Effect of High-Pressure Torsion on the Microstructure and Mechanical Properties of an AMg5 Aluminum Alloy with Calcium and Zirconium Additions

Abstract

The effect of high-pressure torsion (HPT) and subsequent annealing on the microstructure, mechanical properties, and temperature stability of an aluminum alloy, the composition of which includes 92.1 wt % Al, 4.6 wt % Mg, 1.3 wt % Ca, 0.8 wt % Mn, 0.3 wt % Fe, 0.2 wt % Zr, and 0.2 wt % Si, is studied. HPT is performed at room temperature; post-deformation annealing is conducted at 100–400°C. HPT is found to result in threefold hardening, which remains unchanged up to 200°C. The high plastic deformations reached during HPT lead to the formation of nano- and submicrocrystalline grain–subgrain microstructure characterized by a high level of internal stresses. The best combination of a high strength (655 MPa) and adequate plasticity (relative elongation is 2%) is reached after HPT at a small number of revolutions. Post-deformation annealing at 350°C ensures the maximum relative elongation to failure (16%) at a flow stress of ~370 MPa in the absence of strain hardening.