Mechanical properties and microstructural evolution of high-pressure torsion-processed Al7075 alloy at elevated temperatures

Abstract

The severe plastic deformation of aluminum alloys can be advantageous for developing a unique microstructure by inducing dynamic recovery and dynamic precipitation. Because dynamic recovery and precipitation are related to temperature changes, an elevated temperature atmosphere during severe plastic deformation may accelerate microstructural changes in aluminum, resulting in different properties compared to that of the room-temperature processed sample. In the present work, the microstructural and mechanical properties of the elevated temperature high-pressure torsion-processed Al7075 alloy were investigated. Experimental results demonstrated that the elevated temperature during high-pressure torsion not only induces a dynamic recovery at a high shear strain regime but also yields coarse Mg, Zn, and Cu-rich precipitates in the aluminum matrix. Although the grain growth occurs from the shear strain of 7.8, evolved precipitates represents larger strength than matrix that result into continuous mechanical properties enhancement in the elevated temperature-processed sample. This result indicates that solute migration acceleration at an elevated temperature could be a suitable method to enhance the mechanical properties of aluminum alloys undergoing severe plastic deformation processing.