Iron-manganese Alloys Research Articles

Study of the effect of magnetic fields on static degradation of Fe and Fe-12Mn-1.2C in balanced salts modified Hanks’ solution

Iron and its alloys are attractive as biodegradable materials because of their low toxicity and suitable mechanical properties; however, they generally have a slow degradation rate. Given that corrosion is an electrochemical phenomenon where an exchange of electrons takes place, the application of magnetic fields from outside the body may accelerate the degradation of a ferrous temporary implant. In the present study, we have investigated the effect of alternating and direct low magnetic field (H = 6.5 kA/m) on the corrosion process of pure iron (Fe) and an iron-manganese alloy (FeMnC) in modified Hanks' solution. A 14-day static immersion test was performed on the materials. The corrosion rate was assessed by mass and cross-sectional loss measurements, scanning electron microscopy, X-ray diffractometry, Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy before and after degradation. The results show that the presence of magnetic fields significantly accelerates the degradation rate of both materials, with the corrosion rate being twice as high in the case of Fe and almost three times as high for FeMnC. In addition, a homogenous degradation layer is formed over the entire surface and the chemical composition of the degradation products is the same regardless of the presence of a magnetic field.

In Vitro Assessment of the Neuro-Compatibility of Fe-20Mn as a Potential Bioresorbable Material for Craniofacial Surgery.

Background and Objectives: Spring-assisted surgery is a popular option for the treatment of non-syndromic craniosynostosis. The main drawback of this procedure is the need for a second surgery for spring removal, which could be avoided if a distractor material could be metabolised over time. Iron-Manganese alloys (FeMn) have a good trade-off between degradation rate and strength; however, their biocompatibility is still debated. Materials and Methods: In this study, the neuro-compatibility of Fe-20Mn (wt.%) was assessed using standard assays. PC-12 cells were exposed to Fe-20Mn (wt.%) and stainless steel via indirect contact. To examine the cytotoxicity, a Cell Tox Green assay was carried out after 1, 2, and 3 days of incubation. Following differentiation, a neurite morphological examination after 1 and 7 days of incubation time was carried out. The degradation response in modified Hank's solution at 1, 3, and 7 days was investigated, too. Results: The cytotoxicity assay showed a higher toxicity of Fe-20Mn than stainless steel at earlier time points; however, at the latest time point, no differences were found. Neurite morphology was similar for cells exposed to Fe-20Mn and stainless steel. Conclusions: In conclusion, the Fe-20Mn alloy shows promising neuro-compatibility. Future studies will focus on in vivo studies to confirm the cellular response to Fe-20Mn.

Biodegradation-affected fatigue behavior of extrusion-based additively manufactured porous iron–manganese scaffolds

Additively manufactured (AM) biodegradable porous iron-manganese (FeMn) alloys have recently been developed as promising bone-substituting biomaterials. However, their corrosion fatigue behavior has not yet been studied. Here, we present the first study on the corrosion fatigue behavior of an extrusion-based AM porous Fe35Mn alloy under cyclic loading in air and in the revised simulated body fluid (r-SBF), including the fatigue crack morphology and distribution in the porous structure. We hypothesized that the fatigue behavior of the architected AM Fe35Mn alloy would be strongly affected by the simultaneous biodegradation process. We defined the endurance limit as the maximum stress at which the scaffolds could undergo 3 million loading cycles without failure. The endurance limit of the scaffolds was determined to be 90 % of their yield strength in air, but only 60 % in r-SBF. No notable crack formation in the specimens tested in air was observed even after loading up to 90 % of their yield strength. As for the specimens tested in r-SBF, however, cracks formed in the specimens subjected to loads exceeding 60 % of their yield strength appeared to initiate on the periphery and propagate toward the internal struts. Altogether, the results show that the extrusion-based AM porous Fe35Mn alloy is capable of tolerating up to 60 % of its yield strength for up to 3 million cycles, which corresponds to 1.5 years of use of load-bearing implants subjected to repetitive gait cycles. The fatigue performance of the alloy thus further enhances its potential for trabecular bone substitution subjected to cyclic compressive loading. Statement of significanceFatigue behavior of extrusion-based AM porous Fe35Mn alloy scaffolds in air and revised simulated body fluid was studied. The Fe35Mn alloy scaffolds endured 90 % of their yield strength for up to 3 × 106 loading cycles in air. Moreover, the scaffolds tolerated 3 × 106 loading cycles at 60 % of their yield strength in revised simulated body fluid. The Fe35Mn alloy scaffolds exhibited a capacity of withstanding 1.5-year physiological loading when used as bone implants.

Magnetic field effect on the dielectric behavior in SrRuO3/Ba(Zr0.3Ti0.7)O3/FeMn/ Ba(Zr0.3Ti0.7)O3/n-Si heterostructure

Interfacial structure plays a dominant role in physical properties of the oxides and their film. In this study, SrRuO3/Ba(Zr0.3Ti0.7)O3/FeMn/Ba(Zr0.3Ti0.7)O3/n-Si heterostructure was fabricated by utilizing pulsed laser deposition technique. The X-ray diffraction was utilized to analyze the multilayers’ crystalline. Dielectric properties of the heterostructure were studied under various magnetic fields. Giant magnetocapacitance characteristic was gained from the heterostructure. It is found that the interfacial polarization between barium zirconate titanate film and iron manganese alloy film is responsible for giant magnetocapacitance. A possible dielectric polarization mechanism was investigated. This work can provide guidance for the development of the multi-functional memory device.

Extrusion-based 3D printing of ex situ-alloyed highly biodegradable MRI-friendly porous iron-manganese scaffolds

Additively manufactured biodegradable porous iron has been only very recently demonstrated. Two major limitations of such a biomaterial are very low biodegradability and incompatibility with magnetic resonance imaging (MRI). Here, we present a novel biomaterial that resolves both of those limitations. We used extrusion-based 3D printing to fabricate ex situ-alloyed biodegradable iron-manganese scaffolds that are non-ferromagnetic and exhibit enhanced rates of biodegradation. We developed ink formulations containing iron and 25, 30, or 35 wt% manganese powders, and debinding and sintering process to achieve Fe-Mn scaffolds with 69% porosity. The Fe25Mn scaffolds had the ε-martensite and γ-austenite phases, while the Fe30Mn and Fe35Mn scaffolds had only the γ-austenite phase. All iron-manganese alloys exhibited weakly paramagnetic behavior, confirming their potential to be used as MRI-friendly bone substitutes. The in vitro biodegradation rates of the scaffolds were very much enhanced (i.e., 4.0 to 4.6 times higher than that of porous iron), with the Fe35Mn alloy exhibiting the highest rate of biodegradation (i.e., 0.23 mm/y). While the elastic moduli and yield strengths of the scaffolds decreased over 28 days of in vitro biodegradation, those values remained in the range of cancellous bone. The culture of preosteoblasts on the porous iron-manganese scaffolds revealed that cells could develop filopodia on the scaffolds, but their viability was reduced by the effect of biodegradation. Altogether, this research marks a major breakthrough and demonstrates the great prospects of multi-material extrusion-based 3D printing to further address the remaining issues of porous iron-based materials and, eventually, develop ideal bone substitutes. Statement of significance3D printed porous iron biomaterials for bone substitution still encounter limitations, such as the slow biodegradation and magnetic resonance imaging incompatibility. Aiming to solve the two fundamental issues of iron, we present ex-situ alloyed porous iron-manganese scaffolds fabricated by means of multi-material extrusion-based 3D printing. Our porous iron-manganese possessed enhanced biodegradability, non-ferromagnetic property, and bone-mimicking mechanical property throughout the in vitro biodegradation period. The results demonstrated a great prospect of multi-material extrusion-based 3D printing to further address the remaining challenges of porous iron-based biomaterials to be an ideal biodegradable bone substitutes.

In vitro and in vivo degradability, biocompatibility and antimicrobial characteristics of Cu added iron-manganese alloy

In recent years, iron (Fe) based degradable metal is explored as an alternative to permanent fracture fixation devices. In the present work, copper (Cu) is added in Fe-Mn system to enhance the degradation rate and antimicrobial properties. Fe-Mn-xCu (x = 0.9, 5 and 10 wt.%) alloys are prepared by the melting-casting-forging route. XRD analysis confirms austenite phase stabilization due to the presence of Mn and Cu. As predicted by Thermo-Calc calculations, Cu rich phase precipitations are noticed along the austenite grain boundaries. Degradation behaviours of Cu added Fe-Mn alloys are investigated through static immersion and electrochemical polarization where enhanced degradation is found for higher Cu added alloys. When challenged against E.Coli bacteria, the Fe-Mn-Cu alloy media extract shows a significant bactericidal effect compare to the base alloy. In vitro cytocompatibility studies, as determined using MG63 and MC3T3-E1 cell lines, indicate increased cell density as a function of time for all the alloys. When implanted in rabbit femur, the newly developed alloy does not show any kind of tissue necrosis around the implants. Better osteogenesis and higher new bone formation are observed with Fe-Mn-10Cu alloy as evident from micro-computed tomography (μ-CT) and fluorochrome labelling.

Collagen Coating Effects on Fe-Mn Bioresorbable Alloys.

Bioresorbable iron-manganese alloys (Fe-30%Mn) are considered as one of the next-generation resorbable materials for orthopedic applications. Previous in vitro study showed that Fe30Mn scaffolds with 10% porosity displayed strong mechanical properties and adequate degradation rate without severe cytotoxicity effect. However, the cellular compatibility of these alloys in terms of cell-to-cell and alloy-to-cell interactions is not ideal. Collagen is the most abundant protein in human bone, providing structural support beneficial to bone healing. We hypothesized that coating collagen on Fe30Mn can improve osteointegration or activities promoting cell adhesion, migration, and proliferation, as the alloy degrades. After preparing collagen coating on Fe-30Mn via spin coating, we conducted a corrosion test and a direct cytotoxicity test on four Fe30Mn groups: non-porous and 10% porosity, with and without collagen coating. Furthermore, we evaluated and compared the morphologies of cells over a period of 7 days. Results showed that there was no significant difference between the collagen-coated and non-coated groups in corrosion rates, yet a significant decrease from the porous non-coated group to the porous collagen-coated group in cytotoxicity level was found. Cell morphology on the porous non-coated group displayed round shape, whereas that on the porous collagen-coated group displayed flattened spreading. The study showed that the collagen coating significantly increased the initial cell viability and adhesion for both the porous and non-porous groups without impeding their degradation rates. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:523-535, 2020.

Effect of Cyclic Martensitic γ–ϵ Transformations on Diffusion Characteristics of Cobalt in an Iron–Manganese Alloy

Effect of Cyclic Martensitic γ–ϵ Transformations on Diffusion Characteristics of Cobalt in an Iron–Manganese Alloy

Local environment dependence of Mn magnetism in bcc iron-manganese alloys: A first-principles study

Magnetic behavior of a $3d$ solute in a ferromagnetic lattice can be very sensitive to local environment, which is the case of manganese in bcc Fe. Body-centered cubic iron-manganese alloys are studied by means of density functional theory in order to elucidate properties of the lowest-energy magnetic states. Multiple magnetic minima are determined even for the simplest case of an isolated Mn and a Mn dimer in bcc iron. The magnetoenergetic landscape is analyzed within and beyond the collinear magnetic approximation. A direct correlation is identified between the local electronic charge and the local magnetic moment of a Mn solute, being either isolated or forming a small cluster. In particular, the presence of a vacancy near the Mn atom, inducing a local charge decrease, tends to favor the antiferromagnetic Fe-Mn interaction while the presence of an interstitial impurity with a strong electronic hybridization with Mn can favor a ferromagnetic Fe-Mn interaction. Energetic and magnetic properties of Fe-Mn alloys are systematically investigated for a large range of Mn concentrations. An unmixing tendency is clearly noted. A detailed magnetic analysis suggests the Mn-Mn magnetic interactions to be generally dominant over the Fe-Mn interactions, both exhibiting an antiferromagnetic tendency. The average magnetic moment of the Mn atoms in locally random alloys tends to be antiparallel (parallel) to lattice Fe moments for Mn concentrations smaller (larger) than approximately 6 at. %. The transition concentration is shown to be lowered if considering Mn clustering which is energetically favorable. The unsolved discrepancies between experimental and theoretical predictions on the critical concentration for the Mn magnetic behavior change in Fe-Mn solid solution are discussed in the light of the obtained results.

In Vivo Evaluation of Biodegradability and Biocompatibility of Fe30Mn Alloy.

This study aims to evaluate the biodegradability and biocompatibility of an alloy of iron and manganese (Fe30Mn) in a bone model in vivo. Resorption of a Fe30Mn wire was compared with traditional permanent 316L stainless steel (SS) wire after bilateral transcondylar femoral implantation in 12 rats. Evaluation of biodegradation over 6 months was performed using radiography, post-mortem histology and microscopic implant surface analysis. Corrosion and resorption of the novel iron-manganese implant with formation of an iron oxide corrosion layer was noted on all post-mortem histological sections and macroscopic specimens (corrosion fraction of 0.84 and 0 for Fe30Mn and 316L SS, respectively). Increased bone ongrowth was observed at the wire-bone interface (bone ongrowth fraction of 0.61 and 0.34 for Fe30Mn and 316L SS, respectively). Occasionally, poorly stained newly formed bone and necrotic bone in contact with corrosion was seen. In bone marrow, Fe30Mn alloy was scored as a mild local irritant compared with 316L SS (biocompatibility score of 8.8 and 5.3, respectively). There was no evidence of systemic adverse reaction. Resorbable iron-manganese alloys may offer a promising alternative to permanent metallic implants. Further in vivo studies to control implant resorption at a rate suitable for fracture healing and to confirm the biocompatibility and biosafety of the resorbable Fe30Mn metallic implant are necessary prior to use in clinical settings.

The Effect of Corrosion in Hank's Solution on the Bending Stiffness of Bars from Sintered Iron-Manganese Alloys

Fe-Mn alloys represent promising degradable biomaterials for temporary implants. To investigate the effect of corrosion on their mechanical properties, iron powders were mixed with 25, 30 and 35 wt.% of a manganese powder, compressed into prismatic bars and sintered. Sintered bars were immersed in Hank's solution for 8 weeks. The bending stiffness of each bar before and after its exposure to electrolyte was examined. The higher the porosity of a bar was, the higher relative reduction in bending stiffness the bar exhibited. A likely explanation was that in a more porous bar Hank’s solution penetrated deeper and affected larger volume fraction of bar’s material.

Utilization of automotive shredder residues in a thermal process for recovery of manganese and zinc from zinc–carbon and alkaline spent batteries

The aim of the study is the recovery by thermal treatment of manganese and zinc from a mixture of zinc–carbon and alkaline spent batteries, on the basis of the different phase change temperatures of the two metal-bearing phases. ASR (Automotive Shredder Residue), containing 68% of carbon, was added to the mixture to act as a reductant to metallic Zn of the zinc-bearing phases. The mixture was subsequently heated in different atmospheres (air, CO2 and N2) and at different temperatures (900°C, 1000°C and 1200°C) and stoichiometric excess of ASR (300%, 600% and 900%). Characterization of the mixture and of the residues of thermal treatment was carried out by chemical analysis, TGA/DTA, SEM and XRD. The results show that recovery of 99% of zinc (grade 97%) is achieved at 1000°C in N2 with a stoichiometric excess of car-fluff of 900%. This product could be suitable for production of new batteries after refining by hydrometallurgical way. Recovery of Mn around 98% in the residue of the treatment is achieved at any temperature and atmosphere tested with a grade of 57% at 900% excess of car-fluff. This residue is enriched in manganese oxide and could be used in the production of iron–manganese alloys.

Scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX) and aerosol time-of-flight mass spectrometry (ATOFMS) single particle analysis of metallurgy plant emissions

The chemical composition of single particles deposited on industrial filters located in three different chimneys of an iron-manganese (Fe–Mn) alloy manufacturing plant have been compared using aerosol time-of-flight mass spectrometry (ATOFMS) and scanning electron microscopy–energy dispersive X-ray spectrometry (SEM-EDX). Very similar types of particles were observed using both analytical techniques. Calcium-containing particles dominated in the firing area of the sintering unit, Mn and/or Al-bearing particles were observed at the cooling area of the sintering unit, while Mn-containing particles were dominant at the smelting unit. SEM-EDX analysis of particles collected downstream of the industrial filters showed that the composition of the particles emitted from the chimneys is very similar to those collected on the filters. ATOFMS analysis of ore samples was also performed to identify particulate emissions that could be generated by wind erosion and manual activities. Specific particle types have been identified for each emission source (chimneys and ore piles) and can be used as tracers for source apportionment of ambient PM measured in the vicinity of the industrial site.

Microstructural, mechanical, corrosion and cytotoxicity characterization of the hot forged FeMn30(wt.%) alloy

An interest in biodegradable metallic materials has been increasing in the last two decades. Besides magnesium based materials, iron-manganese alloys have been considered as possible candidates for fabrication of biodegradable stents and orthopedic implants. In this study, we prepared a hot forged FeMn30 (wt.%) alloy and investigated its microstructural, mechanical and corrosion characteristics as well as cytotoxicity towards mouse L 929 fibroblasts. The obtained results were compared with those of iron. The FeMn30 alloy was composed of antiferromagnetic γ-austenite and ε-martensite phases and possessed better mechanical properties than iron and even that of 316L steel. The potentiodynamic measurements in simulated body fluids showed that alloying with manganese lowered the free corrosion potential and enhanced the corrosion rate, compared to iron. On the other hand, the corrosion rate of FeMn30 obtained by a semi-static immersion test was significantly lower than that of iron, most likely due to a higher degree of alkalization in sample surrounding. The presence of manganese in the alloy slightly enhanced toxicity towards the L 929 cells; however, the toxicity did not exceed the allowed limit and FeMn30 alloy fulfilled the requirements of the ISO 10993-5 standard.

Mössbauer analysis of the solid-phase mechanical synthesis of nitrogen chromium-nickel and chromium-manganese austenite

Nanostructured austenite alloys lean-alloyed with nickel and manganese and precipitation-hardened with nitrides are prepared via solid-phase mechanical synthesis in a ball mill by milling powders of bcc iron-nickel and iron-manganese alloys together with chromium nitrides and subsequently annealing them in a range of temperatures near the upper boundary of α → γ transformations.

Direct In-Situ Investigation of Selective Surface Oxidation During Recrystallization Annealing of a Binary Model Alloy

The study of high temperature oxidation processes depends mainly on ex situ investigations after the high temperature process is completed. In this study Ambient Pressure Photoelectron Spectroscopy was used to investigate its potential for an in situ analysis of the underlying mechanisms of selective oxidation occurring during high temperature annealing. As an example, the evolution of the surface oxide states of an iron-manganese model alloy (with 2 wt% Mn) during an annealing step simulating recrystallization annealing was studied. It was shown that an investigation of the surface after the annealing step does not provide reliable information about the oxidation state during the annealing step. At low partial pressures of water in a forming gas atmosphere the kinetics of water dissociation on the surface are not high enough to provide enough oxygen for reaching the thermodynamically expected activities. This unexpected low oxygen activity on the surface is also shown to affect the uptake of hydrogen into the Fe–2Mn sample.

Effect of microstructure and strain on the degradation behavior of novel bioresorbable iron–manganese alloy implants

Advancing the understanding of microstructural effects and deformation on the degradability of Fe-Mn bioresorbable alloys (specifically, Fe-33%Mn) will help address the current problems associated with designing degradable fracture fixation implants for hard tissues. Potentiostatic polarization tests were conducted on a wide variety of metal samples to examine how different deformation processes affect the instantaneous rate of degradation of Fe-Mn alloys. Large-strain machining (LSM), a novel severe plastic deformation (SPD) technique was utilized during these experiments to modify the degradation properties of the proposed Fe-Mn alloy. It was discovered that Fe-33%Mn after LSM with a rake angle of 0° (effective strain = 2.85) showed the most promising increase in degradation rate compared to as-cast, annealed, and additional deformation conditions (rolled and other LSM parameters) for the same alloy. The mechanisms for enhancement of the corrosion rate are discussed.

Effect of Chemical Composition on the Crystal Lattice and Physical Properties of Iron-Manganese Alloys With High Content of Aluminum

Physical properties of cast alloys Fe + (16.8 – 25.6)% Mn + (0 – 14.4)% Al + (0.02 – 2.18)% C + (0.001 – 0.135)% N are studied by the methods of metallographic and x-ray diffraction analysis and by measurement of the density, thermal conductivity and heat capacity.

Influence of gaseous atmosphere during a thermal process for recovery of manganese and zinc from spent batteries

The aim of the work is the recovery by thermal treatment of manganese and zinc from a mixture of zinc–carbon and alkaline spent batteries, due to the different phase change temperatures of the metals. Activated charcoal, as a reductant of the zinc-bearing phases to metallic Zn, was added to the mixture that was heated in different atmospheres (air, nitrogen, carbon dioxide) at different temperatures and residence times. Characterization of the mixture and of the residues of thermal treatment was carried out by chemical analysis, thermogravimetric and differential thermal analysis, scanning electron microscope and X-ray diffraction and allowed to understand the mechanisms of reduction of zinc and to interpret the formation of different compounds during the process. Results show that recovery of 99% of Zn (grade 96%) at 1200 °C and 97% of Zn (grade 99%) at 1000 °C, are achieved in N2 at 30 min residence time. Recovery of Mn at 1200 °C and 30 min residence time was around 90–100% (90% grade). These products are suitable, after refining, for production of new batteries or higher value-added products. The residue of the treatment, enriched in manganese oxide, could be used in the production of iron–manganese alloys.

A first-principles study aided with Monte Carlo simulations of carbon doped iron-manganese alloys

We have investigated the complex magnetic properties of Fe1−x Mn x C y alloys by using an iterative combination of ab initio calculations and Monte Carlo simulations. The latter gives insight into finite temperature magnetism and allows to determine the critical temperature of magnetic phase transitions. We restrict the investigation to ordered systems with 25, 50 and 75% manganese and study the influence of carbon at octahedral interstitial sites on the magnetic properties. The combination of ab initio calculations with Monte Carlo simulations turns out to be a powerful tool to determine the complex magnetic structures, which originate from the competition of ferro- and antiferromagnetic interactions in the FeMn alloys.