Optimizing the tensile properties of Al-11Si-0.3Mg alloys: Role of Cu addition

In the present work, the role of Cu addition on the tensile properties of both as-cast and solution-treated Al-11Si-0.3Mg alloys was systematically investigated. For as-cast alloy, a fine and uniform microstructure can be obtained by employing efficient refinement and modification with the combinative addition of B, La and Sr. The addition of Cu causes slight coarsening of alpha-Al dendrite, but has insignificant effect on the size and morphology of eutectic Si particles, resulting in a promotion of strength coupled with unremarkable reduction of elongation. The strengthening effects of Cu addition mainly depends on the weight ratio of Cu/Mg in the experimental alloy, of which the quality value of Q calculated shows that the optimized tensile properties of Cu-dropped Al-11Si-0.3Mg can be achieved with the weight ratio of Cu/Mg of 5: 1, referring to 383 MPa and 430 MPa in as-cast condition and solution-treated condition, respectively. (C) 2015 Elsevier B.V. All rights reserved.