Mechanical properties and structural stability of a bulk nanostructured metastable aluminum-magnesium system

Abstract

The mechanical properties and structural stability of a high-pressure torsion (HPT)-induced bulk nanostructured metastable Al-Mg system were examined after natural aging at room temperature for 60 days. The sample demonstrated a high yield strength of 1.3-1.5 GPa with an excellent plasticity by achieving a high strain rate sensitivity of 0.036. The high hardness is attributed to the concurrent contributions of grain refinement and solid solution strengthening. An X-ray diffraction analysis revealed a high compositional microstrain of similar to 0.0202 due to the supersaturation of Mg in the Al matrix after processing. This microstrain increased to similar to 0.0274 after natural aging due to the heterogeneous distribution of supersaturated Mg solutes without any nucleation of a second phase, thereby demonstrating a reasonable structural stability.