Low-resistivity expansion alloy material and preparation method thereof

Abstract

The invention relates to a low-resistivity expansion alloy material and a preparation method thereof, and belongs to the technical field of expansion alloy materials. The low-resistivity expansion alloy material comprises the following chemical components in percentage by weight: 51-51.5% of Ni, less than or equal to 0.005% of C, less than or equal to 0.005% of S, less than or equal to 0.005% of P, less than or equal to 0.005% of Si, less than or equal to 0.005% of Cu, less than or equal to 0.03% of Mo, less than or equal to 0.005% of Al, less than or equal to 0.05% of Cr, less than or equal to 0.1% of Mn, less than or equal to 0.005% of Ti and the balance of Fe and inevitable impurities. According to the method, refining is conducted through a triple method, electric furnace smelting, electroslag remelting, vacuum consumable smelting and step-by-step impurity removal are conducted, purity progression is achieved, structure refinement and defect control are conducted through a subsequent heat treatment process, the influence of alloy elements and impurities on the electrical resistivity is reduced, and therefore the performance requirement is met.

Description

Technical Field

[0001] The present invention belongs to the technical field of expansion alloy materials, and relates to a low-resistivity expansion alloy material and a preparation method thereof. Background Art

[0002] Expansion alloys, also known as precision alloys, are a class of alloy materials with special expansion coefficients. Due to having a variety of excellent performance characteristics: low expansion coefficient, good mechanical properties, good electrical and thermal conductivity, and good sealing properties with materials such as glass and ceramics, they are widely used in multiple fields.

[0003] With the continuous progress of electronic technology, the performance requirements of electronic devices are getting higher and higher, especially in terms of electrical conductivity and thermal expansion performance. Therefore, a low-resistivity expansion alloy material is needed, with a resistivity < 0.365 μΩm. Traditional expansion alloy materials such as 4J50 and 4J52 cannot meet the above requirements.

[0004] Therefore, it is necessary to develop an expansion alloy material with matching properties of low resistivity and high expansion coefficient. Summary of the Invention

[0005] The purpose of the present invention is to provide a low-resistivity expansion alloy material and a preparation method thereof. The conductivity of the expansion alloy material prepared by the present invention is lower than 0.365 μΩm.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A low-resistivity expansion alloy material, comprising the following chemical components in weight percentages: Ni: 51 - 51.5%, C ≤ 0.005%, S ≤ 0.005%, P ≤ 0.005%, Si ≤ 0.005%, Cu ≤ 0.005%, Mo ≤ 0.03%, Al ≤ 0.005%, Cr ≤ 0.05%, Mn ≤ 0.1%, Ti ≤ 0.005%, and the balance is Fe and unavoidable impurities.

[0008] A preparation method of a low-resistivity expansion alloy material, comprising the following preparation process:

[0009] S1. Electric furnace melting:

[0010] Weigh the materials according to the ratio of the low-resistivity expansion alloy, evacuate to 0.1 - 0.3 Pa, add alloy elements in the order of increasing melting point, and refine at 1550 - 1600 °C for 20 - 35 min to obtain an ingot;

[0011] S2. Electroslag remelting:

[0012] Under the protection of high-purity argon gas, the ingot is subjected to electroslag remelting. The remelting current is controlled at 5 kA, and the electroslag remelting rate is controlled at 6 - 8 Kg / min. The remelting current is decreased to 3 kA at a rate of 1 kA / 5 min until the mold is filled, i.e., the electroslag remelting is completed. After casting for 2 h, demolding is carried out, and air cooling is performed to obtain the electroslag remelted ingot;

[0013] S3. Vacuum consumable melting:

[0014] The electroslag remelted ingot is held at 1150 - 1200 °C for 8 - 12 h for homogenization annealing. After the annealing is completed, the temperature is decreased to 600 °C and then air cooled. The obtained alloy rod is used as a consumable electrode for vacuum consumable remelting. The melting rate of the vacuum consumable melting is maintained at 90 - 150 kg / h. After the melting is completed, demolding is carried out, and the ingot is placed in an argon protection furnace and slowly cooled to 200 - 220 °C and then taken out of the furnace to obtain the alloy ingot;

[0015] S4. Heat treatment:

[0016] The alloy ingot is subjected to a primary annealing treatment under hydrogen protection, and then air cooled to 600 °C. It is then heated up to 1120 - 1150 °C for a primary hot rolling treatment. After cooling to room temperature, cold drawing is carried out with a deformation amount of 90%. Then, it is subjected to a secondary annealing treatment under argon protection, and then a secondary hot rolling treatment for 2 - 2.5 h. After completion, it is cooled to room temperature by water mist cooling to obtain the alloy ingot;

[0017] S5. Final surface treatment:

[0018] The alloy ingot is heated to 950 - 1000 °C for final heat treatment. After completion, it is quickly cooled to 450 - 500 °C and held for 2 - 4 h to obtain the low-resistivity expansion alloy material.

[0019] As a preferred technical solution of the present invention, in step S2, a premelted slag of 55 - 65 parts by weight of CaF2, 15 - 25 parts by weight of CaO, and 15 - 25 parts by weight of Al2O3 is used as the slag material, and it is baked at 600 - 700 °C for 24 h before use.

[0020] As a preferred technical solution of the present invention, in step S2, the casting temperature is 1350 - 1370 °C.

[0021] As a preferred technical solution of the present invention, in step S4, the time of the primary annealing treatment is 20 - 25 h, and the temperature is 1160 - 1180 °C.

[0022] As a preferred technical solution of the present invention, in step S4, the rolling deformation amount of the primary hot rolling treatment is 80% - 90%, and the final rolling temperature is 800 - 850 °C.

[0023] As a preferred technical solution of the present invention, in step S4, the time of the primary hot rolling treatment is 2 to 4 hours.

[0024] As a preferred technical solution of the present invention, in step S4, the temperature of the secondary annealing treatment is 720 to 745 °C, and the time is 50 to 70 minutes.

[0025] As a preferred technical solution of the present invention, in step S4, the temperature of the secondary hot rolling treatment is 1100 to 1150 °C.

[0026] As a preferred technical solution of the present invention, in step S5, the time of the final heat treatment is 30 to 45 minutes.

[0027] The expansion alloy in the present invention contains the following components: Ni: 51 to 51.5%, C ≤ 0.005%, S ≤ 0.005%, P ≤ 0.005%, Si ≤ 0.005%, Cu ≤ 0.005%, Mo ≤ 0.03%, Al ≤ 0.005%, Cr ≤ 0.05%, Mn ≤ 0.1%, Ti ≤ 0.005%, and the balance is Fe and inevitable impurities. Among them, iron is used as the matrix material, and nickel can adjust the thermal expansion coefficient, and the two have good electrical conductivity. Therefore, using the iron-nickel alloy as the matrix can effectively reduce the resistivity of the expansion alloy.

[0028] At the same time, by reducing the impurities in the iron-nickel expansion alloy through the process, electron scattering can be systematically reduced, the lattice structure can be optimized, and the formation of adverse phases can be inhibited, ultimately achieving a significant decrease in resistivity. Cr in the components can improve oxidation resistance and corrosion resistance, and C ≤ 0.005% can reduce grain boundary brittleness. In this formulation, the contents of C, S, and P are strictly controlled to be ≤ 0.005%, greatly reducing their adverse effects on the crystal structure and electron conduction of the alloy, which helps to reduce the resistivity.

[0029] Controlling the contents of silicon (Si), copper (Cu), and aluminum (Al) to be ≤ 0.005% can avoid excessive interference of these elements on electron conduction and maintain the low resistivity of the expansion alloy.

[0030] When preparing the expansion alloy, first, electric furnace melting can be carried out for preliminary alloying and composition homogenization. Specifically, by evacuating the air, oxidation and gas residues during the melting process can be reduced, the impurity content can be lowered, the formation of high-resistance oxides (such as Al2O3, SiO2) can be avoided, and the materials are added in the order of melting points to avoid composition segregation caused by incomplete melting of high-melting-point elements (such as Fe, Mo), thereby improving the alloy uniformity.

[0031] In step S2, through electroslag remelting, the ingot is rapidly melted under high current, and the slag is used to adsorb impurities such as S and P to further purify the molten metal. And the solidification rate is controlled by decreasing the current (1 kA / 5 min) to help form fine columnar crystals, reduce shrinkage cavities and porosity, and improve the density. Through this step, the contents of harmful impurities such as S and P are significantly reduced, the internal defects of the ingot are eliminated, and the conductivity is improved.

[0032] In step S3, first through homogenization annealing, the composition segregation is eliminated, atomic diffusion is promoted, a single solid solution phase is formed, and higher purity alloy is achieved through vacuum consumable melting to reduce lattice distortion and phase interface scattering, and significantly reduce the resistivity.

[0033] In step S4, first, annealing treatment is carried out under hydrogen protection. The surface oxide is reduced by hydrogen, and at the same time, it penetrates into the interior of the alloy to remove residual oxygen and carbon. Then, high-temperature annealing is carried out to eliminate cold working stress, promote recrystallization, and form uniform equiaxed crystals. Through one-time hot rolling and cold drawing treatments, the grain structure is further optimized, and the grain size is regulated through the heat treatment cycle process to improve the grain boundary cleanliness and the electron mobility.

[0034] In step S5, first through the final heat treatment, heat preservation is carried out at 950 - 1000 °C to help eliminate surface microcracks and oxide layers, prevent surface deterioration during subsequent use, and then rapidly cool to 450 - 500 °C, which can help precipitate nanoscale copper-rich phases, thereby optimizing the conductivity and reducing the resistivity.

[0035] Advantages of the present invention:

[0036] (1) In the present invention, by optimizing the composition design on the premise of ensuring qualified expansion coefficient, an expansion alloy with low resistivity is obtained;

[0037] (2) In the present invention, refining is carried out by the triple process: electric furnace melting → electroslag remelting → vacuum consumable melting, removing impurities step by step to achieve progressive purity, and through subsequent heat treatment processes, the microstructure is refined and defects are controlled to reduce the influence of alloying elements and impurities on the resistivity, so as to meet the performance requirements. Specific embodiments

[0038] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following combines examples to describe in detail the specific embodiments, structures, features and their effects according to the present invention.

[0039] Example 1

[0040] It includes chemical components with the following weight percentages: Ni: 51%, C ≤ 0.005%, S ≤ 0.005%, P ≤ 0.005%, Si ≤ 0.005%, Cu ≤ 0.005%, Mo ≤ 0.03%, Al ≤ 0.005%, Cr ≤ 0.05%, Mn ≤ 0.1%, Ti ≤ 0.005%, and the balance is Fe and unavoidable impurities.

[0041] Preparation of low-resistivity expansion alloy material:

[0042] S1. Electric furnace melting:

[0043] Weigh the raw materials according to the ratio of the low-resistivity expansion alloy, evacuate to 0.1 Pa, add alloy elements in the order of increasing melting point, and refine at 1550 °C for 20 min to obtain an ingot.

[0044] S2. Electroslag remelting:

[0045] Under the protection of high-purity argon, the ingot is subjected to electroslag remelting. Control the remelting current at 5 kA, control the electroslag remelting rate at 6 Kg / min, gradually decrease the remelting current to 3 kA, with a current reduction rate of 1 kA / 5 min. Stop when the mold is full, that is, the electroslag remelting is completed. Pour at 1350 °C, remove the mold after 2 h, and air-cool to obtain an electroslag remelted ingot. During electroslag remelting, use a premelted slag of 55 parts of CaF2, 15 parts of CaO, and 15 parts of Al2O3 as the slag material, and bake it at 600 °C for 24 h before use.

[0046] S3. Vacuum consumable melting:

[0047] Keep the electroslag remelted ingot at 1150 °C for 8 h for homogenization annealing. After annealing, cool to 600 °C and then air-cool. Use the obtained alloy bar as a consumable electrode for vacuum consumable remelting. Keep the melting rate of vacuum consumable melting at 90 kg / h. After melting, remove the mold, put the ingot into an argon protection furnace and cool slowly to 200 °C before taking it out to obtain an alloy ingot.

[0048] S4. Heat treatment:

[0049] Under the protection of hydrogen, anneal the alloy ingot at 1160 °C for 20 h for the first time, then air-cool to 600 °C, continue to heat up to 1120 °C for the first hot rolling treatment for 2 h. The rolling deformation amount of the first hot rolling treatment is 80%, and the final rolling temperature is 800 °C. After cooling to room temperature, perform cold drawing treatment with a deformation amount of 90%. Then, under the protection of argon, perform the second annealing treatment at 720 °C for 50 min, and then perform the second hot rolling treatment at 1100 °C for 2 h. After completion, cool to room temperature by water mist cooling to obtain an alloy ingot.

[0050] S5. Final surface treatment:

[0051] Heat the alloy ingot to 950 °C for a final heat treatment for 30 min. After completion, quickly cool it to 450 °C and hold for 2 h to obtain the low-resistivity expansion alloy material.

[0052] Example 2

[0053] It includes chemical components with the following weight percentages: Ni: 54.3%, C: 0.003%, S: 0.002%, P: 0.0045%, Si: 0.002%, Cu: 0.001%, Mo: 0.03%, Al: 0.005%, Cr: 0.03%, Mn: 0.061%, Ti: 0.004%, and the balance is Fe and unavoidable impurities.

[0054] Preparation of the low-resistivity expansion alloy material:

[0055] S1. Electric furnace melting:

[0056] Weigh the alloy according to the ratio of the low-resistivity expansion alloy, evacuate to 0.2 Pa, and add alloying elements in ascending order of melting point. Refine at 1570 °C for 25 min to obtain an ingot.

[0057] S2. Electroslag remelting:

[0058] Under the protection of high-purity argon, subject the ingot to electroslag remelting. Control the remelting current at 5 kA and the electroslag remelting rate at 7 Kg / min. Gradually decrease the remelting current to 3 kA at a rate of 1 kA / 5 min until the mold is full, i.e., the electroslag remelting is completed. Cast at 1360 °C, remove the mold after 2 h, and air-cool to obtain an electroslag remelted ingot. During the electroslag remelting, use a premelted slag of 60 parts of CaF2, 20 parts of CaO, and 20 parts of Al2O3 as the slag material, and bake it at 650 °C for 24 h before use.

[0059] S3. Vacuum consumable melting:

[0060] Keep the electroslag remelted ingot at 1170 °C for 10 h for homogenization annealing. After the annealing is completed, cool it to 600 °C and then air-cool. Use the obtained alloy rod as a consumable electrode for vacuum consumable remelting. Maintain the melting rate of the vacuum consumable melting at 100 kg / h. After melting, remove the mold, and place the ingot in an argon protection furnace and slowly cool it to 210 °C before taking it out of the furnace to obtain an alloy ingot.

[0061] S4. Heat treatment:

[0062] The alloy ingot is annealed once at 1170 °C for 23 h under hydrogen protection, then air-cooled to 600 °C, and then heated up to 1130 °C for a hot rolling treatment for 3 h. The rolling deformation amount of the first hot rolling treatment is 85%, the final rolling temperature is 820 °C, and after cooling to room temperature, a cold drawing treatment is carried out with a deformation amount of 90%. Then, under argon protection, a secondary annealing treatment is carried out at 725 °C for 60 min, and then a secondary hot rolling treatment is carried out at 1130 °C for 2.2 h. After completion, it is cooled to room temperature by water mist cooling to obtain an alloy ingot;

[0063] S5. Final surface treatment:

[0064] The alloy ingot is heated to 970 °C for a final heat treatment for 35 min, and after completion, it is rapidly cooled to 470 °C and held for 3 h to obtain the low-resistivity expansion alloy material.

[0065] Example 3

[0066] It includes the following chemical components by weight percentage: Ni: 51.5%, C ≤ 0.005%, S ≤ 0.005%, P ≤ 0.005%, Si ≤ 0.005%, Cu ≤ 0.005%, Mo ≤ 0.03%, Al ≤ 0.005%, Cr ≤ 0.05%, Mn ≤ 0.1%, Ti ≤ 0.005%, and the balance is Fe and unavoidable impurities.

[0067] Preparation of the low-resistivity expansion alloy material:

[0068] S1. Electric furnace melting:

[0069] According to the low-resistivity expansion alloy ratio, ingredients are prepared, the vacuum is pumped to 0.3 Pa, and alloying elements are added in the order of increasing melting point. It is refined at 1600 °C for 35 min to obtain an ingot;

[0070] S2. Electro-slag remelting:

[0071] Under high-purity argon protection, the ingot is subjected to electro-slag remelting. The remelting current is controlled at 5 kA, the electro-slag remelting rate is controlled at 8 Kg / min, the remelting current is decreased to 3 kA, and the current reduction rate is 1 kA / 5 min until the mold is filled, i.e., the electro-slag remelting is completed. It is cast at 1370 °C, and after 2 h, the mold is removed and air-cooled to obtain an electro-slag remelted ingot. During the electro-slag remelting, a pre-melted slag of 65 parts of CaF2, 25 parts of CaO, and 25 parts of Al2O3 is used as the slag material, and it is baked at 700 °C for 24 h before use;

[0072] S3. Vacuum consumable melting:

[0073] The electroslag remelting ingot is held at 1200 °C for 12 h for homogenization annealing. After the annealing is completed, it is cooled to 600 °C and then air-cooled. The obtained alloy rod is used as a consumable electrode for vacuum consumable remelting. The melting rate of the vacuum consumable melting is maintained at 150 kg / h. After the melting is completed, it is demolded. The ingot is placed in an argon protection furnace and slowly cooled to 220 °C and then taken out of the furnace to obtain an alloy ingot;

[0074] S4, Heat treatment:

[0075] Under hydrogen protection, the alloy ingot is annealed at 1180 °C for 25 h, then air-cooled to 600 °C, and then heated up to 1150 °C for a primary hot rolling treatment for 4 h. The rolling deformation amount of the primary hot rolling treatment is 90%, and the final rolling temperature is 850 °C. After cooling to room temperature, cold drawing treatment is carried out with a deformation amount of 90%. Then, under argon protection, it is subjected to a secondary annealing treatment at 745 °C for 70 min, and then a secondary hot rolling treatment at 1150 °C for 2.5 h. After completion, it is cooled to room temperature by water mist cooling to obtain an alloy ingot;

[0076] S5, Final surface treatment:

[0077] The alloy ingot is heated to 1000 °C for a final heat treatment for 45 min. After completion, it is quickly cooled to 500 °C and held for 4 h to obtain the low-resistivity expansion alloy material.

[0078] Comparative example 1

[0079] The difference between comparative example 1 and example 1 is that vacuum consumable remelting is not used in comparative example 1, and the remaining operations are the same.

[0080] Comparative example 2

[0081] The difference between comparative example 2 and example 1 is that step S5 is not carried out in comparative example 2, and the remaining operations are the same.

[0082] Comparative example 3

[0083] The difference between comparative example 3 and example 1 is that in step S2 of comparative example 3, the remelting current is not decreased, and the remaining operations are the same.

[0084] Comparative example 4

[0085] Comparative example 4 is commercial expansion alloy 4J50.

[0086] Comparative example 5

[0087] Comparative example 5 is commercial expansion alloy 4J52.

[0088] Performance test:

[0089] Group Resistivity / μΩm <![CDATA[Coefficient of expansion / ×10 -6 > Example 1 0.33 10.42 Example 2 0.35 10.42 Example 3 0.37 10.43 Comparative Example 1 0.39 10.53 Comparative Example 2 0.38 10.55 Comparative Example 3 0.39 10.52 Comparative Example 4 0.44 10.20 Comparative Example 5 0.43 10.65

[0090] According to the above data, for the expansion alloy material prepared in the embodiment, the resistivity < 0.365 μΩm, and the expansion coefficient between 30 and 450 °C is between that of 4J50 and 4J52. Therefore, the effect of ensuring both the expansion coefficient and having a low resistivity can be achieved.

[0091] The above are only the preferred embodiments of the present invention, and do not impose any formal restrictions on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A low-resistivity expansion alloy material, characterized in that, It comprises chemical components in the following weight percentages: Ni: 51 - 51.5%, C ≤ 0.005%, S ≤ 0.005%, P ≤ 0.005%, Si ≤ 0.005%, Cu ≤ 0.005%, Mo ≤ 0.03%, Al ≤ 0.005%, Cr ≤ 0.05%, Mn ≤ 0.1%, Ti ≤ 0.005%, and the balance is Fe and inevitable impurities.

2. A preparation method of the low-resistivity expansion alloy material as described in claim 1, characterized in that, It includes the following preparation process: S1. Electric furnace melting: Weigh materials according to the proportion of the low-resistivity expansion alloy, evacuate to 0.1 - 0.3 Pa, add alloy elements in the order of increasing melting point, and refine at 1550 - 1600 °C for 20 - 35 min to obtain an ingot. S2. Electroslag remelting: Under the protection of high-purity argon, subject the ingot to electroslag remelting. Control the remelting current at 5 kA, control the electroslag remelting rate at 6 - 8 Kg / min, gradually decrease the remelting current to 3 kA at a rate of 1 kA / 5 min until the mold is full, i.e., the electroslag remelting is completed. After casting for 2 h, remove the mold and air-cool to obtain an electroslag remelted ingot. S3. Vacuum consumable melting: Keep the electroslag remelted ingot at 1150 - 1200 °C for 8 - 12 h for homogenization annealing. After annealing, cool to 600 °C and then air-cool. Use the obtained alloy rod as a consumable electrode for vacuum consumable remelting, maintain the melting rate of vacuum consumable melting at 90 - 150 kg / h. After melting, remove the mold, put the ingot into an argon-protected furnace and slowly cool to 200 - 220 °C before taking it out of the furnace to obtain an alloy ingot. S4. Heat treatment: Under the protection of hydrogen, conduct a primary annealing treatment on the alloy ingot, then air-cool to 600 °C, continue to heat up to 1120 - 1150 °C for a primary hot rolling treatment, cool to room temperature and then conduct a cold drawing treatment with a deformation amount of 90%. Then, conduct a secondary annealing treatment under the protection of argon, and then conduct a secondary hot rolling treatment for 2 - 2.5 h. After completion, cool to room temperature by water mist cooling to obtain an alloy ingot. S5. Final surface treatment: Heat the alloy ingot to 950 - 1000 °C for final heat treatment. After completion, quickly cool to 450 - 500 °C and keep it warm for 2 - 4 h to obtain the low-resistivity expansion alloy material.

3. The preparation method of the low-resistivity expansion alloy material according to claim 2, characterized in that, In step S2, during the electroslag remelting, use a premelted slag of 55 - 65 parts by weight of CaF2, 15 - 25 parts by weight of CaO, and 15 - 25 parts by weight of Al2O3 as the slag material, and bake it at 600 - 700 °C for 24 h before use.

4. The preparation method of the low-resistivity expansion alloy material according to claim 2, characterized in that, In step S2, the casting temperature is 1350 - 1370 °C.

5. The preparation method of the low-resistivity expansion alloy material according to claim 2, characterized in that, In step S4, the time of the primary annealing treatment is 20 - 25 h, and the temperature is 1160 - 1180 °C.

6. The preparation method of the low-resistivity expansion alloy material according to claim 2, characterized in that, In step S4, the rolling deformation amount of the primary hot rolling treatment is 80% - 90%, and the final rolling temperature is 800 - 850 °C.

7. The preparation method of the low-resistivity expansion alloy material according to claim 2, characterized in that, In step S4, the time of the primary hot rolling treatment is 2 - 4 h.

8. The preparation method of the low-resistivity expansion alloy material according to claim 2, wherein In step S4, the temperature of the secondary annealing treatment is 720 - 745 °C, and the time is 50 - 70 min.

9. The preparation method of the low-resistivity expansion alloy material according to claim 2, characterized in that, In step S4, the temperature of the secondary hot rolling treatment is 1100 - 1150 °C.

10. The preparation method of the low-resistivity expansion alloy material according to claim 2, wherein In step S5, the time of the final heat treatment is 30 - 45 min.