Fig. 1. Designed laser scanning path. (a) Spiral scanning structure; (b) schematic of weld formation

Fig. 2. Tensile-shear samples under different overlapping combination modes. (a) Cu/Al; (b) Al/Cu

Fig. 3. Surface morphologies and cross sections of welds formed under different overlapping combination modes

Fig. 4. Surface stereo formation images under different overlapping combination modes. (a) Cu/Al; (b) Al/Cu

Fig. 5. Schematics of different laser welding processes. (a) Continuous laser; (b) nanosecond laser

Fig. 6. Test results of interfaces on Al side and Cu side for overlapping combination mode of Cu/Al. (a) SEM image of interface on Al side; (b) EDS mapping on Al side; (c) SEM image on Cu side; (d) EDS mapping on Cu side

Fig. 7. Defects of joints for overlapping combination mode of Al/Cu

Fig. 8. Morphology of joint for overlapping combination mode of Al/Cu. (a) Overall morphology; (b) region on Al side; (c) interface between Al and Cu; (d) microstructure of region Ⅰ; (e) microstructure of region Ⅱ; (f) enlarged image of interface between Al and Cu; (g) EDS image of typical region

Fig. 9. XRD test results of Al/Cu weld region. (a) Cu side; (b) Al side

Fig. 10. Cu-Al binary phase diagram and phase distribution within joint

Fig. 11. Morphology of joint for overlapping combination mode of Cu/Al. (a) Overall morphology; (b) region on Al side; (c) interface between Al and Cu; (d) region on Cu side; (e) EDS image of typical region

Fig. 12. Tensile-shear test results of substrates and joints under different overlapping combination modes