Fig. 1. Experimental device and scheme. (a) Experimental device of laser shock peening; (b) experimental device of ultrasonic shock peening; (c) processing scheme

Fig. 2. Schematic of hardness test points

Fig. 3. Three dimensional surface morphologies of 2024-T351 aluminum alloy samples under different treatment methods. (a) Original sample; (b) LSP; (c) UIP; (d) LSP＋UIP

Fig. 4. Surface average linear roughnesses of 2024-T351 aluminum alloy samples under different treatment methods

Fig. 5. Surface metallographic structures of 2024-T351 aluminum alloy samples under different treatment methods. (a) Original sample; (b) LSP; (c) UIP; (d) LSP＋UIP

Fig. 6. TEM images of 2024-T351 aluminum alloy sample sections under different treatment methods. (a) Original sample; (b) LSP; (c) UIP; (d) LSP＋UIP

Fig. 7. Surface micro-hardnesses of 2024-T351 aluminum alloys under different treatment methods

Fig. 8. Surface residual stresses of 2024-T351 aluminum alloys under different treatment methods

Fig. 9. Schematic of effect of LSP＋UIP on surface morphology and microstructure of 2024-T351 aluminum alloy