Fe Sn System Research Articles

Electrical current-assisted reactive crucible melting technique: Case study of the Fe-Sn system

Modern materials science relies heavily on the advancement of combinatorial high-throughput experimental and computational methods to discover new advanced materials. Among these methods, the reactive crucible melting (RCM) technique stands out as particularly promising. However, a significant challenge in RCM combinatorial analysis is the occurrence of "missing" phases. In this study, we successfully addressed this limitation through the application of electrical current stressing. Furthermore, we investigate the influence of electric current stressing on diffusion rates and the phase formation processes within the reactive crucible. We employed Comsol Multiphysics modeling to analyze the experimental results in the framework of electromigration theory, focusing on the distribution of electrical field lines, temperature gradients, and current density values. Additionally, through the integration of finite element calculations with analysis of Electron Backscatter Diffraction (EBSD) and Magneto-Optical Kerr Effect (MOKE) data, we estimated the gradient of internal stresses along the boundaries of the crucible's reaction volume induced by the diffusion of electrically-induced vacancies and adatoms. Due to modest values of the current density in our experiment and the disparity between the rates of crucible body dissolution and vacancy diffusion, no compressive or tensile stresses were observed. Nonetheless, we propose that the developed electrical current-assisted reactive crucible melting technique holds promise for synthesizing metastable phases existing under high positive or negative pressures.

Simulation of diffusion processes during electrothermal treatment of reaction crucibles of the Fe-Sn system

Simulation of diffusion processes during electrothermal treatment of reaction crucibles of the Fe-Sn system

Thermodynamic modeling of the Fe-Sn system including an experimental re-assessment of the liquid miscibility gap

The usage of low-grade ferrous scrap has increased over decades to decrease CO2 emissions and to produce steel products at a low cost. A serious problem in melting post-consumer scrap material is the accumulation of tramp elements, e.g., Cu and Sn, in the liquid steel. These tramp elements are difficult to remove during conventional steelmaking processes. Sn is considered as one of the most harmful tramp elements because, together with Cu, it sometimes induces the liquid metal embrittlement in high-temperature ferrous processing, e.g., continuous casting and hot rolling. Furthermore, the chemical interaction between Fe and Sn plays an important role in the Sn smelting process. The raw material used in the Sn smelting process is SnO2 (cassiterite), in which Fe3O4 is a gangue in the Sn ore. In the process, the reduction of Fe3O4 is unavoidable, which results in forming a Fe-Sn alloy (hardhead). The recirculation of the hardhead decreases the furnace capacity and increases the energy consumption in the smelting. The need to efficiently recover Sn from secondary resources is therefore inevitable. The CALculation of PHAse Diagrams (CALPHAD) approach helps to predict the equilibrium state of the multicomponent system. Previously reported studies of the Fe-Sn system show inconsistencies in the calculations and the experimental results. Mainly the miscibility gap in the liquid phase was under debate, as experimental data of the phase boundary are scattered. Experimental study and re-optimization of model parameters were carried out with emphasis on the correct shape of the miscibility gap. Three different experimental techniques were employed: differential scanning calorimetry, electromagnetic levitation, and contact angle measurement. The present thermodynamic model has higher accuracy in predicting the solubility of Sn in the body-centered cubic (bcc), compared to previous assessments. This is achieved by re-evaluating the Gibbs energies of the FeSn and FeSn2 compounds and the peritectic reaction related to Fe5Sn3. Also, the inconsistencies related to the miscibility gap around XSn = 0.31-0.81 were resolved. The database developed in the present study can contribute to the development of a large CALPHAD database containing tramp elements.

Thermodynamical and topological properties of metastable Fe3Sn

The Fe–Sn-based kagome compounds attract intensive attention due to its attractive topological transport and rich magnetic properties. Combining experimental data, first-principles calculations, and Calphad assessment, thermodynamic and topological transport properties of the Fe–Sn system were investigated. Density functional theory (DFT) calculations were performed to evaluate the intermetallics’ finite-temperature heat capacity (Cp). A consistent thermodynamic assessment of the Fe–Sn phase diagram was achieved by using the experimental and DFT results, together with all available data from previous publications. Here, we report that the metastable phase Fe3Sn was introduced into the current metastable phase diagram, and corrected phase locations of Fe5Sn3 and Fe3Sn2 under the newly measured corrected temperature ranges. Furthermore, the anomalous Hall conductivity and anomalous Nernst conductivity of Fe3Sn were calculated, with magnetization directions and doping considered as perturbations to tune such transport properties. It was observed that the enhanced anomalous Hall and Nernst conductivities originate from the combination of nodal lines and small gap areas that can be tuned by doping Mn at Fe sites and varying magnetization direction.

Interaction of exogenous refractory nanoparticles of Al2O3 and MgAl2O4 with nonferrous metal impurities in iron melts

The exogenous refractory nanoparticles is proposed for refining iron-based melts from nonferrous metal impurities. Investigated the heterophase interaction of Al2O3 and MgAl2O4 nanoparticles with Sb/Sn/Cu and showed that the degree of removal of nonferrous metal impurities was in the Fe-Sb system up to 30 rel.%, in the Fe-Sn system up to 29 rel. % and in the Fe-Cu system up to 23 rel. %. The existence of refractory nanoparticles in a liquid metal was proved by studying the structural properties of the melt. In the melts, after the introduction of the nanoparticles, inversion of the temperature coefficient of surface tension is observed, as well as multidirectional change depending on the nature of the nanoparticles and the holding time during interfacial interaction. Decompression and compression of the melts after the introduction of nanoparticles and the multidirectional nature of the dependences of properties indicate a possible change in the cluster structure of liquid metal.

Magnetodiffusion Effect of the Fe–Sn System in a Magnetic Field at 730°С

An experimental study is performed of the effect constant and pulsed magnetic fields have on the coefficient of diffusion for Sn in α-Fe in the 39.8–557.2 kА m−1 range of magnetic field intensities and 1‒21 Hz range of frequencies at 730°С. It is found that the pulsed magnetic fields have a considerable effect on the coefficient of diffusion for Sn in α-Fe. Resonant behavior of the coefficient of bulk diffusion at pulsed magnetic field intensities of more than 238.8 kА m−1 is observed. Possible mechanisms of the observed effect are discussed.

Effect of Tin on the Phase Transformations of Cast Irons

Copper, manganese and essentially tin are used as alloying elements for obtaining cast irons with a fully pearlitic matrix in the as-cast state. Addition of tin, at a level of about 0.10-0.15 mass%, seems to be the only practical way for avoiding growth of ferrite in the stable eutectoid reaction and to fully transform the matrix of the material to pearlite in the metastable eutectoid system. While the role of copper and manganese has been previously rationalized, the way tin affects the eutectoid transformation in cast irons is still a matter of debate. The present work makes use of an assessment of the Fe-Sn system and of experimental data in the Fe-C-Sn system to evaluate the effect of tin on phase equilibria in this latter system. One ternary parameter is estimated and the resulting modification is applied to literature data on Fe-CSi- Sn equilibria. Finally, solid-state phase transformation temperatures are calculated and used to discuss experimental information dealing with pearlitic cast irons. It is proposed that pearlite formation in Sn-bearing cast irons is associated to the transient formation of a Fe3SnC compound which has an ordered FCC structure.

Aerosol nanoparticles in the Fe-Sn system over a wide composition range

Aerosol nanoparticles in the Fe-Sn system over a wide composition range

Four High-Temperature Ferromagnets in the Hf–Fe–Sn System

We report the synthesis and characterization of four new ferromagnetic compounds discovered using Sn flux: Hf1.823(16)Fe5Sn3.815(14), HfFe2–xSnx, and two polymorphs of Hf1–xFe2Snx. All are closely related to HfFe2 Laves phase parent structures. HfFe2–xSnx (x ≈ 0.3–0.4) adopts the MgZn2-type (C14) crystal structure, whereas Hf1–xFe2Snx (x ≈ 0.1–0.4) adopts both the MgCu2-type (C15), and MgNi2-type (C36) structures. They crystallize in P63/mmc, Fd3̅m, and P63/mmc, respectively, with measured unit-cell parameters of a = 4.9238(7) Å and c = 7.9643(12) Å; a = 7.068(2) Å; and a = 4.9944(4) Å and c = 16.2604(15) Å, although phase width leads to a range of unit cell edge lengths. Hf1.823(16)Fe5Sn3.815(14) adopts a more complicated, incommensurately modulated structure in the superspace group Xmmm(00γ)000 with an orthorhombic subcell a = 9.7034(12) Å, b = 16.823(2) Å, and c = 8.4473(10) Å, three centering vectors of (1/2 0 0 1/2), (0 1/2 0 1/2), and (1/2 1/2 0 0), and a single-component modulation vector q = 0.2768(8)c*. The structure is composed of alternating slabs of the Fe-bonded Kagomé nets observed in the HfFe2 parent structures alternated with Sn-rich Th2Zn17-type slabs, with Hf atoms primarily occurring at the interfaces between the slabs. All four compounds are ferromagnetic metals at room temperature, with Curie temperatures ranging from 467(2) to 658(2) K. Their coercive fields are remarkably low, between 2(1) and 15(2) Oe. Interestingly, in two of three cases the addition of nonmagnetic Sn atoms in place of magnetic Hf or Fe atoms in the HfFe2 structure seems to strengthen rather than weaken magnetic coupling and increase TC. Fits to electrical resistivity data for the compound suggest that electron scattering in the Laves phase polymorphs shows substantial contributions from electron–magnon and/or electron–electron scattering, while the electrical behavior of Hf1.823(16)Fe5Sn3.815(14) is dominated by electron–phonon scattering, as is the case in most metals.

Solvent grain boundary diffusion in binary solid solutions: a new approach to evaluate solute grain boundary segregation

A new method to estimate solute grain boundary (GB) segregation from solvent GB diffusion measurements in binary solid solutions is proposed for the systems with restricted solubility and intermediate stoichiometric phases. The method is based on the model of complex formation: solvent atoms (A) interact with solute ones (B) at GB with the formation of AB chemical bond. A description of solvent GB diffusion is then given. Using such an approach, a new equation for the dependence of solvent GB diffusion coefficient on solute bulk concentration is derived for the systems with simple atomic attraction with AB complex formation in GB. Theoretical results predict non-linear dependence of solvent GB diffusion coefficient on solute bulk content, which is in agreement with earlier published experimental data regarding the ease of grain boundary diffusion in alloys of different chemical compositions. More importantly, the equation deduced permits to evaluate, on one hand, the characteristics of solute GB segregation from solvent GB diffusion measurements and, one the other hand, GB diffusion coefficient in pure solvent. Such a numerical data analysis for Fe–Sn system is in agreement with experimental results. In special cases, such an analysis can be done analytically.

Electronic and magnetic structures of FeSn compound investigated by first principle, mean field and series expansions calculations

Self-consistent ab initio calculations, based on the DFT (Density Functional Theory) approach and using the FLAPW (Full potential Linear Augmented Plane Wave) method, are performed to investigate both electronic and magnetic properties of the FeSn compounds. Polarized spin and spin–orbit coupling are included in calculations within the framework of the antiferromagnetic state between two adjacent Fe planes. The antiferromagnetic and ferromagnetic energies of FeSn systems are estimated. Magnetic moments considered to lie along (010) axes are computed. Obtained data from ab initio calculations are used as input for the high temperature series expansions (HTSEs) calculations to compute other magnetic parameters.

Solidification morphologies in monotectic alloys

We model the Fe-Sn system by using a higher order polynomial to describe the free energy of the liquid, and study three different aspects in morphological evolution in the monotectic alloy. Firstly, phase separation, in which case the liquid decomposes into two, is investigated inside of the spinodal decomposition region. Secondly, we study the core-shell morphology in the Fe-Sn alloy, which arises by spinodal decomposition in 2D. Finally, stable lamellar and unstable droplet morphologies in directional solidication are investigated.

Simulation of thermally induced processes of diffusion and phase formation in layered Fe-Sn and Fe-Zr systems

The simulation results of thermally induced processes of diffusion and phase formation for the Fe-Sn and Fe-Zr layered systems experimentally investigated by Mossbauer spectroscopy are presented. Simulation has been carried out using the specially designed DIFFUSION program, the basic functional possibilities of which are described in detail. The physical model is based on the phenomenological Darken theory and on the interdiffusion mechanism of components along the continuous diffusion channels of phases in two-phase regions of the system. The simulation results agree well with the experimental data. The character of phase transformations in the investigated layered systems is determined by the change in a local concentration of components during their interdiffusion and corresponds to the features of the equilibrium diagrams for both binary systems.

Peculiarity of component interaction in Er–Fe–Sn ternary system at 670 K and 770 K

The isothermal sections of the phase diagram of Er–Fe–Sn ternary system were constructed at 770 and 670 K in the whole concentration range using X-ray and metallographic analyses. Component interaction in the Er–Fe–Sn system at 670 K results the existence of two ternary compounds, ErFe 6Sn 6 (YCo 6Ge 6-type) and Er 5Fe 6Sn 18 (Tb 5Rh 6Sn 18-type), while at 770 K only one intermediate ErFe 6Sn 6 phase was observed. The existence of the interstitial solid solution ErFe x Sn 2 (up to 5 at.% Sn) was found at both temperatures.

ChemInform Abstract: The Pr-Fe-Sn Ternary System: Phase Diagram and Crystal Structure of PrFe0.4Sn2.

Abstract The isothermal section of Pr–Fe–Sn system at 670 K has been investigated by EDAX and X-ray phase analysis. Two ternary compounds, Pr 6 Fe 13 Sn and PrFe 0.4 Sn 2 have been found. Crystal structure of the PrFe 0.4 Sn 2 compound was refined to be isotypic with CeNiSi 2 ( a =4.545(1) A, b =16.833(3) A, c =4.448(1) A).

Measurements of thermal diffusivity of spherical samples. Fe-Sn system

An experimental setup is described, which enables one to measure the thermal diffusivity of metals and alloys by the pulse method for spherical samples. Results are given of the investigation of thermal diffusivity of Fe-Sn alloy in the neighborhood of the solid st ate-liquid state transition; also give are X-ray electron spectra of valence bands of the Fe-S n system with different tin content.

Sn–Bi–Fe thermodynamic modeling and Sn–Bi/Fe interfacial reactions

Knowledge of Sn–Bi/Fe interfacial reactions and phase equilibria of Sn–Bi–Fe is of fundamental importance for Sn–Bi-based solder applications. Thermodynamic modeling of the binary Fe–Sn system and the ternary Sn–Bi–Fe system is carried out using the CALPHAD (calculation of phase diagram) method, and the calculated results show good agreement with the experimental information. The Sn–57wt%Bi/Fe interfacial reactions are examined between 250 and 500 °C. A peculiar phenomenon is observed that the reaction rates of Fe with molten Sn–57wt%Bi solder are lower at higher temperatures. This peculiar phenomenon is due to the different intermetallic compounds formed at different temperatures. The transition of the interfacial reaction products with temperatures is caused by the ternary phase equilibria tie-line shift, and can be well illustrated by the calculated Sn–Bi–Fe isothermal sections at different temperatures.

Thermodynamic description of the Cu–Fe–Sn system at the Cu–Fe side

A thermodynamic description of the ternary Cu–Fe–Sn system at the Cu–Fe side is presented. The thermodynamic parameters of the sub-systems, Cu–Fe, Cu–Sn and Fe–Sn, are taken from earlier SGTE-based assessments, and those of the ternary Cu–Fe–Sn system are optimized in this study by using the experimental tin activity and phase equilibrium data. The present ternary description is valid for tin contents up to 60 wt%.

Anomalous Hall effect and magnetoresistance of (FexSn1−x)1−y(SiO2)y films

Structural, magnetic and transport properties were investigated for heterogeneous (FexSn1−x)1−y(SiO2)y films deposited on oxidized silicon substrates at room temperature with RF magnetron sputtering. X-ray diffraction indicated that the films consist of a nanocrystalline phase of FeSn2 embedded into an amorphous background. For (FexSn1−x)92.33(SiO2)7.67, it was demonstrated that with the increase in the Fe component an evolution from negative isotropic magnetoresistance (MR) behaviour to one with a mixture of anisotropic magnetoresistance and isotropic negative MR occurs. On fixing the SiO2 percentage and decreasing the Fe–Sn ratio, the negative transverse MR first increases and then decreases. For samples having a fixed Fe–Sn ratio, the negative transverse MR increases with the increase in SiO2. Compared with the Fe–Sn system, the addition of 7.67 at.% SiO2 enhances the saturated Hall resistivity. Further increase in SiO2 introduces a complicated saturated Hall resistivity dependence on the concentration of SiO2.

Investigation on the giant Hall effect of (Fe xSn 100− x) 1− y(SiO 2) y granular films

(Fe x Sn 100− x ) 1− y (SiO 2) y granular films have been fabricated by a magnetron-sputtering technique and the Hall resistivity of the films has been investigated in the Fe concentration range from x = 71 to 73, and in the SiO 2 volume fraction range from y = 0.45 to 0.65. Compared with the Fe–Sn system, a significant enhancement has been observed for the Hall resistivity at room temperature for x = 71, y = 0.65, as high as 75 μΩ cm. This value of the saturated Hall resistivity is almost three orders larger in magnitude than that of pure Fe and about 10 times higher than that of the Fe 68Sn 32 granular alloy films reported earlier. The magneto-resistance of the films has also been studied.