Fig. 1 a Temperature vs. (fs)1/2 curves of Al7075 and Al7075-5Si alloy; solidification paths of b Al7075, c Al7075-5Si alloys simulated by using Scheil-Gulliver model in Thermo-Calc software

Fig. 2 SEM image and elements distribution of Al7075-5Si powders detected by using EDS mapping: a SEM image of Al7075-5Si powders, b Al, c Si, d Mg, e Cu, f Zn

Fig. 3 Effects of laser energy density on the relative densities of the SLM-processed Al7075 and Al7075-5Si cubic samples

Fig. 4 a Vickers hardness testing of Al7075-5Si cubes with different laser energy densities at the different positions along the same direction, b engineering stress-strain curves of Al7075-5Si alloy with different laser energy densities after SLM printing

Fig. 5 a Vickers hardness testing of Al7075 and Al7075-5Si cubes under the laser energy density of 112.5 J/mm3 at the different positions along the same direction; b engineering stress-strain curves of SLM-processed Al7075 and Al7075-5Si alloy under the laser energy density of 112.5 J/mm3, c mechanical properties comparison of SLM-processed Al alloys from different literature [10,17,23,24,25,37,38,39,40,41,42,43]

Fig. 6 SEM images of fracture surfaces of a, b Al7075 alloy and c, d Al7075-5Si alloy after SLM printing, the inset in d is the enlargement of dimple in d

Fig. 7 Optical microstructure images of the un-etched cubic samples after SLM: a Al7075, b Al7075-5Si

Fig. 8 Polished and etched SEM images of a, b Al7075, c, d Al7075-5Si cubes in the building direction

Fig. 9 EBSD analysis results of SLM-processed samples in the building direction. Inverse pole figure maps of a Al7075 and b Al7075-5Si; d, e distribution of sub-structural grains (in yellow) and recrystallized grains (in blue) of a, b, respectively; g, h {100}, {110} and {111} pole figures corresponding to the textures intensity of a, b, respectively; c and f grain size distribution and XRD patterns of SLM-processed Al7075 and Al7075-5Si samples, respectively

Fig. 10 a Scanning transmission electron microscopy (STEM) bright-field image of Al7075-5Si, showing the precipitated phases at the grain boundaries. The green arrows point the eutectic Si, and the purple arrows are the Mg2Si phase; b-f EDS elements distribution analysis results: b Al, c Zn, d Mg, e Cu, f Si; g, h TEM images and the corresponding selected area electron diffraction (SAED) patterns of Al7075-5Si, showing the phase composition in the marked zones A and B

Fig. 11 a STEM bright-field image of the precipitates in Al7075-5Si, and b EDS elemental line distribution analysis result in the marked arrow direction in a

Fig. 12 Solidification schematics of Al7075 with/without Si modification during SLM