Synergistic effects of Cr and Sr addition on the mechanical and corrosion properties of A356.2 alloy

Abstract

In this study, synergistic effects of Cr and Sr addition on the microstructure, mechanical and corrosion properties of A356.2 alloy are investigated. Al 10Cr and Al 10Sr ribbons were prepared through melt-spinning technology. Besides α-Al phase, nano-size spherical Al 7 Cr and Al 4 Sr particles exist respectively, which will reduce concentration and improve inoculant effect. Synergistic addition of Cr and Sr can refine α-Al dendrites and modify eutectic Si. When 2.0%Al-10Cr and 0.4%Al-10Sr ribbons were added (CS4 alloy), A356.2 alloy show the best inoculated effect. YS, UTS, El and HV are respectively 33.8%, 15%, 32.8% and 19.6% higher than A356.2 alloy (CS0). Moreover, ribbons show better properties than ingots in the same addition level. With Cr and Sr addition, the fracture occurs to smaller porosity, cleavage plane and tearing ridges. Al and Al 13 Cr 4 Si 4 form the clear and stabile Al 13 Cr 4 Si 4 /Al interface, thereby facilitating heterogeneous nucleation and grain refinement for A356.2 alloy. They have good interface crystallographic match and some orientation relationships (ORs). The element Sr, especially finer Al 4 Sr in Al 10Sr ribbons, promotes the formation of twins, fine fibrous and granular Si. • Al 10Cr and Al 10Sr ribbons were prepared by melt-spinning. • The synergistic addition Cr and Sr refine the α-Al grain and modify the eutectic Si of A356.2 alloy. • The reinforced A356.2 alloy exhibits excellent mechanical and corrosion properties. • The Al 13 Cr 4 Si 4 phase has better lattice mismatch with α-Al. • Sr element modifies eutectic Si through promoting the formation of twins.