Fig. 1 Dominant physical phenomena during melting [45]

Fig. 2 a A schematic represents in situ heat treatment during the laser remelts; b a 3D morphology of LPBF-ed Ti–12Mo–6Zr–2Fe sample; c bright-field TEM image of a selected area containing α″ phase; d the SAED pattern along the [$\overline{1 }$11]β zone axis collected from the black dotted circle in c showing the orientation relationship of [$\overline{1 }$10]α″//[$\overline{1 }$11]β; e–h EDX elemental maps of Ti, Mo, Zr, and Fe collected from c, respectively; i the engineering (solid lines) and true (dotted lines) stress–strain curves of as-fabricated simple-scanned (AF-SS), (chess-scanned) AF-CS, and (solution heat-treated chess-scanned) ST–CS Ti–12Mo–6Zr–2Fe alloys [61]

Fig. 3 Lamellar mechanical twins in LPBF-ed Ti-35Nb-7Zr-5Ta alloy before a, b and after c, d deformation, e schematic illustration of interaction mechanism between twin and dislocation during tensile deformation, f tensile yield strength vs elongation of the Ti-35Nb-7Zr-5Ta alloy samples and other representative β-Ti alloys fabricated by various materials processing methods [28]

Fig. 4 a Schematic diagram of microstructure evolution and globularization mechanism with different heat treatment times, TEM morphology of the LPBF-ed b and heat-treated c Ti-Nb-Zr-Ta-Si alloys, d yield strength and elongation to failure of Ti-Nb-Zr-Ta alloys and Ti-Nb-Zr-Ta-Si alloys [65]

Fig. 5 a, c Inverse pole figure (IPF) images taken in the three orthogonal planes. b, d $\left\{001\right\}$ and $\left\{011\right\}$ pole figures of the products measured in the y–z plane [84]

Fig. 6 a Schematic of MTCDS technique. Points B and E are the intersections between the top and bottom layers. Points B and C are the intersections between the left and right adjacent melt pools. The melt pool angle θ is the angle between line CD and the horizontal direction. The columnar grain angle α is the angle between the GDCG and the horizontal direction. The TGD is normal to the melt pool boundary and approximately normal to line CD. b, c SEM and EBSD images of single melt track. d-g Inverse pole figure and h-k 〈001〉 pole figure of 〈001〉 dendrites with different spatial orientation. l The elastic modulus along the construction direction with the 〈001〉 crystallographic orientation. m Letters S, C, U, and T produced by scanning speeds of 600, 800, 1000, and 1400 mm/s, respectively, exhibiting different deviation angles relative to the building direction. The surrounding matrix is produced at the scanning speed of 1400 mm/s [96]

Fig. 7 Corrosion behavior and characteristics of passive films of laser powder bed fusion produced Ti-6Al-4V in static and dynamic Hank’s solution [100]