Corrosion studies on Fe-30Mn-1C alloy in chloridecontaining solutions with view to biomedical application

TL;DR

This study investigates the corrosion behavior of Fe-30Mn-1C alloy in chloride solutions at body temperature, revealing active dissolution and preferential grain boundary corrosion, with implications for biodegradable biomedical implants.

Contribution

It provides a comprehensive electrochemical and surface analysis of FeMnC alloy in simulated body fluids, highlighting its corrosion mechanisms and effects of buffer solutions, advancing biodegradable implant material research.

Findings

FeMnC shows active dissolution in all tested electrolytes.

Corrosion occurs preferentially along Mn-rich grain boundaries.

Surface coatings are hindered by dissolution processes.

Abstract

Austenitic Fe-30Mn-1C (FeMnC) is a prospective biodegradable implant material combining high mechanical integrity with adequate corrosion rates. The fast solidified TWIP alloy, its constituents and 316L stainless steel were electrochemically analysed in various electrolytes at 37 {\deg}C under laminar flow. Potentiodynamic polarization tests were conducted in Trisbuffered simulated body fluid (SBF), in Tris-buffered saline (TBS) and in 150 mM - 0.15 mM NaCl solutions (pH 7.6, 10, 5, 2) to study initial corrosion stages. Active dissolution of FeMnC is revealed in all electrolytes and is discussed on basis of the Fe and Mn behaviour plus is compared to that of 316L. The role of Tris (Tris(hydroxymethyl)aminomethane) as organic buffer for SBFs is critically assessed, particularly with view to the sensitivity of Fe. SEM studies of FeMnC corroded in NaCl revealed preferential dissolution along Mn-rich grain boundary regions. Static immersion tests of FeMnC in SBF with surface and solution analyses (SEM/EDX, XPS, ICP-OES) indicated that dissolution processes interfere with the formation of permeable surface coatings comprising hydroxides and salts.