Al Alloy Wires Research Articles

Microstructure and Mechanical Properties of 7075 Al Alloy TIG-Welded Joint with 7075 Al Alloy Wire as Filler

Microstructure and Mechanical Properties of 7075 Al Alloy TIG-Welded Joint with 7075 Al Alloy Wire as Filler

Study on the effects of alloying elements on porosity in Al-Mg-Sc-Zr alloy fabricated by wire arc directed energy deposition

Wire arc directed energy deposition (WA-DED) technology has broad application prospects in man-ufacturing large-size and complex metal components due to its low production costs and high depos-ition efficiency. However, pores are still challenging in WA-DED-processed aluminum (Al) alloys. Although many works have been discussed in this field, the relevant studies about the effect of alloying elements on porosity are fewer. In this work, Al alloy wires with 0.36Sc and 0.11Zr (LAEW, wt%) and 0.72Sc and 0.23Zr (HAEW) were selected to fabricate single-pass multi-layer compone-nts with different welding speeds, and the pores were analyzed by X-ray computed tomography (XCT) technology. As the content of Sc and Zr elements increased, the density of Al-Mg-Sc-Zr components significantly decreased. The highest porosity, number density, and the largest average diameter of pores in components with HAEW were about 7.37 %, 6.04 × 102 /mm3, and 46.77 ± 29.31 μm, respectively, which were significantly higher than those of LAEW. The second phases of all components were mainly Al3(Sc1-x, Zrx) phases. Compared to LAEW, the Al3(Sc1-x, Zrx) phases of components with HAEW had a larger area fraction and average diameter, as well as a higher number density at the same process parameters, the highest values were around 3.00 %, 1.27 ± 0.89 μm, and 15.20 × 103 /mm2. Al3(Sc1-x, Zrx) phases could not only serve as the nucleation cores of bubbles but also hinder bubbles escape. In addition, the Sc element significantly increased the viscosity of Al melt. Therefore, the main influencing factors of pores in components with HAEW were not only process parameters, but also the Al3(Sc1-x, Zrx) phases. However, for LAEW, the process parameters were the major influencing factors on porosity due to lower area fraction and number density of Al3(Sc1-x, Zrx) phases. This work has laid a theoretical foundation for WA-DED-processed high-strength Al-Mg-Sc-Zr alloys.

Three principles for preparing Al wire with high strength and high electrical conductivity

The trade-off relation between the strength and the electrical conductivity has been a long-standing dilemma in metallic materials. In the study, three key principles, i.e. elongated grains, sharp texture and nano-scale precipitates, were presented for preparing Al wire with high strength and high electrical conductivity based on the specially designed experiments for breaking the mutually exclusive relation between the strength and the electrical conductivity. The results show that the elongated grains could lead to a higher electrical conductivity in Al wire without sacrificing the strength; while, the <111> sharp texture can efficiently strengthen the Al wire without influencing the electrical conductivity. Furthermore, nano-scale precipitates with proper size can simultaneously improve the strength and electrical conductivity of Al alloy wire. Under the guidance of the above three key principles, Al wires with high strength and high conductivity were prepared.

High-Speed Drawing of Al Alloy Wire by Diamond-Coated Drawing Die Under Environmentally Friendly Water-Based Emulsion Lubrication

It is environmentally friendly to use water-based emulsion instead of the oil when cold drawing Al alloy production. In this research, adopting specially prepared water-based emulsion, contact angles and tribological properties of as-selected multilayer diamond films are clarified. The contact angle on diamond film is much smaller than that on WC-Co with the same surface roughness, and tribological behaviors of the diamond film are much better. The effects of surface roughness Ra of the film, lubrication, and water content in the emulsion W are studied, indicating that the contact angle increases with W or Ra. For the diamond film, lower Ra is beneficial for reducing the coefficient of friction (COF), Al alloy ball wear and oxidation, while lower W contributes to the reduction of the COF, ball oxidation, and coated disk wear. Finally, high-speed drawing of high-quality 6021 Al alloy wires (AWs) is accomplished, proving that using coated drawing dies, the water-based emulsion (W &lt; 80 vol %) can totally replace oil, and coated dies under the water-based emulsion lubrication present much elongated lifetime and can guarantee the production quality, compared to uncoated ones under the oil lubrication, in spite of slightly severer wire oxidation.

Process Development of Al-alloy Wire Bonding for High-Temperature Power Electronics

Abstract In this work, process parameters are developed for an Al-alloy wire for high-temperature power electronics. Shear and pull forces of the bonds on IGBT devices reach 2200 g and 1100 g respectively, without causing any die cratering. Comparison of the Al-alloy wire and standard Al wire bonded on battery cells shows that both the pull and shear forces of the bonds with the Al-alloy wire are improved by ~20%. This indicates that this Al-alloy wire potentially could be used for bonding on the power electronics and batteries in automotive industry, where better mechanical strength and wider bond window are required.

Microstructure evolution and mechanical property improvement of aluminum alloys with high magnesium content during continuous rheo-extrusion

Due to superior mechanical properties and corrosion resistance, aluminum alloys with high magnesium content varying from 3 to 10 wt% have been widely used as aircraft welding wire and automotive materials. However, it remains challenging to produce high magnesium containing aluminum alloys in wire form through conventional casting, extrusion and rolling. Therefore, the present work employs continuous rheo-extrusion to manufacture Al alloy wires with high magnesium contents, which can eliminate the formation of coarse dendrites and thus improve mechanical properties. Microstructures and properties of the alloy wires were investigated by metallurgical microscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Results show that coarse dendrites were completely converted into equiaxed grains. A solid solution with high solubility of Mg and nanosized Al3Mg2 phases were formed in the alloy due to the high cooling rate in continuous rheo-extrusion. Such microstructural features incurred serrated plastic deformation in tensile tests due to the interactions between the solid solution atoms and dislocations. With increasing magnesium content, ultimate tensile strength increased while the elongation decreased gradually. Ultimate tensile strength and elongation of Al-5Mg (wt%) alloy wires were improved by 73% and 8% than that of conventional casting respectively.

Interface Characterization and Performances of a Novel Pure Al Clad Al Alloy Wire

Based on the principle of skin effect, a pure Al clad Al alloy wire is designed to break the mutually exclusive relation between strength and electrical conductivity. Actually, bimetallic composite wires offer the ability to blend the desired properties of various metals into a single wire, for example, combining the high‐conductivity of pure Al (outer layer) and the high‐strength of Al alloy (core). Thus, a novel method is adopted to prepare a pure Al clad Al alloy wire (ACAW) and the metallurgical bonding between pure Al and Al alloy is achieved by compressing the Al alloy cylinder into a hollow pure Al cylinder followed by a series of processes including forging, rolling, and cold‐drawing. A perfect interface is obtained as the fine grains are found across the interface. Furthermore, a linear rule of mixtures is applied to calculate the performance of ACAW as compared with the measured performance of ACAW. The measured strength of ACAW is the same as the calculated strength. Interestingly, the measured electrical conductivity of ACAW (58.17%IACS) is higher than the calculated electrical conductivity (57.60%IACS). Consequently, ACAW is an effective approach for combining the high‐conductivity of pure Al and the high‐strength of Al alloy.

Tribological properties of diamond films for high-speed drawing Al alloy wires using water-based emulsions

Abstract Tribological tests are conducted on diamond films under different lubrications, and influences of film type, lubrication, test parameters on coefficient of friction (COF) and film wear (Id) are studied. Diamond films perform better than WC-Co under water-based emulsion lubrication, and the boron doped micro-crystalline and nano-crystalline composite diamond (BDMC-NCCD) film shows the best overall behavior. Considering the performance and economy, the water content in the emulsion is optimized as about 80 vol%. Under this drawing condition, the quality of the production is similar to that drawn by the uncoated dies under the oil lubrication, however, the coated dies present much prolonged lifetime and lower temperature. Most importantly, the use of the water-based lubrication is much more environmentally friendly.

Mechanical and Electrical Properties of an Al-Fe-Mg-Cu-B System Alloy for Electrical Wire Fabricated by Wire Drawing

In this study, an Al-0.7wt%Fe-0.2wt%Mg-0.2wt%Cu-0.02wt%B alloy was designed to fabricate an aluminum alloy for electrical wire having both high strength and high conductivity. The designed Al alloy was processed by casting, extrusion and drawing processes. Especially, the drawing process was done by severe deformation of a rod with an initial diameter of 12 mm into a wire of 2 mm diameter; process was equivalent to an effective strain of 3.58, and the total reduction in area was 97 %. The drawn Al alloy wire was then annealed at various temperatures of 200 to 400 °C for 30 minutes. The mechanical properties, microstructural changes and electrical properties of the annealed specimens were investigated. As the annealing temperature increased, the tensile strength decreased and the elongation increased. Recovery or/and recrystallization occurred as annealing temperature increased, and complete recrystallization occurred at annealing temperatures over 300 °C. Electric conductivity increased with increasing temperature up to 250 °C, but no significant change was observed above 300 °C. It is concluded that, from the viewpoint of the mechanical and electrical properties, the specimen annealed at 350 oC is the most suitable for the wire drawn Al alloy electrical wire.

Nano-scale precipitates: The key to high strength and high conductivity in Al alloy wire

Outstanding mechanical and conductive properties are vital to Al alloys used as overhead conductors. However, high strength and high electrical conductivity are usually mutually exclusive in metallic materials. In this study, we present a novel method to achieve high strength and high conductivity in an Al-Mg-Si conductor. Numerous dispersive nano-scale precipitates were obtained using an artificial aging treatment for a 6201RE Al alloy conductor. The precipitation of the alloying elements in the form of nano-scale precipitates is determined to play a strengthening role, decreasing the concentration of alloying elements in the matrix and reduce lattice distortion such that high strength (352.3MPa) and high electrical conductivity (56.0% IACS) are achieved simultaneously in a 6201RE Al alloy. High strength and enhanced electrical conductivity could be achieved by introducing the nano-scale precipitates in the Al alloy. Finally, the strengthening mechanisms and the electrical conductivity induced by the nano-scale precipitates were discussed.

Deformation behavior of Cu-12wt%Al alloy wires with continuous columnar crystals in dieless drawing process

The microstructure and mechanical properties of Cu-12wt%Al alloy wires which are composed of continuous columnar crystals after dieless drawing forming at drawing speed of 1.0–1.4 mm/s and deformation temperature of 600–900°C were analyzed, and deformation behavior of the alloy during dieless drawing forming was experimentally investigated. The results showed that in the above-mentioned conditions, recrystallization phenomenon was not found during dieless drawing forming. When a drawing speed of 1.0 mm/s was used, the grain boundaries were out of straight gradually with increasing deformation temperature from 600°C to 900°C, and tensile strength of the dieless drawn Cu-12wt%Al alloy wires increased while elongations decreased with increasing deformation temperature. At drawing speed of 1.1–1.2 mm/s and deformation temperature of 600°C, the effect of dieless drawing forming process on the microstructure of the alloy was inconspicuous, and when drawing speed was up to 1.3–1.4 mm/s, the grain boundaries of continuous columnar crystals became zigzag while there was little effect of drawing speed of 1.1–1.4 mm/s on the elongation and tensile strength of the alloy wires.

Improvement of the structure properties for special steel wire by cold-rolling technique

The classical method of the producing special-steel wire is generally cold-drawing. The raw material for drawing is hot rolled rod bundle, the technical process is: annealing - soda wash - acid wash - water wash - stoving - coating - drawing, after numerous cycles of the technical process as shown above, the special-steel wire with thin diameter can been obtained. However the process steps are numerous, the production period is longer and the prouction cost is higher.Now we take new three-high cold continuous rolling technique the special-steel wire with thin diameter has been obtained without intermdiate annealing, The production rate has been remarkably raised, the production cost has been reduced and the production environment has been improved. In the further investigation, we know that, for two different kinds of special-steel wire produced by cold-rolling technique and by cold-drawing technique respectively, there is a marked difference in the structure properties of the wire. The present paper describes that, under two different kinds of technique as stated above, for Fe  Cr  Al special-steel wire, the surface state, the rate of the increasing in weight for high temperature oxidation, the variation of the alloy content, the oxide film and the section shape are obviously different. The results show that the cold - rolling technique can improve the surface state of the Fe  Cr  Al alloy wire, favor to form the compact oxide film in the surface and increase the oxidation resistance at high temperature of the alloy wire.

Determination of cobalt in solid matrices by neutron activation analysis

The concentration of cobalt in 2 solid matrices was determined by neutron activation analysis (NAA) using standard solutions which were prepared by dissolving pure cobalt in nitric acid. The matrices assayed were a cobalt-aluminium wire and an iron foil and the respective Co concentrations found were 0.488% and 0.138%. Both solid materials can equally be used as standard references of cobalt in NAA. Subcadmium and epicadmium neutron fluxes in the reactor core were determined using Co−Al and Au−Al alloy wires. Very good agreement was obtained for all irradiation configurations of the target monitors cobalt and gold.