Comparison and evolution of Ti6Al4V bioalloy fabricated by laser and electron beam additive manufacturing: Mechanical features and anisotropic electrochemical properties

With current technology, most biomedical implants are made using metal-based alloys, with a growing preference for metal additive manufacturing (AM) to achieve customized properties. Therefore, this study investigated Ti-6Al-4V (Ti64) alloys produced using two common AM techniques: electron beam melting (EBM) and selective laser melting (SLM). The aim is to compare the microstructure, mechanical properties, and anisotropy electrochemical corrosion behavior of Ti64 samples scanned with SLM-XX, SLM-XY, and EBM-XX strategies. Surface roughness, microstructure, and microhardness tests were conducted to establish correlations with the manufacturing process and surface characteristics. Optical and scanning electron microscopy microstructural analysis revealed notable variations influencing mechanical performance. Moreover, anisotropy-assessing electrochemical corrosion evaluations showed that SLM samples exhibited superior corrosion resistance compared to EBM samples. Notably, the (YZ) planes in the SLM-XY sample demonstrated the highest corrosion resistance (Rct-4.45 x106 Omega.cm2), attributed to reduced dislocation density and enhanced passivation. Furthermore, results showed that the method of fabrication affected the wettability of Ti64 alloys. The SLM-XY samples exhibited the lowest water contact angle (84.45 degrees), whereas the EBM samples showed the highest (99.87 degrees). Finally, bioactivity assessments after 21 days in simulated body fluid (SBF) revealed no cracking or surface damage in any of the tested samples. The formation of calcium-and phosphorus-rich deposits indicates their potential suitability for orthopedic applications.