Fig.1 SEM micrographs showing the morphologies of a Ti6Al4V powders; b TiB2 powders; c Ti6Al4V + 3 wt% TiB2 powders; d a magnification figure of c

Fig.2 a A process window; b, c surface appearance of the as-built samples

Fig.3 OM and SEM micrographs of cracks in the as-built samples with 3 wt% TiB2 on the longitudinal section at varied energy densities: a, e 156.25 J/mm3; b-d 104.17 J/mm3

Fig.4 SEM micrograph displaying the morphology of side wall of the cracked position

Fig.5 Line graphs showing the variation of density with the content of TiB2 and optical micrographs showing the appearance of pores and cracks at different energy densities

Fig.6 Variation of Gibbs free energy ΔG with temperature

Fig.7 Partial section of the Ti-B binary phase diagram

Fig.8 XRD patterns of the as-built TiB/Ti6Al4V composites with different contents of TiB2

Fig.9 EDS images showing the cross section of the as-built TiB/Ti6Al4V composites

Fig.10 SEM micrographs on the cross and longitudinal sections displaying the morphologies of matrix and TiB needles for the as-built samples at the energy density of 416.67 J/mm3: a, e 1 wt%, cross section; b, f 3 wt%, cross section; c, g 1 wt%, longitudinal section; d, h 3 wt%, longitudinal section

Fig.11 SEM micrographs on the cross section showing the microstructures of the as-built samples with 1 wt% TiB2 and the morphology of TiB phase at varied energy densities: a, e 416.67 J/mm3; b, f 250 J/mm3; c, g 156.25 J/mm3; d, h 104.17 J/mm3

Fig.12 SEM micrographs showing the microstructures of the as-built samples with 1 wt% TiB2 on the longitudinal section at varied energy densities: a 416.67 J/mm3; b 250 J/mm3; c 156.25 J/mm3; d 104.17 J/mm3

Fig.13 Vickers microhardness of the as-built samples with different additions of TiB2 at different energy densities

Fig.14 Variation of friction coefficient with different additions of TiB2

Fig.15 SEM morphologies of the worn surfaces for the as-built samples: a, d Ti6Al4V; b, e 1 wt% TiB/Ti6Al4V; c, f 3 wt% TiB/Ti6Al4V