Fe-Mn System Research Articles

Controlled Nano Cu precipitation through age treatment: a method to enhance the biodegradation, mechanical, antimicrobial properties and biocompatibility of Fe-20Mn-3Cu alloys.

Iron-manganese (Fe-Mn) based degradable biomaterials have been proven as a suitable substitute to permanent internal fracture-fixation devices. However, lower degradation and bacterial infection are still major concerns. To overcome these limitations, in this work, we have incorporated copper (Cu) in Fe-Mn system. The objective is to produce Cu nano-precipitates and refined microstructure through suitable combination of cold-rolling and age-treatment, so that degradation is improved eventually. High resolution transmission electron microscope (TEM) and scanning transmission electron microscope (STEM) confirmed the Cu rich composition of the nano-precipitates. Number of precipitates increased as aging time increased. Three-dimensional visualization of Fe, Mn and Cu atomic distributions using atom probe tomography (APT), indicated that Cu precipitates were in 15-50 nm range. Large number of nano-precipitates along with lower dislocation density led to highest strength (1078 MPa) and ductility (37 %) for the 6-hr age-treated sample. On the other hand, nano-precipitates and refined microstructure resulted highest degradation for the 12 hr of age treated sample (0.091 mmpy). When E.Coli bacteria was cultured with the sample extract, significantly higher antibacterial efficacy was observed for the sample having higher nano-precipitates. Higher degradation rate did not cause cyto-toxicity, rather promoted statistically higher cell proliferation (1.5 times within 24 hr) in in vitro cell-material interaction studies. In vivo biocompatibility of the alloy containing large nano-precipitates was confirmed from higher new bone regeneration (60%) in rabbit femur model. Overall study suggested that the optimization of the thermo-mechanical processes can effectively tailor the Fe-Mn-Cu alloys for successful internal fracture fixation. STATEMENT OF SIGNIFICANCE: : In the present work, we have reported a noble thermo-mechanical approach to simultaneously achieve Cu nano-precipitates and grain refinement in Fe-20Mn-3Cu alloy. Significant reduction in bacterial growth was observed in the sample containing high Cu precipitation. This is extremely significant in the present context. Cu nano-precipitates and grain refinement improved the degradation rate. Highest yield strength was observed after 12 hours of age treatment (493 MPa). We have theoretically calculated various factors of yield strength. High degradation rate did not cause cytotoxicity, rather promoted cell viability. We have reported that the released Cu ion concentration in vivo was not only below toxic limit, but also helped in new bone regeneration.

A third generation CalPhaD assessment of the Fe–Mn–Ti system Part II: The ternary system Fe–Mn–Ti

The ternary Fe–Mn–Ti system plays an important role in the development of several different functional and structural materials, which can be applied e.g., as shape-memory alloys or for hydrogen storage. Since the corresponding materials properties are closely connected to the thermodynamic behavior of the individual phases in the alloys, thermodynamic calculations can provide useful information for a sustainable and straightforward alloy development. Therefore, a 3rd generation CalPhaD description of the Fe–Mn–Ti system was developed, which applies advanced sublattice models for several phases such as A12, A13 and C14, to ensure physically meaningful estimations of their thermodynamic properties. Moreover, the modelling was supported by experimental investigations on the phase relations in the ternary Fe–Mn–Ti system, based on diffusion-couple experiments at 800, 900 and 1000 °C. During these experiments, several local phase equilibria between A1, A2, A3, A12, B2, C14 and MnTi1-x were established and subsequently investigated using SEM/BSE-imaging, EPMA and EBSD.

A third generation CalPhaD assessment of the Fe–Mn–Ti system part I: The binary subsystems Fe–Mn, Fe–Ti and Mn–Ti

The binary systems Fe–Mn, Fe–Ti and Mn–Ti play remarkable roles in the development of numerous structural and functional materials. As their properties are closely related to the thermodynamic behavior of the phases in the corresponding alloys, the calculation of phase equilibria is crucial for a sustainable and straightforward alloy development. In that course, thermodynamic descriptions within the framework of 3rd generation CalPhaD databases of the binary systems Fe–Mn, Fe–Ti and Mn–Ti were developed. To ensure physically meaningful estimations of the individual thermodynamic properties, advanced sublattice models for several phases, such as A12 (α-Mn), A13 (β-Mn) and C14 (hexagonal Laves phase) were applied. The modelling was supported by heat-capacity measurements for the C14–Mn2Ti phase, to provide a thermodynamically profound basis for a subsequent description of the phase relations. Through the combination of the advanced models and reliable thermodynamic data for each system, thermodynamic descriptions could be derived, which facilitate reliable calculations from 0 K to far beyond the melting point of the individual alloys.

Degradation of Textile Dye by Bimetallic Oxide Activated Peroxymonosulphate Process

The sulphate radical based advanced oxidation processes (AOPs) are highly in demand these days, owing to their numerous advantages. Herein, the Fe-Mn bimetallic oxide particle was used to activate peroxymonosulphate (PMS) for Rhodamine B (RhB) degradation. Three bimetallic catalysts were synthesized via the chemical precipitation method with different concentrations of metals; Fe-Mn (1:1), Fe-Mn (1:2) and Fe-Mn (2:1). The best performance was shown by Fe-Mn (2:1) system at optimized conditions; 96% of RhB was removed at optimized conditions. Scavenging experiments displayed the clear dominance of hydroxyl radical in pH 3, while sulphate radical was present in a large amount at pH 7 and 10. The monometallic Fe and Mn oxides were also synthesized to confirm the synergistic effect that was present in the bimetallic oxide system. The application of optimized condition in real textile wastewater was conducted, which revealed the system works efficiently at high concentrations of PMS and catalyst dosage.

Thermodynamic and atomic mobility assessment of the Co–Fe–Mn system

Thermodynamic and atomic mobility assessment of the Co–Fe–Mn system

A newly isolated indigenous metal-reducing bacterium induced Fe and Mn oxides synergy for enhanced in situ As(III/V) immobilization in groundwater

Iron-manganese binary oxides (Fe-Mn oxides) have the potential to immobilize arsenite/arsenate [As(III/V)] in situ in natural environments. However, the As(III/V) immobilization performances of Fe-Mn oxides in the presence of indigenous metal-reducing bacteria in reducing groundwater systems have received limited attention. Here, As(III/V) immobilization by Fe-Mn oxides and the interactions of Fe and Mn oxide components in groundwater in the presence of a newly isolated indigenous metal-reducing bacterium (Bacillus sp. FMR) were investigated. Microcosm experiments were performed with artificial groundwater and mineral phases (Fe, Mn and Fe-Mn oxides) with As(III) or As(V) in the presence or absence of strain FMR under anoxic conditions. The Fe oxides in anaerobic cultures without bacteria exhibited better immobilization performances for As(III) [69% As(T) removal efficiency] and As(V) (70%) than Mn oxides (19% and 17%, respectively). Comparably, the involvement of bacteria induced the re-release of arsenic adsorbed on the single Fe and Mn oxides under anoxic conditions, whereas this shift in arsenic adsorption–desorption was not observed in Fe-Mn oxide systems because the Mn oxide components inhibited the reductive dissolution of the Fe oxide components. The As(T) removal efficiencies of Fe-Mn oxides in the presence of bacteria increased by 17% for As(III) and 16% for As(V) compared with anaerobic incubation without bacteria. The interaction of Fe and Mn oxides in Fe-Mn oxides resulted in a slightly increased mobilization of As(III/V) in the absence of bacteria, whereas there was a synergistic effect in the presence of bacteria. The favorability of indigenous bacteria for As(III/V) immobilization and the synergy between Fe and Mn oxides provide novel insights for in-situ As(III/V) immobilization in high arsenic-containing groundwater.

THERMODYNAMIC MIXING FUNCTIONS OF A MULTICOMPONENT LIQUID METAL AND SLAG

The work proposes a thermodynamic model of a multicomponent condensed phase applicable to metal and slag melts. The integral and partial thermodynamic mixing functions: Gibbs energy, enthalpy, entropy, heat capacity have been obtained using configurational statistical sum. Methods for estimating of model parameters using available data on activity coefficients and heats of mixing, Wagner interaction parameters have been suggested. Using binary Fe-Mn system as an example, the high accuracy of the calculation of the mixing thermodynamic functions of the metal phase in the entire concentration range has been shown. Mixing heat capacity has been shown to comply 3rd law of thermodynamics. Suggested thermodynamic model is already being used in steelmaking control system «Master» at metallurgical plant «Zaporizhstal», and in heat projecting and control system «DesigningMelt» at XuanSteel metallurgical works (PRC).

Interfacial Behaviour in Ferroalloys: The Influence of Sulfur in FeMn and SiMn Systems

The present study has investigated the influence of sulfur content in synthetic FeMn and SiMn from 0 to 1.00 wt pct on interfacial properties between these ferroalloys and slags. The effect of experimental parameters such as temperature and holding time was evaluated. Interfacial interaction between ferroalloys and slags was characterized by interfacial tension and apparent contact angle between metal and slag, measured based on the Young–Laplace equation and an inverse modelling approach developed in OpenFOAM. The results show that sulfur has a significant influence on both interfacial tension and apparent contact angle, decreasing both values and promoting the formation of a metal-slag mixture. Despite the fact that sulfur was added only to the ferroalloys, most of sulfur is distributed into slag after reactions with the metal phase. Increasing the maximum experimental temperature in the sessile drop furnace also resulted in a decrease of both interfacial properties, resulting in higher mass transfer rates and intensive reactions between metal and slag. The effect of holding time demonstrated that after reaching equilibrium in FeMn-slag and SiMn-slag systems (both with and without sulfur), interfacial tension and apparent contact angle remain constant.

Experimental investigation and thermodynamic modeling of the ternary Ti–Fe–Mn system for hydrogen storage applications

The Ti–Fe–Mn alloys have attracted extensive interests due to the excellent hydrogen storage properties of the TiFe and TiMn2 (i.e. the C14 Laves phase) intermetallic compounds. The phase equilibria involving these two phases are essential for the design of hydrogen storage materials. In order to accelerate the design process, a thermodynamic description of the ternary Ti–Fe–Mn system was developed by experimental phase diagram study, ab initio calculations and CALPHAD-type thermodynamic modeling in the present work. The phase equilibria involving TiFe and C14 Laves phases were investigated by using electron probe microanalysis (EPMA). The partial isothermal sections at 1273 and 1373 K were established. Ab initio calculations were carried out to assist the determination of the thermodynamic parameters for the C14 Laves phase. The Ti-Mn system was re-assessed to reproduce the phase diagram data over the entire composition range. The Ti-Fe-Mn system was modeled and optimized based on reliable binary descriptions and experimental data. The TiFe and C14 Laves phases were well described to reproduce the phase equilibria with other phases in the ternary system. Moreover, the developed thermodynamic description of the Ti-Fe-Mn system was successfully applied for the prediction of phase constitutions of hydrogen storage alloys, demonstrating evidently the reliability of the practical use of present model parameters.

The effect of Si addition and thermomechanical processing in an Fe-Mn alloy for biodegradable implants: Mechanical performance and degradation behavior

Among iron-based materials, the Fe-Mn system appears to be highly suitable for the development of biodegradable metals for orthopaedic and vascular applications. The versatility of tailoring such steels by alloying provides many opportunities to customise biodegradable devices. In the field of applications where a high load-bearing capacity is required, the addition of Si could constitute an effective strategy to improve the mechanical properties while maintaining a similar corrosion susceptibility and biocompatibility. In this study, the microstructure, mechanical properties, and corrosion behaviour of Fe-30 Mn-5Si (wt.%) alloy are presented, discussed, and assessed in comparison with a binary Fe-30 Mn formulation. Emphasis is placed on characterising the alloys in processed conditions by using conventional thermomechanical rolling and annealing techniques, which are feasible and allow for scale-up. Such techniques affect phases equilibrium, internal stresses and grain size, thus altering the degradation behaviour. The addition of Si resulted in excellent microstructural homogeneity and was used to tailor the relative abundances of austenitic and martensitic phases by applying different heat treatment strategies. As a result, the mechanical resistance was improved by 70 % compared to the base alloy, the strain hardening ability was improved while keeping good ductility. Electrochemical corrosion tests and static degradation experiments showed that both alloys corrode at a similar rate, although the addition of Si appeared to induce a slower degradation in the initial stage and a faster one in the long term.

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.

Ab initio based models for temperature-dependent magnetochemical interplay in bcc Fe-Mn alloys

Body-centered cubic (bcc) Fe-Mn systems are known to exhibit a complex and atypical magnetic behavior from both experiments and 0 K electronic-structure calculations, which is due to the half-filled $3d$ band of Mn. We propose effective interaction models for these alloys, which contain both atomic-spin and chemical variables. They were parameterized on a set of key density functional theory (DFT) data, with the inclusion of noncollinear magnetic configurations being indispensable. Two distinct approaches, namely a knowledge-driven and a machine-learning approach have been employed for the fitting. Employing these models in atomic Monte Carlo simulations enables the prediction of magnetic and thermodynamic properties of the Fe-Mn alloys, and their coupling, as functions of temperature. This includes the decrease of Curie temperature with increasing Mn concentration, the temperature evolution of the mixing enthalpy, and its correlation with the alloy magnetization. Also, going beyond the defect-free systems, we determined the binding free energy between a vacancy and a Mn atom, which is a key parameter controlling the atomic transport in Fe-Mn alloys.

Роль марганцю і рідкофазного оброблення електричним струмом на формування залізовмісних фаз у доевтектичних сплавах системи Al–Si–Fe–Mn

Роль марганцю і рідкофазного оброблення електричним струмом на формування залізовмісних фаз у доевтектичних сплавах системи Al–Si–Fe–Mn

Thermodynamic first order interaction coefficient between nitrogen and manganese in liquid steel

A simple theory of thermodynamic properties of liquid nitrogen solution in Fe–Mn alloys is proposed. This theory is completely analogous to the theory for liquid nitrogen solution in alloys of the Fe–Cr system proposed previously by the authors in 2019. The theory is based on the lattice model of the considered Fe–Mn solutions. The model assumes a FCC lattice. The atoms of Fe and Mn are in these lattice sites. Nitrogen atoms are located in octahedral interstices. The nitrogen atom interacts only with the metal atoms located in the lattice sites neighboring to it. This interaction is pairwise and it is assumed that the energy of this interaction depends neither on the composition nor on the temperature. Furthermore, the solution in the Fe–Mn system is assumed to be perfect. Within the framework of the proposed theory, a relation was obtained that expresses the value of the Sieverts law constant for N solubility in liquid Mn through the similar constant for the N solubility in liquid Fe and the Wagner N–Mn interaction coefficient in liquid Fe. The values of the Sieverts law constants in this relation are taken directly from the experimental measurements of the solubility of N in liquid Fe and in liquid Mn. In this case, the obtained relation is considered as an equation with respect to the Wagner interaction coefficient $$\varepsilon _{{\text{N}}}^{{{\text{Mn}}}}$$ . The equation’s solution gives the value of Wagner interaction coefficient $$\varepsilon _{{\text{N}}}^{{{\text{Mn}}}}$$ = –5.25 in liquid steel at a temperature of 1873 K. Wagner interaction coefficient $$\varepsilon _{{\text{N}}}^{{{\text{Mn}}}}$$ is related with Langenberg interaction coefficient $$e_{{\text{N}}}^{{{\text{Mn}}}}$$ by the relation deduced by Lupis and Elliott in 1965. The relation includes the atomic masses of Fe and Mn. By substituting the value $$\varepsilon _{{\text{N}}}^{{{\text{Mn}}}}$$ = –5.25 and solving the resulting equation with respect to $$e_{{\text{N}}}^{{{\text{Mn}}}}$$ , we obtain the value $$e_{{\text{N}}}^{{{\text{Mn}}}}$$ = –0.0230. This value corresponds to the experimental data of Beer (1961), which is likely one of the most probable of all experimental values of $$e_{{\text{N}}}^{{{\text{Mn}}}}$$ for liquid steel at 1873 K. Another such value is $$e_{{\text{N}}}^{{{\text{Mn}}}}$$ = 0.0209 obtained by Shin with coworkers in 2011.

A thermodynamic description of the Al–Cu–Fe–Mn system for an immiscible medium-entropy alloy design

A thermodynamic description of the Al–Cu–Fe–Mn quaternary system has been developed for the design of high-strength immiscible dual-phase medium-entropy alloys. A new thermodynamic assessment for the Al–Cu–Mn ternary sub-system is performed, covering the entire composition range. Thermodynamic parameters of B2 and AlCuFe_τ and φ phases in the Al–Cu–Fe ternary sub-system are also revised based on a previous description that used different constituent binary descriptions. The reliability of the developed thermodynamic description for the Al–Cu–Fe–Mn quaternary system is experimentally confirmed by designing, fabricating, and analysing the phase structures of Al–Cu–Fe–Mn medium-entropy alloys.

Structural and magnetic properties of new members of the 3:29 phase from the Ce–Fe–Mn system and 1:11 from the Ce–Co–Mn

The Ce–Fe–Mn and Ce–Co–Mn systems have been re-visited with the intent of finding new potential phases for application as permanent magnets. Two new ternary compounds, Ce3(Fe0.638Mn0.362)29 (Nd3(Fe,Ti)29-type, space group P21/c, No. 14, Pearson Symbol mP128) and CeCo8Mn3 (Ce(Ni,Mn)11-type, space group P4/mbm, No. 127, Pearson Symbol tP24) have been discovered in the compositional range where the Ce2(T,Mn)17 (T = Fe, Co) phases are expected to exist with a (H)–Th2Ni17-type structure (space group P63/mmc, No. 194, Pearson Symbol hP38). Detailed investigations of the crystal structures have been performed using X-ray powder diffraction (XRPD) with supporting energy-dispersive X-ray (EDS) analysis. Compositions of the new compounds have been defined based on the EDS analysis as follows: Ce9.7Fe57.5Mn32.8 and Ce9.2Co65.2Mn25.6. A short discussion on the crystal structure peculiarities of the 1:5, 1:11, 1:12, 2:17 and 3:29 compounds in the Ce–T–Mn (T = Fe, Co, Ni, Cu) systems has been made. We present magnetic measurements on selected representatives of the studied phases. The most interesting being the Ce3(Fe0.638Mn0.362)29 phase which has a transition temperature well above room temperature. CeNi4.95Mn6.05 and CeCo8Mn3 exhibits properties characteristic of a canted antiferromagnetic state.

Influence of Cooling and Strain Rates on the Hot Ductility of High Manganese Steels Within the System Fe–Mn–Al–C

The ductility curves of high manganese steel grades with a stepwise increasing [Al] content of 0, 1, 3, 5, and 8 wt% for two strain rates (0.01 and 0.001 s−1) and for a varying cooling rate (–3 and −7 Ks−1) have been determined to investigate their influence on the hot ductility behavior. The tests have been conducted at the hot tensile testing unit of the Department of Ferrous Metallurgy of RWTH Aachen University. This equipment is able to perform testing of semisolid samples, e.g., during solidification. After the tensile testing, the specimens are investigated using the scanning electron microscope/energy‐dispersive X‐ray spectroscopy as well as by light optical microscopy to clarify the role of the cooling and strain rates on the hot ductility of high manganese steels and on the formations of precipitates. Furthermore, thermodynamic modeling using the commercial software ThermoCalc is performed. A shifting of the decay of the ductility maximum to lower temperatures down to ≈1273 K for both an increasing strain rate and an increasing cooling rate is determined and this effect is explained through their influences on the microstructure and fracture behavior. Micrograph analyses show that (MnS) precipitates form in contact with early (AlN) precipitates.

Role and behavior of ultra-thin gold films on the fiber materials surface in the CO oxidation process

The work continues a series of studies aimed at enhancing catalytic properties of metal fibers formed by the pendant drop melt extraction (PDME) method. In this paper, we show that deposition of the thin gold film on the metal fibers leads to a change in the catalytic performance of the samples under study. Au-coated fibers of titanium, zirconium and alloys of the Fe–Cr–Al, Ni–Cr–Al–Y, Ni–Cr–Al–Pt–Ir–Hf, Ni–Cu–Fe–Mn systems were tested as catalysts in the reaction of CO oxidation. We have found that the deposition of gold makes titanium, zirconium, and Fe–Cr–Al fibers catalytically active, while in the initial state they have not shown any evidence of catalytic activity. In the case of Ni–Cu–Fe–Mn fibers, which could oxidize CO themselves, the deposition of Au film significantly increases their catalytic properties. It was found that during the catalytic process, gold film coalesces to droplets with the predominant size of 11–14 nm.

The Formation of Iron-Containing Intermetallic Phases in Al–12%Si Alloy by Using Tungsten Addition

The use of silumins as construction materials in mechanical and aircraft engineering is often limited due to the presence of large crystals of intermetallic phases of the Al–Si–Fe and Al–Si–Fe–Mn systems in their structure. This paper shows the formation of iron-containing intermetallic phases in Al–12%Si by using tungsten addition in amount 0.01–0.5 mass%. It has been found that introduction of 0.01 mass% W leads to the transition of the needle-shaped β-phase into the α-phase having more compact blocky form and polyhedral crystals, with a decrease in the dimensions of the α-phase by more than 2 times. The addition in amount of 0.05, 0.1, and 0.5 mass% W leads to the decrease in the dimensions of α- and β-phases by an average of 1.5 times. The change in the formation of iron-containing intermetallic phases in Al–12%Si alloy after the tungsten addition leads to an increase in mechanical properties by an average of 20%.

Molecular dynamics study of the thermodynamic and kinetic properties of the solid-liquid interface in FeMn

The solid-liquid phase equilibria as a function of temperature and composition has been computed for the Fe-Mn system using a semi-grand canonical Monte Carlo technique. Interaction between atoms were modeled using a second nearest neighbor modified embedded atom method potential. In addition, the excess solid-liquid interfacial free energy (γ) and its anisotropy has been computed from the capillary fluctuation method. The results indicate that there is very little variation in γ with temperature/composition. We also propose a new MD simulation method for computing solute trapping behavior that is able to access relatively low interface velocities. The segregation coefficient as a function of velocity for the Fe-Mn system was determined for three temperatures and the results are discussed within the framework of previously proposed theoretical models.