High Strength and Ductility of Nanostructured Al Alloy 2024 Subjected to High Pressure Torsion

The structure and mechanical properties of Al-based alloy 2024 after high-pressure torsion (HPT) was investigated. Alloy 2024 with homogeneous structure and grain size about 70 nm was obtained using HPT at 6 GPa pressure and 5 turns of the anvils at room temperature. The nanostructured alloy possessed very high UTS (Ultimate tensile stress) above 1100 MPa at room temperature, and superplastic behaviour at temperatures over 300°С. The microhardness of the nanostructured alloy after superplastic deformation (1.5 GPa) was greater than that after the standard treatment of the coarse-grained alloy (1.2 GPa). The influence of HPT parameters and heat treatment on the structure and deformation behaviour of the alloy was studied. The opportunity of achieving a combination high strength and good ductility in metals and alloys opens perspectives for industrial applications, particularly, in micro-systems and for high-strength items with complex geometry which could be obtained by superplastic forming.