Hybrid additive manufacturing of biocompatible Ti–Ta composite structures for biomedical applications

Rapid advances in 3D hybrid additive manufacturing have provided opportunities to the use of Ta as a highly effective biomaterial. In this study, we used electron beam melting (EBM) process to fabricate Ti–6Al–4V 3D structures (EBM-Ti64) and then applied cold spray additive manufacturing to deposit commercially pure (CP) Ti, Ti–Ta composite and pure Ta coatings on the EBM-Ti64 substrate to explore the biocompatibility of Ti–Ta composite structures through hybrid additive manufacturing. The microstructure, microhardness, corrosion resistance and biocompatibility were evaluated. Feedstock powders and process parameters of cold spray determine the microstructures of the deposited coating. Microhardness and indentation testing of Ti–Ta composite reveal the weight ratio of Ta influences the microhardness. In particular, higher corrosion resistance was achieved on cold sprayed Ti–30%Ta composite compared to CP Ti and pure Ta coatings. Moreover, live/dead and MTS assay demonstrate that the cold sprayed coatings were non-toxic, while the EBM-Ti64 substrate shows some cytotoxicity signs which might be related to the released toxic ions. This study confirms the biocompatible Ti–Ta composite structures can be manufactured through a combination of EBM and cold spray, opening opportunities for the rapid hybrid manufacture of biocompatible implants. Graphic abstract: [Figure not available: see fulltext.].