Fig. 1. Schematic process principle of conventional laser direct deposition and high-speed laser direct deposition^[5]

Fig. 2. Influence of carrier gas flow rate on powder beam convergence characteristics. (a) Powder spot diameter; (b) powder spot distance; (c) peak mass concentration of powder

Fig. 3. Influence of powder feed rate on powder beam convergence characteristics. (a) Powder spot diameter; （b） powder spot distance； （c） peak mass concentration of powder

Fig. 4. Comparison of single-pass deposition layers with different process parameters under constant heat input and mass energy^[13]. (a) P = 400 W, v = 400 mm/min; (b) P = 500 W, v = 500 mm/min; (c) P = 750 W, v =750 mm/min; (d) P = 900 W, v = 900 mm/min

Fig. 5. 3D profiles of laser direct deposition surfaces ^[15]. (a) P = 400 W, v = 0.2 m/min; (b) P = 500 W, v = 0.4 m/min

Fig. 6. Change of microstructure of sedimentary layer with laser power^[26]. (a) Bonding zone; (b) deposition zone

Fig. 7. Change of microstructure of sedimentary layer with scanning speed^[26]. （a） Bonding zone； （b） deposition zone

Fig. 8. Morphology of Laves phase particles^[32]. (a) 1 kW; (b) 3.5 kW

Fig. 9. Section morphology of massive deposition samples under different laser powers and scanning speeds^[13].（a） P=400 W， v=400 mm/min； （b） P=500 W， v=500 mm/min； （c） P=750 W， v=750 mm/min； （d） P=900 W， v=900 mm/min

Fig. 10. Cross section and hot crack of additive alloy with different laser scanning speed and heat input^[22].（a） 2 mm/s， 500 J/mm； （b） 3 mm/s， 500 J/mm； （c） 4 mm/s， 500 J/mm； （d） 5 mm/s， 500 J/mm； （e） 6 mm/s， 500 J/mm； （f） 5 mm/s， 300 J/mm； （g） 5 mm/s， 400 J/mm； （h） 5 mm/s， 560 J/mm； （i） 5 mm/s， 600 J/mm

Fig. 11. Thermal cracks in long chain Laves phase in Inconel 718 deposited samples^[32]

Fig. 12. Curve of hardness change^[37]. (a) Different laser powers; (b) different scanning speeds

Fig. 13. Macroscopic morphology of section of sediment layer^[41]. (a) High-speed laser cladding; (b) conventional laser cladding

Fig. 14. Macro morphology and surface detection of sediment layer^[52]. (a) Conventional laser cladding; (b) high-speed laser cladding

Fig. 15. Microstructure of high-speed laser cladding deposition layer and traditional laser cladding deposition layer^[48]. (a) High-speed laser cladding; (b) conventional laser cladding

Fig. 16. EBSD results of high-speed laser cladding K648 superalloy deposition layer^[49]

Fig. 17. Hardness distribution of high-speed laser cladding and conventional laser cladding layer^[52]

Table 1. Comparison of process parameters and microstructure properties between conventional laser direct deposition and high-speed laser direct deposition^[4]