Mechanical and in vitro study of an isotropic Ti6Al4V lattice structure fabricated using selective laser melting

This study presents an evaluation of the effects of pore diameter and porosity on the mechanical properties and biocompatibility of Ti6Al4V ELI periodic lattice structures, fabricated using SLM technology. Lattice structures of titanium alloys are in high demand for biomedical applications and are particularly useful as bone substitutes. A series of lattice structures with pore diameters of 500, 600, and 700 mu m and porosities of 60% and 70% were designed by repeating an octahedral unit cell. Based on SEM and micro-CT observations, good morphological agreement was detected between the original designs and the SLM-produced structures. Microstructural analysis using TEM showed that the typically acicular alpha' martensitic microstructure was obtained in the strut, which contributes to the brittle behavior of the lattice structure. Uniaxial compression tests were conducted, and the deformation behavior was recorded using a digital camera. Finite element analysis (FEA) of compression process was also conducted to enhance the understanding of the deformation mechanism. The surface chemistry of the lattice structure was analyzed using XPS methodology. The cytocompatibility of the lattice was also investigated with an in vitro test. The results show that the lattice structures with biocompatible surfaces have a comparable compressive strength (71-190 MPa) and elastic modulus (2.1-4.7 GPa) to trabecular bone. (C) 2018 Elsevier B.V. All rights reserved.