Microstructure and electrochemical corrosion behavior of TA2 with nano/micro TiC particle reinforcement

Abstract

TA2 pure titanium (Titan Grade 2-EN) is commonly used in marine and biomedical applications due to its outstanding biocompatibility and resistance to corrosion. Nevertheless, the limited hardness of TA2 presently reduces the service life of the components. Directed energy deposition (DED) technology can improve the properties of conformal materials, opening up new possibilities. In this work, 8% micro-TiC/TA2, 8% nano-TiC/TA2, and 4% micro/4% nano-TiC/TA2 composites were fabricated by DED to investigate the effects of different scales of TiC reinforcement on the properties of TA2. The majority of micro-TiC remaining unfused in the composite, exhibiting only a small amount of micro-TiC dissolution. In comparison, the nano-TiC/TA2 displays a conspicuous dendritic structure with well-developed dendritic growth, boasting up to three dendrites. In contrast, the 4%micro/4%nano-TiC/TA2 exhibits a mixed crystal morphology, characterized predominantly by dendritic growth along the unmelted TiC, with other TiC phases also present in the deposited layer. Performance tests demonstrated that TiC can increase the microhardness of titanium. The 4% micro/4% nano-TiC/TA2 composite achieved the highest average microhardness of 542 HV0.2, representing a 160.58% increase compared to TA2. Additionally, the composites demonstrated improved corrosion resistance relative to TA2, with the 8% micro-TiC/TA2 composite exhibiting the best corrosion resistance. This outcome can be attributed to the effective physical barrier properties of the micron-sized TiC.