Beryllium-aluminum alloy preparation method based on under-aging process and beryllium-aluminum alloy

Abstract

The invention discloses a beryllium-aluminum alloy preparation method based on an under-aging process, and belongs to the technical field of beryllium-aluminum alloys. The preparation method comprises the following steps: preparing A1-Zn-Mg-Cu alloy powder and beryllium powder; the A1-Zn-Mg-Cu alloy powder and beryllium powder are mixed to be uniform, and mixed powder is obtained; performing cold isostatic pressing, primary degassing, secondary degassing and hot isostatic pressing on the mixed powder in sequence, and cooling to room temperature along with a furnace after the cold isostatic pressing, the primary degassing, the secondary degassing and the hot isostatic pressing are finished to obtain a blank; and the blank is subjected to solid solution and under-aging in sequence, and the beryllium aluminum alloy is obtained, the solid solution comprises the following steps: heating to 420-480 DEG C at a heating rate of 10-50 DEG C / min, keeping the temperature for 1-3 hours, and quenching with water to room temperature; and in the under-aging process, the temperature is increased to 110-140 DEG C at the heating rate of 10-50 DEG C / min, heat preservation is conducted for 1-6 h, and then furnace cooling is conducted to the room temperature. The beryllium-aluminum alloy prepared through the method has high strength and ductility.

Description

Technical Field

[0001] The invention belongs to the technical field of beryllium aluminum alloys, and in particular relates to a beryllium aluminum alloy preparation method based on an under-aging process and the beryllium aluminum alloy. Background Art

[0002] Beryllium aluminum alloy combines the advantages of beryllium and aluminum, and has the rigidity of beryllium and the toughness of aluminum. It has the characteristics of light weight, high specific strength, high specific stiffness, good thermal stability, high toughness, high modulus, and corrosion resistance. It is an important new structural material. At the same time, due to its excellent thermal and optical properties, it can be widely used in automobiles, computers, aerospace electronic equipment, etc.

[0003] However, traditional beryllium aluminum alloys have certain limitations in performance. On the one hand, in terms of strength, when the beryllium content in beryllium aluminum alloys is high, although its specific stiffness and thermal properties are relatively excellent, the strength improvement of the material is limited, and it is difficult to meet some application scenarios with extremely high requirements for structural strength. On the other hand, insufficient elongation is also a major problem. Beryllium aluminum alloys under traditional preparation processes often show lower elongation and poor toughness of the material. This makes it easy to crack, brittle fracture and other problems during the processing and forming process, which greatly limits the processing technology of the material and the manufacture of complex parts.

[0004] From the perspective of preparation methods, the current common methods for preparing beryllium aluminum alloys also have many shortcomings. In the traditional smelting and casting method, due to the large difference in the melting points of beryllium and aluminum, it is difficult to achieve uniform mixing during the smelting process, which easily leads to component segregation, thereby affecting the consistency and stability of material properties. Moreover, the volatilization of beryllium during the smelting process will cause harm to the environment and the health of operators. Although the powder metallurgy method can improve the uniformity of the composition to a certain extent, the preparation process is complicated and the cost is high. At the same time, during the pressing and sintering process, the powder is prone to defects such as pores, which affect the density and mechanical properties of the material. In addition, the hot working process parameters have a great influence on the organization and properties of the beryllium aluminum alloy. It is difficult to accurately control the process parameters in the existing preparation method, so that it is impossible to stably prepare a beryllium aluminum alloy material with both high strength and high elongation.

[0005] Therefore, it is urgent to develop a new method for preparing high-strength and high-elongation beryllium aluminum alloy. Summary of the invention

[0006] To solve the above technical problems, the present invention provides a preparation method of beryllium-aluminum alloy based on under-aging process and the beryllium-aluminum alloy. On the one hand, by adding appropriate amounts of Zn, Mg, and Cu as strengthening elements to form η (MgZn2), T (Al2Mg3Zn3), and S (CuMgAl2) precipitation phases to strengthen the aluminum matrix. On the other hand, a large ratio of beryllium-aluminum ratio is combined with solution treatment and under-aging heat treatment process to avoid excessive growth of precipitation phases, so as to comprehensively improve the strength and elongation of the alloy.

[0007] In the first aspect, the present invention provides a preparation method of beryllium-aluminum alloy based on under-aging process, and the preparation method includes:

[0008] Step S1, preparing A1-Zn-Mg-Cu alloy powder;

[0009] The A1-Zn-Mg-Cu alloy powder, by mass percentage, includes the following components: zinc 5-9%, magnesium 1-3%, and copper 0.2-3%, and the balance is aluminum;

[0010] Step S2, preparing beryllium powder;

[0011] Step S3, mixing the A1-Zn-Mg-Cu alloy powder and beryllium powder evenly to obtain a mixed powder;

[0012] The mass percentage of beryllium powder in the mixed powder is 60-65%;

[0013] Step S4, subjecting the mixed powder to cold isostatic pressing, primary degassing, secondary degassing, and hot isostatic pressing in sequence, and then cooling to room temperature with the furnace after completion to obtain a blank;

[0014] Step S5, subjecting the blank to solution treatment and under-aging in sequence to obtain the beryllium-aluminum alloy;

[0015] The solution treatment is: heating at a heating rate of 10-50 °C / min to 420-480 °C, holding for 1-3 h, and then quenching to room temperature with water;

[0016] The under-aging is: heating at a heating rate of 10-50 °C / min to 110-140 °C, holding for 1-6 h, and then cooling to room temperature with the furnace.

[0017] According to the preparation method described in the first aspect of the present invention, in the step S1, the average particle size of the A1-Zn-Mg-Cu alloy powder is 10-30 μm.

[0018] According to the preparation method described in the first aspect of the present invention, in the step S1, the preparation process of the A1-Zn-Mg-Cu alloy powder is as follows:

[0019] Step S11: Prepare raw materials according to the components and mass percentages of the A1-Zn-Mg-Cu alloy powder;

[0020] Step S12: Vacuum melt and atomize the prepared raw materials in sequence to obtain the A1-Zn-Mg-Cu alloy powder.

[0021] According to the preparation method described in the first aspect of the present invention, in the step S2, the average particle size of the beryllium powder is 5 - 20 μm.

[0022] According to the preparation method described in the first aspect of the present invention, in the step S2, the preparation process of the beryllium powder is atomization powder making, gas flow impact or mechanical grinding.

[0023] According to the preparation method described in the first aspect of the present invention, in the step S3, the mixing time of the A1-Zn-Mg-Cu alloy powder and the beryllium powder is 12 - 36 h.

[0024] According to the preparation method described in the first aspect of the present invention, in the step S4, the pressure of the cold isostatic pressing is 50 - 250 MPa, and the pressure holding time is 10 - 30 min;

[0025] The vacuum degree of the first degassing is 1×10 -1 -1×10 -2 Pa, the heat preservation temperature is 450 - 550 °C, and the heat preservation time is 12 - 36 h;

[0026] The vacuum degree of the second degassing is 1×10 -3 -1×10 -4 Pa, the heat preservation temperature is 500 - 600 °C, and the heat preservation time is 12 - 36 h;

[0027] Among them, the temperature of the second degassing is higher than that of the first degassing;

[0028] The heat preservation temperature of the hot isostatic pressing is 660 - 800 °C, the pressure holding pressure is 50 - 150 MPa, and the heat preservation and pressure holding time is 5 - 10 h.

[0029] According to the preparation method described in the first aspect of the present invention, in the step S5, the solution treatment is as follows: heat up at a heating rate of 20 - 40 °C / min to 460 - 480 °C, keep warm for 1.5 - 2.5 h, and then water quench to room temperature;

[0030] The underaging treatment is as follows: heat up at a heating rate of 20 - 40 °C / min to 110 - 130 °C, keep warm for 2 - 4 h, and then cool in the furnace to room temperature.

[0031] In the second aspect of the present invention, a beryllium-aluminum alloy is proposed, and the beryllium-aluminum alloy is prepared by using the aforementioned preparation method.

[0032] For the beryllium-aluminum alloy according to the second aspect of the present invention, the tensile strength of the beryllium-aluminum alloy is 420 - 450 MPa, the yield strength is 300 - 340 MPa, and the elongation is 1.5 - 3.0%.

[0033] The solution proposed by the present invention has the following technical effects:

[0034] In the present invention, on the one hand, by adding appropriate amounts of Zn, Mg, and Cu as strengthening elements to form η(MgZn2), T(Al2Mg3Zn3), and S(CuMgAl2) precipitation phases to strengthen the aluminum matrix; on the other hand, a large beryllium-aluminum ratio is combined with a solution treatment and under-aging heat treatment process to avoid excessive growth of the precipitation phases, thereby comprehensively improving the strength and elongation of the alloy.

[0035] In addition, the tensile strength of the beryllium-aluminum alloy of the present invention is 420 - 450 MPa, the yield strength is 300 - 340 MPa, and the elongation is 1.5 - 3.0%. Description of the Drawings

[0036] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0037] Figure 1 It is a scanning electron microscope image of the beryllium-aluminum alloy prepared in Example 1 of the present invention. Detailed Embodiments

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0039] In the first aspect of this embodiment, a preparation method of a beryllium-aluminum alloy based on an under-aging process is proposed, and the preparation method includes:

[0040] Step S1, preparing A1-Zn-Mg-Cu alloy powder.

[0041] Step S2, preparing beryllium powder.

[0042] Step S3: Mix the A1-Zn-Mg-Cu alloy powder and beryllium powder evenly to obtain a mixed powder.

[0043] Step S4: Perform cold isostatic pressing, primary degassing, secondary degassing, and hot isostatic pressing on the mixed powder in sequence. After completion, cool it in the furnace to room temperature to obtain a blank.

[0044] Step S5: Perform solution treatment and under-aging on the blank in sequence to obtain the beryllium-aluminum alloy.

[0045] On the one hand, in the present invention, by adding appropriate amounts of Zn, Mg, and Cu as strengthening elements to form η (MgZn2), T (Al2Mg3Zn3), and S (CuMgAl2) precipitation phases to strengthen the aluminum matrix; on the other hand, adopting a large beryllium-aluminum ratio combined with solution treatment and under-aging heat treatment processes to avoid excessive growth of the precipitation phases, thereby comprehensively improving the strength and elongation of the alloy.

[0046] Specifically, in this embodiment, the mass fraction of the beryllium phase is 60-65%, and the volume fraction is about 70%, and the rest is the aluminum framework. In fact, it is an aluminum-based beryllium particle-reinforced composite material; on this basis, the physical characteristics of the aging precipitation sequence of the aluminum phase will change due to the addition of a large proportion of the beryllium phase. Therefore, the traditional aging process of the aluminum phase is no longer applicable to the alloy material of the present invention. Therefore, the present invention performs under-aging heat treatment with low temperature and short time on the beryllium-aluminum alloy with specific components and contents to make the performance of the aluminum phase optimal. For the beryllium-aluminum alloy with specific components and contents in this embodiment, aging treatment with excessive extended time and increased temperature will instead cause the precipitation phases η (MgZn2), T (Al2Mg3Zn3), and S (CuMgAl2) to grow, thereby reducing the beryllium-aluminum interface bonding strength, increasing the aluminum phase stress, and increasing stress corrosion, etc.

[0047] In step S1, prepare the A1-Zn-Mg-Cu alloy powder.

[0048] In some embodiments, the A1-Zn-Mg-Cu alloy powder, by mass percentage, includes the following components: 5-9% zinc, 1-3% magnesium, and 0.2-3% copper, with the balance being aluminum.

[0049] Preferably, the A1-Zn-Mg-Cu alloy powder, by mass percentage, includes the following components: 5-7.5% zinc, 1-2% magnesium, and 0.2-2% copper, with the balance being aluminum.

[0050] Further preferably, the A1-Zn-Mg-Cu alloy powder, by mass percentage, includes the following components: 5-6% zinc, 1-1.5% magnesium, and 0.2-1.5% copper, with the balance being aluminum.

[0051] The composition design of the A1-Zn-Mg-Cu alloy has an impact on the properties of the final beryllium-aluminum alloy product. Specifically, different strengthening elements and different contents of the same strengthening element may generate different types and amounts of strengthening precipitation phases, thereby affecting the product properties.

[0052] In this embodiment, Zn and Mg are the main strengthening elements. When they coexist, they will form η(MgZn2) and T(Al2Mg3Zn3) phases. According to the atomic weight calculation, the atomic ratio of Mg:Zn = 1:(1 - 2), and the mass ratio is about 1:(3 - 5). Therefore, when the Mg content is 1 - 3%, the Zn content is 5 - 9%.

[0053] The range of the Mg and Zn contents mainly considers the volume fraction range of the strengthening precipitation phases in the composite material strengthening theory. Too few strengthening precipitation phases cannot play a strengthening role, and too many strengthening precipitation phases may increase the stress corrosion of this material and the low-density requirements of the material for aerospace applications. For this reason, through a large number of theoretical calculations and experimental studies, the applicant designed that when the total volume content of the strengthening precipitation phases in the aluminum matrix of the beryllium-aluminum alloy in this embodiment is 3 - 6%, the strength and elongation of the beryllium-aluminum alloy are the best.

[0054] The main function of the Cu element is to increase the interfacial adhesion work of the Be / Al interface, enhance the bonding between Be and Al atoms, thereby improving the bonding strength of the Al / Be interface; at the same time, Cu can also reduce the potential difference between the aluminum grain boundary and the grain interior, change the precipitate phase structure and refine the grain boundary precipitate phase, inhibit the tendency of intergranular cracking, and thus improve the stress corrosion resistance of the alloy; in addition, Cu can also generate the strengthening phase S(CuMgAl2) to further strengthen the aluminum matrix and enhance the strength of the beryllium-aluminum alloy. Because Cu is mainly not used for strengthening, and the density of Cu is relatively high, it is not easy to add too much. Generally, the solubility of Cu in aluminum at room temperature is about 4%. Considering the dissolution of other solid solution elements in aluminum in this embodiment, less than 3% of Cu is selected to be dissolved in Al, and then it diffuses with beryllium.

[0055] In some embodiments, in the step S1, the average particle size of the A1-Zn-Mg-Cu alloy powder is 10 - 30 μm.

[0056] In this embodiment, the selection of the particle size range of the A1-Zn-Mg-Cu alloy powder considers the problem of powder mixing with beryllium powder. If the A1-Zn-Mg-Cu alloy powder is too coarse or too fine, it will lead to uneven powder mixing in the later stage, and finally the structure of the beryllium-aluminum composite material will be uneven; in addition, too fine A1-Zn-Mg-Cu alloy powder will also increase the oxygen content on the surface of the aluminum powder, resulting in too high impurity content in the final beryllium-aluminum alloy.

[0057] In some embodiments, in the step S1, the preparation process of the A1-Zn-Mg-Cu alloy powder is as follows:

[0058] Step S11: Prepare raw materials according to the components and mass percentages of the A1-Zn-Mg-Cu alloy powder.

[0059] Step S12: Vacuum melt and atomize the prepared raw materials in sequence to obtain the A1-Zn-Mg-Cu alloy powder.

[0060] In step S2, prepare beryllium powder.

[0061] In some embodiments, in step S2, the average particle size of the beryllium powder is 5 - 20 μm.

[0062] In this embodiment, the particle size range of the beryllium powder is selected considering the problem of mixing powder with the A1-Zn-Mg-Cu alloy powder. If the beryllium powder is too coarse or too fine, it will lead to uneven mixing of the powder in the later stage, and finally the structure of the beryllium-aluminum composite material will be uneven; in addition, if the beryllium powder is too fine, it will also increase the oxygen content on the surface of the beryllium powder, resulting in too high impurity content in the final beryllium-aluminum alloy.

[0063] In some embodiments, in step S2, the preparation process of the beryllium powder is atomization powder making, gas flow impact or mechanical grinding.

[0064] In step S3, mix the A1-Zn-Mg-Cu alloy powder and the beryllium powder evenly to obtain a mixed powder.

[0065] In some embodiments, in step S3, the mass percentage of the beryllium powder in the mixed powder is 60 - 65%.

[0066] In some embodiments, in step S3, the mixing time of the A1-Zn-Mg-Cu alloy powder and the beryllium powder is 12 - 36 h.

[0067] In step S4, perform cold isostatic pressing, primary degassing, secondary degassing and hot isostatic pressing on the mixed powder in sequence, and then cool it in the furnace to room temperature to obtain a blank.

[0068] In this embodiment, the cooling method is to cool in the furnace to room temperature to slow down the cooling rate and avoid situations such as residual stress, stress corrosion, deformation, and fracture.

[0069] In some embodiments, in step S4, the pressure of the cold isostatic pressing is 50 - 250 MPa, and the pressure holding time is 10 - 30 min;

[0070] The vacuum degree of the primary degassing is 1×10 -1 -1×10 -2 Pa, the heat preservation temperature is 450 - 550 °C, and the heat preservation time is 12 - 36 h;

[0071] The vacuum degree of the secondary degassing is 1×10 -3 -1×10 -4 Pa, the heat preservation temperature is 500 - 600 °C, and the heat preservation time is 12 - 36 h;

[0072] Among them, the temperature of the secondary degassing is higher than that of the primary degassing;

[0073] The heat preservation temperature of the hot isostatic pressing is 660 - 800 °C, the pressure holding pressure is 50 - 150 MPa, and the heat preservation and pressure holding time is 5 - 10 h.

[0074] Preferably, the pressure of the cold isostatic pressing is 100 - 200 MPa, and the pressure holding time is 15 - 25 min;

[0075] The heat preservation temperature of the primary degassing is 480 - 520 °C, and the heat preservation time is 18 - 24 h;

[0076] The heat preservation temperature of the secondary degassing is 530 - 570 °C, and the heat preservation time is 18 - 24 h;

[0077] The heat preservation temperature of the hot isostatic pressing is 750 - 780 °C, the pressure holding pressure is 80 - 120 MPa, and the heat preservation and pressure holding time is 6 - 8 h.

[0078] In this embodiment, a large amount of adsorbed gas on the surface of the mixed powder is removed through primary degassing. Through secondary degassing, the amorphous layer Al2O3 on the surface of the mixed powder is transformed into γ - Al2O3, and the adsorption of residual oxygen is removed. Therefore, the secondary degassing requires a higher vacuum degree than the primary degassing. The hot isostatic pressing in this embodiment adopts liquid - phase sintering, so the heat preservation temperature of the hot isostatic pressing needs to be higher than the melting point of aluminum, 660 °C. The higher the temperature, the better the heat treatment effect on beryllium particles.

[0079] The selection of the cold isostatic pressing pressure in this embodiment needs to consider the yield strength of the aluminum and beryllium phases, especially the yield strength of the beryllium phase, to make it deform, fill, and sinter densely. Therefore, the minimum pressure shall not be lower than 50 MPa.

[0080] In the step S5, the blank is subjected to solution treatment and under - aging in sequence to obtain the beryllium - aluminum alloy.

[0081] In some embodiments, in the step S5, the solution treatment is as follows: heating at a heating rate of 10 - 50 °C / min to 420 - 480 °C, keeping warm for 1 - 3 h, and then quenching to room temperature in water; the under - aging is as follows: heating at a heating rate of 10 - 50 °C / min to 110 - 140 °C, keeping warm for 1 - 6 h, and then cooling to room temperature with the furnace.

[0082] Preferably, the solution treatment is as follows: heating to 460 - 480°C at a heating rate of 30°C / min, holding for 1.5 - 2.5 h, and then water quenching to room temperature; the under-aging treatment is as follows: heating to 110 - 130°C at a heating rate of 20 - 40°C / min, holding for 2 - 4 h, and then furnace cooling to room temperature.

[0083] More preferably, the solution treatment is as follows: heating to 470°C at a heating rate of 30°C / min, holding for 2 h, and then water quenching to room temperature; the under-aging treatment is as follows: heating to 120°C at a heating rate of 30°C / min, holding for 2 h, and then furnace cooling to room temperature.

[0084] The purpose of the solution treatment in this embodiment is homogenization treatment, enabling the strengthening elements to dissolve back into the aluminum matrix, facilitating the subsequent controlled precipitation. The purpose of the under-aging treatment is to precipitate strengthening phases under controlled conditions, improve the beryllium / aluminum interface structure, modulate the beryllium-aluminum two-phase relationship, and thus improve the properties of the alloy material. If the heating rate in this embodiment is too large, stress non-uniformity will occur, resulting in a thermal shock effect and damaging the material body; if the heating rate is too small, the solution state will be entered prematurely, and stress non-uniformity will also occur.

[0085] In addition, the cooling method in this embodiment is furnace cooling to room temperature to slow down the cooling rate and avoid the generation of residual stress, stress corrosion, deformation, fracture, etc.

[0086] In the second aspect of this embodiment, a beryllium-aluminum alloy is proposed, and the beryllium-aluminum alloy is prepared by using the aforementioned preparation method.

[0087] In some embodiments, the tensile strength of the beryllium-aluminum alloy is 420 - 450 MPa, the yield strength is 300 - 340 MPa, and the elongation is 1.5 - 3.0%.

[0088] In some embodiments, the total volume content of the strengthening precipitates in the aluminum matrix of the beryllium-aluminum alloy is 3 - 6%.

[0089] In some embodiments, the strengthening precipitates in the aluminum matrix of the beryllium-aluminum alloy are η(MgZn2), T(Al2Mg3Zn3), and S(CuMgAl2).

[0090] Example 1

[0091] First step, prepare A1-Zn-Mg-Cu alloy powder with an average particle size of 15 μm by using vacuum melting and atomization powder preparation process; wherein, the A1-Zn-Mg-Cu alloy powder, by mass percentage, includes the following components: zinc 5.9%, magnesium 2.5%, and copper 1.6%, and the balance is aluminum;

[0092] Second step, prepare beryllium powder with an average particle size of 15 μm by using the gas impact process;

[0093] In the third step, 1 kg of A1-Zn-Mg-Cu alloy powder and 1.6 kg of beryllium powder are mixed in a mechanical mixer for 12 h to obtain mixed powder;

[0094] In the fourth step, the mixed powder is loaded into a rubber sheath and then subjected to cold isostatic pressing, primary degassing, secondary degassing and hot isostatic pressing in sequence. After completion, it is cooled to room temperature in the furnace to obtain a blank;

[0095] Among them, the pressure of cold isostatic pressing is 50 MPa and the pressure holding time is 30 min;

[0096] The vacuum degree of primary degassing is 1×10 -1 -1×10 -2 Pa, the heat preservation temperature is 550 °C, and the heat preservation time is 36 h;

[0097] The vacuum degree of secondary degassing is 1×10 -3 -1×10 -4 Pa, the heat preservation temperature is 600 °C, and the heat preservation time is 24 h;

[0098] The heat preservation temperature of hot isostatic pressing is 780 °C, the pressure holding pressure is 150 MPa, and the heat preservation and pressure holding time is 10 h.

[0099] In the fifth step, the blank is subjected to solution treatment and under-aging in sequence to obtain a beryllium-aluminum alloy;

[0100] Among them, the solution treatment is: heating at a heating rate of 30 °C / min to 460 °C, after heat preservation for 1 h, quenching in water to room temperature;

[0101] The under-aging is: heating at a heating rate of 30 °C / min to 120 °C, after heat preservation for 2 h, cooling to room temperature in the furnace.

[0102] Example 2

[0103] The difference from Example 1 is that in the fifth step, the heat preservation time during the under-aging process is 4 h.

[0104] Example 3

[0105] The difference from Example 1 is that in the fifth step, the heat preservation time during the under-aging process is 6 h.

[0106] Example 4

[0107] In the first step, an A1-Zn-Mg-Cu alloy powder with an average particle size of 20 μm is prepared by a vacuum melting and atomization powder preparation process; among them, the A1-Zn-Mg-Cu alloy powder, by mass percentage, includes the following components: 5.2% of zinc, 2.1% of magnesium and 1.2% of copper, and the balance is aluminum;

[0108] In the second step, beryllium powder with an average particle size of 20 μm is prepared by an atomization powder-making process;

[0109] In the third step, 1 kg of A1-Zn-Mg-Cu alloy powder and 1.5 kg of beryllium powder are mixed in a mechanical mixer for 24 h to obtain a mixed powder;

[0110] In the fourth step, the mixed powder is put into a rubber sheath and then subjected to cold isostatic pressing, primary degassing, secondary degassing, and hot isostatic pressing in sequence, and after cooling to room temperature in the furnace, a blank is obtained;

[0111] Among them, the pressure of cold isostatic pressing is 100 MPa and the pressure holding time is 20 min;

[0112] The vacuum degree of primary degassing is 1×10 -1 -1×10 -2 Pa, the heat preservation temperature is 500 °C, and the heat preservation time is 24 h;

[0113] The vacuum degree of secondary degassing is 1×10 -3 -1×10 -4 Pa, the heat preservation temperature is 550 °C, and the heat preservation time is 36 h;

[0114] The heat preservation temperature of hot isostatic pressing is 800 °C, the pressure holding pressure is 100 MPa, and the heat preservation and pressure holding time is 5 h.

[0115] In the fifth step, the blank is subjected to solution treatment and under-aging in sequence to obtain a beryllium aluminum alloy;

[0116] Among them, the solution treatment is as follows: heating to 420 °C at a heating rate of 10 °C / min, after heat preservation for 3 h, quenching to room temperature with water;

[0117] The under-aging is as follows: heating to 110 °C at a heating rate of 10 °C / min, after heat preservation for 2 h, cooling to room temperature in the furnace.

[0118] Example 5

[0119] In the first step, A1-Zn-Mg-Cu alloy powder with an average particle size of 10 μm is prepared by a vacuum melting and atomization powder-making process; among them, the A1-Zn-Mg-Cu alloy powder, by mass percentage, includes the following components: 7.5% of zinc, 2.0% of magnesium, and 2.0% of copper, and the balance is aluminum;

[0120] In the second step, beryllium powder with an average particle size of 10 μm is prepared by a mechanical grinding process;

[0121] In the third step, 1 kg of A1-Zn-Mg-Cu alloy powder and 1.5 kg of beryllium powder are mixed in a mechanical mixer for 36 h to obtain a mixed powder;

[0122] Step 4: After loading the mixed powder into a rubber sheath, perform cold isostatic pressing, primary degassing, secondary degassing, and hot isostatic pressing in sequence. After completion, cool it in the furnace to room temperature to obtain a blank;

[0123] Among them, the pressure of cold isostatic pressing is 250 MPa, and the pressure holding time is 10 min;

[0124] The vacuum degree of primary degassing is 1×10 -1 -1×10 -2 Pa, the heat preservation temperature is 450 °C, and the heat preservation time is 36 h;

[0125] The vacuum degree of secondary degassing is 1×10 -3 -1×10 -4 Pa, the heat preservation temperature is 500 °C, and the heat preservation time is 12 h;

[0126] The heat preservation temperature of hot isostatic pressing is 750 °C, the pressure holding pressure is 50 MPa, and the heat preservation and pressure holding time is 8 h.

[0127] Step 5: Perform solution treatment and under-aging on the blank in sequence to obtain beryllium aluminum alloy;

[0128] Among them, the solution treatment is: heating at a heating rate of 50 °C / min to 480 °C, after heat preservation for 1 h, quenching in water to room temperature;

[0129] The under-aging is: heating at a heating rate of 50 °C / min to 140 °C, after heat preservation for 4 h, cooling in the furnace to room temperature.

[0130] Comparative Example 1

[0131] The difference from Example 1 is that it does not include the solution treatment and under-aging treatment in Step 5.

[0132] Comparative Example 2

[0133] The difference from Example 1 is that it does not contain the strengthening elements Zn, Mg, and Cu.

[0134] Comparative Example 3

[0135] BeAl-F in beryllium aluminum alloy in GB / T 26063-2003

[0136] Perform mechanical property tests on the beryllium aluminum alloys of Examples 1-5 and Comparative Examples 1-3, and the results are shown in Table 1.

[0137] Table 1

[0138]

[0139]

[0140] As can be seen from Table 1, compared with the beryllium-aluminum alloy of the same process without strengthening elements in Comparative Example 1, the beryllium-aluminum alloy of Example 1 has better tensile strength and yield strength; compared with the beryllium-aluminum alloy without solution treatment and under-aged heat treatment in Comparative Example 2, the beryllium-aluminum alloy of Example 1 has better tensile strength and yield strength without reducing the elongation; compared with the beryllium-aluminum alloy of GB / T 26063-2003 (Comparative Example 3), the tensile strength and yield strength of the beryllium-aluminum alloys of Examples 1-5 increase by about 50%.

[0141] Figure 1 Figure is the scanning electron micrograph of the beryllium-aluminum alloy prepared in Example 1. It can be seen that nano-scale strengthening precipitated phase particles are dispersed on the aluminum matrix.

[0142] In summary, the solution proposed by the present invention has the following technical effects:

[0143] On the one hand, by adding appropriate amounts of Zn, Mg, and Cu as strengthening elements, η (MgZn2), T (Al2Mg3Zn3), and S (CuMgAl2) precipitated phases are formed to strengthen the aluminum matrix; on the other hand, a large beryllium-aluminum ratio is combined with solution treatment and under-aged heat treatment processes to avoid excessive growth of the precipitated phases, thereby comprehensively improving the strength and elongation of the alloy.

[0144] In addition, the tensile strength of the beryllium-aluminum alloy of the present invention is 420-450 MPa, the yield strength is 300-340 MPa, and the elongation is 1.5-3.0%.

[0145] Please note that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as these combinations of technical features do not conflict, they should be considered as falling within the scope described in this specification. The above embodiments only represent several implementation manners of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A method for preparing beryllium aluminum alloy based on under-aging process, characterized in that: The preparation method comprises: Step S1, preparing Al-Zn-Mg-Cu alloy powder; The Al-Zn-Mg-Cu alloy powder comprises the following components by mass percentage: 5-9% zinc, 1-3% magnesium and 0.2-3% copper, with the balance being aluminum; Step S2, preparing beryllium powder; Step S3, mixing the Al-Zn-Mg-Cu alloy powder and the beryllium powder evenly to obtain a mixed powder; The mass percentage of beryllium powder in the mixed powder is 60-65%; Step S4, sequentially performing cold isostatic pressing, primary degassing, secondary degassing and hot isostatic pressing on the mixed powder, and then cooling to room temperature in a furnace to obtain a blank; Step S5, performing solid solution treatment and under-aging on the blank in sequence to obtain the beryllium aluminum alloy; The solid solution is: heating to 420-480°C at a heating rate of 10-50°C / min, keeping the temperature for 1-3h, and then quenching with water to room temperature; The under-aging process is as follows: heating the temperature to 110-140° C. at a heating rate of 10-50° C. / min, keeping the temperature for 1-6 hours, and then cooling the temperature to room temperature along with the furnace.

2. The preparation method according to claim 1, characterized in that: In the step S1, the average particle size of the Al-Zn-Mg-Cu alloy powder is 10-30 μm.

3. The preparation method according to claim 1, characterized in that: In the step S1, the preparation process of the Al-Zn-Mg-Cu alloy powder is as follows: Step S11, preparing raw materials according to the composition and mass percentage of the Al-Zn-Mg-Cu alloy powder; Step S12, vacuum melting and atomization powdering are performed on the prepared raw materials in sequence to obtain the Al-Zn-Mg-Cu alloy powder.

4. The preparation method according to claim 1, characterized in that: In the step S2, the average particle size of the beryllium powder is 5-20 μm.

5. The preparation method according to claim 1, characterized in that: In the step S2, the beryllium powder is prepared by atomization powder making, air flow impact or mechanical grinding.

6. The preparation method according to claim 1, characterized in that: In step S3, the mixing time of the Al-Zn-Mg-Cu alloy powder and the beryllium powder is 12-36 hours.

7. The preparation method according to claim 1, characterized in that: In step S4, the cold isostatic pressing pressure is 50-250 MPa, and the holding time is 10-30 min; The vacuum degree of the primary degassing is 1×10 -1 -1×10 -2 Pa, holding temperature is 450-550℃, holding time is 12-36h; The vacuum degree of the secondary degassing is 1×10 -3 -1×10 -4 Pa, holding temperature is 500-600℃, holding time is 12-36h; Wherein, the temperature of the secondary degassing is greater than the temperature of the primary degassing; The holding temperature of the hot isostatic pressing is 660-800° C., the holding pressure is 50-150 MPa, and the holding time is 5-10 hours.

8. The preparation method according to claim 1, characterized in that: In the step S5, the solid solution is: heating to 460-480°C at a heating rate of 20-40°C / min, keeping the temperature for 1.5-2.5h, and then quenching with water to room temperature; The under-aging process is as follows: heating the temperature to 110-130°C at a heating rate of 20-40°C / min, keeping the temperature for 2-4 hours, and then cooling the temperature to room temperature in the furnace.

9. A beryllium aluminum alloy, characterized in that: The beryllium aluminum alloy is prepared by the preparation method described in any one of claims 1 to 8.

10. The beryllium aluminum alloy according to claim 9, characterized in that: The beryllium aluminum alloy has a tensile strength of 420-450 MPa, a yield strength of 300-340 MPa, and an elongation of 1.5-3.0%.

Images