Fig. 1. Diagram of ultrasonic coupling modes and devices in laser manufacturing process

Fig. 2. Electron backscattered diffraction analysis of 316L with or without ultrasound^[25]. (a) Grain distribution without ultrasound;(b) grain distribution with ultrasound; (c) inverse pole figure without ultrasound; (d) inverse pole figure with ultrasound

Fig. 3. Schematic diagram of multi-scale and multi-physical phenomena in the L-DED process^[28]

Fig. 4. Numerical simulation of ultrasonic effect^[28]. (a) Flow stress in mushy zone during ultrasonic assisted laser deposition; (b) severe convection of solute in molten pool caused by ultrasound

Fig. 5. Ultrasonic assisted laser powder bed fusion^[59]. (a) Schematic illustrations of technological process; (b) sub-grain structure without ultrasound； (c) sub-grain structure with ultrasound

Fig. 6. Schematic diagram of collaborative technology of laser cladding and ultrasonic impact^[41]

Fig. 7. Microstructure evolution of 304 stainless steel deposited by ultrasonic directional energy deposition^[45]. （a） Original microstructure； （b） depth of blue represents the local dislocation density after ultrasonic impact； （b1）（b2） magnification map of the corresponding position； （c1）（c2） subgrain formation； （d1）（d2） recrystallized grain formation； （e） final status

Fig. 8. Optical microstructure of welded joints^[80]. (a)‒(c) Laser welding macroscopic weld cross-section, fusion line, and weld center area; (d)‒(f) ultrasonic assisted laser welding macroscopic weld cross-section, fusion line, and weld center area

Fig. 9. Schematic diagram of laser impact combined with ultrasonic impact peening^[38]. (a) Ultrasonic impact peening; (b) laser impact peening

Fig. 10. Microstructure of the near-surface layer of AISI 1045^[93]. (a) Steel in the initial state; (b) LHT; (c) UIT; (d) UIT + LHT;(e) LHT + UIT

Fig. 11. Scanning electron microscope (SEM) analysis of micropore inlet^[14]. (a) With ultrasound; (b) without ultrasound

Fig. 12. Water-based ultrasonic assisted laser drilling^[117]. (a) Diagram of mechanism; (b) surface morphology of micropore

Fig. 13. Growth mechanism of bismuth-based nanosheets prepared by ultrasonic assisted liquid laser ablation^[134]

Fig. 14. Mechanism diagram of material removal by ultrasonic assisted laser polishing^[138]