Superplasticity and mechanical properties of Al–Mg–Si alloy doped with eutectic-forming Ni and Fe, and dispersoid-forming Sc and Zr elements

Abstract

Abstract The development of Al–Mg–Si-based alloys with advanced superplasticity and improved mechanical properties is an important task for further applications of superplastic blow-forming technology in the production of complex-shape parts. The current study focuses on the influence of eutectic forming Ni and Fe and dispersoid forming Sc and Zr alloying elements on the microstructural evolution, superplastic behavior, and tensile properties at room temperature for the Al-1.2%Mg-0.7%Si-1.0%Cu (AA6013-type) alloy. The X-Ray diffraction, scanning, and transmission electron microscopy were used for microstructural characterization. The bimodal particle size distribution was observed after the thermomechanical treatment of the alloy studied. The high density of the L12 coherent dispersoids with a mean size of 10\xa0±\xa01\xa0nm providing a significant Zener pinning effect was formed during homogenization annealing. The near-equiaxed coarse particles with a size in a range of 0.5–5.0\xa0μm belonged pre-dominantly to the Mg2Si and Al9FeNi phases, which led to an important particle-stimulated nucleation (PSN) effect. The alloys studied exhibited a superplastic behavior in temperature and strain rate limits of 440–520\xa0°C and 1\xa0×\xa010−3 s−1 - 1\xa0×\xa010−2 s−1, respectively, with an elongation-to-failure range of 350–480%. The age-hardening heat treatment provided a yield strength of 370\xa0±\xa04\xa0MPa, an ultimate tensile strength of 415\xa0±\xa02\xa0MPa, and elongation of 6\xa0±\xa01%.