Novel non-equilibrium partitioning model and the developed strong and ductile Al–7.5Mg–0.5Sc–0.3Zr–0.6Si alloy for selective laser melting

Strong and ductile Al alloys and their suitable design strategy have long been desired in selective laser melting. This work reports a non-equilibrium partitioning model and the correspondingly designed Al–7.5Mg–0.5Sc–0.3Zr–0.6Si alloy. This model effectively quantifies the influence of Mg and Si on hot cracking in aluminum alloy by considering the non-equilibrium partitioning under high cooling rates in selective laser melting. The designed Al–7.5Mg–0.5Sc–0.3Zr–0.6Si alloy exhibits no hot cracks and achieves a remarkably enhanced strength–ductility synergy (a yield strength of (412 ± 8) MPa and a uniform elongation of (15.6 ± 0.6)%), superior to previously reported Al–Mg–Sc–Zr and Al–Mn. A tensile cracking model is proposed to explore the origin of the improved ductility. Both the non-equilibrium partitioning model and the novel Al–7.5Mg–0.5Sc–0.3Zr–0.6Si alloy offers a promising opportunity for producing highly reliable aluminum parts through selective laser melting.