with the heating process, and the pressure holding and heat preservation time is 2 hours.

[0089] Hot forging: The hot forging sample is cylindrical, with dimensions of Φ100 mm×50 mm, the forging temperature is 800 °C, the heat preservation time is 1 h, and the forging ratio (pre-forging thickness / post-forging thickness) is 4:1.

[0090] The thermal conductivity of the copper alloy prepared in this comparative example reaches 301 W / (m·K). When performing high-temperature tensile at 500 °C, the tensile strength and yield strength are 241 MPa and 168 MPa respectively, and the elongation after fracture is 29%.

[0091] Comparative Example 5

[0092] The difference between this comparative example and Example 4 is only that the alloy composition is changed to: Ag: 3%, Zr: 0.5%, Cr: 0.35%, Nb: 0.4%, and the balance is Cu, and the rest of the steps and conditions are the same.

[0093] When the contents of Cr and Nb are exchanged, the thermal conductivity of the obtained copper alloy reaches 311 W / (m·K). When performing high-temperature tensile at 500 °C, the tensile strength and yield strength are 255 MPa and 167 MPa respectively, and the elongation after fracture is 29%.

Claims

1. A silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties, characterized in that: The composition includes, by mass fraction, 2.7% to 3.5% Ag, 0.4% to 0.6% Zr, 0.2% to 0.5% Cr, 0.15% to 0.45% Nb, and the balance is Cu; and the total mass fraction of Cr and Nb is less than or equal to 1%; The silver-zirconium-copper matrix contains Cr2Nb phase.

2. The silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties according to claim 1, characterized in that: When the ratio of the mass fraction of Cr to the mass fraction of Nb is 1.1-1.35, Cr and Nb exist completely in the silver-zirconium-copper matrix in the form of Cr2Nb phase.

3. The silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties according to claim 1 or 2, characterized in that: The size of the Cr2Nb phase is 50-100 nm; The silver-zirconium-copper matrix also contains a continuous Ag precipitated phase with a size of 5 to 20 nm and a Cu4AgZr phase with a size of 200 to 500 nm.

4. A method for preparing silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties according to any one of claims 1 to 3, characterized in that: The raw materials are weighed according to the designed silver-zirconium-copper ratio; pure copper, pure silver, Cr-Nb master alloy and Cu-Zr master alloy are powdered by vacuum melting and gas atomization to obtain pre-alloyed powder; the pre-alloyed powder is subjected to vacuum hot pressing sintering and multi-stage deformation aging treatment to obtain the pre-alloyed powder.

5. The method for preparing silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties according to claim 4, characterized in that: The vacuum melting gas atomization powder making process is as follows: melt the prepared raw materials in a crucible, control the melting temperature to be 1200-1500° C., and keep the temperature for 30-60 minutes; after the melting is completed, raise the ceramic blocking rod in the crucible to make the melt gas-atomized and broken along the liquid guide tube, so as to promote the rapid solidification of the high-temperature liquid silver-zirconium-copper liquid, and collect the pre-alloyed powder after complete cooling; The medium of the gas atomization powder making is argon gas, and the pressure is 3-4Mpa.

6. The method for preparing silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties according to claim 5, characterized in that: The particle size of the pre-alloyed powder is less than 74 μm, and the oxygen content is less than 0.0028%.

7. The method for preparing silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties according to claim 4, characterized in that: The vacuum hot pressing sintering conditions are: vacuum degree is 10 -3 ~10 -5 Pa, the mold size is Φ20-40mm, the pressure is 5-20MPa, the hot pressing temperature is 830-850℃, the pressurization process is synchronized with the heating process, and the pressure holding time is 1.5-2h.

8. A method for preparing silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties according to claim 4 or 7, characterized in that: The multi-stage deformation aging treatment includes 3 to 6 unidirectional cold rollings, with a total deformation of 80% to 95%; an aging treatment is performed after each unidirectional cold rolling, the temperature of any aging treatment is 350 to 500° C., and the time of any aging treatment is 15 to 60 minutes.

9. The use of silver-zirconium-copper with high thermal conductivity and excellent high-temperature mechanical properties as claimed in any one of claims 1 to 3, characterized in that: Used to prepare aviation engine combustion chamber lining materials.

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