Exploring microstructure refinement and deformation mechanisms in severely deformed LPBF AlSi10Mg alloy

An additively produced AlSi10Mg aluminium alloy was post-processed by Equal Channel Angular pressing at 150ºC. This resulted in a fabrication of the novel submicrometer-grained (SMG) microstructure, which was subsequently characterised by optical microscopy, scanning electron microscopy, and transmission electron microscopy. In addition, the deformation mechanisms were also studied in detail at different scales. The post-deformation studies show that the predominant deformation mechanism of the alloy matrix was dislocation slip. However, the heterogeneous microstructure also activated another important mesoscale deformation mechanism - the plastic deformation gradient (incompatible deformation) that existed between the boundaries of the melt pools and their interiors and the Al/Si interfaces. More importantly, the TEM analysis provided evidence for the deformation twinning of the hard Si phase as well as for the deformation-induced amorphisation of the Si phase. The revealed synergy of different deformation modes sheds light on the good balance between strength and ductility and opens a new horizon for the development of the next generation of structural materials.