With the continuous and rapid development of national economy and the gradual improvement of people's living standards, the demand for electric power increases sharply. It is urgent to improve the transmission capacity of aluminum wire and develop large capacity transmission lines. Aluminum wire is a key material applied in the field of power engineering, which has the advantages of low density, high conductivity, high strength and low cost. As microalloyed elements, lanthanum and cerium are easy to form high melting point compounds with impurity elements such as H, O, Fe and S in aluminum casting process, because of their high chemical activity and affinity, which can improve the strength of aluminum wire without sacrificing too much conductivity. Therefore, rare earth microalloying has become a research hotspot. In this paper, Al-xRE (x=0, 0.1, 0.2, 0.3, 0.4, 0.5; %, mass fraction) alloy was smelted by using commercial pure aluminum, Al-10%La intermediate alloy and Al-15%Ce intermediate alloy in aluminum smelting furnace. The melting temperature was 750 ℃, and the pouring temperature was 700 ℃. Then, the ingot was extruded, the extrusion temperature was 400 ℃, the extrusion speed was 2 mm·s-1. The effects of La and Ce rare earth mixture on microstructure, conductivity, mechanical properties and texture of extruded industrial pure aluminum were studied. The microstructure was characterized by optical microscopy (OM), scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The conductivity and tensile tests of rare-earth aluminum alloys with five components were carried out by using QJ-36 DC type double-arm bridge tester and DNS200 type universal electronic drawing machine, respectively. The results showed that when La and Ce were added, Al-Fe-Si-La-Ce phase was formed at the grain boundary, and the grain of aluminum alloy gradually became fine. When the rare earth content was greater than 0.3%, AlLa3 phase and AlCe3 phase appeared in the grain, and the grain began to appear obvious refinement. The conductivity of aluminum alloy increased firstly and then decreased. When the rare earth content was 0.2%, the conductivity of aluminum alloy reached the maximum value of 64.5%IACS, and when the rare earth content was 0.5%, the conductivity of aluminum alloy reached the minimum value of 61.7%IACS. When the rare earth content was less than 0.3%, the mechanical properties of the alloy had little change, but when the rare earth content was more than 0.3%, the strength and hardness of the alloy gradually increased. The maximum average tensile strength was 90 MPa, the minimum average elongation was 41.6%, and the maximum average hardness was HV 24.9. Compared with pure aluminum, its average tensile strength and hardness were increased by 38.5% and 19.1%, respectively, but its elongation was only reduced by 9.2%. In addition, the effect of La and Ce mixed rare earth on the texture of industrial pure aluminum was studied. With the increase of rare earth content, the grains with <001> orientation decreased gradually, and the grains with <111> orientation increased continuously. The dislocation density in the alloy increased constantly. The texture strength of ｛100｝ plane increased first and then decreased, and also inhibited the formation of <100>//extrusion direction (ED) and Cube textures. Analysis indicated that when rare earth elements content was less than 0.2%, La and Ce would combine with impurities in Al matrix, and refined the matrix, which increased the conductivity of aluminum alloy. When rare earth content was greater than 0.2%, La and Ce were in solid solution state which reduced the conductivity. When the rare earth content was greater than 0.3%, the grain was obviously refined, and according to the Holpage formula, the material strength was significantly improved. On the other hand, La, Ce and Al formed a solid solution, resulting in lattice distortion of pure aluminum, which also improved the material strength. In the figures of Image Processing Facility (IPF), the results showed that when La and Ce rare earth content was more than 0.3%, the grain orientation from <111> to <001> was obviously inhibited. The dislocation density of the small grain in the rare earth aluminum alloy microstructure was higher, indicating that the grain refinement was enhanced when the rare earth content was greater than 0.3%, which could be found through Kernel Average Misorientation (KAM) figures. Otherwise, the more the <111> orientations existed in aluminum alloy, the greater the dislocation density. Orientation Distribution Function (ODF) figures showed that in the cross section, the mixed texture of <110>//ED and <100>//ED appeared when the rare earth content was less than 0.4%, but when the rare earth content was increased to 0.5%, the rare earth elements may inhibit the formation of <100>//ED texture, and only <110>//ED texture existed; In the longitudinal section, Cube and <100>//ED textures were difficult to be detected due to the inhibition of <100> orientation texture during hot extrusion when the rare earth content was 0.5%. The Pole figures (PF) showed the texture strength of ｛100｝ plane of rare earth aluminum alloy corresponded to the mechanical properties. The texture strength of ｛100｝ plane was weak, and the higher the corresponding macro-strength. Therefore, it could be found that, designing the composition content of La and Ce mixed rare earth could regulate the texture of ｛100｝ surface of industrial pure aluminum, thus improving the mechanical properties of aluminum alloy. © Editorial Office of Chinese Journal of Rare Metals. All right reserved.
