Effect of aging treatment on phase evolution and mechanical properties of selective laser melted Al-Mg-Er-Zr alloy

Abstract

• The precipitation L1 2 -Al 3 Zr primary phase refines the grain size and forms bimodal grain structure. • Al 3 (Er,Zr) particles greatly improves the mechanical properties, with strength of 510 MPa and elongation of 16 %. • Dislocations, as a diffusion path to accelerate atomic migration, play an important role in the evolution of phases. Er and Zr modified Al-Mg alloy was manufactured by selective laser melting. The effect of aging treatment on phase evolution and mechanical properties of alloy has been studied. The results show that bimodal grain structures (2.8 ± 1.1 μm) could be obtained, thanks to the Al 3 Zr primary phases promoting the formation of equiaxed grains (0.8 ± 0.3 μm) at the boundary of molten pool. During the aging of 375 °C, Al 3 (Er,Zr) particles with the size of 2–5 nm were produced via synergistic precipitation of Er and Zr, which would greatly improve the strength and reach 510 ± 9 MPa. At the same time, the Mg-rich phase was dissolved, the Mn-rich phase was precipitated, and dislocations could accelerate the diffusion of solute atoms during the evolution of the phases.