Microstructure refinement for superior ductility of Al–Si alloy by electron beam melting

Abstract

Refining the microstructure to improve the ductility of an Al‒Si alloy is challenging. In this paper, we report for the first time a novel microstructure refinement approach for AlSi10Mg (wt%) alloys using electron beam melting (EBM) technology, without the addition of any modification elements. The synergetic effect of superheating, fast cooling, and preheating contributes to a refined Si phase with a fine granular structure (0.5–2 μm) within bimodal Al grains (40 μm grains and 0.5–2 μm sub-grains). The results provide good evidence for the proposed refinement mechanism. A maximum ductility of approximately 32.7 % with a tensile strength of approximately 136 MPa was achieved for the as-built AlSi10Mg EBM alloy. After solution heat treatment and T6-like aging, nano-Si precipitates formed which strengthened the alloys. The pathway developed in this study for refining the Al–Si alloy microstructure to improve the tensile ductility will provide a feasible and fast manufacturing method for improving the microstructure and mechanical properties of other low-melting temperature alloys in the near future using EBM technology.