A low resistivity expanded alloy material and a method of making the same

Abstract

The application 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: 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 of Fe and inevitable impurities. In the application, the refining is carried out through a triple method: electric furnace smelting, electroslag remelting and vacuum consumable smelting, impurities are removed step by step, purity is gradually increased, and through subsequent heat treatment processes, the organization is refined and defects are controlled, the influence of alloy elements and impurities on the resistivity is reduced, and thus the performance requirements are met.

Description

Technical Field

[0001] This invention belongs to the field of expansion alloy materials technology, and relates to a low resistivity expansion alloy material and its preparation method. Background Technology

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

[0003] With the continuous advancement of electronic technology, the performance requirements of electronic devices are becoming increasingly stringent, especially in terms of conductivity and thermal expansion properties. Therefore, a low-resistivity expansion alloy material is needed, achieving a resistivity of <0.365μΩm. Traditional expansion alloy materials such as 4J50 and 4J52 cannot meet these requirements.

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

[0005] The purpose of this invention is to provide a low resistivity expansion alloy material and its preparation method. The expansion alloy material prepared by this invention has an electrical conductivity of less than 0.365 μΩm.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A low resistivity expansion alloy material comprises the following chemical composition by weight percentage: 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%, with the balance being Fe and unavoidable impurities.

[0008] A method for preparing a low resistivity expansion alloy material includes the following preparation process:

[0009] S1, Electric furnace smelting:

[0010] According to the low resistivity expansion alloy proportion, the material is prepared and vacuumed to 0.1-0.3 Pa. Alloy elements are added in order of increasing melting point, and the mixture is refined at 1550-1600℃ for 20-35 minutes to obtain the ingot.

[0011] S2, Electroslag Remelting:

[0012] Under the protection of high-purity argon, the ingot is electroslag remelted. The remelting current is controlled at 5kA and the electroslag remelting rate is controlled at 6-8Kg / min. The remelting current is then reduced to 3kA at a rate of 1kA / 5min until the crystallizer is full, at which point the electroslag remelting is complete. After casting for 2 hours, the ingot is demolded and air-cooled to obtain the electroslag remelted ingot.

[0013] S3, Vacuum self-consumable melting:

[0014] The electroslag remelted ingot was held at 1150-1200℃ for 8-12 hours for homogenization annealing. After annealing, the temperature was lowered to 600℃ and then air-cooled. The resulting alloy rod was used as a consumable electrode for vacuum consumable remelting. The melting rate of vacuum consumable remelting was maintained at 90-150 kg / h. After melting, the ingot was demolded and placed in an argon-protected furnace for slow cooling to 200-220℃ before being taken out of the furnace to obtain the alloy ingot.

[0015] S4. Heat treatment:

[0016] The alloy ingot is annealed under hydrogen protection, then air-cooled to 600℃, and then hot-rolled to 1120-1150℃. After cooling to room temperature, it is cold-drawn with a deformation of 90%. Then it is annealed under argon protection, and then hot-rolled for 2-2.5 hours. After completion, it is cooled to room temperature by water mist to obtain the alloy ingot.

[0017] S5. Final surface treatment:

[0018] The alloy ingot is heated to 950–1000°C for final heat treatment, and then rapidly cooled to 450–500°C and held for 2–4 hours to obtain the low resistivity expansion alloy material.

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

[0020] As a preferred embodiment of the present invention, in step S2, the pouring temperature is 1350-1370℃.

[0021] As a preferred embodiment of the present invention, in step S4, the annealing process takes 20 to 25 hours and the temperature is 1160 to 1180°C.

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

[0023] As a preferred embodiment of the present invention, in step S4, the time for the first hot rolling process is 2 to 4 hours.

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

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

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

[0027] The expansion alloy in this invention contains the following components: 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%, with the balance being Fe and unavoidable impurities. Iron is used as the matrix material, and its coefficient of thermal expansion can be adjusted. Furthermore, both iron and nickel have good electrical conductivity; therefore, using an iron-nickel alloy as the matrix can effectively reduce the resistivity of the expansion alloy.

[0028] Simultaneously, by reducing impurities in the iron-nickel expanded alloy through processing, electron scattering can be systematically reduced, the crystal structure optimized, and the formation of undesirable phases suppressed, ultimately resulting in a significant decrease in resistivity. Cr in the composition can improve oxidation resistance and corrosion resistance, while C ≤ 0.005% can reduce grain boundary brittleness. In this formulation, the contents of C, S, and P are strictly controlled to ≤ 0.005%, greatly reducing their adverse effects on the alloy's crystal structure and electronic conduction, thus contributing to lower resistivity.

[0029] By controlling the content of silicon (Si), copper (Cu), and aluminum (Al) to ≤0.005%, these elements can be prevented from causing excessive interference to electronic conduction, thus maintaining the low resistivity of the expansion alloy.

[0030] When preparing expansion alloys, the first step is to melt them in an electric furnace, which can achieve preliminary alloying and composition homogenization. Specifically, vacuuming is used to reduce oxidation and gas residue during the melting process, reduce impurity content, and avoid the formation of high-resistivity oxides (such as Al2O3 and SiO2). The materials are added in order of melting point to avoid compositional segregation caused by incomplete melting of high-melting-point elements (such as Fe and Mo), thereby improving the uniformity of the alloy.

[0031] In step S2, the ingot is rapidly melted under high current through electroslag remelting, and the molten metal is further purified by adsorbing impurities such as sulfur (S) and phosphorus (P) using the slag. Furthermore, the solidification rate is controlled by gradually decreasing the current (1 kA / 5 min), which helps form fine columnar crystals, reduces shrinkage cavities and porosity, and increases density. This step significantly reduces the content of harmful impurities such as S and P, eliminates internal defects in the ingot, and improves conductivity.

[0032] In step S3, homogenization annealing is first used to eliminate compositional segregation, promote atomic diffusion, and form a single solid solution phase. Then, vacuum arc remelting is used to achieve a higher purity alloy, reduce lattice distortion and phase interface scattering, and significantly reduce resistivity.

[0033] In step S4, the alloy is first annealed under hydrogen protection. This process reduces surface oxides and simultaneously penetrates the alloy interior to remove residual oxygen and carbon. Then, high-temperature annealing eliminates cold working stress, promotes recrystallization, and forms uniform equiaxed grains. A single hot rolling and cold drawing process further optimizes the grain structure. The grain size is controlled through a heat treatment cycle, improving grain boundary cleanliness and electron mobility.

[0034] In step S5, the final heat treatment at 950–1000°C helps eliminate surface microcracks and oxide layers, preventing surface degradation during subsequent use. Then, rapid cooling to 450–500°C helps precipitate a nanoscale copper-rich phase, thereby optimizing conductivity and reducing resistivity.

[0035] The beneficial effects of this invention are:

[0036] (1) In this invention, an expansion alloy with low resistivity is obtained by optimizing the composition design while ensuring that the expansion coefficient is qualified.

[0037] (2) In this invention, the refining process is carried out by a three-step process: electric furnace melting → electroslag remelting → vacuum self-consumption melting, removing impurities step by step to achieve progressive purity. The subsequent heat treatment process is used to refine the structure and control defects, thereby reducing the influence of alloying elements and impurities on resistivity and thus meeting the performance requirements. Detailed Implementation

[0038] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0039] Example 1

[0040] The chemical composition includes 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%, with the balance being Fe and unavoidable impurities.

[0041] Preparation of low resistivity expansion alloy materials:

[0042] S1, Electric furnace smelting:

[0043] According to the low resistivity expansion alloy proportioning, the material was evacuated to 0.1 Pa, and the alloying elements were added in order of increasing melting point. The ingot was then refined at 1550℃ for 20 minutes.

[0044] S2, Electroslag Remelting:

[0045] Under the protection of high-purity argon, the ingot is electroslag remelted. The remelting current is controlled at 5kA and the electroslag remelting rate is controlled at 6Kg / min. The remelting current is then reduced to 3kA at a rate of 1kA / 5min until the crystallizer is full, at which point the electroslag remelting is complete. The ingot is then poured at 1350℃ and demolded after 2 hours. After air cooling, the electroslag remelted ingot is obtained. During the electroslag remelting, a pre-melted slag of 55 parts CaF2, 15 parts CaO, and 15 parts Al2O3 is used as the slag material and baked at 600℃ for 24 hours before use.

[0046] S3, Vacuum self-consumable melting:

[0047] The electroslag remelted ingot was held at 1150℃ for 8 hours for homogenization annealing. After annealing, it was cooled to 600℃ and then air-cooled. The resulting alloy rod was used as a consumable electrode for vacuum consumable remelting. The melting rate of vacuum consumable remelting was maintained at 90 kg / h. After melting, the ingot was demolded and placed in an argon-protected furnace to be slowly cooled to 200℃ before being taken out of the furnace to obtain the alloy ingot.

[0048] S4. Heat treatment:

[0049] The alloy ingot was annealed at 1160℃ for 20 hours under hydrogen protection, then air-cooled to 600℃, and then hot-rolled at 1120℃ for 2 hours. The rolling deformation of the first hot rolling treatment was 80%, and the final rolling temperature was 800℃. After cooling to room temperature, it was cold-drawn with a deformation of 90%. Then, under argon protection, it was annealed at 720℃ for 50 minutes, and then hot-rolled at 1100℃ for 2 hours. After completion, it was cooled to room temperature by water mist to obtain the alloy ingot.

[0050] S5. Final surface treatment:

[0051] The alloy ingot was heated to 950°C for a final heat treatment of 30 minutes, then rapidly cooled to 450°C and held for 2 hours to obtain the low resistivity expansion alloy material.

[0052] Example 2

[0053] The chemical composition includes 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%, with the balance being Fe and unavoidable impurities.

[0054] Preparation of low resistivity expansion alloy materials:

[0055] S1, Electric furnace smelting:

[0056] According to the low resistivity expansion alloy proportioning, the material was evacuated to 0.2 Pa, and the alloying elements were added in order of increasing melting point. The ingot was then refined at 1570℃ for 25 minutes.

[0057] S2, Electroslag Remelting:

[0058] Under the protection of high-purity argon, the ingot is electroslag remelted. The remelting current is controlled at 5kA and the electroslag remelting rate is controlled at 7Kg / min. The remelting current is then reduced to 3kA at a rate of 1kA / 5min until the crystallizer is full, at which point the electroslag remelting is complete. The ingot is then poured at 1360℃ and demolded after 2 hours. After air cooling, the electroslag remelted ingot is obtained. During the electroslag remelting, a pre-melted slag of 60 parts CaF2, 20 parts CaO, and 20 parts Al2O3 is used as the slag material and baked at 650℃ for 24 hours before use.

[0059] S3, Vacuum self-consumable melting:

[0060] The electroslag remelted ingot was held at 1170℃ for 10 hours for homogenization annealing. After annealing, it was cooled to 600℃ and then air-cooled. The resulting alloy rod was used as a consumable electrode for vacuum consumable remelting. The melting rate of vacuum consumable remelting was maintained at 100 kg / h. After melting, the ingot was demolded and placed in an argon-protected furnace to be slowly cooled to 210℃ before being taken out of the furnace to obtain the alloy ingot.

[0061] S4. Heat treatment:

[0062] The alloy ingot was annealed at 1170℃ for 23 hours under hydrogen protection, then air-cooled to 600℃, and then hot-rolled at 1130℃ for 3 hours. The rolling deformation of the first hot rolling treatment was 85%, and the final rolling temperature was 820℃. After cooling to room temperature, it was cold-drawn with a deformation of 90%. Then, under argon protection, it was annealed at 725℃ for 60 minutes, and then hot-rolled at 1130℃ for 2.2 hours. After completion, it was cooled to room temperature by water mist to obtain the alloy ingot.

[0063] S5. Final surface treatment:

[0064] The alloy ingot was heated to 970°C for a final heat treatment of 35 minutes, then rapidly cooled to 470°C and held for 3 hours to obtain the low resistivity expansion alloy material.

[0065] Example 3

[0066] The chemical composition includes the following weight percentages: 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%, with the balance being Fe and unavoidable impurities.

[0067] Preparation of low resistivity expansion alloy materials:

[0068] S1, Electric furnace smelting:

[0069] According to the low resistivity expansion alloy proportioning, the material was evacuated to 0.3 Pa, and the alloying elements were added in order of increasing melting point. The ingot was then refined at 1600℃ for 35 minutes.

[0070] S2, Electroslag Remelting:

[0071] Under the protection of high-purity argon, the ingot is electroslag remelted. The remelting current is controlled at 5kA and the electroslag remelting rate is controlled at 8Kg / min. The remelting current is then reduced to 3kA at a rate of 1kA / 5min until the crystallizer is full, at which point the electroslag remelting is complete. The ingot is then poured at 1370℃ and demolded after 2 hours. It is then air-cooled to obtain the electroslag remelted ingot. During the electroslag remelting, a pre-melted slag of 65 parts CaF2, 25 parts CaO, and 25 parts Al2O3 is used as the slag material and baked at 700℃ for 24 hours before use.

[0072] S3, Vacuum self-consumable melting:

[0073] The electroslag remelted ingot was held at 1200℃ for 12 hours for homogenization annealing. After annealing, it was cooled to 600℃ and then air-cooled. The resulting alloy rod was used as a consumable electrode for vacuum consumable remelting. The melting rate of vacuum consumable remelting was maintained at 150 kg / h. After melting, the ingot was demolded and placed in an argon-protected furnace to be slowly cooled to 220℃ before being taken out of the furnace to obtain the alloy ingot.

[0074] S4. Heat treatment:

[0075] The alloy ingot was annealed at 1180℃ for 25 hours under hydrogen protection, then air-cooled to 600℃, and then hot-rolled at 1150℃ for 4 hours. The rolling deformation of the first hot rolling treatment was 90%, and the final rolling temperature was 850℃. After cooling to room temperature, it was cold-drawn with a deformation of 90%. Then, under argon protection, it was annealed at 745℃ for 70 minutes, and then hot-rolled at 1150℃ for 2.5 hours. After completion, it was cooled to room temperature by water mist to obtain the alloy ingot.

[0076] S5. Final surface treatment:

[0077] The alloy ingot was heated to 1000℃ for final heat treatment for 45 minutes, then rapidly cooled to 500℃ and held for 4 hours 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 arc remelting was not used in Comparative Example 1, but all other operations were the same.

[0080] Comparative Example 2

[0081] The difference between Comparative Example 2 and Example 1 is that step S5 was not performed in Comparative Example 2, while the rest of the operations were the same.

[0082] Comparative Example 3

[0083] The difference between Comparative Example 3 and Example 1 is that in Comparative Example 3, the remelting current was not reduced in step S2, while the rest of the operations were the same.

[0084] Comparative Example 4

[0085] Comparative Example 4 is the commercial expansion alloy 4J50.

[0086] Comparative Example 5

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

[0088] Performance testing:

[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] Based on the above data, it can be seen that the resistivity of the expansion alloy material prepared in the example is <0.365μΩm, ​​and the expansion coefficient at 30-450℃ is between 4J50 and 4J52. Therefore, it can achieve the effect of ensuring both expansion coefficient and low resistivity.

[0091] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A low resistivity Invar alloy material characterized in that, Chemical components including 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%, the balance being Fe and inevitable impurities; Including the following preparation process: S1, electric furnace smelting: According to the low resistivity expansion alloy ratio, the vacuum is extracted to 0.1~0.3Pa, the alloying elements are sequentially added in the order from low to high melting point, and the ingot is obtained by refining at 1550~1600℃ for 20~35min; S2, electroslag remelting: The ingot is electroslag remelted under high-purity argon protection, the remelting current is controlled to be 5kA, the electroslag remelting rate is controlled to be 6~8kg / min, the remelting current is decreased to 3kA, the current reduction rate is 1kA / 5min, until the crystallizer is filled, the electroslag remelting is completed, the demolding is carried out after 2h pouring, and the electroslag remelted ingot is obtained by air cooling; S3, vacuum consumable smelting: The electroslag remelted ingot is homogenized annealed at 1150~1200℃ for 8~12h, after annealing, the temperature is decreased to 600℃ and then air cooled, the obtained alloy rod is used as a consumable electrode, vacuum consumable remelting is carried out, the melting speed of the vacuum consumable smelting is maintained at 90~150kg / h, the mold is demolded after the smelting is completed, the ingot is placed in an argon protection furnace and slowly cooled to 200~220℃ to be taken out, and the alloy ingot is obtained; S4, heat treatment: The alloy ingot is once annealed under hydrogen protection, then air cooled to 600℃, heated to 1120~1150℃ for once hot rolling treatment, cooled to room temperature, cold-drawn with a deformation of 90%, then twice annealed under argon protection, then twice hot-rolled for 2~2.5h, and the alloy ingot is obtained by water mist cooling to room temperature after completion; S5, final surface treatment: The alloy ingot is heated to 950~1000℃ for final heat treatment, and then quickly cooled to 450~500℃ for 2~4h to obtain the low resistivity expansion alloy material.

2. The method of producing a low resistivity expansion alloy material according to claim 1, characterized by, In step S2, 55~65 parts by weight of CaF2, 15~25 parts by weight of CaO and 15~25 parts by weight of Al2O3 are used as slag, and the slag is baked at 600~700℃ for 24h before use.

3. The method of producing a low resistivity expansion alloy material according to claim 1, characterized by, In step S2, the pouring temperature is 1350~1370℃.

4. The method of producing a low resistivity expansion alloy material according to claim 1, characterized by, In step S4, the once annealing treatment is carried out for 20~25h at 1160~1180℃.

5. The method of producing a low resistivity expansion alloy material according to claim 1, characterized by, In step S4, the once hot rolling treatment is carried out with a rolling deformation of 80%~90% and a final rolling temperature of 800~850℃.

6. The method of producing a low resistivity expansion alloy material according to claim 1, characterized by, In step S4, the once hot rolling treatment is carried out for 2~4h.

7. The method of producing a low resistivity expansion alloy material according to claim 1, characterized by, In step S4, the twice annealing treatment is carried out at 720~745℃ for 50~70min.

8. The method of producing a low resistivity expansion alloy material according to claim 1, characterized by, In step S4, the twice hot rolling treatment is carried out at 1100~1150℃.

9. The method of producing a low resistivity expansion alloy material according to claim 2, characterized by, In step S5, the final heat treatment is carried out for 30~45min.