The effect of surface laser texturing on the corrosion performance of the biocompatible β-Ti12Mo6Zr2Fe alloy

Abstract

Laser materials processing is a very attractive technology, due not only to the vast number of applications in a wide range of materials and industrial segments but also due to the constant progress in the development of laser devices in terms of power, control, and costs. In metals processing technology, a high and precisely controlled density of energy concentrated in a small region imposes specific characteristics for the surface, keeping bulk properties unchanged. Alternatively, laser surface modification can result in outstanding surface properties to ordinary/low-cost metals. In the present work, the corrosion behavior of the Ti12Mo6Zr2Fe β-metastable alloy has been evaluated after laser surface melting and re-solidification under an inert atmosphere. It was found that this processing route produced significant metallurgical and chemistry changes on the surface of the alloy, including grain refinement and oxide formation. It resulted in a significant improvement in the corrosion properties in comparison to the passivated metal, as observed in potentiodynamic polarization curves and by electrochemical impedance spectroscopy (EIS) in simulated body fluid (SBF). Electrical equivalent circuit (EEC) modeling of impedance data suggests that a duplex porous/dense passive layer present in the untreated alloy enables the occurrence of charge-transfer mechanisms at some extension while a thicker oxide layer present after laser texturing increases the capacitive behavior of the surface.