Atomic resolution analysis of precipitates formed in an HPTE deformed Al-Mg-Si alloy

Improving both mechanical and electrical properties is one of the key requirements for reducing energy losses in power lines. Here, we investigate the structural evolution and hardening of Al 6101 grade, which is a versatile alloy known for its high electrical conductivity. Structure and properties changes were induced by severe plastic deformation followed by artificial aging. Nano indentation maps show improvement in hardness, which is connected to the formation of intermetallic phases. A range of hardening phases with different shapes and Mg/Si ratios have been identified by APT. HR(S)TEM imaging shows that the structure of most particles is only partially ordered due to the high defect density in severely deformed Al matrix. The observed particles exhibit several different crystalline structures, and their orientation relationships with the Al matrix differ from the ones previously established. Moreover, many nanometer sized precipitates consist of several different phases. These structural features are a consequence of non-equilibrium growth conditions of the precipitates and affect further thermal evolution as observed by DSC.