Fig. 1. Schematics of sample assembly and tensile sample

Fig. 2. Macroscopic morphologies of cross section and weld of Al/Cu composite laser welded joint under different V values. (a) V=20 mm/s; (b) V=40 mm/s; (c) V=60 mm/s; (d) V=80 mm/s; (e) V=100 mm/s

Fig. 3. Variation curves of penetration and weld width at Al and Cu sides. (a) Weld width at Al side; (b) penetration and weld width at Cu side

Fig. 4. Microstructures of Al/Cu laser welded joint when V=60 mm/s. (a) Overall appearance of weld; (b) Cu side weld morphology; (c) enlarged view of area c in Fig. 4(a); (d) enlarged view of area d in Fig. 4(a); (e) enlarged view of area e in Fig. 4(d); (f) enlarged view of area f in Fig. 4(a); (g)(h) distributions of elements in area d in Fig. 4(a); (i) element line distribution in area f in Fig. 4(a)

Fig. 5. Microstructures of aluminum/copper laser welded joints under different V values. (a) V=20 mm/s; (b) V=40 mm/s; (c) V=80 mm/s; (d) V=100 mm/s

Fig. 6. Fracture load of Al/Cu blue-red composite laser welded joint versus welding speed

Fig. 7. Fracture morphologies of Al/Cu joint at Al side when V=60 mm/s

Fig. 8. Contact resistance of samples under different welding speeds