High-strength and high-heat-resistance Al-Fe alloy conductive material and preparation method thereof

Abstract

The invention discloses a high-strength and high-heat-resistance Al-Fe series alloy conductive material and a preparation method thereof, and the material comprises the following chemical components in percentage by weight: 0.5-1.0% of Fe, 0.4-0.6% of Zr and the balance of aluminum. Firstly, an alloy rod is obtained through gas-assisted continuous casting extrusion, the alloy rod contains an Al6Fe phase of dozens of nanometers to hundreds of nanometers and an alpha-Al matrix with the high Zr solid solubility, then a nanoscale Al3Zr phase is formed through low-temperature aging to stabilize the Al6Fe phase, the Zr element is sufficiently separated out through high-temperature aging to improve the conductivity of the alloy, and the alloy rod is prepared. The Al6Fe phase and the Al3Zr phase synergistically improve the mechanical property and the heat resistance of the alloy; the conductive material is low in raw material cost and beneficial to popularization and application.

Description

Technical Field

[0001] The invention relates to a high-strength and high-heat-resistant Al-Fe alloy conductive material and a preparation method thereof, belonging to the technical field of aluminum alloy processing and preparation. Background Art

[0002] The iron-containing phase in the Al-Fe alloy has high-temperature stability and can hinder the movement of grain boundaries to improve creep resistance. At the same time, the extremely low solid solubility of Fe in the aluminum matrix (~0.02wt.% at room temperature) is conducive to obtaining higher conductivity. Therefore, Al-Fe alloy is a heat-resistant aluminum alloy conductive material with great application prospects.

[0003] The commonly used preparation process for heat-resistant aluminum alloy conductive materials is casting. The aluminum alloy conductive materials prepared by casting have low strength, mainly because the cooling rate of conventional casting is low. The iron-containing phase is mainly coarse Al3Fe phase distributed along the grain boundary. This phase is mostly plate-like or long needle-like, which contributes little to the strength of the alloy and will split the aluminum matrix and reduce the toughness of the alloy.

[0004] When a process with a higher cooling rate is used (such as laser powder bed melting), a fine dispersed metastable phase Al6Fe will be formed in the aluminum matrix. This phase is mostly in the form of short rods with a diameter of about tens of nanometers and has a coherent relationship with the aluminum matrix: It is very beneficial to improve the strength of the alloy, but compared with Al3Fe, the thermal stability of Al6Fe phase is poorer; Wang Yueting et al. found that the Al6Fe particles formed during the non-equilibrium solidification process will gradually coarsen when exposed to high-temperature heat, and gradually dissolve in the matrix after 300℃ / 100h.

[0005] The calculation results of Qu et al. based on the empirical electron theory (EET) of solids and molecules also show that the number of covalent electron pairs of the strongest bond of Al6Fe (0.6760) is significantly smaller than that of Al3Fe (1.0834), and the Al6Fe phase is easier to decompose when heated. Therefore, how to further improve the heat resistance of aluminum alloys containing Al6Fe phase while maintaining the strength and conductivity of aluminum alloys to give them broader application prospects has become a top priority. Summary of the invention

[0006] The object of the present invention is to provide a high-strength and high-heat-resistant Al-Fe alloy conductive material and a preparation method thereof, so as to solve the problems existing in the prior art.

[0007] The technical solution of the present invention is as follows:

[0008] One of the purposes of the present invention is to provide a high-strength and high-heat-resistant Al-Fe alloy conductive material, whose chemical composition by weight percentage is: Fe 0.5-1.0%, Zr 0.4-0.6%, and the balance is aluminum.

[0009] The second object of the present invention is to provide a method for preparing a high-strength and high-heat-resistant Al-Fe alloy conductive material, which includes: material preparation, smelting, gas-assisted continuous casting and extrusion, and two-stage aging to obtain the conductive material, specifically including the following steps:

[0010] (1) According to their chemical compositions, Al-10Fe master alloy, Al-5Zr master alloy and high-purity aluminum ingot were weighed respectively.

[0011] (2) Al-10Fe master alloy, Al-5Zr master alloy and high-purity aluminum ingot are placed in a furnace for melting, and stirred until the mixture is uniform, thereby completing the smelting. Preferably, the melt temperature is maintained at 800-840° C. during stirring.

[0012] Preferably, the specific process of gas-assisted continuous casting and extrusion is: the smelted metal melt flows into the extrusion wheel groove from the preheated funnel located above the extrusion wheel. Under the action of the inert gas, the melt spreads out closely against the wall of the extrusion wheel groove and begins to solidify. After encountering a blockage, the solidifying billet begins to accumulate and gradually transfers into the mold cavity, and is finally extruded from the mold hole to form an alloy rod.

[0013] Preferably, the inner hole diameter of the funnel is 2-3 mm, and the funnel needs to be heated to 800-840° C. before pouring the alloy melt.

[0014] Preferably, the inert gas is nitrogen, and the gas pressure is 0.2-0.4 MPa.

[0015] Preferably, the rotation speed of the extrusion wheel is 8-12 rpm.

[0016] Preferably, the preheating temperature of the extrusion die cavity is 200-350°C, and the die hole diameter is 9.5 mm.

[0017] Preferably, in double-stage aging, the first-stage aging temperature is 280-300°C, the time is 50-100h, and the second-stage aging temperature is 340-360°C, the time is 24-120h.

[0018] The principle of the present invention is as follows: firstly, an alloy rod is obtained by gas-assisted continuous casting and extrusion, wherein the alloy rod contains an Al6Fe phase of tens to hundreds of nanometers and α-Al grains with a high Zr solid solubility and a size not exceeding ten microns. Then, a high-density nanoscale Al3Zr phase is formed by first-stage aging to stabilize the Al6Fe phase. A second-stage aging is performed to fully precipitate the Zr element to improve the electrical conductivity of the alloy. The Al6Fe phase and the Al3Zr phase synergistically improve the mechanical properties and heat resistance of the alloy.

[0019] Beneficial effects of the present invention:

[0020] (1) For α-Al solid solution with Zr solubility exceeding 0.4%, Al3Zr phase can be formed during short-term aging (first-stage aging) below 300°C without significantly changing the morphology and size of Fe-containing phase and α-Al grains; the Al3Zr phase precipitated during the first-stage aging process can pin the Al6Fe phase boundary to prevent the coarsening of the Al6Fe phase during the second-stage aging process; the higher temperature during the second-stage aging process is conducive to the complete precipitation of Zr element and improves the electrical conductivity of the alloy.

[0021] (2) The nanoscale Al3Zr phase in the alloy can stabilize the Al6Fe phase to further improve the heat resistance of the alloy. At the same time, both can pin dislocations and jointly improve the strength level of the alloy, making the alloy have the characteristics of high strength and high heat resistance. In addition, the alloy elements Fe and Zr added in the present invention are low in price, which is conducive to promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a flow chart for preparing high-strength and high-heat-resistant Al-Fe alloy conductive materials;

[0023] Figure 2 This is the principle diagram of gas-assisted continuous casting and extrusion.

[0024] In the figure: 1-funnel; 2-melt; 3-extrusion wheel; 4-extrusion wheel groove; 5-mold cavity; 6-mold; 7-extrusion rod; 8-injection device. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0026] The device used in the embodiment of the present invention is as follows Figure 2 As shown, it includes a funnel 1, an extrusion wheel 3, an extrusion wheel groove 4, a mold cavity 5, a mold 6, an extrusion rod 7, and an air jet device 8; the smelted metal melt 2 flows out from the preheated funnel 1 located above the extrusion wheel 3 to the extrusion wheel groove 4, and the air jet device 8 above the extrusion wheel groove sprays inert gas. Under the action of the inert gas, the melt spreads closely against the wall of the extrusion wheel groove and begins to solidify. Under the rotation of the extrusion wheel and the action of the plug on the mold cavity 5, the solidified billet is continuously extruded from the mold 6 to obtain a product alloy rod 7.

[0027] Example 1

[0028] The present invention relates to a method for preparing a high-strength and high-heat-resistant Al-Fe alloy conductive material, comprising the following steps:

[0029] (1) Material preparation: According to the mass percentage of Fe: 1%; Zr 0.5%; the balance is Al, weigh Al-10Fe master alloy, Al-5Zr master alloy and high-purity aluminum ingot respectively.

[0030] (2) Melting: The aluminum-iron master alloy, aluminum-zirconium master alloy and aluminum ingot are placed in a furnace for melting and stirred until the mixture is uniform. During the stirring process, the melt temperature is maintained at 820°C. Finally, the melt temperature is maintained at 810°C for 60 minutes to complete the melting.

[0031] (3) Preparation of Al-Fe-Zr alloy rod by gas-assisted continuous casting and extrusion: the molten alloy flows out from a funnel (funnel diameter is 2.8 mm) located above the extrusion wheel groove, and an inert gas (nitrogen gas, gas pressure is 0.2 MPa) is sprayed above the extrusion wheel groove. Under the combined action of gravity and the inert gas jet, the alloy melt spreads along the extrusion wheel groove to form a metal thin layer. Under the action of the extrusion wheel (rotation speed is 8 rpm) and the plug, the metal thin layer on the wheel groove wall continuously enters the mold and accumulates, and then is extruded from the mold hole to form an alloy rod; the funnel preheating temperature is 820°C, and the mold hole diameter is 9.5 mm.

[0032] (4) The alloy rod obtained in step (3) is subjected to a heat treatment at 290° C. / 100 h+350° C. / 80 h to obtain a high-performance Al-Fe alloy rod: the tensile strength and electrical conductivity are 189 MPa and 58.2% IACS, respectively.

[0033] (5) The alloy rod obtained in step (4) was subjected to a heat resistance test at 400°C / 1h, and its tensile strength was found to be 181 MPa.

[0034] Example 2

[0035] The present invention relates to a method for preparing a high-strength and high-heat-resistant Al-Fe alloy conductive material, comprising the following steps:

[0036] (1) Material preparation: According to the mass percentage of Fe: 0.7%; Zr: 0.4%; the balance is Al, weigh Al-10Fe master alloy, Al-5Zr master alloy and high-purity aluminum ingot respectively.

[0037] (2) Melting: The aluminum-iron master alloy, aluminum-zirconium master alloy and aluminum ingot are placed in a furnace for melting and stirred until the mixture is uniform. During the stirring process, the melt temperature is maintained at 810°C. Finally, the melt is kept at 800°C for 60 minutes to complete the melting.

[0038] (3) Preparation of Al-Fe-Zr alloy rod by gas-assisted continuous casting and extrusion: the molten alloy melt flows out from a funnel (funnel diameter is 3.0 mm) located above the extrusion wheel groove, and an inert gas (nitrogen gas, gas pressure is 0.3 MPa) is sprayed above the extrusion wheel groove. Under the combined action of gravity and the inert gas jet, the alloy melt spreads along the extrusion wheel groove to form a metal thin layer. Under the action of the extrusion wheel (rotation speed is 10 rpm) and the plug, the metal thin layer on the wheel groove wall continuously enters the mold and accumulates, and then is extruded from the mold hole to form an alloy rod; the funnel preheating temperature is 810°C, and the mold hole diameter is 9.5 mm.

[0039] (4) The alloy rod obtained in step (3) is subjected to a heat treatment at 300°C / 100h+360°C / 24h to obtain a high-performance Al-Fe alloy rod: the tensile strength and electrical conductivity are 185MPa and 58.4%IACS, respectively.

[0040] (5) The alloy rod obtained in step (4) was subjected to a heat resistance test at 400°C / 1h, and its tensile strength was measured to be 174 MPa.

[0041] Example 3

[0042] The present invention relates to a method for preparing a high-strength and high-heat-resistant Al-Fe alloy conductive material, comprising the following steps:

[0043] (1) Material preparation: According to the mass percentage of Fe: 0.5%; Zr: 0.6%; the balance is Al, weigh Al-10Fe master alloy, Al-5Zr master alloy and high-purity aluminum ingot respectively.

[0044] (2) Melting: The aluminum-iron master alloy, the aluminum-zirconium master alloy and the aluminum ingot are charged into a furnace for melting and stirred until the mixture is uniform. During the stirring process, the melt temperature is maintained at 840°C. Finally, the melt is kept at 840°C for 60 minutes to complete the melting.

[0045] (3) Preparation of Al-Fe-Zr alloy rod by gas-assisted continuous casting and extrusion: the molten alloy flows out from a funnel (funnel diameter is 2.0 mm) located above the extrusion wheel groove, and an inert gas (nitrogen gas, gas pressure is 0.4 MPa) is sprayed above the extrusion wheel groove. Under the combined action of gravity and the inert gas jet, the alloy melt spreads along the extrusion wheel groove to form a metal thin layer. Under the action of the extrusion wheel (rotation speed is 12 rpm) and the plug, the metal thin layer on the wheel groove wall continuously enters the mold and accumulates, and then is extruded from the mold hole to form an alloy rod; the funnel preheating temperature is 840°C, and the mold hole diameter is 9.5 mm.

[0046] (4) The alloy rod obtained in step (3) is subjected to a heat treatment at 280° C. / 100 h+340° C. / 120 h to obtain a high-performance Al-Fe alloy rod: the tensile strength and electrical conductivity are 180 MPa and 58.7% IACS, respectively.

[0047] (5) The alloy rod obtained in step (4) was subjected to a heat resistance test at 400°C / 1h, and its tensile strength was measured to be 166 MPa.

[0048] Comparative Example 1

[0049] (1) Material preparation: According to the mass percentage of Fe: 1%; Zr: 0.5%; the balance is Al, weigh the aluminum-iron master alloy, the aluminum-zirconium master alloy and the high-purity aluminum ingot respectively.

[0050] (2) Melting: The aluminum-iron master alloy, aluminum-zirconium master alloy and aluminum ingot are placed in a furnace for melting and stirred until the mixture is uniform. During the stirring process, the melt temperature is maintained at 820°C. Finally, the melt temperature is maintained at 810°C for 60 minutes to complete the melting.

[0051] (3) Casting: The molten metal in step (2) is cast to prepare an aluminum-iron alloy rod with a diameter of 9.5 mm.

[0052] (4) The alloy rod obtained in step (3) is subjected to a heat treatment at 290°C / 100h+350°C / 80h. After the heat treatment, the tensile strength and electrical conductivity are 140 MPa and 58.7% IACS, respectively.

[0053] (5) The alloy rod obtained in step (4) was subjected to a heat resistance test at 400°C / 1h, and its tensile strength was measured to be 135 MPa.

[0054] Comparative Example 2

[0055] The steps and conditions of this embodiment are the same as those of embodiment 1, except that: Zr is not added, that is, the materials are prepared as follows: Fe: 1.0%; the remainder is Al, which are respectively called Al-10Fe alloy and high-purity aluminum ingot.

[0056] After heat treatment, the tensile strength and electrical conductivity of the obtained alloy rod are 130 MPa and 61.3% IACS, respectively.

[0057] The obtained alloy rod was subjected to a heat resistance test at 400°C / 1h, and its tensile strength was measured to be 90MPa.

[0058] By comparing Examples 1 and 2 with Comparative Examples 1 and 2, it can be seen that the alloy prepared by the present invention has more excellent comprehensive properties and can meet the requirements of special heat-resistant aluminum alloy wires. The reasons are as follows: During conventional casting, the second phase in the alloy is coarse Al3Fe and Al3Zr (D0 23), the strengthening effect is weak; the second phase in the gas-assisted continuous casting extruded alloy of the present invention is Al6Fe with a small size, and a large amount of nano-scale Al3Zr (L12) is formed after the first stage aging, which can improve the strength of the alloy while delaying the coarsening of the Al6Fe phase. Therefore, the alloy has excellent mechanical properties and heat resistance; in addition, the full precipitation of Zr element after the second stage aging makes the alloy have good electrical conductivity.

Claims

1. A high-strength and high-heat-resistant Al-Fe alloy conductive material, characterized in that: Calculated by weight percentage, its chemical composition is: Fe 0.5-1.0%, Zr 0.4-0.6%, and the balance is aluminum.

2. A method for preparing the high-strength and high-heat-resistant Al-Fe alloy conductive material as claimed in claim 1, characterized in that: The specific steps include: (1) Material preparation: Al-10Fe master alloy, Al-5Zr master alloy and high-purity aluminum ingot were weighed respectively according to their chemical compositions; (2) Melting: Place the Al-10Fe master alloy, Al-5Zr master alloy and high-purity aluminum ingot into a furnace for melting, and stir until the mixture is uniform to complete the melting; (3) preparing alloy rods by gas-assisted continuous casting and extrusion; (4) Performing double-stage aging on the alloy rod obtained in step (3) to obtain a conductive material.

3. The method for preparing the high-strength and high-heat-resistant Al-Fe alloy conductive material according to claim 2, characterized in that: During stirring in step (2), the melt temperature is maintained at 800-840°C.

4. The method for preparing the high-strength and high-heat-resistant Al-Fe alloy conductive material according to claim 2, characterized in that: In step (3), the specific process of gas-assisted continuous casting and extrusion is as follows: the smelted metal melt flows into the extrusion wheel groove from the preheated funnel located above the extrusion wheel. Under the action of the inert gas, the melt spreads out closely against the wall of the extrusion wheel groove and begins to solidify. After encountering a blockage, the solidifying billet begins to accumulate and gradually transfers into the extrusion die cavity, and is finally extruded from the die hole to form an alloy rod.

5. The method for preparing the high-strength and high-heat-resistant Al-Fe alloy conductive material according to claim 4, characterized in that: In step (3), the inner hole diameter of the funnel is 2-3 mm, and the funnel needs to be heated to 800-840° C. before pouring the alloy melt.

6. The method for preparing the high-strength and high-heat-resistant Al-Fe alloy conductive material according to claim 4, characterized in that: In step (3), the inert gas is nitrogen and the gas pressure is 0.2-0.4 MPa.

7. The method for preparing the high-strength and high-heat-resistant Al-Fe alloy conductive material according to claim 4, characterized in that: The rotation speed of the extrusion wheel in step (3) is 8-12 rpm.

8. The method for preparing the high-strength and high-heat-resistant Al-Fe alloy conductive material according to claim 4, characterized in that: In step (3), the preheating temperature of the extrusion die cavity is 200-350°C, and the die hole diameter is 9.5 mm.

9. The method for preparing the high-strength and high-heat-resistant Al-Fe alloy conductive material according to claim 2, characterized in that: In step (4), the first stage aging temperature is 280-300°C, the time is 50-100h, and the second stage aging temperature is 340-360°C, the time is 24-126h.

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