Microstructure, mechanical properties and aging behaviors of as-extruded Mg–5Li–3Al–2Zn–1.5Cu alloy

An experimental investigation into the microstructure, mechanical properties and aging behaviors of as-extruded Mg–5Li–3Al–2Zn–1.5Cu alloy is conducted. The results show that, during the hot extrusion process, the large bulk intermetallic compounds (AlLi, AlCuMg and Al2Cu phases) of as-cast alloy are crushed into small bulk compounds. The dynamic recrystallization (DRX) takes place, which results in the refinement of grains significantly. A fibrous type texture of (0 0 0 2) basal plane is formed through the hot extrusion. Tensile tests reveal that the mechanical properties of the alloy are greatly improved after the hot extrusion. Due to the continuous and discontinuous precipitations of AlLi phases, the as-extruded alloy presents age hardening effect at the aging time of 14 h and 48 h, respectively.

Research highlights▶ Compounds are crushed, grains are refined and texture is formed through hot extrusion. ▶ The mechanical properties of alloy are greatly improved after hot extrusion. ▶ Second phases, grain refinement and texture affect the mechanical properties. ▶ Age hardening presents because of the continuous and discontinuous precipitations.