Fig. 1. Typical thermal cracks^[35-37]. (a)(b) Solidification cracks with irregular dendritic morphology; (c)(d) liquefaction cracks without dendritic characteristics; (e)(f) solidification cracks; (g)(h) morphology and dislocation maps of the liquefaction crack region; (i)‒(k) single pass of LPBFed AA7075 alloy shows different pool shapes and thermal crack sensitivities

Fig. 2. Typical pores^[32,57-58]. (a) Unfused and metallurgical pores; (b) keyhole pore; (c) shrinkage pores; (d) schematic diagrams of pore formation mechanism in LDED process

Fig. 3. Principle of high flux forming^[74]

Fig. 4. High entropy alloy phase with high flux forming^[74]. (a) XRD patterns; (b) measured composition versus predicted composition; (c) SEM image and elemental mapping

Fig. 5. Backscatter image of sample section and grain direction of welded structure section obtained by electron backscatter diffraction (EBSD)

Fig. 6. Tensile property curves of TiNbCrVNi alloy^[90]

Fig. 7. Cross-section morphology of thin-walled parts under different process parameters^[84]. (a) 2.8 J/mm; (b) 3.2 J/mm; (c) 3.6 J/mm; (d) 4.0 J/mm; (e) 4.4 J/mm

Fig. 8. Performance test results of the samples under different processing parameters^[84]. (a) Average microhardness of alloy cross-section; (b) engineering stress-strain curves of the alloy under compression at room temperature

Fig. 9. LPBF forming process and geometric relationship between parameters^[72]. (a) Simplified LPBF forming process. Geometric relationship between the layer thickness c and the channel spacing d for the following cases: (b)ml¯ <c, (c)ml¯ >c, and (d)ml¯ =c

Fig. 10. Temperature distribution in the micro-region (4 mm×2 mm×1 mm) around the 200 s laser spot of LPBF process^[92]

Fig. 11. LPBF formed samples^[89]

Fig. 12. Tensile samples formed by LPBF(after polishing)^[89]

Fig. 13. Original sample formed by LDED^[76]

Fig. 14. Warping deformation of HEA formed by LPBF without improvement^[92]

Fig. 15. Samples formed by improved LPBF forming ^[92]

Fig. 16. Z-shape (left) and strip (right) scanning strategies^[93]

Fig. 17. Nb₃Ta₃Mo(Ti₂Ni)₃ high entropy alloy impeller entity formed by LPBF^[93]