Bio-tribocorrosive performance of additively manufactured Ti-6Al-4 V alloy via laser powder bed fusion (L-PBF)

The tribocorrosion behaviour and performance of Ti-6Al-4 V alloy produced by laser powder bed fusion (L-PBF) was investigated in a simulated body-fluid environment and compared with that of the conventionally made alloy. The additively manufactured alloy included two main categories namely: as-printed and post-thermal treated samples (stress-relieved and annealed). Using a custom-designed tribometer, all the samples were tested in phosphate buffered saline plus 2 g/L Albumin solution under open circuit potential (OCP) and potentiostatic condition at 0.4 V/V_Ag/AgCl at sliding magnitude of 3 mm and frequency of 3 Hz for 5000 cycles. The key results included total, chemical, and mechanical volume losses together with surface damage characteristics of different samples. The L-PBF samples showed a much better tribocorrosion performance under both OCP and potentiostatic conditions when compared to the conventional alloy. As-printed samples showed a volume loss which was 60–70% of the volume loss measured for the conventional samples. The tribocorrosion performance of the as-printed sample was slightly improved by the annealing treatment, (around 5%), and the annealed samples showed a much better corrosion resistance and more stable oxide films. It is believed that the electrochemical reactions at the rubbed interface of the annealed samples played a significant role in improving their tribocorrosion resistance.