Effects of processing paths on microstructure evolution and properties of high-strength and high-conductivity Al-Mg-Si alloys

The improvement of the integrated strength and conductivity of aluminum alloys is of great significance for their applications in overhead transmission lines. In this study, we comprehensively investigated the influence of the microstructure of Al-Mg-Si alloys on their properties under both conventional aging and multi-pass rolling plus aging treatments by using transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD). The results indicate that, in comparison with the conventional aging treatment, the samples subjected to two-stage rolling display a pronounced <111> orientation. The grain size decreases from 2444 mu m to 23.5 mu m, the precipitation size of the beta" phase decreases from 2.67 nm to 1.2 nm, and simultaneously, the dislocation density increases substantially from 0.03 x 10(14)/m(2) to 2.74 x 10(14)/m(2). Owing to multiple strengthening mechanisms, the yield strength of the rolled sample reaches 282.17 MPa, representing an increase of 79.79 MPa compared to the pre-rolled condition. Simultaneously, the increase in the number of precipitated phases and the decrease in the number of solid solution atoms in the sample minimize the interference in electrical conductivity, thereby enhancing it to 57.54 %IACS, with an improvement of 4.3 %IACS. The elongated grains, <111> texture, and beta" phase are identified as the primary factors contributing to the enhanced mechanical and electrical properties of the Al-Mg-Si alloy.