Surface treatment of Fe63Mn27Si4Cr6 shape memory alloy at varied plasma powers for enhancement of the corrosion resistance, mechanical, and tribological properties

Abstract

Iron-based shape memory alloys (Fe-SMAs) are used in civil engineering. However, acid-induced corrosion is a major concern for such applications. In this study, the surfaces of shape memory Fe63Mn27Si4Cr6 alloy samples were treated with plasma at different powers (300–450 W). The treatment procedure was accomplished via applying a gaseous mixture containing 90 % nitrogen and 10 % acetylene. The structure, the phase-type, the chemical composition, and mechanical and tribological features were investigated by optical microscopy, surface profile, X-ray diffraction (XRD), microhardness techniques, and oscillating ball-on-disk tribometer. The treated surface specimens revealed a significant micro-hardness of about 725 HV0.1 compared to the pristine one (220 HV0.1). The wear and corrosion characteristics of the uncoated and coated modified specimens were studied by potentiodynamic corrosion resistance (PDR) and electrochemical impedance spectroscopy (EIS) in a highly corrosive media (1.0 M HCl). The obtained findings showed that the treated surfaces improved the corrosion resistance of Fe-MSC. This improvement increased when the plasma processing powers were augmented. At 450 W, the coated Fe-MSC specimen exhibited the highest protective capacity value (99.9 %). The surface morphology examination by scanning electron microscopy (SEM) exhibits an improved corrosion resistance for the modified Fe-MSC specimens, especially at the higher power of plasma processing.