Engineering an ultra-fine grained microstructure, twins and stacking faults in PBF-LB/M Al-Si alloy via KoBo extrusion method

In this study, the microstructural and mechanical properties of an PBF-LB/M AlSi10Mg alloy extruded by the KoBo process are investigated. Electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analyses revealed an ultrafine-grained face-centred cubic (f.c.c.) matrix with a high density of stacking faults (SFs) and sigma-CSL twin boundaries (TBs). The KoBo processed sample exhibited an attractive combination of mechanical properties - moderate tensile strength of 324 MPa and excellent ductility - elongation at break of -10%. The unique alloy microstructure obtained has the potential to exhibit superior properties such as improved radiation resistance, high temperature stability, resistance to intergranular corrosion and cyclic deformation. Overall, the results of this study provide a simple way to tailor the strength and ductility of PBF-LB/ M-Al-Si alloys through grain boundary engineering and manipulation of TBs and SFs through interface engineering.