Additively manufactured porous Ti6Al4V Alloy with excellent mechanical properties, corrosion resistance, in vitro and in vivo biocompatibility

In view of the insufficient bearing capacity of porous Ti6Al4V (TC4) alloy, four kinds of porous TC4 alloys with a wall thickness of 200 mu m and a side length ranging from 400 to 700 mu m were designed and subsequently prepared by Additive Manufacturing (Selective Laser Melting, SLM). The results indicated that the porous TC4 alloy was primarily comprised of alpha' phase and a small amount of beta phase. As the side length increased, the size and volume of the acicular alpha' phase increased while the beta phase decreased. Besides, the dislocation density also increased with the increase of side length. The porous TC4 alloy with a side length of 700 mu m exhibited the maximum dislocation density of 6.07x1014 m2. The yield strength and elastic modulus initially decreased and then increased with the increase of side length. Moreover, the increase in side length induced the decrease of Icorr from 1.807 x 10-6 to 4.777 x 10- 7 A/cm2, especially that sample 7-2 presented the best corrosion resistance with the smallest Icorr value (4.777 x 10- 7 A/cm2). It was observed by in vitro assessment that the optical density (OD) of the porous TC4 alloys surpassed 75 % on days 1, 4, and 7. It was noteworthy that the OD value of the porous TC4 alloys with a side length of 700 mu m surpassed 100 % on day 7. Furthermore, the number of adherent cells displayed an increasing trend with the increase in side length. After implanting into the alveolar bone of rabbits at 12th week, the porous TC4 alloy with a side length of 700 mu m induced bone growth due to a higher percentage of bone volume compared to the dental implant. After 12 weeks of in vivo experiments, the results showed that the porous TC4 alloy could reduce the inflammatory response, promote the growth of bone tissue, and have excellent osteogenic properties.