Enhanced corrosion resistance of Ti-5 wt.% TiN composite compared to commercial pure Ti produced by selective laser melting in HCl solution

Abstract In order to further improve the corrosion resistance of commercial pure titanium (CP–Ti), the ex-situ formed Ti-5 wt.% TiN composite was developed by selective laser melting (SLM) and the corrosion behavior of the SLM-produced CP-Ti and Ti-5 wt.% TiN composite in 0.5 M HCl solution was investigated. The results show that the Ti-5 wt.% TiN composite consists of α′-Ti, δ-TiN and e-Ti2N, where the acicular α′ martensite (∼0.73 μm) is much smaller than that (∼1.37 μm) in the CP-Ti. The passive film formed on the surface of the Ti-5 wt.% TiN composite and CP-Ti is mainly composed of TiO2. However, the Ti-5 wt.% TiN composite exhibits higher corrosion resistance than the CP-Ti, which is attributed to the fact that TiN as the micro-cathode preferentially induces the composite to enter the passivation state. The immersing tests also confirmed that the addition of 5 wt% TiN can efficiently improve the corrosion resistance of CP-Ti.