Comparative Analysis of Corrosion and Biocompatibility of Ni45Ti55 and SS316L Steel Deposited by Micro-Plasma Additive Manufacturing Process

Abstract

This study presents a comparative investigation of Ni45Ti55 and SS316L alloys deposited via micro-plasma additive manufacturing (MPAM), with emphasis on corrosion resistance, electrochemical behavior, ion release, and cell viability. Electrochemical analyses, including potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), demonstrated that Ni45Ti55 exhibits a lower corrosion current density and higher polarization resistance than SS316L, confirming its superior passivation and slower corrosion kinetics. The enhanced resistance of Ni45Ti55 is attributed to the formation of a stable and protective titanium oxide (TiO<inf>2</inf>) layer, whereas SS316L relies on a chromium-rich oxide film that offers moderate stability but is more vulnerable under aggressive physiological conditions. Cell viability assessments further revealed that Ni45Ti55 is more biocompatible, as its TiO<inf>2</inf> layer effectively suppresses metallic ion leaching. In contrast, SS316L released higher amounts of Fe, Cr, and Ni ions, which are associated with cytotoxic and pro-inflammatory responses. Notably, Ni45Ti55 showed significantly reduced ion release, underscoring its long-term durability and suitability for biomedical environments. To the best of our knowledge, this is the first report directly correlating ion leaching with cell viability for MPAM-processed NiTi and SS316L alloys, thereby providing new insights into their corrosion mechanisms and biomedical applicability. © 2025 Elsevier B.V., All rights reserved.