Anisotropic mechanical behavior of biomedical Ti-13Nb-13Zr alloy manufactured by selective laser melting

The anisotropic microstructure and mechanical properties of Ti-13Nb-13Zr alloy via selective laser melting (SLM) are investigated for the first time in this study. Owing to the re-melting of the previous layer(s) and the thermal gradient, the prior 13 columnar grains grow in the building direction while scanning direction are mainly consist of finer equiaxed grains, which result in the higher nanohardness in horizontal section (5.18 +/- 0.2 GPa) than in vertical section (4.63 0.2 GPa). The as-fabricated longitudinal samples show slight higher ultimate tensile strength (UTS) (1020 +/- 15 MPa) and yield strength (YS) (794.63 +/- 15 MPa) than transverse samples (UTS of 996 +/- 13 MPa and YS of 794 +/- 15 MPa) because of the enhancement of twins in vertical section. The SLM processed samples show no element segregation because of the complete melting and repeatedly re-melting, and the refined microstructure due to the high cooling rate in SLM process, which make the tensile strength superior higher than those obtained by powder metallurgy (750 MPa). Owing to the columnar grain morphology, in building direction, the failure can be postponed, which results in the longitudinal samples (6.5 +/- 0.3%) exhibit higher ductility than transverse samples (5 +/- 0.3%). (C) 2018 Elsevier B.V. All rights reserved.