Fig. 1. SLM powder materials and forming process. (a) Morphology of AlSi10Mg powder; (b) distribution of AlSi10Mg powder particle size; (c) morphology of CuSn10 powder; (d) distribution of CuSn10 powder particle size; (e) mass fraction of CuSn10 and AlSi10Mg powders; (f) power distribution of gradient layer; (g) scanning speed distribution of gradient layer

Fig. 2. Physical and microstructure images of FGM samples formed by SLM. (a) Physical image of sample 1; (b) physical image of sample 2; (c) microstructure images of sample 1, illustrated with enlarged view of transition zone and CuSn10 interface region (top right) and local enlarged view (bottom right); (d) microstructure images of sample 2, illustrated with local enlarged view of transition zone (top right) and enlarged view of transition zone and CuSn10 interface region (bottom right)

Fig. 3. SEM images of sample 2 transition zones prepared by SLM

Fig. 4. Schematic diagrams of EDS point position in transition region. (a) Sample 1; (b) mapping resutls of fusion zone at sample 1 interface; (c) sample 2; (d) mapping resutls of fusion zone at sample 2 interface; (e) dot line plot of EDS point scan results corresponding to Cu and Al elements in transition region for sample 1 and sample 2

Fig. 5. XRD patterns and phase diagram calculation results of sample 2. (a) XRD patterns of different transition regions in cross-section of sample 2; (b) Al-Cu-Sn ternary phase diagram at 800 K calculated by CALPHAD; (c) phase molar fraction of vertical cross-section from CuSn10 to AlSi10Mg at 500 K

Fig. 6. Dot line plot and EBSD results of sample 1 and sample 2 in transition region. (a) Dot line plot of physical phase content change in whole transition region; (b) EBSD results in 70%‒80% region

Fig. 7. Analysis results of sample 1 and sample 2. (a)(b) Kernel average misorientation (KAM) maps of 0‒20% AlSi10Mg transition layer area in sample 1; (c)(d) KAM maps of 0‒20% AlSi10Mg transition layer area in sample 2; (e)(f) KAM maps of 80% AlSi10Mg transition layer area in sample 1; (g)(h) KAM maps of 80% AlSi10Mg transition layer area in sample 2; SEM images and EDS results of micro-cracks in 20% AlSi10Mg transition layer area of (i) sample 1 and (j) sample 2; (k) SEM image and EDS result of macro-cracks in 80% AlSi10Mg transition layer area of sample 1; (l) SEM image and EDS result of 80% AlSi10Mg transition layer area of sample 2

Fig. 8. Dot line plots of microhardness distribution in Z-direction of longitudinal section of samples. (a) Sample 1; (b) sample 2