AU2017239456A1

AU2017239456A1 - Lightweight high-conductivity heat-resistant aluminium wire and preparation method therefor

Info

Publication number: AU2017239456A1
Application number: AU2017239456A
Authority: AU
Inventors: Jie BIN; Zhaohe GAO; Hongying Li
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2016-03-25
Filing date: 2017-03-24
Publication date: 2018-09-06
Anticipated expiration: 2037-03-24
Also published as: WO2017162199A1; PH12018550142A1; CN105734353A; CN105734353B; AU2017239456B2; PH12018550142B1

Abstract

A lightweight high-conductivity heat-resistant aluminium wire and a preparation method therefor, said wire including 0.035-0.06 wt% of B, 0.1-0.2 wt% of Zr, 0.1-0.3 wt% of Er and unavoidable impurities, the remainder being Al. The preparation steps are smelting, on-the-spot rapid component analysis, refining, rapid cooling casting, blank annealing, extruding and drawing. The conductivity of the aluminium wire at 20°C is greater than or equal to 62% IACS.

Description

LIGHTWEIGHT HIGH-CONDUCTIVITY HEAT-RESISTING ALUMINUM WIRE AND MANUFACTURING METHOD THEREFOR

BACKGROUND

Technical Field

The present invention relates to a lightweight high-conductivity heat-resisting aluminum wire and a manufacturing method therefor, and belongs to the technical field of electric materials.

Related Art

According to a strategic plan of energy interconnection, power networks in China will implement "power transmission from west to east, mutual supply between south and north, and nationwide interconnection". Because of long power transmission lines, large power transmission capacities, and complex natural environments, to reduce transmission line losses and line construction costs and save limited corridor resources, higher requirements such as high conductivity and good heat resistance and sag resistance are imposed on power transmission wires. Therefore, researching of a low-density aluminum wire with high conductivity and good heat resistance becomes a technical problem urgently to be resolved in the industry.

Under an external electric field, directed motion of free electrons in a metal produces current. Periodic abnormal points (or irregular points) in the crystal field impede the directed motion of the electrons and lead to scattering of electronic waves. Conductivity of metal materials are closely related to an average free path (an average value of distances between neighboring abnormal points) of the free electrons, and a smaller average free path of the free electrons leads to a lower conductivity of the materials. All of impurity elements, dissolved atoms, and crystal defects in the metal may cause the crystal field to partially deviate from a periodic location of the crystal field, shortening the average free path of the free electrons and reducing the conductivity of the metal. Impact of impurities on the conductivity is closely related to a type and content of the impurity elements and a status of the impurity elements in the metal. Obvious impurity elements such as Ti, V, Cr, and Mn in industrial pure aluminum have relatively great impact on the conductivity. Especially, when impurity elements having relatively high content are dissolved in an aluminum matrix, the conductivity of an aluminum conductor is greatly reduced. The dissolved atoms cause lattice distortion to break the periodicity of the Coulombic potential field of the metal, and become a scattering center of conduction electrons. A higher molar concentration of the dissolved atoms leads to a smaller distance between neighboring scattering centers, and a smaller average free path of the electrons leads to a lower conductivity. Using Zr as an example, if a small number of Zr atoms are dissolved in the aluminum matrix, the conductivity of an alloy is significantly reduced. High-purity A1 with purity of 99.99% has a maximum conductivity of 64.94% IACS at 20°C, a density of 2.7 g/cm3, a strength only of 80-100 MPa, and a recrystallizing temperature of 150°C. A 6021 alloy in which 0.6-0.9 wt% Mg, 0.5-0.9 wt% Si, 0.5 wt% Fe, 0.1 wt% Cu, and 0.1 wt% Zn are added is a common high-strength electric aluminum alloy with a tensile strength reaching 295-325 MPa. However, the conductivity of the alloy at 20°C is only 52.5-55% IACS.

The present invention aims to improve micro-alloying of heat resistance and strength of the aluminum conductor, especially, when component proportions of the alloy are improperly designed, the conductivity performance is adversely affected. A technical difficulty of researching the lightweight high-conductivity heat-resisting aluminum wire is to seek balance among the conductivity, the heat resistance, and the specific strength. Usually, the conductivity and the heat resistance are in a trade-off relationship. In an existing disclosed technical solution, the two usually cannot be taken into account at the same time. In a technical solution in which the conductivity is high, the heat resistance is undesirable, and in a technical solution in which the heat resistance is good, the conductivity is undesirable. In Patent Publication No. CN102230113A, the disclosed components are 0.06-0.15 wt% Zr, 0.15-0.30 wt% Er, and 0.1-0.2 wt% Fe. Through micro-alloying of Zr, Er, and Fe, an aluminum electric wire manufactured by using a continuous casting and continuous rolling process has a conductivity of only 59.5-60.5% IACS, a short-time heat-resistance temperature of 210°C, a long-time heat-resistance temperature of 180°C, and a tensile strength of 157 MPa, and a density parameter of the alloy is not disclosed. In Patent Publication No. CN103498083A, the disclosed components are 0.01 0.2 wt% Er, 0 0.3 wt% Zr, and 0 0.2 wt% B. It can be learned from parameters recorded in the embodiments of the patent that, the conductivity in the embodiment in which Er, Zr, and B are contained is merely 60% IACS, and the conductivity in the embodiment in which only one or more of Er and Zr are contained is merely 58% IACS. Parameters such as the density, the strength, and the heat resistance and the continuous casting and continuous rolling process parameter are not disclosed.

Therefore, it is a long-time pursuit of improving, by optimizing alloy components and a manufacturing process without reducing the conductivity, the heat resistance and the specific strength of the aluminum wire and manufacturing a lightweight high-conductivity heat-resisting aluminum wire in the art.

SUMMARY

An objective of the present invention is to overcome the disadvantages in the prior art and provide a lightweight high-conductivity heat-resisting aluminum wire that has a proper component proportion and a small number of alloying elements and that is simple and flexible in process and low in production costs, and a method for manufacturing the lightweight high-conductivity heat-resisting aluminum wire. According to the present invention, a small number of alloying elements relatively less adversely affecting the conductivity are added, to generate purification, modification, refining, and dispersion strengthening effects. Compared with high-purity aluminum with purity of 99.99%, the present invention greatly improves the heat resistance and the specific strength of the wire on the premise that the conductivity is reduced slightly, thereby satisfying service requirements of lightweight, high conductivity, and heat resistance of a large-capacity long-distance power transmission line.

Technical solutions of the present invention:

The present invention provides a lightweight high-conductivity heat-resisting aluminum wire, including, in mass percentage, the following components: B: 0.035^).06 wt%;

Zr: 0.1-0.2 wt%;

Er: 0.2-0.4 wt% (not including 0.2 wt%); and impurity elements Ti, V, Cr, and Mn have a total content less than or equal to 0.01 wt%, and others are Al, where

Zr and Er are added according to a mass ratio of Zr:Er=l :1.5-2.5. Preferably, Zr and Er are added according to a mass ratio of Zr:Er=l :1.5-2.

According to the lightweight high-conductivity heat-resisting aluminum wire in the present invention, during casting, the wire is cooled to the room temperature at a speed of 20-300°C/s, and then quick high-temperature annealing is performed for 1-10 h at 480°C-500°C.

According to the lightweight high-conductivity heat-resisting aluminum wire in the present invention, the wire has a spherical A13(Er, Zr) composite particle of the order of nanometers, and the spherical A13(Er, Zr) composite particle of the order of nano meters has an L12 structure coherent with a matrix.

The present invention provides a method for manufacturing a lightweight high-conductivity heat-resisting aluminum wire, including the following steps: step 1: after an industrial pure aluminum ingot is heated to 740°C-780°C and melted, preparing an Al-Zr intermediate alloy and an Al-Er intermediate alloy according to a designed mass percentage of components Zr and Er in the aluminum wire, adding the intermediate alloys to an aluminum melt, after the intermediate alloys are completely melted and the melt is stirred evenly, performing rapid component analysis on a Zr-Er-Al alloy melt in furnace, cooling the alloy melt to 720°C 730°C to perform heat preservation, and adding an Al-B intermediate alloy for refining, to obtain a blank after standing, slagging, and casting; and step 2: after the blank is annealed, extruding and pulling out the blank into monofilaments.

According to the method for manufacturing a lightweight high-conductivity heat-resisting aluminum wire in the present invention, an additive amount of the Al-B intermediate alloy is determined based on the following two parts: an Al-B intermediate alloy prepared according to a designed mass percentage of a component B, and an Al-B intermediate alloy prepared as a ratio of mass of B to total content of impurity elements Ti, V, Cr, and Mn in the Zr-Er-Al alloy melt is 2-5:1.

According to the method for manufacturing a lightweight high-conductivity heat-resisting aluminum wire in the present invention, the casting manner may be changed according to a device configuration condition on a production line, and an ingot blank may be obtained by ordinary casting or semi-continuous casting, or a pole blank may be obtained by continuous casting.

According to the method for manufacturing a lightweight high-conductivity heat-resisting aluminum wire in the present invention, during casting, the cast ingot is cooled to the room temperature at a speed of 20-300°C/s.

According to the method for manufacturing a lightweight high-conductivity heat-resisting aluminum wire in the present invention, during casting, water cooling is applied.

According to the method for manufacturing a lightweight high-conductivity heat-resisting aluminum wire in the present invention, an annealing process of the blank is: an annealing temperature is 480°C-500°C, and the blank is cooled in the furnace after staying at the temperature for 1-10 h.

According to the method for manufacturing a lightweight high-conductivity heat-resisting aluminum wire in the present invention, an extrusion manner may be changed according to a device configuration condition on a production line, conventional hot extrusion may be performed by using a heated ingot blank or continuous extrusion may be performed by using a pole blank at the room temperature, and the hot extrusion is performed at the temperature of 300°C-450°C.

According to the method for manufacturing a lightweight high-conductivity heat-resisting aluminum wire in the present invention, an extrusion ratio of the hot extrusion or the continuous extrusion at the room temperature is greater than or equal to 80, and a total extrusion deformation amount is greater than or equal to 80%.

According to the method for manufacturing a lightweight high-conductivity heat-resisting aluminum wire in the present invention, multi-pass cool pullout is performed by using an extruded pole blank, and a diameter of the pole blank on which pullout is performed may be determined according to an actual need. Especially, the diameter of the used pole blank may be determined according to a service strength requirement, and the strength of the monofdament is adjusted and controlled based on different pullout deformation amounts.

According to the method for manufacturing a lightweight high-conductivity heat-resisting aluminum wire in the present invention, multi-pass pullout is performed after the extrusion, and a pass elongation coefficient is 1.2-1.5, a total accumulated elongation coefficient is 5.5-10.5, lubrication may be performed by using an ordinary lubricant or an emulsion. The emulsion also has a cooling function, so that the temperature of the aluminum wire does not exceed 180°C.

According to the method for manufacturing a lightweight high-conductivity heat-resisting aluminum wire in the present invention, the manufactured wire has a density less than or equal to 2.71 g/cm3, a conductivity greater than 62% IACS at 20°C, a short-time heat-resistance temperature reaching 230°C, a long-time heat-resistance temperature reaching 210°C, and a tensile strength greater than or equal to 165 MPa.

Beneficial effects of the present invention

According to a theory of metal conduction, impurities and crystal defects have great impact on the conductivity of aluminum. Lower content of the impurities and less crystal defects such as lattice distortion and a grain boundary indicate a better conductivity of a metal crystal. In obvious impurities in industrial aluminum, Ti, V, Cr, and Mn have relatively great adverse impact on the conductivity, especially when the impurities are dissolved in an aluminum matrix.

In the present invention, an additive amount of B is the sum of a designed mass percentage (0.035-0.06 wt%) of the component B in the aluminum wire and mass of B that is determined as 2-5 multiples of the total content of the impurity elements Ti, V, Cr, and Μη in the industrial pure aluminum. When the element B is used as a refining agent and a modifier, synergism among B, Zr, and Er brings unexpected technical effects.

In an alloy smelting process in the present invention, the additive amount of the Al-B intermediate alloy is determined based on two parts. The content of B in the alloy melt is far greater than 0.06 wt%, and is used as the refining agent and the modifier. First, when B is used as the refining agent, B inevitably reacts with the impurities such as T i and V to generate a boride having a relatively large specific gravity, which is removed as a slag (shown in FIG. 2 and FIG. 3), thereby greatly improving the conductivity of an aluminum conductor. Second, redundant B is used as the modifier to generate a modification effect, so that the Fe-rich phrase continuously distributed along the grain boundary changes into discontinuous particles. This not only can improve the conductivity performance of the aluminum wire but also can improve the strength and the heat stability of the aluminum wire. In addition, a requirement on purity of the industrial pure aluminum ingot used as a raw material can be lowered, thereby greatly reducing alloy manufacturing costs. The inventor finds that if content of B in the added refining agent and modifier is excessively small, causing the content of B in the alloy matrix to be less than 0.035%, the conductivity of the material is reduced. However, if an excessive amount of B is added as the refining agent and the modifier (content of B is 8 multiples of the total content of Ti and V), relatively more coarse Al-B compounds appear in the aluminum, and the conductivity of the material is also obviously reduced.

The element Er is prone to be adsorbed on a cx-Al crystal nucleus, to generate A13Er to prevent growth of an α-Al dendrite crystal, thereby refining a secondary dendrite structure. The primary A13Er is pushed to the crystal boundary, and forms a eutectic compound containing an α-Al phase and an A13Er phase when the melt is entirely coagulated finally. As a rare-earth element, Er and the impurity elements such as Fe form a compound, to generate purification and modification effects. FIG. 6 shows a second-phase particle and an energy spectrum analysis result in Comparison Example 2. In Comparison Example 2, B is not added, and FIG. 6(b) shows that a mixed phase of A13Er and (Al, Fe) or a ternary compound (Al, Fe, Er) may be formed in the crystal. Without the effect of B, the element

Er is more prone to react with the impurity elements to form a compound or an A13X phase. The advantages of the present invention are to restrain the formation of an Er-contained impurity phase through generation of impurity removal and modification effects by B through synergism among B, Zr, and Er, and to inhibit the coarse primary phase from being formed through rapid cooling in a casting process, so that Zr and Er mainly exist in a metastable supersaturated solid solution state, thereby facilitating, in a subsequent annealing process, precipitation of a large number of A13(Er, Zr) composite particles coherent with a matrix, as shown in FIG. 5. The principle of precipitation of the A13(Er, Zr) ternary phase in the present invention is: In the annealing process, Er with a relatively quick diffusion rate first forms particles in the matrix, to provide a nucleation particle for desolventizing and precipitation of Zr, facilitating decomposition of the Al-Zr solid solution. Zr with a relatively slow diffusion rate gathered on an outer layer of the A13Er particles, to form a spherical A13(Er, Zr) composite particle of the order of nanometers that has an L12 structure coherent with a matrix.In the present invention, precipitation of the A13(Er, Zr) composite particle of the order of nanometers has the following advantages: On one hand, a solid solution degree of Zr and Er in the aluminum matrix is reduced, and the conductivity of the aluminum wire is improved. On the other hand, the dispersed A13(Er, Zr) composite particle of the order of nanometers that is coherent with a crystal generates a pinning effect for dislocation, a sub-grain, and a crystal boundary, has obvious reinforcement and recrystallization inhibition functions, and can effectively improve the strength and the heat resistance of the aluminum conductor.

The manufacturing process including casting, annealing, extrusion, and pullout used in the present invention can be distinguished from a continuous casting and continuous rolling process of another aluminum wire, and has advantages of a short production procedure and simple and flexible process control. The manufactured wire has relatively good heat resistance and specific strength under the condition of ensuring a relatively high conductivity. The rapid cooling casting in the present invention has a particular function of inhibiting generation of the coarse primary phase, so that the cast blank has relatively high supersaturated solid solubility, thereby providing a driving force for precipitation of small dispersed second-phase particles in a subsequent annealing process. In the present invention, the cast blank is annealed at a high temperature for a short time. A primary function thereof is to precipitate a large number of dispersed second-phase particles, especially to precipitate many A13(Er, Zr) composite particles of the order of nanometers coherent with a crystal. A secondary function thereof is to properly eliminate constituent segregation, structure segregation, and a casting stress of the blank, thereby improving the casting structure and the production performance. In addition, compared with the average annealing time of the aluminum alloy and the annealing time in the disclosed patent, the present invention has a relatively short annealing time, and therefore, has advantages of energy saving and consumption cut-down. The present invention uses extrusion for plastic deformation, having advantages of flexible production and simple process control. The ingot blank may be extruded into a wire bar at once, or the continuously cast pole blank may be continuously extruded into a wire blank with a relatively small diameter. Compared with rolling deformation, the present invention has larger deformation and severe three-dimensional stress state, and therefore, can greatly improve the casting structure and improve the subsequent production performance. In the present invention, multi-pass cool pullout is performed by using an extruded pole blank to obtain an aluminum alloy monofilament. The diameter of the blank may be determined according to an actual need. Especially, the diameter of the used blank may be determined according to a service strength requirement, and the strength of the monofilament is adjusted and controlled based on different pullout deformation amounts.

In conclusion, in the present invention, based on a proper proportion of the elements Al, B, Zr, and Er and a proper additive amount of the B-contained refining agent, B generates purification and modification effects and a micro-alloying function synergizing Zr and Er through rapid cooling casting, short-time high-temperature annealing of the cast blank, and extrusion with a large deformation amount. The manufactured wire has a conductivity greater than or equal to 62% IACS at 20°C, a long-time heat-resistance temperature reaching 210°C, a short-time heat-resistance temperature reaching 230°C, and a tensile strength greater than or equal to 165 MPa. The density (<2.71 g/cm3) is relatively close to the density 2.7 g/cm3 of pure aluminum. Therefore, a capacity of a power transmission line can be improved and transmission line losses can be reduced. The wire has good sag resistance and heat resistance. This can increase a distance between tower poles on the power transmission lines, and improve security stability and a service life of long-distance large-capacity power transmission lines. In the present invention, a production procedure is short, process control is simple and flexible and on which a relatively low requirement is imposed, a small number of alloying elements are added, content is low, the number of used expensive rare-earth elements is reduced, there is no restrict requirement on the content of impurities in the raw material and the quality of the cast blank, and the energy consumption is not high. Therefore, the present invention further has an advantage of relatively low production costs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1(a) shows a cast metallographic structure in Embodiment 1; FIG. 1(b) shows a cast metallographic structure in Embodiment 2; FIG. 1(c) shows a cast metallographic structure in Embodiment 3; FIG. 2 shows an image of a microstructure of a smelt slag in Embodiment 2 of the present invention; FIG. 3 shows an energy spectrum analysis result of a particle in FIG. 2; FIG. 4(a) shows an image of a metallographic structure of an alloy in Comparison Example 2; FIG. 4(b) shows an image of a metallographic structure of an alloy in Embodiment 2; FIG. 4(c) shows an image of a metallographic structure of an alloy in Comparison Example 1; FIG. 5(a) shows a low-power TEM image of an alloy in Embodiment 2; FIG. 5(b) shows a high-power TEM image of an alloy in Embodiment 2; FIG. 5(c) shows a high-resolution TEM appearance of an A13(Er, Zr) composite particle in an alloy in Embodiment 2; FIG. 6(a) shows an appearance of a microstructure of an annealed alloy in Comparison

Example 2; FIG. 6(b) shows an energy spectrum analysis result of a precipitated phase at an identified point A in FIG. 6(a); FIG. 6(c) shows an energy spectrum analysis result of a precipitated phase at an identified point B in FIG. 6(a); FIG. 6(d) shows an energy spectrum analysis result of a precipitated phase at an identified point C in FIG. 6(a); and FIG. 7 to FIG. 10 show performance detection reports of Φ4 aluminum wires manufactured in Embodiment 2.

It can be learned from FIG. 1(a), FIG. 1(b), and FIG. 1(c) that joint addition of elements Zr and Er has an obvious grain refining effect, and larger content of the elements Zr and Er indicates an obvious grain refining effect.

It can be learned from the appearance of the microstructure of the slag and the energy spectrum analysis result in Embodiment 2 shown in FIG. 2 and FIG. 3 that, there is another phase different from a white AlFe phase. The phase features relatively dark edges and a bright center. The energy spectrum analysis result shows that the phase is a phase containing Al, B, Ti, and V. This indicates that the impurities Ti and V and B definitely form a compound in the slag. This is one of important reasons for improving the conductivity of the alloy.

It can be learned from FIG. 4(a) that when B is not used as a refining agent, relatively more continuous impurity phases exist on a crystal boundary. It can be learned from FIG. 4(b) that after a boron refining agent of a proper mass ratio is used, relatively more point phases appear in the matrix, and continuous phases on the crystal boundary are transformed into discontinuous stripes and points. It can be learned from FIG. 4(c) that after excessive B is used as a refining agent, relatively more coarse second phases appear in the matrix, which is shown as a compound of Al and B in the energy spectrum analysis result. With reference to the relatively low conductivity of the material in Comparison Example 2, it indicates that addition of excessive B has an adverse impact on the conductivity of the material.

Around a precipitated phase shown in FIG. 5(a), clear Ashby-Brown stress contrast can be observed. The precipitated phase and the matrix still keep good coherence. A housing and a kernel of a precipitated phase shown in FIG. 5(b) shows an obvious contrast difference. A region shown in FIG. 5(c) may be divided into three parts: a matrix, a housing of a precipitated phase, and a kernel of the precipitated phase. The housing of the precipitated phase uses an LI2 structure corresponding to an electron diffraction spot. A diffraction strength corresponding to the housing of the precipitated phase is stronger than that of the kernel. The precipitated phase is determined as an AB(Erl-xZrx) composite phase in which the kernel contains rich Er and the housing contains rich Zr. FIG. 5(a), FIG. 5(b), and FIG. 5(c) prove that in a process of annealing the alloy in the present invention, a large number of A13(Er, Zr) composite particles of the order of nanometers coherent with the matrix are precipitated, thereby ensuring that the conductivity, the heat resistance, and the strength are all taken into account. FIG. 6(a) to FIG. 6(d) show a second-phase particle and the energy spectrum analysis result in Comparison Example 2. FIG. 6(b) shows that a point A in the crystal may be a mixed phase of A13Er and (Al, Fe), or a ternary compound (Al, Fe, Er). FIG. 6(c) shows that a particle phase at a point B on the crystal boundary is an ABEr phase. FIG. 6(d) shows that a needle-like phase a point C on the crystal boundary is an A13Fe phase. In Comparison Example 2, B is not added. The element Er is more prone to form a compound or an A13X phase together with impurity elements. This proves that the element B has a function of facilitating precipitation of the A13(Erl -xZrx) ternary composite phase.

It can be learned from FIG. 7 to FIG. 10 that for the aluminum wire manufactured in Embodiment 2 of the present invention, the conductivity reaches 62% IACS at 20°C, a short-time heat-resistance temperature reaches 230°C (when the wire is kept at 230°C for 1 h, a residual tensile strength rate reaches 92%), and the tensile strength is 165 MPa. Therefore, the aluminum wire can be used as a material for powerfully supporting excellent performance of the wire in the present invention.

DETAILED DESCRIPTION

Embodiment 1

Using an industrial pure aluminum ingot with purity greater than 99.7%, an intermediate alloy Al-11.34% Zr, and an intermediate alloy Al-4.7% Er as raw materials, first, the intermediate alloys Al-Zr and Al-Er are added after the industrial pure aluminum is melted at 760°C, after the intermediate alloys are completely melted and the melt is stirred evenly, rapid component analysis is performed on a Zr-Er-Al alloy melt in furnace, and the alloy melt is cooled to 730°C to perform heat preservation. Then, according to 2 multiples of the total content of impurity elements Ti and V in the alloy melt and a mass percentage of B in the alloy, an Al-2.5% B intermediate alloy is added for refining, so that the mass percentages of the elements are: B is 0.035 wt%, Zr is 0.1 wt%, Er is 0.21 wt%, a sum of the impurity elements such as Ti, V, Cr, and Mn is 0.001 wt%, and the remaining is Al. Then, stirring, standing, slagging, and water cooling casting are sequentially performed. The blank is cooled in the furnace after staying at 480°C for 10 h. Next, hot extrusion is performed at 420°C, where an extrusion ratio is 89.7 and an extrusion deformation amount is 98.7%, to obtain a Φ9.5 round aluminum pole. 5-pass pullout is performed on the round aluminum pole to obtain a Φ4.0 mm aluminum wire. The aluminum wire is tested in terms of the conductivity, the tensile strength, the heat resistance, and the density, and a result is shown in Table 1.

Table 1

Embodiment 2

Using an industrial pure aluminum ingot with purity greater than 99.7%, an intermediate alloy Al-11.34% Zr, and an intermediate alloy Al-4.7% Er as raw materials, first, the intermediate alloys Al-Zr and Al-Er are added after the industrial pure aluminum is melted at 760°C, after the intermediate alloys are completely melted and a melt is stirred, rapid component analysis is performed on a Zr-Er-Al alloy melt in furnace, and the alloy melt is cooled to 730°C to perform heat preservation. Then, according to 3.5 multiples of the total content of impurity elements Ti and V in the alloy melt and a mass percentage of B in the alloy, an Al-2.5% B intermediate alloy is added for refining, so that the mass percentages of the elements are: B is 0.05 wt%, Zr is 0.1 wt%, Er is 0.21 wt%, a sum of the impurity elements such as Ti, V, Cr, and Mn is 0.001 wt%, and the remaining is Al. Then, stirring, standing, slagging, and water cooling casting are sequentially performed. The blank is cooled in the furnace after staying at 490°C for 8 h. Next, hot extrusion is performed at 420°C, where an extrusion ratio is 89.7 and an extrusion deformation amount is 98.7%, to obtain a Φ9.5 round aluminum pole. 5-pass pullout is performed on the round aluminum pole to obtain a Φ4.0 mm aluminum wire. The aluminum wire is tested in terms of the conductivity, the tensile strength, the heat resistance, and the density, and a result is shown in Table 2.

Table 2

Embodiment 3

Using an industrial pure aluminum ingot with purity greater than 99.7%, an intermediate alloy Al-11.34% Zr, and an intermediate alloy Al-4.7% Er as raw materials, first, the intermediate alloys Al-Zr and Al-Er are added after the industrial pure aluminum is melted at 760°C, after the intermediate alloys are completely melted and the melt is stirred evenly, rapid component analysis is performed on a Zr-Er-Al alloy melt in furnace, and the alloy melt is cooled to 730°C to perform heat preservation. Then, according to 5 multiples of the total content of impurity elements Ti and V in the alloy melt and a mass percentage of B in the alloy, an Al-2.5% B intermediate alloy is added for refining, so that the mass percentages of the elements are: B is 0.06 wt%, Zr is 0.2 wt%, Er is 0.4 wt%, a sum of the impurity elements such as Ti, V, Cr, and Mn is 0.001 wt%, and the remaining is Al. Then, stirring, standing, slagging, and water cooling casting are sequentially performed. The blank is cooled in the furnace after staying at 500°C for 1 h. Next, hot extrusion is performed at 420°C, where an extrusion ratio is 89.7 and an extrusion deformation amount is 98.7%, to obtain a Φ9.5 round aluminum pole. 5-pass pullout is performed on the round aluminum pole to obtain a Φ4.0 mm aluminum wire. The aluminum wire is tested in terms of the conductivity, the tensile strength, the heat resistance, and the density, and a result is shown in Table 3.

Table 3

Comparison Example 1

Using an industrial pure aluminum ingot with purity greater than 99.7%, an intermediate alloy Al-11.34% Zr, and an intermediate alloy Al-4.7% Er as raw materials, first, the intermediate alloys Al-Zr and Al-Er are added after the industrial pure aluminum is melted at 760°C, after the intermediate alloys are completely melted and a melt is stirred, rapid component analysis is performed on a Zr-Er-Al alloy melt in furnace, and the alloy melt is cooled to 730°C to perform heat preservation. Then, according to 8 multiples of the total content of impurity elements Ti and V in the alloy melt and a mass percentage of B in the alloy, an Al-2.5% B intermediate alloy is added for refining, so that the mass percentages of the elements are: B is 0.10 wt%, Zr is 0.1 wt%, Er is 0.21 wt%, a sum of the impurity elements such as Ti, V, Cr, and Mn is 0.001 wt%, and the remaining is Al. Then, stirring, standing, slagging, and water cooling casting are sequentially performed. The blank is cooled in the furnace after staying at 490°C for 8 h. Next, hot extrusion is performed at 420°C, where an extrusion ratio is 89.7 and an extrusion deformation amount is 98.7%, to obtain a Φ9.5 round aluminum pole. Multi-pass pullout is performed on the round aluminum pole to obtain a Φ4.0 mm aluminum wire. The aluminum wire is tested in terms of the conductivity, the tensile strength, the heat resistance, and the density, and a result is shown in Table 4.

Table 4

Comparison Example 2

Materials are prepared by using industrial pure aluminum, 0.2% Zr, and 0.4% Er. Raw materials are an industrial pure aluminum ingot with purity greater than 99.7%, an intermediate alloy Al-11.34% Zr, and an intermediate alloy Al-4.7% Er. The intermediate alloys Al-Zr and Al-Er are added after the industrial pure aluminum is melted at 760°C, after the intermediate alloys are completely melted and a melt is stirred, rapid component analysis is performed on a Zr-Er-Al alloy melt in furnace, and the alloy melt is cooled to 730°C to perform heat preservation. Then, stirring, standing, slagging, and water cooling casting are sequentially performed. The cast ingot is cooled in the furnace after staying at 500°C for 1 h. Next, hot extrusion is performed at 420°C, where an extrusion ratio is 89.7 and an extrusion deformation amount is 98.7%, to obtain a Φ9.5 round aluminum pole. 5-pass pullout is performed on the round aluminum pole to obtain a Φ4.0 mm aluminum wire. The aluminum wire is tested in terms of the conductivity, the tensile strength, the heat resistance, and the density, and a result is shown in Table 5.

Table 5

In the three embodiments of the present invention, each of the obtained aluminum alloy wires has a density less than or equal to 2.71 g/cm3, a conductivity greater than or equal to 62% IACS at ambient temperature of 20°C, a short-time heat-resistance temperature reaching 230°C, and a long-time heat-resistance temperature reaching 210°C. In Comparison Example 1, excessive B is added, and other components are the same as those in Embodiment 1 and Embodiment 2. The annealing process is the same as that in Embodiment 2. In Comparison Example 2, the element B is not added, and other components are the same as those in Embodiment 3. In each of the two comparison examples, the conductivity is less than 61% IACS, the residual strength rate after annealing is performed for one hour at 230°C is less than 90%, and the residual strength rate after annealing is performed for 400 hours at 210°C is also less than 90%. It can be learned from the performance parameters obtained in the foregoing embodiments and comparison examples that, as the refining agent and the modifier, if an excessive small amount of B is added, content of B in the alloy matrix is less than 0.035 wt%, or if an excessive large amount of B is added or the added B is 8 multiples of Ti and V, the conductivity performance and the heat resistance of the wire are reduced.

Claims

CLAIMS What is claimed is:

1. A lightweight high-conductivity heat-resisting aluminum wire, comprising, in mass percentage, the following components: B: 0.035-0.06 wt%; Zr: 0.1-0.2 wt%; Er: 0.2-0.4 wt% (not comprising 0.2 wt%); and impurity elements Ti, V, Cr, and Mn have a total content less than or equal to 0.01 wt%, and others are Al, wherein Zr and Er are added according to a mass ratio of Zr:Ei^l :1.5-2.5.
2. The lightweight high-conductivity heat-resisting aluminum wire according to claim 1, wherein during casting, the wire is cooled to the room temperature at a speed of 20-300°C/s, and then high-temperature annealing is performed for 1-10 h at 480°C-500°C.
3. The lightweight high-conductivity heat-resisting aluminum wire according to claim 1, wherein the wire has a spherical A13(Er, Zr) composite particle of the order of nanometers.
4. The lightweight high-conductivity heat-resisting aluminum wire according to claim 3, wherein the spherical A13(Er, Zr) composite particle of the order of nanometers has an LI2 structure coherent with a matrix.
5. The lightweight high-conductivity heat-resisting aluminum wire according to claim 1, wherein the wire has a density less than or equal to 2.71 g/cm3, a conductivity greater than 62% LACS at 20°C, a short-time heat-resistance temperature reaching 230°C, a long-time heat-resistance temperature reaching 210°C, and a tensile strength greater than or equal to 165 MPa.
6. A method for manufacturing the lightweight high-conductivity heat-resisting aluminum wire according to claim 1, comprising the following steps: step 1: after an industrial pure aluminum ingot is heated to 740°C-780°C and melted, preparing an Al-Zr intermediate alloy and an Al-Er intermediate alloy according to a designed mass percentage of components Zr and Er in the aluminum wire, adding the intermediate alloys to an aluminum melt, after the intermediate alloys are completely melted and the melt is stirred evenly, performing rapid component analysis on a Zr-Er-Al alloy melt in furnace, and adding an Al-B intermediate alloy for refining and casting, to obtain an aluminum alloy blank; and step 2: after the blank is annealed, extruding and pulling out the blank into monofilaments.
7. The method for manufacturing the lightweight high-conductivity heat-resisting aluminum wire according to claim 6, wherein an additive amount of the Al-B intermediate alloy is determined based on the following two parts: an Al-B intermediate alloy prepared according to a designed mass percentage of a component B, and an Al-B intermediate alloy prepared as a ratio of mass of B to total content of impurity elements Ti, V, Cr, and Mn in the Zr-Er-Al alloy melt is 2-5:1.
8. The method for manufacturing the lightweight high-conductivity heat-resisting aluminum wire according to claim 6, wherein an ingot blank is obtained by ordinary casting or semi-continuous casting, or a pole blank is obtained by continuous casting.
9. The method for manufacturing the lightweight high-conductivity heat-resisting aluminum wire according to claim 8, wherein during casting, the cast ingot is cooled to the room temperature at a speed of20 300°C/s.
10. The method for manufacturing the lightweight high-conductivity heat-resisting aluminum wire according to claim 9, wherein during casting, water cooling is applied.
11. The method for manufacturing the lightweight high-conductivity heat-resisting aluminum wire according to claim 8, wherein the ingot blank or the pole blank has an annealing temperature of 480°C 500°C, and is cooled in the furnace after staying at the temperature for 1-10 h.
12. The method for manufacturing the lightweight high-conductivity heat-resisting aluminum wire according to claim 8, wherein hot extrusion is performed on the ingot blank at the temperature of 300°C-450°C, and continuous extrusion is performed on the pole blank at the room temperature.
13. The method for manufacturing the lightweight high-conductivity heat-resisting aluminum wire according to claim 12, wherein an extrusion ratio of the hot extrusion or the continuous extrusion at the room temperature is greater than or equal to 80, and an extrusion deformation amount is greater than or equal to 80%.
14. The method for manufacturing the lightweight high-conductivity heat-resisting aluminum wire according to any one of claims 6 to 13, wherein multi-pass pullout is performed after the extrusion, and a pass elongation coefficient is 1.2-1.5, a total accumulated elongation coefficient is 5.5-10.5, lubrication and cooling are performed by using an ordinary lubricant or an emulsion during pullout, and the temperature of the aluminum wire is controlled to be less than or equal to 180°C.
15. The method for manufacturing the lightweight high-conductivity heat-resisting aluminum wire according to claim 14, wherein the manufactured wire has a density less than or equal to 2.71 g/cm3, a conductivity greater than 62% IACS at 20°C, a short-time heat-resistance temperature reaching 230°C, a long-time heat-resistance temperature reaching 210°C, and a tensile strength greater than or equal to 165 MPa.