Composition, microstructure and corrosion resistance of DED-LB additively manufactured Ti–6Al–4V alloy: Comparison with wrought alloy

The titanium alloy Ti–6Al–4V is widely used in medical applications due to its favourable mechanical properties, biocompatibility, and excellent corrosion resistance . This study aims to study the composition, structure and electrochemical behaviour of additively manufactured Ti–6Al–4V alloy produced by a directed-energy deposition of powder using a laser beam (DED-LB) and compare it to wrought alloy produced by conventional metallurgy . The surface morphology and composition of the chemo-mechanically polished wrought and DED-LB samples were analysed by X-ray diffraction, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, atomic force microscopy coupled with scanning Kelvin probe force microscopy and X-ray photoelectron spectroscopy. The electrochemical behaviour was assessed using potentiodynamic polarisation and electrochemical impedance spectroscopy in three simulated physiological solutions (Hanks' balanced salt solution, NaCl, and artificial saliva) at 37 °C. Both alloys show highly protective corrosion behaviour in the tested media, confirming that DED-LB Ti–6Al–4V is a promising alternative to conventional manufacturing methods for advanced metallurgical engineering applications . The alloys exhibit similar general chemical composition but different microstructure, with a lamellar αʼ-martensitic phase in the DED-LB fabricated alloy surrounded by prior β grains contrasting equiaxed α+β structure of the wrought alloy . Differences in microstructure are related to differences in local chemical composition, which affect the course of the corrosion when polarised to high positive potentials of 6 V Ag/AgCl .