Mechanical anisotropy of laser powder bed fusion fabricated Ti-41Nb alloy using pre-alloyed powder: Roles played by grain morphology and crystallographic orientation

Abstract

This work investigated the influence of the grain morphology and crystallographic orientation on the mechanical anisotropy of a laser powder bed fusion produced (L-PBFed) Ti-41 Nb alloy using pre-alloyed alloy for dental implants. The microstructure of L-PBFed Ti-41Nb alloy consists of columnar grains of a high aspect ratio with a strong< 001 > preferred orientation along the building direction (BD). To evaluate the mechanical anisotropy of L-PBFed Ti-41 Nb alloy, the external loading was compressed either perpendicular or parallel to BD (i.e., horizontal and vertical samples, respectively). Compression results show that the compressive yield strength (CYS) of horizontal samples is significantly higher than that of vertical samples. At the early stage of deformation, obvious {332}< 113 > mechanical twins are preferentially detected in the nearly< 001 > orientated grains along the compression axis. The dominant reasons for the lower CYS of vertical samples can be attributed to the easier activation of {332}〈113〉 mechanical twins in the typical columnar grains with strong< 001 > crystallographic orientation. It is suggested that the anisotropy of the L-PBFed alloy can be utilized through simple position control such as adjustment of the BD and reasonable structural design.