Fig. 1. Morphology and particle size distribution of Ti6Al7Nb alloy powder. (a) Powder morphology; (b) particle size distribution

Fig. 2. Photos of rectangular and tensile samples as well as machining dimension diagram of standard tensile sample. (a) Rectangular sample photo; (b) machining dimension diagram of tensile sample; (c) tensile sample photo

Fig. 3. Relative density of Ti6Al7Nb alloy formed under different process parameters

Fig. 4. Influence of main LPBF forming parameters of on relative density. (a) Effect of scanning speed on relative density; (b) effect of hatching spacing on relative density; (c) effect of laser power on relative density

Fig. 5. XRD patterns of Ti6Al7Nb alloy samples. (a) XRD patterns of as-built and heat-treated samples; (b) enlarged illustration of the shaded portion in Fig. (a)

Fig. 6. SEM comparison of XZ surface of Ti6Al7Nb alloy before and after aging treatment

Fig. 7. Morphology statistics of α phase in Ti6Al7Nb alloy in different heat treatment states. (a) Aspect ratio of phase α;

Fig. 8. Microstructures of as-built Ti6Al7Nb alloy at optimum process parameters. (a) Optical microscopy image; (b)‒(c) SEM images

Fig. 9. OM and SEM images of XZ plane of Ti6Al7Nb alloy in solid solution state. (a) S1-OM; (b) S2-OM; (c) S3-OM; (d) S1-SEM; (e) S2-SEM; (f) S3-SEM

Fig. 10. OM and SEM images of XZ plane of Ti6Al7Nb alloy in solid solution and aging state. (a) SA1-OM; (b) SA2-OM; (c) SA3-OM; (d) SA1-SEM; (e) SA2-SEM; (f) SA3-SEM

Fig. 11. Hardness of Ti6Al7Nb alloy before and after heat treatment

Fig. 12. Tensile properties at room temperature and stress‒strain curves of Ti6Al7Nb alloy before and after heat treatment

Fig. 13. Tensile fracture morphology at room temperature of LPBF samples in as-built and heat treatment states. (a)‒(d) Tensile fracture of the sample in as-built state; (e)‒(f) tensile fracture of S1 sample; (g)‒(h) tensile fracture of SA1 sample; (i)‒(j) tensile fracture of S2 sample; (k)‒(l) tensile fracture of SA2 sample; (m)‒(n) tensile fracture of S3 sample; (o)‒(p) tensile fracture of SA3 sample