On the microstructure and corrosion behaviors of selective laser melted CP-Ti and Ti-6Al-4V alloy in Hank’s artificial body fluid

In order to elucidate the distinct corrosion properties of CP-Ti and Ti-6Al-4V alloys manufactured by selective laser melting (SLM) as biomaterials in human body fluids. Electrochemical measurements were carried out to investigate the corrosion behaviors of SLM-produced CP-Ti and Ti-6Al-4V alloys in artificial simulated body fluid (Hank's solution). The results show that SLM-produced CP-Ti possesses better corrosion resistance compared with Ti-6Al-4V alloy in Hank's solution. The microstructural characteristics reveal that the SLM-produced CP-Ti consisting of single α -Ti phase benefits the formation of compact and stable passive film on samples, thereby effectively inhibiting attack of corrosive ions on titanium matrix. However, the inferior corrosion resistance of SLM-produced Ti-6Al-4V alloy is attributed to the overwhelmingly large amount of acicular α , martensite in microstructure. The high-energy α ' martensite enhances the anodic activity in corresponding solution environments. Less β -Ti phase in the microstructure weakens the stability of passive film and results in the formation of numerous galvanic cell, consequently inducing the higher corrosion rate.