Tuning strength-ductility combination of the additively manufactured Al12Si based alloys via compositional regulation and plastic deformation

The enhanced strength-ductility synergy of Al12Si alloy manufactured via laser powder bed fusion (LPBF) was obtained through compositional regulation and post-fabrication plastic deformation. Microstructural characterizations showed that the typical synergy of multiple crystallised defects in brittle Si eutectic phase, including stacking faults (SFs), ultrafine nanotwins and 9R structure, co-contribute to the superb elongation of 23.7 % with the ultimate tensile strength of 189 MPa in as-LPBFed Al12Si alloy after hot-rolling deformation with a reduction rate of 70 %. In tandem with a trace of Mn and Fe additions, the UTS increases to 240 MPa with the El of 19.1 % under the same condition. Such an excellent strength-ductility synergy is mainly attributed to the formation of ultrafine α-Al₁₂(Fe,Mn)₃Si particles. This work offers a new perspective on the modification Al–Si alloys with the desired mechanical properties via LPBF and hot-rolling.