Novel Al-Fe-RE-based alloy wire and preparation method thereof

Abstract

The invention discloses a novel Al-Fe-RE-based alloy wire and a preparation method thereof, and relates to the technical field of aluminum alloy wire preparation. The Al-Fe-RE-based alloy comprises the following components in percentage by weight: 0.2-0.8% of Fe, 0.1-0.4% of RE, 0.01-0.2% of B, less than or equal to 0.05% of Si, less than or equal to 0.003% of Cu, less than or equal to 0.015% of Ga, less than or equal to 0.003% of Mg and the balance of aluminum. The preparation method comprises the following steps: after melting a pure aluminum ingot, adding iron into a melt in the form of an aluminum-iron intermediate alloy; adding boron in the form of an aluminum-boron intermediate alloy; the method comprises the following steps: adding trace elements magnesium, silicon, copper and gallium into molten aluminum liquid in a powder form, carrying out purification treatment on a melt by utilizing a refining agent, adding rare earth elements into the melt in a form of high-purity rare earth metal or rare earth intermediate alloy, removing scum on the surface of the melt, pouring the alloy melt into a mold, and carrying out rolling, wire drawing and aging heat treatment to obtain the magnesium-silicon-copper-gallium alloy. And the Al-Fe-RE-based aluminum alloy conductor can be obtained. The obtained aluminum alloy conductor has excellent conductivity and mechanical property, the conductivity is larger than or equal to 62% IACS, the tensile strength is larger than or equal to 110 MPa, the compression creep resistance is larger than or equal to 66%, and the elongation is larger than or equal to 14%.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of aluminum alloy wires, and particularly relates to a novel Al-Fe-RE-based alloy wire and a preparation method thereof. Background Art

[0002] The Al-Fe-RE-based alloy with Fe as the main alloying element has high electrical conductivity and creep resistance, and is a currently widely used aluminum alloy conductor material. For aluminum alloys, usually Fe is a harmful element. The addition of a high content of Fe easily forms coarse needle-shaped iron-rich phases, causing stress concentration and reducing mechanical properties. In order to control the morphology of the iron-rich phases, a large amount of research work has been carried out, such as alloying treatment by adding impurity elements such as Mn, Cr, Zr, increasing the cooling rate, and adopting large deformation treatment. Compared with the latter two methods, alloying treatment is a more economical, effective and easy-to-operate method. However, alloying treatment usually reduces the electrical conductivity while increasing the mechanical properties. In recent years, with the rapid development of the power industry, in order to reduce power loss, and at the same time improving the mechanical properties and electrical conductivity of aluminum alloy conductors has gradually become a hot issue explored in the field of materials science.

[0003] Patent No. CN202310838832.X prepared a high-conductivity Al-Fe-RE-based alloy containing the rare earth metal element Ce, with an electrical conductivity of only 61% IACS and a tensile strength of only 85 MPa. A high-conductivity Al-Fe alloy containing rare earth Ce and a preparation method thereof provided by Patent No. CN117070806A is to first add magnesium, silicon, copper and gallium to the aluminum melt, and then add iron and boron. Adding magnesium, silicon, copper and gallium first will cause the preferential formation of strengthening phases or solid solutions, affecting the electrical conductivity of the alloy. When adding iron and boron later, due to the presence of other elements in the melt, it may affect the distribution uniformity of iron and boron, thus affecting the grain refinement effect and strength. The tensile strength of the Al-Fe-Mg-Cu-B-RE-based metal aluminum alloy provided by Patent No. CN202311523706.1 is greater than that of the hard-state Al-Fe-RE-based aluminum alloy in the national standard, and the elongation is greater than that of the soft-state Al-Fe-RE-based aluminum alloy, but the electrical conductivity is also only 61% IACS.

[0004] Based on this, how to balance the electrical strength and mechanical properties of Al-Fe-based aluminum alloy wires is an urgent problem to be solved at present. Summary of the Invention

[0005] In view of the above deficiencies, the present invention provides a novel Al-Fe-RE-based alloy wire and a preparation method thereof, aiming to synergistically improve the electrical and mechanical properties of Al-Fe-RE-based aluminum alloy conductor materials by doping different proportions of modified metal elements and improving the process flow. The specific technical solutions are as follows:

[0006] A new type of Al-Fe-RE based alloy wire, by weight percentage, includes the following chemical components: Fe 0.2 - 0.8%, RE: 0.1 - 0.4%, B: 0.01 - 0.2%, Si ≤ 0.05%, Cu ≤ 0.003%, Ga ≤ 0.015%, Mg ≤ 0.003%, and the balance is aluminum.

[0007] Preferably, the RE is any one of La, Ce, Y, and Er.

[0008] Preferably, the conductivity of the new type of Al-Fe-RE based alloy wire ≥ 62% IACS, the tensile strength ≥ 110 MPa, the compressive creep resistance ≥ 66%, and the elongation rate ≥ 14%.

[0009] The present invention also provides a preparation method for the above-mentioned new type of Al-Fe-RE based alloy wire, including the following steps:

[0010] (1) Put pure aluminum into a melting furnace for melting, adjust the melt temperature to 720 - 750 °C, and stir the melt;

[0011] During the heating, melting, and heat preservation processes of the aluminum alloy in the melting furnace, it is necessary to be in full contact with nitrogen for protection treatment to promote the removal of harmful gases such as hydrogen and oxygen dissolved in the high-temperature melt, ensure the compactness of the alloy, and reduce the crack tendency during solidification;

[0012] (2) First, add iron to the melt in the form of an aluminum-iron master alloy, add boron in the form of an aluminum-boron master alloy, stir, and keep warm for 10 min;

[0013] (3) Then add trace elements of magnesium, silicon, copper, and gallium to the melt in powder form, stir, and keep warm for 30 - 50 min;

[0014] (4) Add a refining agent to the melt after heat preservation for purification treatment;

[0015] (5) Add high-purity rare earth metals or rare earth master alloys to the purified melt, stir, and keep warm for 10 - 20 min;

[0016] (6) Control the temperature at 700 - 720 °C, let it stand for 10 - 20 min, then let the slag or inclusions float to the surface of the aluminum alloy melt, and remove the floating slag on the surface of the melt;

[0017] (7) Pour the alloy melt after slag removal into a mold, and obtain the Al-Fe-RE based aluminum alloy wire through rolling, wire drawing, and aging heat treatment.

[0018] Preferably, in step (2), the content of impurity elements in the aluminum-iron master alloy is less than 0.1 wt%; the content of impurity elements in the aluminum-boron master alloy is less than 0.1 wt%.

[0019] Preferably, in step (4), the refining agent is one of a boron-containing master alloy, a metal fluoride salt, and hexachloroethane; the boron-containing master alloy can be an Al-B master alloy; the metal fluoride salt can be sodium hexafluoroaluminate (Na3AlF6), etc. The refining agent can remove or convert trace impurity elements such as Cr, Mn, V, etc. in the alloy into harmless phases and precipitate them.

[0020] Preferably, in step (4), the addition amount of the refining agent accounts for 0.1-0.3% of the weight of the melt.

[0021] Preferably, in step (5), the purity of the high-purity rare earth metal is ≥99.9 wt%.

[0022] Preferably, in step (5), the content of impurity elements in the rare earth master alloy is less than 0.1 wt%.

[0023] Preferably, in step (7), the aging heat treatment temperature is 280-320 °C, and the time is 8-12 h.

[0024] The invention principle is as follows:

[0025] In the present invention, iron and boron elements are added first to make their distribution in the melt more uniform, forming fine compounds or second-phase particles, thereby playing a role in refining the grains and improving the strength of the alloy. For example, the addition of boron elements can react with impurity elements such as Ti and V in the aluminum alloy to form borides, reducing the scattering effect of impurity elements on electrons and playing a role in purifying the aluminum liquid. Then, the synergistic effect of adding elements such as magnesium, silicon, copper, and gallium further increases the strength. Magnesium can form strengthening phases such as Mg2Al3 with aluminum, improving the strength, hardness, and corrosion resistance of the alloy, and improving the plasticity and processing performance of the aluminum alloy; silicon can form an Al-Si eutectic phase with aluminum and a Mg2Si strengthening phase with magnesium, improving the strength, hardness, and casting performance of the alloy, reducing casting defects, and improving the wear resistance of the aluminum alloy; copper can form strengthening phases such as Al2Cu with aluminum, significantly improving the strength, hardness, and heat resistance of the alloy, and at the same time, an appropriate amount of copper can improve the electrical conductivity of the aluminum alloy; gallium can refine the grains of the aluminum alloy, improve the strength and toughness of the alloy, lower the melting point of the aluminum alloy, improve the processing performance, and improve the corrosion resistance of the aluminum alloy.

[0026] The rare earth metal elements added in the present invention, namely lanthanum (La), cerium (Ce), yttrium (Y), and erbium (Er), have a further strengthening effect on the aluminum alloy conductor. The rare earth elements can be used as grain refiners to inhibit the growth of grains, reduce cracks and defects; they can form intermetallic compounds with high hardness with aluminum (such as Al4Ce, Al3La, etc.), improve the tensile strength, yield strength, and hardness of the aluminum alloy, and improve the fatigue performance of the aluminum alloy; they can optimize the oxide film on the surface of the aluminum alloy, improve the corrosion resistance of the aluminum alloy in harsh environments such as humidity and salt spray, and extend the service life of the aluminum alloy.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] Aiming at the problem that it is difficult to balance the electrical strength and mechanical properties of Al-Fe-based aluminum alloy wires, the present invention effectively reduces the impurity content of the aluminum alloy wire and improves the microstructure of the aluminum alloy wire by doping different proportions of modified metal elements and improving the process flow, and synergistically improves the electrical and mechanical properties of the Al-Fe-RE-based aluminum alloy conductor material. The conductivity of the aluminum alloy wire prepared by the present invention is ≥62% IACS, the tensile strength is ≥110 MPa, the compressive creep performance is ≥66%, and the elongation is ≥14%, showing good application prospects in the power industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for description in the embodiments.

[0030] Figure 1 It is a SEM diagram of the cross-section of the novel Al-Fe-RE-based alloy wire of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] The following will describe in detail the specific embodiments of the present invention, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0032] Example 1

[0033] Raw material composition: by weight percentage, including 0.5% Fe, 0.01% B, 0.05% Si, 0.002% Cu, 0.014% Ga, 0.002% Mg, 0.2% La, and the balance is Al.

[0034] Preparation method:

[0035] (1) Put pure aluminum into a melting furnace for melting, adjust the melt temperature to 750 °C, and stir the melt.

[0036] (2) First, add iron to the melt in the form of an aluminum-iron master alloy with an impurity element content of less than 0.1 wt%, add boron in the form of an aluminum-boron master alloy with an impurity element content of less than 0.1 wt%, stir, and keep warm for 10 min;

[0037] (3) Then, add trace elements of magnesium, silicon, copper, and gallium to the melt in powder form, stir, and keep warm for 30 min;

[0038] (4) Add 0.2% of hexachloroethane by weight of the melt to the melt after heat preservation for purification treatment, and remove or convert trace impurity elements such as Cr, Mn, V, etc. in the alloy into harmless phases for precipitation.

[0039] (5) Add high-purity rare earth metals with a purity of ≥99.9 wt% to the purified melt, stir, and keep warm for 10 min;

[0040] (6) Control the temperature at 720 °C, let it stand for 10 min, then let the slag or inclusions float to the surface of the aluminum alloy melt, and remove the floating slag on the melt surface;

[0041] (7) Pour the alloy melt after slag removal into a mold, and obtain the Al-Fe-RE-based aluminum alloy wire through rolling, wire drawing, and aging heat treatment at 300 °C for 10 h.

[0042] Example 2

[0043] Raw material composition: By weight percentage, it includes 0.5% Fe, 0.07% B, 0.05% Si, 0.002% Cu, 0.014% Ga, 0.002% Mg, 0.2% Ce, and the balance is Al.

[0044] Preparation method:

[0045] (1) Put pure aluminum into a melting furnace for melting, adjust the melt temperature to 750 °C, and stir the melt.

[0046] (2) First, add iron to the melt in the form of an aluminum-iron master alloy with an impurity element content of less than 0.1 wt%, add boron in the form of an aluminum-boron master alloy with an impurity element content of less than 0.1 wt%, stir, and keep warm for 10 min;

[0047] (3) Then, add trace elements of magnesium, silicon, copper, and gallium to the melt in powder form, stir, and keep warm for 40 min;

[0048] (4) Add 0.1% of hexachloroethane by weight of the melt to the melt after heat preservation for purification treatment, and remove or convert trace impurity elements such as Cr, Mn, V, etc. in the alloy into harmless phases for precipitation.

[0049] (5) Add a rare earth master alloy with an impurity element content of less than 0.1 wt% to the purified melt, stir, and keep warm for 20 min;

[0050] (6) Control the temperature at 720 °C. After standing for 20 min, let the slag inclusions or impurities float to the surface of the aluminum alloy melt, and remove the dross on the melt surface;

[0051] (7) Pour the alloy melt after slag removal into a mold, and obtain the Al-Fe-RE based aluminum alloy wire through rolling, wire drawing and aging heat treatment at 280 °C for 12 h.

[0052] Example 3

[0053] Raw material composition: By weight percentage, it includes 0.5% Fe, 0.14% B, 0.05% Si, 0.002% Cu, 0.014% Ga, 0.002% Mg, 0.3% Y, and the balance is Al.

[0054] Preparation method:

[0055] (1) Put pure aluminum into a melting furnace for melting, adjust the melt temperature to 750 °C, and stir the melt.

[0056] (2) First, add iron to the melt in the form of an aluminum-iron master alloy with an impurity element content of less than 0.1 wt%, add boron in the form of an aluminum-boron master alloy with an impurity element content of less than 0.1 wt%, stir, and keep warm for 10 min;

[0057] (3) Then add trace elements magnesium, silicon, copper, and gallium to the melt in powder form, stir, and keep warm for 30 min;

[0058] (4) Add 0.2% of hexachloroethane based on the weight of the melt to the melt after heat preservation for purification treatment, and remove or convert trace impurity elements such as Cr, Mn, V, etc. in the alloy into harmless phases for precipitation.

[0059] (5) Add high-purity rare earth metals with a purity of ≥99.9 wt% to the purified melt, stir, and keep warm for 10 min;

[0060] (6) Control the temperature at 720 °C. After standing for 10 min, let the slag inclusions or impurities float to the surface of the aluminum alloy melt, and remove the dross on the melt surface;

[0061] (7) Pour the alloy melt after slag removal into a mold, and obtain the Al-Fe-RE based aluminum alloy wire through rolling, wire drawing and aging heat treatment at 300 °C for 10 h.

[0062] Example 4

[0063] Raw material composition: By weight percentage, it includes 0.5% Fe, 0.2% B, 0.05% Si, 0.002% Cu, 0.014% Ga, 0.002% Mg, 0.3% Er, and the balance is Al.

[0064] Preparation method:

[0065] (1) Put pure aluminum into a melting furnace for melting, adjust the melt temperature to 720 °C, and stir the melt.

[0066] (2) First, add iron to the melt in the form of an aluminum-iron master alloy with an impurity element content of less than 0.1 wt%, add boron in the form of an aluminum-boron master alloy with an impurity element content of less than 0.1 wt%, stir, and keep warm for 10 min;

[0067] (3) Then add trace elements of magnesium, silicon, copper, and gallium to the melt in powder form, stir, and keep warm for 50 min;

[0068] (4) Add 0.3% of hexachloroethane by weight of the melt to the melt after heat preservation for purification treatment, and remove or convert trace impurity elements such as Cr, Mn, V, etc. in the alloy into harmless phases for precipitation.

[0069] (5) Add a rare earth master alloy with an impurity element content of less than 0.1 wt% to the purified melt, stir, and keep warm for 10 min;

[0070] (6) Control the temperature at 700 °C, let it stand for 20 min, then let the slag or inclusions float to the surface of the aluminum alloy melt, and remove the floating slag on the melt surface;

[0071] (7) Pour the alloy melt after slag removal into a mold, and obtain the Al-Fe-RE-based aluminum alloy wire through rolling, wire drawing, and aging heat treatment at 320 °C for 8 h.

[0072] Comparative example 1

[0073] Raw material composition: By weight percentage, it includes 0.5% Fe, 0.02% B, 0.001% Si, 0% Cu, 0% Ga, 0% Mg, 0.04% Ce, and the balance is Al, that is, the content of the added modification elements is significantly lower than that of each component in Example 1.

[0074] Preparation method: The same as that of Example 1.

[0075] Comparative example 2

[0076] Raw material composition: The same as that of Example 2.

[0077] The difference in the preparation process between this comparative example and Example 2 lies in that: in step (2), the magnesium, silicon, copper, and gallium elements are added first, and in step (3), the iron and boron elements are added next. The other steps are the same as those in Example 2, which are specifically as follows:

[0078] (1) Put pure aluminum into a melting furnace for melting, adjust the melt temperature to 750 °C, and stir the melt.

[0079] (2) First, add trace elements of magnesium, silicon, copper, and gallium to the melt in the form of powder, stir, and keep warm for 10 min;

[0080] (3) Then, add iron to the melt in the form of an aluminum-iron master alloy with an impurity element content of less than 0.1 wt%, and add boron in the form of an aluminum-boron master alloy with an impurity element content of less than 0.1 wt%, stir, and keep warm for 40 min;

[0081] (4) Add 0.1% of hexachloroethane by weight of the melt to the melt after heat preservation for purification treatment, and remove or convert trace impurity elements such as Cr, Mn, V, etc. in the alloy into harmless phases for precipitation.

[0082] (5) Add a rare earth master alloy with an impurity element content of less than 0.1 wt% to the purified melt, stir, and keep warm for 20 min;

[0083] (6) Control the temperature at 720 °C, let the slag or inclusions float to the surface of the aluminum alloy melt after standing for 20 min, and remove the floating slag on the surface of the melt;

[0084] (7) Pour the alloy melt after slag removal into a mold, and obtain the Al-Fe-RE-based aluminum alloy wire through rolling, wire drawing, and aging heat treatment at 280 °C for 12 h.

[0085] The raw material compositions of each example and each comparative example are shown in Table 1:

[0086] Table 1

[0087]

[0088]

[0089] Detect the electrical conductivity and mechanical properties of the materials prepared in each example and each comparative example respectively, and the results are shown in Table 2:

[0090] Table 2

[0091] Group Conductivity Tensile strength / MPa Creep resistance Elongation Example 1 62.2% IACS 122 66％ 15.7％ Example 2 62.8% IACS 147 67％ 14.6％ Example 3 63.6% IACS 154 68％ 14.2％ Example 4 62.5% IACS 138 67％ 14.9％ Comparative example 1 60.9% IACS 102 63％ 21.8％ Comparative example 2 61.3% IACS 89 60％ 29.6％

[0092] Conclusion: The above data indicate that the conductivity and tensile strength of the Al-Fe-RE based alloy wire prepared by the method according to the present invention are significantly improved compared with those of the Al-Fe alloy wire without modified metal elements, indicating that appropriate addition of different proportions of modified elements (trace elements), and the process flow of adding iron and boron elements first and then magnesium, silicon, copper and gallium elements during preparation can make their distribution in the melt more uniform, forming fine compounds or second-phase particles (see Figure 1 ), thereby playing a role in refining grains and improving the strength of the alloy, and synergistically improving the electrical and mechanical properties of the Al-Fe-RE based aluminum alloy conductor material.

[0093] The foregoing description of specific exemplary embodiments of the invention has been presented for purposes of illustration and example. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many modifications and variations are possible in light of the above teaching. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the invention and its practical application, so that those skilled in the art can implement and utilize the various different exemplary embodiments of the invention, as well as various different selections and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A novel Al-Fe-RE based alloy wire, characterized in that: The chemical composition is as follows by weight percentage: Fe 0.2-0.8%, RE: 0.1-0.4%, B: 0.01-0.2%, Si≤0.05%, Cu≤0.003%, Ga≤0.015%, Mg≤0.003%, and the balance is aluminum.

2. A novel Al-Fe-RE based alloy wire according to claim 1, characterized in that: The RE is any one of La, Ce, Y, and Er.

3. A novel Al-Fe-RE based alloy wire according to claim 1, characterized in that: The electrical conductivity of the novel Al-Fe-RE based alloy wire is ≥62% IACS, the tensile strength is ≥110 MPa, the compressive creep performance is ≥66%, and the elongation is ≥14%.

4. A method for preparing the novel Al-Fe-RE based alloy wire according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) Put pure aluminum into a melting furnace for melting, adjust the melt temperature to 720-750°C, and stir the melt; (2) first adding iron to the melt in the form of an aluminum-iron master alloy and adding boron in the form of an aluminum-boron master alloy, stirring, and keeping warm for 10 minutes; (3) adding trace elements of magnesium, silicon, copper and gallium in powder form to the melt, stirring and keeping warm for 30-50 minutes; (4) adding a refining agent to the melt after heat preservation for purification; (5) adding high-purity rare earth metal or rare earth master alloy to the purified melt, stirring, and keeping warm for 10-20 minutes; (6) Control the temperature at 700-720°C, let it stand for 10-20 minutes, and then remove the scum on the surface of the melt; (7) The alloy melt after slag removal is poured into a mold, and subjected to rolling, wire drawing and aging heat treatment to obtain the Al-Fe-RE based aluminum alloy wire.

5. The method for preparing a novel Al-Fe-RE based alloy wire according to claim 4, characterized in that: In step (2), the content of impurity elements in the aluminum-iron master alloy is less than 0.1 wt %; the content of impurity elements in the aluminum-boron master alloy is less than 0.1 wt %.

6. The method for preparing a novel Al-Fe-RE based alloy wire according to claim 4, characterized in that: In step (4), the refining agent is one of boron-containing master alloy, metal fluoride salt and hexachloroethane.

7. The method for preparing a novel Al-Fe-RE based alloy wire according to claim 4, characterized in that: In step (4), the amount of the refining agent added is 0.1-0.3% of the weight of the melt.

8. The method for preparing a novel Al-Fe-RE based alloy wire according to claim 4, characterized in that: In step (5), the purity of the high-purity rare earth metal is ≥99.9wt%.

9. The method for preparing a novel Al-Fe-RE based alloy wire according to claim 4, characterized in that: In step (5), the content of impurity elements in the rare earth master alloy is less than 0.1wt%.

10. The method for preparing a novel Al-Fe-RE based alloy wire according to claim 4, characterized in that: In step (7), the aging heat treatment temperature is 280-320°C and the time is 8-12h.

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