Fe Ni Mn Research Articles

Die-cast multicomponent near-eutectic and hypoeutectic Al–Si–Ni–Fe–Mn alloys: Microstructures and mechanical properties

Microstructures and mechanical properties of near-eutectic and hypoeutectic Al–Si–Ni–Fe–Mn alloys were studied under as-cast condition. Near-eutectic 78Al15Si4Ni2.5Fe0.5Mn (wt.%) and hypoeutectic 83.6Al11Si3Ni1.9Fe0.5Mn (wt.%) alloys were processed by high pressure die casting. These two alloys have the same ternary eutectic mixture of α-Al, Si and Al6(FeNiMn) with a melting point of 567 °C. Primary intermetallic phases of block-like Al17(FeNiMn)4Si and plate-like Al4(FeNiMn)Si2 in these two alloys were observed. Precipitates of Si and Ni-contained phase coexist in primary α-Al grains of hypoeutectic alloy. The lattice parameters of Al6(FeNiMn), Al17(FeNiMn)4Si, and Al4(FeNiMn)Si2 phases are slightly changed compared with orthorhombic Al3Ni, orthorhombic Al5.6Fe2 and tetragonal FeAl3Si2 phases from the database, respectively. These two alloys have excellent mechanical properties at high temperatures. The ultimate tensile strength (UTS) at 300 °C ranges from 135 ± 6 MPa (hypoeutectic alloy) to 157 ± 6 MPa (near-eutectic alloy), which is superior to commercial A383 alloy and some other heat-resistant alloys. Therefore, these near-eutectic and hypoeutectic Al–Si–Ni–Fe–Mn alloys have huge potential for industrial application at elevated temperatures.

Significance of Mn concentration on aging behavior, microstructure evolution and mechanical properties of Fe–Ni–Mn alloys

Fe–Ni–Mn alloys, are ultra-high-strength steels, with suitable ductility and age-hardenability in the solution annealed (SA) condition. However, they suffer from grain boundary embrittlement after aging at ∼480OC, when Mn content goes beyond a specific value. This study was conducted to investigate systematically the effects of the Mn concentration on the microstructural evolution, aging behavior, and the resulting mechanical properties of Fe–10Ni–xMn alloys containing 3.5, 6 and 9Mn wt.%. Samples containing 3.5 and 6 wt.% Mn showed age-hardenability during aging and higher Mn content resulted in a higher hardness value which in turn showed higher strength. The Mn content of about 9 wt.% led to the stability of the austenite phase at room temperature (RT). The results showed that although age-hardening did not occur in this microstructure, a good combination of strength and ductility was achieved. Studying the effects of Mn content in a wide range, resulted in different properties by introducing the proper chemical composition and the preferred heat treatments in this type of alloys, which could be age-hardenable, easy to fabricate, and low-cost.

Corrosion behavior of (Fe,Ni)–Gd intermetallic compounds in FeNi-based neutron-absorbing steels

In this paper, microstructures of Fe–12Ni–1.4Mn–(0–4 wt%)Gd steels were quantitatively analyzed, and corrosion behavior of the alloys in solutions containing H3BO3 and Cl– was investigated through potentiodynamic polarization tests and corrosion morphology observation. The addition of Gd to the Fe–12Ni–1.4Mn alloy formed secondary phases, mainly (Fe,Ni)17Gd2 and a small amount of (Ni,Fe)4Gd. As the Gd content increased, the total amount of the secondary phase linearly increased. In a NaCl solution, the pitting corrosion resistance of the alloys was reduced by the addition of Gd. In a HCl solution, both uniform and pitting corrosion occurred, and the resistance to both types of corrosion decreased as the Gd content increased. In the two solutions, the corrosion susceptibility increased in the order of matrix < (Fe,Ni)17Gd2 < (Ni,Fe)4Gd. The high susceptibility to corrosion of the Gd-rich phase is due to the fact that Gd is electrochemically active compared to the other constituent elements of the matrix and also has a low ability to form passive films. Also, in a H3BO3 solution, both uniform and pitting corrosion were observed in the alloys. Although Gd is electrochemically active compared to Fe–Ni–Mn matrix, uniform corrosion resistance was improved by addition of Gd and the Gd-rich phase behaved as a noble phase only in the H3BO3 solution. This is considered to be because H3BO3 selectively adsorbs to the Gd-rich phase and protects it from dissolution. However, because the protective ability of the H3BO3 adsorbed layer was weaker than that of the passive film of the matrix, pitting occurred at the Gd-rich phase.

High energy density liquid state asymmetric supercapacitor devices using Co–Cr–Ni–Fe–Mn high entropy alloy

Synthesis of CoCrNiFeMn high entropy alloy by induction melting and ball-milling them into nanoparticles for high energy density and power density asymmetric liquid state supercapacitor device.

Characterisation of the mechanisms taking place during liquid phase sintering of PM boron steels with the help of artificial intelligence

ABSTRACT Liquid phase sintering (LPS) of powder metallurgy (PM) components is a well-recognised strategy to enhance the densification of pressed-and-sintered compacts. This work reports the investigation on the liquid phase formation when a Fe–Ni–Mn–C–B master alloy (MA) is used as a boron carrier in combination with two iron base powders pre-alloyed with Mo. Through differential scanning calorimetry tests, quantitation of the microstructure with the help of artificial intelligence, as well as measurement of sintered density and strength as a function of sintering temperature, it was possible to unravel the mechanisms that take place before and during LPS. It was confirmed that a cascade of events takes place in the solid state prior to reaching the temperature necessary for a eutectic reaction to form a liquid. Additionally, the pre-alloyed Mo content was identified as a factor that modifies the initiation of LPS but not the LPS mechanisms per se.

Microstructure and correlated mechanical properties study of Ni–(Fe, Co)–Mn–(Al, In) as-spun ribbons

The Ni–Mn–based shape memory alloys as a promising candidate of elastocaloric material has been reported in many literatures, especially on bulk samples. The as-spun ribbon, which has a larger surface area and is more efficient for heat transfer, is rarely studied and hence of importance. In the present work, we succeeded in producing very long as-spun Ni–Fe–Mn–(Al, In) ribbons, with around 300 mm in length. The microstructure and mechanical properties of these as-spun ribbons were thoroughly investigated by scanning electron microscopy and electron backscattered diffraction (SEM-EBSD), nanoindentation and 3-points bending experiments. Through SEM-EBSD analyses, the microstructure and texture of the as-spun ribbons were studied. A gradient in microstructure exists along the thickness direction (TD) of the ribbon, which is induced by the temperature gradient during fast rate solidification, resulting in fine equiaxed grains along the surface contacted with the rotating wheel in melt spinning process and elongated grains, respectively. Both equiaxed and elongated grains possess a strong {001} fiber texture (<001>//TD). Nanoindentation analyses show little variation of hardness between the two different microstructures. The ductility index of both Ni–Fe–Mn–Al and Ni–Fe–Mn–In ribbons are within the range of intermetallic materials. The substitution of In by Al allows to increase very slightly the ductility index, which can reach 0.75. The fine equiaxed grains show better tensile resistance than the elongated grains in 3-points bending test. The substitution of In by Al improves the maximum bending strain by a factor of 3. The maximum strain for Ni–Fe–Mn–Al as-spun ribbons can reach 3% before fracture. Fractography shows that, the intergranular fracture is the main damage mechanism in these as-spun ribbons.

Structure and mechanical properties of high strength austenitic Mn–Ni–Cu–V–C dispersionally hardened steel

The paper presents the results of a study of the structure and mechanical properties of high-strength austenitic dispersionally hardened Mn–Ni–V–C steel with a yield strength of at least 700 MPa. Its composition and the hardening method were selected so that the steel meets the requirements for high strength and nonmagnetic properties. It is shown that the introduction of 1–2% Cu into Mn–Ni–V–C steel expands the region of existence of the γ-phase in the Fe–Ni–Mn phase diagram, narrows the two-phase γ+α-region and shifts it towards lower Mn contents, increasing stability of austenite to martensitic transformation during cold deformation. A numerical assessment of the influence of alloying austenite-forming elements Ni, Mn, Cu on the critical degree of cold plastic deformation, leading to the formation of deformation martensite in steel, is proposed. The temperature range of the reverse transformation of this martensite into austenite during annealing is established, depending on the nickel content in the steel. For precipitation hardened steel with a composition of 10%Mn; 10%Ni; 2%Cu; 0.3–0.4%C; ~1.4%V the regularities of dissolution upon heating for quenching and precipitation during aging of particles of the strengthening carbide phase VC were studied. It has been shown that the maximum strength is achieved after quenching from 1150°C and aging at 650°C for 15 hours. Taking into account the studies carried out on the stability of austenite, static and cyclic strength and durability, the optimal alloying range of steel with nickel, manganese and copper was substantiated, and the optimal mode of heat treatment was revealed, which provides a combination of high strength with good ductility and toughness of steel.

A hybrid trimetallic–organic framework-derived N, C co-doped Ni–Fe–Mn–P ultrathin nanosheet electrocatalyst for proficient overall water-splitting

Fabrication of hybrid trimetallic-organic framework-derived N, C co-doped Ni–Fe–Mn–P ultrathin nanosheet electrocatalyst demonstrating excellent performance with low overpotentials and cell voltage for HER, OER and overall water splitting.

Effect of post-deformation annealing on the microstructure and mechanical behavior of an Fe–Ni–Mn steel processed by high-pressure torsion

Research was conducted to investigate the effects of high-pressure torsion (HPT) and post-deformation annealing (PDA) on the microstructure evolution and mechanical behavior of an Fe-9.6Ni-7.1Mn (at.%) steel with an initial lath martensitic microstructure. The experimental results showed that HPT processing led to the formation of an ultrafine grain martensitic microstructure accompanied by small amounts of strain-induced austenite. Phase analysis and microstructural examination confirmed that during PDA at 600 °C a large fraction of fine and coaxial austenite grains was introduced in the microstructure by diffusionless shear mechanism whereas its volume fraction at ambient temperature was drastically decreased by increasing the annealing time. Also, the grain size was reduced from a value of about 5.2 μm in the solution-treated specimen to ultrafine values of about 570 and 280 nm for the martensite and austenitic phases, respectively, after PDA for 7.2 ks. PDA yielded an outstandingly good combination of an ultimate tensile strength (∼1340 MPa) and fracture strain (∼11.9%) in comparison to the solution-annealed condition which can be attributed to the finer grain size and the presence of shear-formed austenite in the microstructure. In addition, the fracture mode changed from a fully ductile nature in the solution-treated specimen to a combination of ductile and brittle nature after applying the HPT and then returned again to a ductile behavior after PDA.

Engineering mechanical properties by controlling the microstructure of an Fe–Ni–Mn martensitic steel through pre-cold rolling and subsequent heat treatment

Experiments were conducted to examine the effects of prior cold rolling and subsequent heat treatment on the microstructure, phase evolution and mechanical properties of an Fe–10Ni–7Mn martensitic steel. The results show that 70% cold rolling leads to deformation-induced austenite formation in the microstructure and reduces the size of the martensite blocks. Prior cold rolling increases the reversed austenite volume fraction under post-deformation intercritical annealing (PDIA) at 600 °C compared with the solution annealed condition. Electron back scattering diffraction and dilatometric studies showed that under PDIA there is a reverse transformation of martensite to austenite through a sequential combination of martensitic and diffusional mechanisms. There is also a precipitation of θ-NiMn particles in the PDIA specimen after subsequent ageing leading to an increase in the ultimate tensile strength in tensile testing. Cyclic tensile testing revealed pseudoelastic behavior in the cold-rolled specimen but this disappeared after PDIA and appeared again after subsequent ageing. • Cold rolling produces deformation-induced austenite formation and also refines the martensite blocks. • The prior austenite and the smaller martensite blocks are the primary potential sites for austenite nucleation during PDIA. • Ultimate tensile strength improves from ~695 MPa for the solution annealed sample to ~1215 MPa for the PDIA processed specimen followed by ageing. • Observed pseudoelasticity in the cold rolled specimen disappears after PDIA. • Pseudoelasticity appears again in the PDIA processed specimen followed by ageing.

Influence of plastic deformation on the microstructural and magnetic properties of some Fe-based alloys

We report the morphological and magnetic properties of deformation-induced martensite characteristics in the austenite phase of Fe69Ni27Mn4 and Fe67Ni27Mn4Zn2 (wt %) alloys after 30% plastic deformation. Scanning electron microscopy (SEM) and also physical property measurement system (PPMS) facilities were applied to investigation to clarify the deformation-induced martensite characteristics from morphological and magnetic points of view. Scanning electron microscope observations showed elongated deformation-induced martensite morphology in the austenite phase of the examined alloys. Additionally, two alloys exhibited typical ferromagnetism in their martensite phase. The saturation magnetization (Msat) was found to be firstly increased and then decreased with increasing temperature. We found that the % Zn addition shifts the Curie temperature (Tc) of Fe–Ni–Mn alloys to higher temperatures. The largest Msat (~ 27 emu·g−1), the Hc (~ 26 Oe), and Tc (~ 248) were obtained for the Fe–Ni–Mn–Zn alloy with a mixed configuration of bcc and fcc phases.

The effect of high-pressure torsion on the microstructure and outstanding pseudoelasticity of a ternary Fe–Ni–Mn shape memory alloy

Abstract Experiments were conducted to examine the effect of high-pressure torsion (HPT) processing on the microstructure and pseudoelastic behavior of a ternary Fe–10Ni–7Mn (wt.%) shape memory alloy in both the solution-annealed and intercritically-annealed conditions. X-ray diffraction (XRD) patterns and electron backscatter diffraction (EBSD) analyses showed that the initial microstructure of the alloy in the solution-annealed condition was a fully lath α′-martensite which partially transformed to a strain-induced austenite (α′→γ) by HPT processing. Also, the austenite formed in the dual phase (α′+γ) specimens after intercritical annealing treatment at 600 °C for 7.2 ks underwent a γ→e→α′ transformation during subsequent HPT processing such that a multi-phase microstructure was formed consisting of α′-martensite, austenite and e-martensite. The HPT processing led to a significant increase in the microhardness value to ~690 Hv due to a high density of dislocations and the associated grain refinement of the microstructure. Cyclic loading-unloading tensile tests at room temperature revealed a strain hysteresis and pseudoelastic behavior in the HPT-processed specimens with different initial microstructures. Outstanding pseudoelasticity values of about 67% and 75% were obtained at the fourteenth loading-unloading cycle after 20 HPT turns in the solution-annealed and intercritically-annealed specimens, respectively.

High Entropy and Sluggish Diffusion "Core" Effects in Senary FCC Al-Co-Cr-Fe-Ni-Mn Alloys.

Relative role of enthalpy and entropy in the stabilization of senary FCC Al-Co-Cr-Fe-Ni-Mn high entropy alloys was investigated via a high throughput combinatorial solid-to-solid diffusion couple approach. Many off-equiatomic compositions of FCC AlpCoqCrrFesNitMnu were generated by the diffusing Al and Ni in equiatomic Co20Cr20Fe20Ni20Mn20 alloy, i.e., the Al48Ni52 vs Co20Cr20Fe20Ni20Mn20 diffusion couple, annealed at 900°, 1000°, 1100°, and 1200 °C. Above 1000 °C, the solubility limit of Al in off-equiatomic AlpCoqCrrFesNitMnu alloy was determined to be higher than the solubility limit of Al in equiatomic AlxCoCrFeNiMn alloy. Compositions corresponding to the highest solubility limit of Al in off-equiatomic AlpCoqCrrFesNitMnu alloy exhibited a lower free energy of mixing, i.e., higher thermodynamic stability, than equiatomic AlxCoCrFeNiMn compositions, at 1100 °C and above. Therefore, the role of enthalpy was estimated to be significant in achieving higher thermodynamic stability in off-equiatomic alloys, since they always have lower entropy of mixing than their equiatomic counterparts. The magnitude of interdiffusion coefficients of individual elements in Al-Co-Cr-Fe-Ni-Mn alloys were compared to the interdiffusion coefficients in relevant quinary, quaternary, and ternary solvent-based alloys. Interdiffusion coefficients were not necessarily lower in FCC Al-Co-Cr-Fe-Ni-Mn alloys; therefore no sluggish diffusion was observed in FCC HEA, but diffusion of individual elements in BCC Al-Co-Cr-Fe-Ni-Mn alloy followed the sluggish diffusion hypothesis except for Ni. All compositions in the FCC Al-Co-Cr-Fe-Ni-Mn alloy were observed to comply with existing empirical single phase formation rules in high entropy alloys.

Use of Borides in Strengthening Fe–Ni–Mn–Mo–V–Ti–Nb Steel

The strength of 30N8G6M3FTB steel alloyed with boron nitride and carbide depends on the compounds Nb6C5, V6C5, NbC, Mo0.72Nb0.28B2, VB, Ti3N1.29, NbN, and NbVN2 formed in surfacing by means of powder-core wire. This material may be used in coating components operating with moderate wear.

Electrodeposition of Ni–Fe–Mn ternary nanosheets as affordable and efficient electrocatalyst for both hydrogen and oxygen evolution reactions

The synthesis of high performance and economical electrocatalysts in the process of overall water splitting is very important for the production of hydrogen energy and has become one of the most important challenges. Here, various Ni, Ni–Fe, Ni–Mn nanosheets and Ni–Fe–Mn ternary nanosheets were created using cost-effective, versatile and binder-free electrochemical deposition methods, and the electrocatalytic activity of various electrodes for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) were investigated in an alkaline environment. Due to the high electrochemical active surface area due to the fabrication of nanosheets, the synergistic effect between different elements on the electronic structure, the high wettability due to the formation of nanosheets and the quick detachment of formed gasses from the electrode, the Ni–Fe–Mn nanosheets electrode showed excellent electrocatalytic activity. In order to deliver the 10 mA cm−2 current density in HER and OER processes, this electrode required values of 64 mV and 230 mV overpotential, respectively. Also, the stability test showed that after 10 h of electrolysis at a current density of 100 mA cm−2, the overpotential changes was very small (less than 4%), indicating that the electrode was excellent electrostatic stability. Also, when using as a bi-functional electrode in the full water splitting system, it only needed a cell voltage of 1528 V to deliver a current of 10 mA cm−2. The results of this study indicate a new strategy for the synthesis of active and stable electrocatalysts.

Use of boride compounds for hardening the steel of the Fe—Ni—Mn—Mo— V—Ti—Nb system

Studies have shown, that the hardening mechanism of «30Н8Г6М3ФТБ» steel alloyed with a complex of carbide and boron nitride is determined by the compounds: Nb6C5, V6C5, NbC, Mo0,72Nb0,28B2, VB, Ti3N1,29, NbN and NbVN2 formed as a result of surfacing with flux-cored wire. This material can be used for surfacing parts that work in conditions of moderate wear. Keywords surfacing, nickel-manganese-molybdenum steel, cored wire, alloying, boron carbide, boron nitride, durometric properties. weld_techn@mail.ru

Centrifugal Metallothermic SHS of Cast Co–Cr–Fe–Ni–Mn–(Х) Alloys

A relatively new approach to obtaining metal materials containing several principal elements in equiatomic concentrations which look promising for replacing commercially used alloys is proposed. Such materials are called high-entropy alloys (HEAs). Studies show that HEAs tend to form a simple solid-solution structure and can also contain ordered intermetallic phases. Such a method of forming metal materials can be regarded as a background for producing new HEAs with elevated performance characteristics. Most studies focus on the relationship between microstructure and measured properties; significantly less attention is paid to studying and developing new effective methods for creating HEAs. In this paper, we study the possibility of obtaining CoCrFeNiMn–(X) HEAs by centrifugal metallothermic SHS. Chemical and technological modes of modifying cast CoCrFeNiMn alloy during synthesis (in situ) by introducing alloying components into the starting exothermic compositions are tested for the first time. The microstructure and phase composition of NiCrCoFeMn alloys synthesized from mixtures containing Ti–Si–B(C) or Al are characterized. The microstructure of CoCrFeNiMn–(Ti–Si–B(C)) HEAs is found to consist of an HEA-based matrix and new structural inclusions of carbides and borides of titanium. High-Al CoCrFeNiMn–Al HEAs are represented by a composite structure containing NiAl as a basis and dispersion nanoprecipitates (~100 nm) of a Cr- and Fe-based solid solution.

Prediction of the Elemental Content of Thin Films Electrodeposited from a Multi–component Solution: Co–Ni–Fe–Mn Thin Film as an Example of Multi–element Electrodeposits

Prediction of the Elemental Content of Thin Films Electrodeposited from a Multi–component Solution: Co–Ni–Fe–Mn Thin Film as an Example of Multi–element Electrodeposits

Centrifugal metallothermic SHS of cast Co–Cr–Fe–Ni–Mn–(X) high-entropy alloys

Centrifugal metallothermic SHS of cast Co–Cr–Fe–Ni–Mn–(X) high-entropy alloys

Magnetocaloric effect in Ni–Fe–Mn–Sn microwires with nano-sized γ precipitates

Ni45.6Fe3.6Mn38.4Sn12.4 microwires, with nanoscale γ-phase precipitates that enhance the magnetocaloric effects (MCEs) and mechanical properties, were prepared by a melt-extraction technique and subsequent high temperature annealing. The atomic ordering degree significantly increased after annealing, leading to a considerable increment in the structural entropy change (ΔStr) from 4.5 J/kg·K in the as-extracted microwire to 26.6 J/kg·K in the annealed one, and the magnetization difference (ΔM) from 35 A·m2/kg to 51 A·m2/kg under a magnetic field of 5.0 T. Consequently, a positive magnetic entropy change (ΔSM) peak of 15.2 J/kg·K with working temperature span (ΔTFWHM) of 12 K for the first-order martensite transformation followed by a negative ΔSM peak of −4.3 J/kg·K with ΔTFWHM = 50 K for the second-order magnetic transition under μ0ΔH = 5.0 T was achieved. By employing both magnetizing and demagnetizing processes for magnetic cooling, the two successive inverse and conventional MCEs in Ni–Fe–Mn–Sn microwires may show potential applications for micro-devices and systems.