Corrosion studies on Fe‐30Mn‐1C alloy in chloride‐containing solutions with view to biomedical application

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 °C under laminar flow. Potentiodynamic polarization tests were conducted in Tris‐buffered simulated body fluid (SBF), in Tris‐buffered saline (TBS) and in 150–0.15 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.

Biodegradable Iron-Based Materials—What Was Done and What More Can Be Done?

“…TWIP steels have excellent strength and ductility. The studies confirmed that TWIP (Fe-Mn-C) alloys degrade in a physiological environment [134][135][136][137].…”

Effect of Selective Laser Melting on Microstructure, Mechanical, and Corrosion Properties of Biodegradable FeMnCS for Implant Applications

“…In Figure 6b, a SEM image of a FeMnCS (SLM) sample surface after 7 days of static immersion in SBF is shown with a relatively homogenous layer of corrosion products. According to EDX studies (Figure 6c-f ), by revealing a high concentration of Ca, P, and O in the layer as well as to previous X-ray photoelectron spectroscopy (XPS) studies of cast Fe-30Mn-1C-0.025S surfaces [11,42] and further investigations of FeMn-based alloys immersed in pseudo-physiological solutions, [8,10] the formation of hydroxyapatite can be assumed. Also, salt precipitations and the formation of oxides are quite probable.…”

“…[7,10,11,42] In contrast to SLM-processed FeMnCS, the cast dual-phase FeMnCS alloy shows a combination of uniform and localized corrosion, leading to a stronger corrosive attack, whereby the analysis of the fundamental corrosion process was presented in previous studies. [11,42] This can be attributed to the enrichment of the most reactive Mn and depletion of Fe along the austenite grain boundaries, which promote the corrosion attack along these areas. Furthermore, finely distributed manganese sulfide precipitates in the cast modification ( Figure 2d) dissolve preferentially in SBF and are initiation sites for pitting corrosion.…”

Biodegradation behaviour of Fe-based alloys in Hanks’ Balanced Salt Solutions: Part II. The evolution of local pH and dissolved oxygen concentration at metal interface

“…Moreover, Dargusch, Dehghan-Manshadi, Shahbazi, Venezuela, Tran, Song, Liu, Xu, Ye and Wen [ 17 ] claimed that the corrosion rates of Fe–Mn alloys increased with increments in Mn content while the corrosion rates derived from potentiodynamic curves were consistent with those obtained from the immersion tests. They also pointed out that while the presence of Fe and Mn oxides post degradation had been consistent across various studies [ 11 , 12 , 14 , [17] , [18] , [19] , [20] , [21] , [22] , [23] ], the presence of Fe/Mn phosphates, has not been consistently observed despite the mention of phosphorus among detected elements in corrosion products [ 5 , 14 ]. The state-of-art on the degradation of Fe–Mn alloys reviewed here clearly highlights that there is a lacuna of knowledge in the field.…”

“…The exact effect of such inclusions on the degradation rate of FeMn-based alloys has not yet been investigated, however Hermawan et al [ 19 ] suggested their potential at triggering micro-galvanic corrosion by providing microsites with different potential than the base metal. Besides these aspects, elemental segregation at grain, or particle boundaries, has been shown to have positive effects on corrosion acceleration for both powder-processed Fe30Mn microstructures [ 39 ] as well as induction melted Fe30Mn1C [ 18 ]. Similarly, tuning the grain sizes also has a marked effect on the degradation rate of both powder-processed [ 29 ] and wrought [ 40 ] Fe-based materials.…”