Microstructural evolution and the mechanical properties of an aluminum alloy processed by high-pressure torsion

Processing by high-pressure torsion (HPT) was performed on disks of an Al-7075 alloy at room temperature. The alloy was initially annealed at 753 K and then processed by HPT under a pressure of 6.0 GPa up to a maximum of ten turns. Measurements of the Vickers microhardness showed lower values at the centers of the disks after small numbers of turns but higher numbers of turns led to a reasonable hardness homogeneity across each disk. After five turns, the grain size at the edge of the disk was ~250 nm. It is demonstrated that results from mechanical testing are consistent with the hardness and microstructural data.