Using ball indentation to determine the mechanical properties of an Al-7475 alloy processed by high-pressure torsion

A commercial Al-7475 alloy with an initial grain size of ~40 μm was processed by high-pressure torsion (HPT) for up to 2 turns at room temperature under a pressure of 6.0 GPa. The mechanical properties of the processed materials were evaluated by the ball-indentation technique to give information on the yield strength and the ultimate tensile strength. Following HPT, microhardness measurements revealed a steady increase in the hardness values from the centers of the samples towards the edges. After 2 turns, the ultimate tensile strength was ~1050 MPa at the edge of the disk and the measured grain size was ~70 nm. The results demonstrate the potential for using HPT to achieve excellent grain refinement in the Al-7475 alloy.