Kovar alloy with high tensile ductility and tensile strength and preparation method

Abstract

The invention discloses a kovar alloy with high tensile ductility and tensile strength and a preparation method thereof. The chemical formula of the kovar alloy is FevNiwCoxAlyTaz, wherein 60 < v < = 70, 40 < w < = 50, 0 < x < = 10, 0 < y < = 10, and 1 < z < = 5. The main element of the preparation method is face-centered cubic Fe-Ni alloy. The Co element is introduced into the solid solution Fe-Ni for chemical regulation and control, the kovar alloy with thermal expansion performance is obtained, but the tensile strength of the face-centered cubic solid solution is low. By introducing a small amount of Al and Ta elements, a coherent (Ni, Fe) 3 (Al, Ta) ordered phase is separated out in a crystal, and then high tensile ductility and tensile strength are achieved. The synthesis steps of the kovar alloy with high tensile ductility and tensile strength are simple and easy to implement, the raw material cost is low, and both the mechanical property and the thermal expansion property of the kovar alloy are achieved.

Description

Technical Field

[0001] The present invention relates to the fields of high-precision instrument technology and chip packaging, and particularly relates to a Kovar alloy with high tensile ductility and tensile strength and a preparation method therefor. Background Art

[0002] The Kovar alloy has the grade of 4J29 alloy, which has a thermal expansion coefficient (3 - 5×10 -6 K -1 ) similar to that of silicon boron hard glass at 20 - 450°C, has a relatively high Curie point, and has good low-temperature tissue stability. It is mainly used in the field of high-precision instruments, such as the glass sealing of electro-vacuum components such as transmitting tubes, oscillating tubes, ignitron tubes, magnetrons, transistors, sealed plugs, relays, lead-out wires of integrated circuits, chassis, housings, brackets, etc. In applications, the expansion coefficients of the glass and the alloy are matched. Appropriate heat treatment should be carried out during the processing to ensure that the material has good deep drawing and stretching properties. However, the classic Kovar alloy has a relatively high Co content ratio (16 - 22%), which is costly. More importantly, the increase in Co content will lead to a decrease in the stability of the austenite face-centered cubic structure, resulting in unstable thermal expansion coefficient, which is a key technical index. With the expansion of application fields, there is an increasing demand for Kovar alloys that take into account mechanical properties in scenarios such as high-voltage transmission line cores and LNG carrier hull materials. Therefore, it is necessary to study a Kovar alloy with high tensile ductility and tensile strength and a preparation method to address the deficiencies of the existing technology and solve or mitigate one or more of the above problems. Summary of the Invention

[0003] The purpose of the present invention is to solve the deficiencies of the existing technology, and provides a Kovar alloy with high tensile ductility and tensile strength and a preparation method therefor. By introducing Co, Al, and Ta elements into the Fe-Ni base face-centered cubic solid solution (FCC) in the preparation method, a Kovar alloy with high tensile ductility and tensile strength is obtained. Among them, the Co element is used to regulate magnetic interaction to control thermal expansion performance, while the Al and Ta elements are used to precipitate a small amount of ordered second phase (L12) to achieve the strengthening and toughening of mechanical properties. The synthesis steps are simple and easy to implement, and the Co content is low, having the advantages of low cost and a more stable phase structure. While achieving the thermal expansion of the Kovar alloy, the mechanical properties are also significantly improved.

[0004] The present invention adopts the following technical solution: A Kovar alloy with high tensile ductility and tensile strength, and the chemical formula of the Kovar alloy is Fe v Ni w Co x Al yTaz, where 60 < v ≤ 70 at%, 40 < w ≤ 50 at%, 0 < x ≤ 10 at%, 0 < y ≤ 10 at%, 1 < z ≤ 5 at%, the Kovar alloy is a coherent duplex alloy with a matrix phase and an ordered phase, the matrix phase is an Fe-Ni-Co phase, the ordered phase is an (Ni, Fe)3(Al, Ta) phase, the space group of the matrix phase is Fm-3m, and the space group of the ordered precipitation phase is Pm-3m.

[0005] Furthermore, the Kovar alloy has a tensile strength of 0.8 - 1.2 GPa and a tensile ductility of 20.0 - 40.0 % at room temperature, and a coefficient of thermal expansion of 3 - 5×10 -6 K -1 .

[0006] Furthermore, the chemical formula of the Kovar alloy is Fe 65 Ni 47 Co4Al6Ta 2， It has a tensile strength of 1.0 GPa and a tensile ductility of 40.0 % at room temperature, and a coefficient of thermal expansion α l of 3.81×10 -6 K -1 .

[0007] Furthermore, the chemical formula of the Kovar alloy is Fe 65 Ni 42 Co4Al6Ta 2， It has a tensile strength of 1.2 GPa and a tensile ductility of 30.0 % at room temperature, and a coefficient of thermal expansion α l of 4.81×10 -6 K -1 .

[0008] Furthermore, the chemical formula of the Kovar alloy is Fe 65 Ni 47 Co4Al6Ta 2， It has a tensile strength of 0.8 GPa and a tensile ductility of 20.0 % at room temperature, and a coefficient of thermal expansion α l of 3.23×10 -6 K -1 .

[0009] Another object of the present invention is to provide a method for preparing the above-mentioned Kovar alloy, characterized in that the method comprises the following steps: S1) Weigh the raw materials of Fe, Ni, Co, Al and Ta respectively according to the designed ratio, mix them and set aside; S2) Uniformly melt the mixture processed in S1) through an electric arc furnace and suction cast it into large-sized blocks; S3) Place the large-sized blocks obtained in S2) under a protective atmosphere for homogenization annealing to obtain samples; S4) Perform rolling treatment on the samples obtained in S3) to obtain rolled samples; S5) After performing recrystallization + aging heat treatment annealing on the rolled samples obtained in S4), a Kovar alloy with high tensile ductility and tensile strength is obtained.

[0010] Furthermore, the purities of Fe, Ni, Co, Al, and Ta in S1) are all > 99.5%.

[0011] Furthermore, the specific process of S3) is as follows: Under a protective atmosphere of vacuum or inert gas, heat to 1000°C - 1200°C, and the annealing treatment time is: 1 - 24 h.

[0012] Furthermore, the cold rolling reduction in S4) is 50 - 90%.

[0013] Furthermore, the specific process of S5) is as follows: The recrystallization temperature is 900 - 1000°C for annealing for 5 - 60 min, and the aging temperature is 600 - 700°C for annealing for 1 - 24 h.

[0014] Compared with the prior art, the present invention can achieve the following technical effects: The Kovar alloy with high tensile ductility and tensile strength of the present invention has a shape and size that hardly change with temperature, has high dimensional stability, precision, and a long service life; more importantly, the low Co content reduces the production cost and provides a stable phase structure.

[0015] The Kovar alloy with high tensile ductility and tensile strength of the present invention has excellent tensile ductility and tensile strength, and overcomes the technical difficulty of hard to balance the mechanical properties and thermal expansion properties of traditional alloys.

[0016] Of course, it is not necessary for any product implementing the present invention to achieve all the above-mentioned technical effects simultaneously. Description of the Drawings

[0017] Figure 1 For the Kovar alloy with high tensile ductility and tensile strength in the embodiment of the present invention, Fe 65 Ni 47 X-ray diffraction structure refinement pattern and high-angle annular dark-field spherical aberration electron microscope image of Co4Al6Ta2 powder at 300K.

[0018] Figure 2For the high tensile ductility and tensile strength Kovar alloy of the embodiments of the present invention, Fe 65 Ni 47 Co4Al6Ta2 thermal expansion and tensile-stress strain curves.

[0019] Figure 3 Are the thermal expansion and tensile-stress strain curves of the high tensile ductility and tensile strength Kovar alloy obtained by using the preparation method of the present invention. Specific embodiments

[0020] The specific embodiments of the present invention will be described in detail below with reference to the specific drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered in isolation, and they can be combined with each other to achieve better technical effects.

[0021] A high tensile ductility and tensile strength Kovar alloy of the present invention, whose chemical formula is Fe v Ni w Co x Al y Ta z , where 60 < v(Fe) ≤ 70 at%, 40 < w(Ni) ≤ 50 at%, 0 < x(Co) ≤ 10 at%, 0 < y(Al) ≤ 10, 1 < z(Ta) ≤ 5 at%. As a specific embodiment, when the high tensile ductility and tensile strength Kovar alloy is Fe 65 Ni 47 Co4Al6Ta2, the Fe 65 Ni 47 Co4Al6Ta2 exhibits the thermal expansion characteristics of Kovar alloy in the temperature range of 100 - 410 K, and the thermal expansion coefficient α l is 3.81×10 -6 , the tensile strength at room temperature reaches σ US = 1.0 GPa, and the tensile strain reaches ε f = 40.0 %.

[0022] The preparation method includes the following steps: S1) Prepare Fe v Ni w Co x Al y Ta z , where 60 < v(Fe) ≤ 70 at%, 40 < w(Ni) ≤ 50 at%, 0 < x(Co) ≤ 10 at%, 0 < y(Al) ≤ 10 at%, 1 < z(Ta) ≤ 5 at% raw materials; S2) Mix the raw materials of different elements in S1); S3) The mixed raw materials are melted evenly by an electric arc furnace and suction-cast into large-sized blocks; S4) The evenly melted sample is subjected to homogenization annealing under a protective atmosphere; S5) The sample is further processed by rolling; S6) After the rolled sample is subjected to recovery and recrystallization + aging heat treatment annealing, a Kovar alloy with high tensile ductility and tensile strength is obtained.

[0023] In the preparation method of the present invention, the disordered FCC phase is the matrix phase, and the ordered phase L12 is the second phase. The low expansion performance is maintained by the matrix phase, and the mechanical behavior is improved by the second phase. Through the synergistic effect of the two phases, a Kovar alloy with high tensile ductility and tensile strength is obtained.

[0024] Example 1 Prepare the Kovar alloy with high tensile ductility and tensile strength having the composition of Fe 65 Ni 47 Co4Al6Ta2 by electric arc furnace melting method, and the specific operation is carried out according to the following steps: S1) Prepare the raw materials required for Fe 65 Ni 47 Co4Al6Ta2, and weigh them according to the stoichiometric ratio. Preferably, the purity of the raw materials is > 99.5%; S2) Mix the raw materials of different elements in S1); S3) The mixed raw materials are melted evenly by an electric arc furnace and suction-cast into large-sized blocks; S4) The evenly melted sample is subjected to homogenization annealing at 1200 °C under a protective atmosphere for 6 h; S5) The sample is further cold-rolled by 70% to obtain a sheet; S6) The rolled sample is annealed at 1000 °C for 5 min for recrystallization, and then aged at 600 °C for 8 h, and a Kovar alloy with high tensile ductility and tensile strength is obtained.

[0025] For the Kovar alloy Fe 65 Ni 47 Co4Al6Ta2 with high tensile ductility and tensile strength obtained in Example 1, X-ray diffraction test is carried out and structural refinement is carried out to confirm that the composite material is composed of two phases, namely the FCC phase with the space group of Fm-3m and the L12 phase with the space group of Pm-3m. The spherical aberration electron microscope test at the atomic resolution confirms this FCC / L12 coherent two-phase microstructure.

[0026] For the Kovar alloy Fe 65 Ni 47Co4Al6Ta2 was measured for thermal expansion, which showed low expansion characteristics in the temperature range of 100 - 410 K. The thermal expansion coefficient (α l ) was 3.81×10 -6 K -1 respectively.

[0027] The Kovar alloy Fe 65 Ni 47 Co4Al6Ta2 with high tensile ductility and tensile strength obtained in Example 1 was subjected to a tensile engineering stress - strain test. Its tensile strength at room temperature reached σ US = 1.0 GPa, and the tensile strain reached ε f = 40.0%.

[0028] As Figure 1 shown are the refined powder X - ray diffraction pattern and high - angle annular dark - field spherical aberration electron microscope image of the Kovar alloy Fe 65 Ni 47 Co4Al6Ta2 with high tensile ductility and tensile strength at 300 K. It can be seen from this figure that the high - strength low - expansion composite material described in the present invention is a FCC and L12 duplex phase, and the crystal structure model is correct; the spherical aberration electron microscope test at atomic resolution confirms this FCC / L12 coherent duplex microstructure.

[0029] As Figure 2 shown are the thermal expansion and tensile stress - strain curves of the Kovar alloy Fe 65 Ni 47 Co4Al6Ta2. From the thermal expansion curve of Fe 65 Ni 47 Co4Al6Ta2 described in the present invention, it can be known that it shows low expansion characteristics (3.81×10 -6 K -1 ) respectively in the temperature range of 100 - 410 K. Its tensile strength at room temperature reaches σ US = 1.0 GPa, and the tensile strain reaches ε f = 40.0%.

[0030] Example 2 The three components of Ta, Ni, and Co have the greatest influence on thermal expansion and mechanical behavior. Therefore, the compositions described in the present invention, namely Fe 65 Ni 40 Co4Al6Ta 0+x (x = 1, 3, 4, 5), Fe 65 Ni 40+yCo4 Al6Ta2(y = 40, 42, 44, 50) and Fe 65 Ni40 Co 0+z The high tensile ductility and tensile strength Kovar alloy of Al6Ta2 (z = 0, 2, 6, 8, 10) is synthesized by the electric arc furnace melting method, and the specific operation is carried out according to the following steps: S1) Prepare Fe 65 Ni 40 Co4Al6Ta 0+x (x = 1, 3, 4, 5), Fe 65 Ni 40+yCo4 Al6Ta2 (y = 40, 42, 44, 50) and Fe 65 Ni 40 Co 0+z Al6Ta2 (z = 0, 2, 6, 8, 10), and weigh them according to the stoichiometric ratio. Preferably, the purity of the raw materials is > 99.5%; S2) Mix the raw material elements of different elements in S1); S3) Melting the mixed raw materials evenly by an electric arc furnace and suction casting them into large-sized blocks; S4) Place the evenly melted sample in a protective atmosphere at 1200 °C for homogenization annealing for 6 h; S5) Further cold-roll the sample by 70% to obtain a sheet; S6) Anneal the rolled sample at 1000 °C for 5 min for recrystallization, and then age it at 650 °C for 8 h to obtain the Kovar alloy with high tensile ductility and tensile strength.

[0031] For the Kovar alloy Fe 65 Ni 40 Co4Al6Ta 0+x (x = 1, 3, 4, 5), Fe 65 Ni 40+xCo4 Al6Ta2 (y = 40, 42, 44, 50) and Fe 65 Ni 40 Co 0+z Al6Ta2 (z = 0, 2, 6, 8, 10) obtained in Example 2, test the thermal expansion curve, and it can be known that it shows low expansion characteristics (3.0 - 5.0×10 -6 K -1 ) in the temperature range of 100 - 410 K.

[0032] As Figure 3 shown, the Kovar alloy Fe 65 Ni 40 Co4Al6Ta 0+x(x = 1, 3, 4, 5), Fe 65 Ni 40+yCo4 Al6Ta2 (y = 40, 42, 44, 50) and Fe 65 Ni 40 Co 0+z From the thermal expansion curves of Al6Ta2 (z = 0, 2, 6, 8, 10), it can be seen that they exhibit low expansion characteristics (3.0 - 5.0×10 - 6 K -1 ) in the temperature range of 100 - 410 K respectively.

[0033] The above has introduced in detail a Kovar alloy with high tensile ductility and tensile strength and its preparation method provided by the embodiments of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

[0034] As used in the specification and claims, certain terms are used to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. The specification and claims do not use the difference in names as a way to distinguish components, but use the difference in functions of components as the criterion for distinction. As mentioned throughout the specification and claims, "comprising" and "including" are open-ended terms, so they should be interpreted as "comprising / including but not limited to". "Substantially" means within an acceptable error range. Those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect. The subsequent description in the specification is the preferred implementation manner for implementing the present application, but the description is for the purpose of explaining the general principle of the present application and is not used to limit the scope of the present application. The protection scope of the present application shall be subject to what is defined by the appended claims.

[0035] It should also be noted that the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a commodity or system including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such a commodity or system. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the commodity or system including the said element.

[0036] It should be understood that the term "and / or" used herein is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: the existence of A alone, the simultaneous existence of A and B, and the existence of B alone. Additionally, the character " / " in this text generally indicates that the associated objects before and after are in an "or" relationship.

[0037] The above description shows and describes several preferred embodiments of the present application. However, as previously mentioned, it should be understood that the present application is not limited to the forms disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications, and environments, and can be changed within the scope of the application concept described herein through the above teachings or the technology or knowledge in the relevant field. Any changes and variations made by those skilled in the art that do not depart from the spirit and scope of the present application shall fall within the protection scope of the appended claims of the present application.

Claims

1. A Kovar alloy with high tensile ductility and tensile strength, characterized in that, The chemical formula of the Kovar alloy is Fe v Ni w Co x Al y Taz, where 60 < v ≤ 70 at%, 40 < w ≤ 50 at%, 0 < x ≤ 10 at%, 0 < y ≤ 10 at%, 1 < z ≤ 5 at%. The Kovar alloy is a coherent duplex alloy with a matrix phase and an ordered phase. The matrix phase is the Fe-Ni-Co phase, and the ordered phase is the (Ni, Fe)3(Al, Ta) phase. The space group of the matrix phase is Fm-3m, and the space group of the ordered precipitated phase is Pm-3m.

2. The Kovar alloy according to claim 1, characterized in that, The Kovar alloy described above has a tensile strength of 0.8 - 1.2 GPa at room temperature, a tensile ductility of 20.0 - 40.0 %, and a coefficient of thermal expansion of 3 - 5×10 -6 K -1 .

3. The Kovar alloy according to claim 1, characterized in that, The chemical formula of the Kovar alloy is Fe 65 Ni 47 Co4Al6Ta 2， At room temperature, the tensile strength is 1.0 GPa and the tensile ductility is 40.0%. In the temperature range of 100 - 410 K, the coefficient of thermal expansion α l is 3.81×10 -6 K -1 .

4. The Kovar alloy according to claim 1, wherein The chemical formula of the Kovar alloy is Fe 65 Ni 44 Co6Al6Ta 2， At room temperature, the tensile strength is 1.2 GPa and the tensile ductility is 30.0%. In the temperature range of 100 - 410 K, the coefficient of thermal expansion α l is 4.81×10 -6 K -1 .

5. The Kovar alloy according to claim 1, characterized in that, The chemical formula of the Kovar alloy is Fe 65 Ni 40 Co8Al6Ta 2， At room temperature, the tensile strength is 0.8 GPa and the tensile ductility is 20.0%. In the temperature range of 100 - 410 K, the coefficient of thermal expansion α l is 3.23×10 -6 K -1 .

6. A method for preparing the Kovar alloy according to any one of claims 1-5 and the preparation method, characterized in that, The method includes the following steps: S1) Weigh the raw materials of Fe, Ni, Co, Al and Ta respectively according to the designed ratio, mix them and set aside; S2) Melt the mixture processed in S1) evenly through an electric arc furnace and suction cast it into large-sized blocks; S3) Place the large-sized blocks obtained in S2) under a protective atmosphere for homogenization annealing to obtain samples; S4) Roll the samples obtained in S3) to obtain rolled samples; S5) After performing recrystallization + aging heat treatment annealing on the rolled samples obtained in S4), a Kovar alloy with high tensile ductility and tensile strength is obtained.

7. The method according to claim 6, wherein The purities of Fe, Ni, Co, Al and Ta in S1) are all >99.5%.

8. The method according to claim 6, wherein The specific process of S3) is: under a protective atmosphere of vacuum or inert gas, heat to 1000°C - 1200°C, and the annealing treatment time is: 1 - 24 h.

9. The method according to claim 6, wherein The cold rolling reduction in S4) is 50 - 90%.

10. The method according to claim 6, characterized in that The specific process of S5) is: annealing at a recrystallization temperature of 900 - 1000°C for 5 - 60 min, and annealing at an aging temperature of 600 - 700°C for 1 - 24 h.

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