CN112391561A

CN112391561A - High-strength high-conductivity aluminum-based conductor and preparation method thereof

Info

Publication number: CN112391561A
Application number: CN202011280118.6A
Authority: CN
Inventors: 陈小红; 郭未椿; 刘平; 周洪雷; 武家艳; 方航; 朱炎波; 任钰鹏; 张道乾
Original assignee: University of Shanghai for Science and Technology
Current assignee: University of Shanghai for Science and Technology
Priority date: 2020-11-16
Filing date: 2020-11-16
Publication date: 2021-02-23

Abstract

The invention discloses a high-strength high-conductivity aluminum-based conductor and a preparation method thereof, wherein the aluminum-based conductor comprises the following substances in percentage by mass: 0.3-0.5% of Fe, 0-0.1% of Si, 0.1-0.3% of Er, and the balance of Al and impurities. Through in-depth research, the invention discovers the action mechanism among all elements, preferably selects the optimal component proportion range of Al-Fe-Si-Er, and finally obtains the alloy wire with excellent comprehensive performance by combining smelting and post-treatment processes.

Description

High-strength high-conductivity aluminum-based conductor and preparation method thereof

Technical Field

The invention belongs to the field of rare earth aluminum alloy manufacturing, and particularly relates to a low-rare earth high-strength high-conductivity rare earth aluminum alloy and a preparation method thereof.

Background

The wire with aluminum as the cable core is widely applied after 1955, and the phenomenon of aluminum entering copper and receding occurs in the cable industry. At present, high-strength and high-conductivity aluminum alloy is mainly used for wires, cables and high-voltage transmission lines, but has poor room-temperature mechanical property and improved electric conductivity.

Microalloying is one of the most effective means for improving the overall performance of aluminum conductor materials. Zr is the most commonly used microalloying element in heat-resistant aluminum conductor material, and Chinese patent CN1924053A discloses a high-conductivity super heat-resistant aluminum alloy lead containing Zr, wherein the addition amount of Zr is several times of that of the common heat-resistant alloy lead, the conductivity can be obviously reduced when the addition amount of Zr is too high, partial solid solution state Zr can be precipitated by adopting long-time heat treatment, and dispersed Al is formed in a matrix₃The Zr metal compound reduces the harmful effect of Zr on the conductivity and improves the heat resistance, so that the high-conductivity super heat-resistant aluminum alloy wire has to be subjected to long-time heat treatment at a certain temperature during production, the energy consumption is high, and continuous production is not easy to realize. In addition, the melting point of Zr is as high as 1852 ℃, and Al is added in the smelting process₃Control of the Zr phase is difficult, and Zr which is easily formed in a solid solution state has a large influence on the conductivity of the Al alloy. The melting point of rare earth element Er is lower than that of Zr and has similar characteristics with Zr, and Al is formed₃Er phase and Al₃The Zr phase structure is the same, and the lattice parameter is close to Al. Chinese patent CN101418401B discloses an Al-Er alloy wire material, which shows that the hardness of the alloy can be improved on the premise of keeping higher conductivity by adding a proper amount of Er in pure aluminum, however, the patent does not ensure thatThe beneficial effect of Er on heat resistance is realized. The Zr and Er have similar physical and chemical properties, and the composite addition of the Zr and the Er can generate positive influence on the heat resistance of the aluminum alloy, and the Chinese patent CN102230113B discloses that the Zr and the Er are compounded to microalloy an Al matrix, wherein the addition of the Zr is limited to a lower level, so that the influence on the electric conductivity is reduced as much as possible on the premise of improving the heat resistance, and the heat resistance is further improved by compounding the Zr and the Er, but the Fe content in the process needs to be controlled within 0.1-0.2%, which limits the mechanical property of the alloy. Fe and Si are elements which are extremely difficult to remove from the aluminum alloy and have important influence on the mechanical property and the conductivity of the alloy. Fe and Al can form short rod-shaped or needle-shaped brittle and hard Al₃Fe phase, although improving ultimate tensile strength of the alloy, Al during drawing₃The Fe phase is very likely to be a crack source to reduce the elongation property of the alloy. When the content of Si is low, the Si exists mainly in a solid solution state, and the conductivity of the alloy is adversely affected. Therefore, reasonable control of Fe and Si in the aluminum alloy is a key factor for obtaining excellent comprehensive performance.

Disclosure of Invention

The invention provides a processing and heat treatment process of an Al-Fe-Si-Er alloy conductor, which improves the yield strength, ultimate tensile strength and elongation percentage of the produced conductor and improves the conductivity of the material.

In order to achieve the purpose, the invention adopts the following technical scheme:

a high-strength high-conductivity aluminum-based conductor is characterized in that: the material composition comprises the following components in percentage by mass: 0.3-0.5% of Fe, 0-0.1% of Si, 0.1-0.3% of Er, and the balance of Al and impurities.

Further, the impurities include, but are not limited to, vanadium, titanium, calcium, lead, tin. The mass of the impurities is less than 0.03 percent of the total mass.

Further, the aluminum-based conductor is formed by smelting pure aluminum, an aluminum-iron intermediate alloy and an aluminum-erbium intermediate alloy. Because the melting point of Er is very high and the solid solubility in aluminum is only 0.017 percent, the melting point of Er and the burning loss of Er can be effectively reduced by adding the Er in the form of master alloy.

According to another aspect of the present invention, there is provided a method for manufacturing a rare earth aluminum alloy wire rod, comprising the steps of:

the method comprises the following steps: accurately weighing pure aluminum ingots, aluminum-iron intermediate alloy and aluminum-erbium intermediate alloy according to the material composition of the aluminum-based conductor, and drying in a drying oven for 10-20 minutes;

step two: feeding the pure aluminum ingot into a crucible, heating to 750 ℃, and melting the pure aluminum ingot;

step three: adding the dried aluminum-iron intermediate alloy and aluminum-erbium intermediate alloy into the molten aluminum, and stirring for 15-20 minutes after melting to ensure that the components are uniform;

step four: adding a refining agent to remove gas and impurities, standing at 690-730 ℃ for 15-20min, fishing dross on the surface of the melt after the standing is finished, casting rare earth aluminum alloy in a preheated iron mold after cooling, and removing surface oxide skin by a mechanical processing vehicle;

step five: carrying out homogenization annealing at 500-600 ℃ for 10-20h, and carrying out hot extrusion to obtain an aluminum alloy bar; continuously drawing the aluminum alloy bar to the wire with the required specification, and annealing for 1-3h at the temperature of 200-280 ℃.

Further, the aluminum-iron intermediate alloy is Al-10Fe intermediate alloy, the aluminum-erbium intermediate alloy is Al-20Er intermediate alloy, and the purity of the aluminum-erbium intermediate alloy is more than 99.5%.

Further, the drying temperature of the oven in the first step is 180-.

Further, the iron mold is preheated to 200-240 ℃ during the casting in the fourth step.

The invention can obtain Al with proper size radius by introducing Fe and Er in a mode of adding intermediate alloy Al-Fe and Al-Er and matching with proper heat treatment process₃Er phase, which forms coherent interface with alpha-Al matrix and reduces the influence on the conductivity, so that the whole alloy is formed by Al₃The precipitation strengthening mechanism mainly adopts an Er phase. The inventor further finds that the rare earth element Er can be added to have good composite effect with Fe and Si. Er can adsorb Fe element to form Al in the solidification process₃Er phase is coatedIn Al₆Around the Fe phase, the Fe element is prevented from aggregating and growing into Al₃The addition of Fe phase and Er will be in Al phase₃Al is formed at the phase interface of Fe and alpha-Al₁₀Fe₂And the Er phase reduces the adverse effect of Fe on the mechanical property of the alloy. Meanwhile, Er can adsorb Si and combine with Si to form an ErSi phase, and Si is promoted to be separated out in a free state, so that the adverse effect of the Si on the conductivity is reduced. Through in-depth research, the invention discovers the action mechanism among all elements, preferably selects the optimal component proportion range of Al-Fe-Si-Er, and finally obtains the alloy wire with excellent comprehensive performance by combining smelting and post-treatment processes.

Drawings

In FIG. 1, a-d are the microstructure diagrams of the alloys prepared in comparative example and examples 1-3, respectively;

FIG. 2 shows Al in the alloy structure of example 2₃Er phase coated Al₆Transmission electron microscopy analysis of the Fe phase structure;

FIG. 3 is a TEM analysis of the ErSi phase and free Si in the alloy structure of example 2;

FIG. 4 shows Al in the alloy structure of example 2₁₀Fe₂Analyzing the Er phase by a transmission electron microscope;

in FIG. 5, a-b are model diagrams of the influence of the alloy structures of the comparative example and the example 2 on the electric conduction respectively;

a-b in fig. 6 are graphs showing the results of vickers hardness and conductivity tests of the alloy wires prepared in examples 6-8, respectively.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments.

Example 1

The method comprises the following steps: accurately weighing pure aluminum ingots, aluminum-iron intermediate alloys and aluminum-erbium intermediate alloys according to the mass percent of 0.4% of Fe, 0.05% of Si, 0.1% of Er and the balance of Al, and drying in a drying oven for 10-20 minutes;

step five: and (3) carrying out homogenizing annealing at 560 ℃ for 13h, and carrying out hot extrusion to obtain the aluminum alloy bar. And continuously drawing the aluminum alloy bar to a wire with the diameter of 4mm, and annealing at 260 ℃ for 1 h.

Example 2

The method comprises the following steps: accurately weighing pure aluminum ingots, aluminum-iron intermediate alloys and aluminum-erbium intermediate alloys according to the mass percent of 0.4% of Fe, 0.05% of Si, 0.2% of Er and the balance of Al, and drying in a drying oven for 10-20 minutes;

Example 3

The method comprises the following steps: accurately weighing pure aluminum ingots, aluminum-iron intermediate alloys and aluminum-erbium intermediate alloys according to the mass percentage of 0.4% of Fe, 0.05% of Si, 0.3% of Er and the balance of Al, and drying in a drying oven for 10-20 minutes;

Example 4

The method comprises the following steps: accurately weighing pure aluminum ingots, aluminum-iron intermediate alloys and aluminum-erbium intermediate alloys according to the mass percentage of 0.3% of Fe, 0.05% of Si, 0.2% of Er and the balance of Al, and drying in a drying oven for 10-20 minutes;

Example 5

The method comprises the following steps: accurately weighing pure aluminum ingots, aluminum-iron intermediate alloys and aluminum-erbium intermediate alloys according to the mass percent of 0.5% of Fe, 0.05% of Si, 0.2% of Er and the balance of Al, and drying in a drying oven for 10-20 minutes;

Example 6

step five: and (3) carrying out homogenizing annealing at 560 ℃ for 13h, and carrying out hot extrusion to obtain the aluminum alloy bar. And continuously drawing the aluminum alloy bar to a wire with the diameter of 4mm, and respectively carrying out annealing treatment at 200 ℃/220 ℃/240 ℃/250 ℃/270 ℃/280 ℃ for 1 h.

Example 7

Example 8

Comparative example

The comparative example is different from the embodiment in that the rare earth element Er is not added, and comprises the following compositions in percentage by mass: 0.4 percent of Fe,0.05 percent of Si, and the balance of Al and impurities, and the preparation process is the same.

Performance detection

The results of the performance testing of the samples of comparative example and examples 1-5 are shown in table 1:

TABLE 1

As can be seen from Table 1, the Yield Strength (YS) and the tensile strength (UTS) of the aluminum alloy provided by the invention are improved by 10-20MPa, about 9% -18% and the electrical conductivity (IACS) is improved by 0.5-1.2IACS after annealing at 260 ℃ for 1 h; particularly, compared with the comparative ratio of the aluminum alloy obtained in the embodiment 2 after annealing, the yield strength is improved by 21MPa, the ultimate tensile strength is improved by 22MPa, the elongation (El) is improved to 13%, the electric conductivity is improved by 1.2% IACS, and the electric conductivity reaches 62.2% IACS.

With specific reference to fig. 1-5, the inventors have discovered through microscopic structure observation that by introducing Fe and Er in a manner of adding master alloys of Al-Fe and Al-Er, and by matching with a proper heat treatment process, Al with a suitable size radius can be obtained₃Er phase, which forms coherent interface with alpha-Al matrix and reduces the influence on the conductivity, so that the whole alloy is formed by Al₃The precipitation strengthening mechanism mainly adopts an Er phase. The inventor further finds that the rare earth element Er can be added to have good composite effect with Fe and Si. Er can adsorb Fe element to form Al in the solidification process₃Er phase coated on Al₆Around the Fe phase, the Fe element is prevented from aggregating and growing into Al₃The addition of Fe phase and Er will be in Al phase₃Al is formed at the phase interface of Fe and alpha-Al₁₀Fe₂And the Er phase reduces the adverse effect of Fe on the mechanical property of the alloy. Meanwhile, Er can adsorb Si and combine with Si to form an ErSi phase, and Si is promoted to be separated out in a free state, so that the adverse effect of the Si on the conductivity is reduced.

The hardness and conductivity performance test results for the samples of examples 6-8 are shown in fig. 6.

As can be seen from fig. 6, after the material is subjected to cold deformation, a large number of dislocations are introduced into the alloy, the conductivity of the material is reduced, and the hardness is increased. During annealing, due to the reduction of dislocation density and the formation of sub-grains within the deformed grains, a softening effect occurs before the recrystallization temperature, the electrical resistance can be restored to a level close to that before cold working, and the hardness is reduced. Meanwhile, after annealing, deformation structures disappear, crystal grains grow up, crystal boundaries are reduced, and the conductivity of the material is improved. At 260 ℃, the conductivity of the material reaches a maximum value basically, and then as the annealing temperature is increased continuously, the closer to the recrystallization temperature, the more obvious the softening effect of the material is, the grain boundary of new grains after recrystallization can block the movement of electrons, and the conductivity is reduced.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equally replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A high-strength high-conductivity aluminum-based conductor is characterized in that: the material composition comprises the following components in percentage by mass: 0.3-0.5% of Fe, 0-0.1% of Si, 0.1-0.3% of Er, and the balance of Al and impurities.

2. A high strength high conductivity rare earth aluminum alloy as claimed in claim 1, wherein: the impurities comprise vanadium, titanium, calcium, lead and tin, and the mass of the impurities is less than 0.03 percent of the total mass.

3. A high strength high conductivity rare earth aluminum alloy as claimed in claim 1, wherein: the aluminum-based conductor is formed by smelting pure aluminum, aluminum-iron intermediate alloy and aluminum-erbium intermediate alloy.

4. A preparation method of a rare earth aluminum alloy wire is characterized by comprising the following steps: the method comprises the following steps:

the method comprises the following steps: according to the material composition of the aluminum-based conductor, pure aluminum ingots, aluminum-iron intermediate alloys and aluminum-erbium intermediate alloys are accurately weighed and placed into an oven to be dried for 10-20 minutes;

5. The method of claim 4, wherein: the aluminum-iron intermediate alloy is an Al-10Fe intermediate alloy, and the aluminum-erbium intermediate alloy is an Al-20Er intermediate alloy.

6. The method of claim 4, wherein: the drying temperature of the drying oven in the first step is 180-200 ℃.

7. The method of claim 4, wherein: in the fourth step, the iron mold is preheated to 200-240 ℃ during casting.