Solid Solution Of Iron Research Articles

Stabilities of substitutional solutes in α-iron under uniaxial strain

Nonuniform strain fields in ferritic/martensitic steels working in extreme conditions might induce segregation of alloying solutes. We optimized the structures of iron alloy systems under uniaxial tensile strains along [001] direction within density-functional theory. The calculated segregation energies of solutes Ni, Cu, Al, and Si decrease drastically in a linear fashion as the tensile strain increases up to 17.5%, while those of Co and Ti only change slightly. The segregation energies of solutes V, Nb, Ta, Cr, Mo, and W first decrease and then increase. These results might indicate that, for all solutes studied except Co and Ti, segregation behaviors happen in ferritic/martensitic steels under tensile strains. The shape deformation effect plays a major role in the segregation energies of solutes Cu, Al, Si, Ni, Nb, Ta, Cr, and Mo, while the volumetric effect is dominant for solutes V and W. The segregation energy changes owing to the tensile strain increase from 8% to 14% exhibit a linear relation with the Young modulus changes of the alloys relative to α-iron, which indicates a correlation between the stabilities of solutes and their bonding strength with iron neighbors. The linearly decreasing mixing energies of solutes Mg, Zn and Ga in α-iron with increasing uniaxial strain might suggest a new possible way of fabricating supersaturated iron solid solutions.

Toward a tunable fabrication of multifunctional iron-aluminum spinels via solution combustion synthesis: The effects of fuel, heating mode, and Fe:Al precursor ratio

The solid solutions of iron and aluminum spinels (hercynite, maghemite, magnetite, and γ-alumina) are promising materials for emerging technologies such as solar thermochemical fuel production and clean dehydrogenation of fossil fuels. Solution combustion synthesis (SCS) is an attractive technique for the fabrication of these materials as it has been used for synthesis of many nanoscale oxides. However, the design space of SCS is large with many synthesis parameters affecting the properties of the combustion products. To optimize the SCS of these materials, it is important to determine which parameters yield the best properties. In the present work, FeAlOx nanocomposites were obtained by SCS using iron nitrate and aluminum nitrate as precursors and oxidizers. Two fuels (citric acid and glycine), three Fe:Al molar ratios (1:2, 1:1, and 2:1) in the precursors, and three heating modes (hotplate, muffle furnace, and microwave oven) were compared. The products were characterized by X-ray diffraction analysis, scanning electron microscopy, Brunauer-Emmett-Teller surface area analysis, and laser diffraction particle size analysis. The fuel used had the largest impact on the combustion behavior and hence the material properties. The high combustion temperature of glycine allowed for the formation of an FeAl2O4/Fe3O4 solid solution, while the lower-temperature combustion of citric acid yielded Al-substituted γ-Fe2O3 with high amorphous content. With citric acid, the specific surface area as high as 200 m2/g was achieved. The effect of Fe:Al precursor ratio was clearly seen in variations of the lattice parameter, which demonstrated the ability to tune the phase composition. The heating mode had minor effects on material properties, but some differences were observed. All products obtained by SCS in a microwave oven had low specific surface areas compared to those obtained with a hotplate and a muffle furnace.

The effect of abrasive additives on the tribotechnical properties of lubricants for the wheel–rail system

The paper studies the polishing power of a tribochemically active abrasive material based on a solid solution of iron and aluminum oxides, as well as a solid solution of aluminum and iron oxides modified by zirconium oxide and yttrium oxide additives, and the tribotechnical properties of a lubricant doped with these abrasive materials. The modified Al2O3·Fe2O3·ZrO2·Y2O3 powders prove to have an essentially higher polishing power producing a considerably lower surface roughness than that of the unmodified Al2O3·Fe2O3 powder. By varying the content of the modifying oxides, one can change the tribochemical activity of the abrasive powder and select the best composition depending on the material to be polished. The addition of these abrasive powders is shown to have an essential effect on the tribotechnical properties of the lubricant for the wheel–rail contact. The laboratory testing of the lubricant compositions suggests their effective applicability to the wheel–rail contact.

Exploring the limits of Fe3+ solid solution in calcium hexaluminate

Calcium hexaluminate (CA6) forms a broad range of solid solutions by substitution of Al3+ with other cations such as, for example, Fe, Co, Mn, etc. Solid solutions of CA6 with magnetic ions have attracted interest because they allow designing the magnetic behavior depending on the composition of each solid solution. In this paper, we have studied materials pertaining to an area of the CaO–Al2O3–Fe2O3 ternary phase diagram that is potentially interesting, but which has not been too much explored so far. We report on various synthesis methods of calcium hexaluminate with iron in solid solution. The percentages of iron introduced have been varied in order to determine the maximum percentage of iron that can enter into solid solution in the calcium hexaluminate such that the materials obtained exhibit magnetic behavior.Graphical Exploring the limits of Fe3+ solid solution in calcium hexaluminate.

Using explosion loading to obtain coatings of chromium carbide and titanium mixtures in deposition mode

The paper presents the results of studies into the microstructure, chemical and phase composition of coatings deposited on a steel substrate using the sliding explosive loading of Cr3C2 chromium carbide and titanium powder mixtures. The equilibrium phase composition of coatings was calculated by computational thermodynamic modeling using the Thermo-Calc software package. The structure and elemental composition were studied using a FEI Versa 3D scanning electron microscope with an integrated EDAX Apollo X system for energy dispersive X-ray microprobe analysis. A Bruker D8 Advance diffractometer was used for X-ray phase analysis. It was shown that when the powder layer is loaded by a sliding detonation wave, it can be shifted along the substrate surface due to the horizontal mass velocity component of compacted material particles. This shift causes the inner layer of the compacted powder and the surface layer of the substrate to melt as a result of friction. The presence of a liquid phase prevents the compacted powder layer deceleration so that the major part of it is removed from the substrate surface. The liquid phase remaining on the surface undergoes rapid quenching due to heat removal into the substrate and forms a deposited coating containing both the components of the initial powder mixture and the components of the substrate to be coated. It was established that the deposited layer structure features by extremely high dispersion (grain size does not exceed 250 nm), and its phase composition turns out to be close to a thermodynamically equilibrium one. When using powder mixtures of chromium carbide with 40% titanium, a coating is formed consisting of titanium carbide with a metal binder based on solid solutions of iron and titanium in chromium.

Effects of the Cooling Rate on the Solidified Structure and Toxic Leaching of an Arsenic Matte

The conversion of arsenic-containing waste residues into arsenic matte can be an important direction for arsenic treatment. In this paper, different parts of factory samples were first taken for study, and it was found that the leaching amount of arsenic at the chilling layer is noticeably low. Then, the effects of the cooling rate on the phase, microstructure, and chemical compositions and the subsequent toxicity leaching of the arsenic matte were studied. The results show that the alloy structure was obviously refined and the cavity size was also significantly reduced with an increase in cooling rate. Many large-strip FeS and arsenic-containing iron solid solutions were embedded in the matrix (Fe2As) of the furnace-cooled and air-cooled samples; additionally, the Fe–As–S phase was probably caused by an insufficient phase separation of FeS from Fe2As in the rapid cooling process of die cooling and water cooling. FeS in the factory samples was dissolved in the leaching solution, while Fe2As could resist the corrosion of the leaching solution; therefore, it was speculated that the dissolution of arsenic was caused by the dissolution of FeS. The leaching mechanism was also discussed in this paper. The cooling rate affects phase, microstructure, and chemical compositions and toxicity leaching of the arsenic matte, which speculated that the dissolution of arsenic was caused by the dissolution of FeS

Analysis on Solid Solution Iron in Copper by XAFS Measurement

Analysis on Solid Solution Iron in Copper by XAFS Measurement

Nonmolten state metalized reduction of saprolitic laterite ores: Effective extraction and process optimization of nickel and iron

Laterite ore is an important raw nickel ore resource, and methods for extracting valuable metals from low-nickel saprolitic laterite has not been fully developed. This paper proposes a technology, called nonmolten state metalized reduction (NSMR), for extracting nickel and iron from saprolitic laterite in a tube furnace. On the basis of the mineralogical study of ores and feasibility analysis of NSMR, the direct metalization behavior of nickel and iron under different influencing factors was systematically studied. Results showed that the recoveries of nickel and iron were only 14.2% and 32.5%, respectively. For the optimization of the reaction process, the effects of additives, predehydration, and regulating mineral composition on the recovery of nickel and iron were investigated, and the results showed that the recoveries of nickel and iron after optimization increased to 94.1% and 87.4%, respectively. The behaviors of nickel and iron before and after optimization were compared and analyzed. Nickel and iron were metalized in situ before optimization but did not migrate or polymerize remarkably. After optimization, most of the nickel–iron solid solution was polymerized and showed a ribbon shape, which is beneficial for magnetic separation. This result confirmed that the optimized process can effectively improve the metalization of nickel and iron. The lower rate of iron recovery as compared with that of nickel recovery was attributed to the different existing states of the two elements in the ore. The newly generated fayalite was the primary reason for the low iron recovery. Meanwhile, a small amount of sporadically embedded ferronickel in the tailings was responsible for the loss of iron and nickel. The proposed innovative technology can realize nonmolten metalized saprolitic laterite ores and effective beneficiation of nickel and iron.

Evaluation of Boron Solubility in Iron Solid Solution by Radio-frequency Glow-discharge Optical Emission Spectroscopy

Evaluation of Boron Solubility in Iron Solid Solution by Radio-frequency Glow-discharge Optical Emission Spectroscopy

Eddy current characterization and electrical properties of nanostructured alloy Cu70Fe30

The nanostructured copper (Cu)–iron (Fe) alloy exhibits interesting properties compared with a conventional alloy due to the critical size effect. The nanocrystalline solid solution Cu70Fe30 was elaborated from elemental iron and copper powders using a high-energy ball mill. The complete formation of face-centered cubic copper–iron solid solution was obtained after 24 h of milling. A crystallite size of 9 nm was obtained after 36 h of milling. The characteristics of eddy currents and the electromagnetic properties (resistivity and hysteresis loop) of these alloys were studied. The goal was to follow the evolution of the impedance (found from eddy current control) and to establish a relationship between the electrical and magnetic properties and the structure (crystallite size) of the materials.

Giant Negative Magnetization in Al9–xFexMo3

We present derivatives of the Al3Ti-type of structure Al8FeMo3 (Al9–xFexMo3) and Al8CuMo3. Structural features are a molybdenum-square lattice and a solid solution of iron (copper) on aluminum sites. By substitution of Al with 3d-transition metals outstanding magnetic properties are found. Typical Pauli paramagnetism is observed above a critical temperature Tc ≈ 93 K. Below Tc the series Al9–xFexMo3 (0.5 < xFe < 1) exhibits the rare coexistence of negative magnetization/diamagnetism in zero-field cooling and ferromagnetism in field-cooling mode. For Al8.33Fe0.67Mo3 the negative magnetization is estimated to the order of ∼50% of the diamagnetic response of superconducting lead. The contribution of Fe to the magnetization is evaluated by 57Fe Mossbauer spectroscopy in zero field and applied external fields. We show that ferromagnetic fluctuations originate from screened magnetic moments of Fe. The magnetic order presumably involves multibands originating from iron and molybdenum in the vicinity of the Fermi...

ВЛИЯНИЕ КОНЦЕНТРАЦИИ ЖЕЛЕЗА НА КРИСТАЛЛИЗАЦИЮ АМОРФНОГО СПЛАВА СИСТЕМЫ Co-Fe-B-Nb

In the modern world, technical devices are being constantly improved, creation of which requires materials with the best functional properties. Amorphous and nanocrystalline iron- and cobalt-based alloys are some of such materials. They have proved to be good in the fields of radio- and microelectronics, due to the fact they have high magnetic characteristics. It is also known that these properties can be improved by the formation of a partially crystalline structure is such alloys. However, such a structure cannot always be formed using a standard method of isothermal annealing; therefore, alloying components are added to the alloy composition to slow down the crystallization process. Different content of added components also affects the sequence of phase transformations during crystallization. As most of the properties are structure-dependent, the formed structure also determines the material characteristics. Therefore, establishment of the dependence of the formed structure in amorphous alloys after heat treatment is an important task of condensed matter physics. The crystallization of the amorphous alloys of Co-Fe-B-Nb system was studied by X-ray diffraction. The samples were crystallized using isothermal annealing of the alloys with different content of components under the same conditions. The dependence of the formed structure on the content of an alloying component is determined. It is shown that the formed structure significantly depends on the concentration of iron. With the iron content of 10 at.% and 16 at.%, the structure consists of cubic cobalt nanocrystals and a solid solution of iron in cobalt. With a decrease in the concentration to 5 at.%, the crystallization mechanism changes: crystallization begins with the precipitation of Co 23 B 6 boride crystals. The reasons for the effect of iron concentration in the alloy composition on crystallization are discussed.

Nuclear Gamma-Resonance Spectroscopy in Study of Nanoscale Composites

Conversion electron Mossbauer spectroscopy was used to study the thin films obtained by co-precipitation of coatings from two sources: magnetron sputtering of a metal tantalum target and thermovacuum evaporation of metallic iron enriched in the 57Fe isotope. The films of required thickness were formed by alternating exposure to a magnetron-generated tantalum flow and a flow of iron vapor from a thermal evaporator. The analysis of the Mossbauer spectra showed that co-precipitation of iron atoms transferred to the vapor state by heating and tantalum atoms from the magnetron plasma forms a solid solution of iron in tantalum. The film structure is mainly a metastable β-modification of tantalum of the tetragonal crystal system. Annealing of the samples at 1100°С led to the transition of the β-tantalum structure into the body-centered cubic structure of the α-modification of tantalum. It is found that magnetron sputtering creates favorable conditions for formation of solid solutions of two metals at temperatures far from the melting temperatures of their components.

Development of smelting technology of refined ferromanganese with special complex reducing agents

The role of manganese in the production of steel is exceptionally high. A feature of the silicothermic process of obtaining refined ferromanganese is the large loss of manganese with waste slag. When waste slag is cooled, it crumbles to form a fine dust due to the polymorphic transformation of calcium orthosilicate β-Ca2SiO4 → γ-Ca2SiO4 at temperature of 450 – 470 °С with an increase in volume by 12.3 %. As the volume increases, considerable internal stresses appear inside the slag, which leads to dispersion of the slags into finely dispersed state during their cooling. This work is devoted to improving the technology of smelting refined ferromanganese grades, using special complex reducing agents. Experiments have been carried out to simulate the smelting process of refined ferromanganese in an ore-thermal refining furnace RCO-0.1 MVA using aluminosilicomanganese (ASM). The technological modes of the smelting process are established, i.e. optimal composition of charge. Charge went evenly without collapses and emissions. The stability of the current load was observed. Thus, the principal possibility of obtaining a refined ferromanganese with the use of a complex ASM alloy as a reducing agent was proved by the largelaboratory experimental melting. The use of ASM as a reducing agent, instead of ferrosilicomanganese, is due to the sufficient content of silicon and aluminum in it. The presence of chemical compounds and solid solutions of iron, silicon and aluminum in ASM should significantly reduce losses of silicon and aluminum for oxidation processes when interacting with air oxygen. And involving ASM alloy in the metallurgical redistribution, in refined ferromanganese smelting, instead of expensive ferrosilicomanganese will make it possible to obtain an alloy with high added value and with the best technological parameters, due to the presence of additional aluminum in it. The results of X-ray phase studies of slag samples show that the mineralogical components are gehlenite, dicalcium silicate and manganosite. It is noted that gelenite in them is the dominant phase, which is a solid solution, preventing the dispersion of slag. As a result of the theoretical and experimental studies, the tasks have been solved - the smelting technology of refined ferromanganese was developed and tested using a special complex reducing agent – ASM.

Interaction of metals and alloys with gas media under spark discharges

The paper studies the penetration of nitrogen, oxygen, hydrogen, carbon, argon and krypton into copper, nickel, molybdenum, titanium, aluminum, iron and different steels under the action of spark discharges in various media based on radioactive indicators using step-by-step radiometric analysis, macro-, micro-, electron-microscopy and activation autoradiography, Mössbauer and Auger spectroscopy, secondary ion-ionic emission, X-ray diffraction and X-ray microanalysis. The study describes distribution features of penetrating atoms and their concentration profiles. Phase composition of near-surface layers is also determined. It is shown that supersaturated solid solutions of iron in copper and copper in iron are formed during simultaneous iron and oxygen penetration in copper and spinel (Fe6Cu3O4)4. Diffusion of iron and carbon results in supersaturated solid solutions of iron and carbon in copper, copper and carbon in iron, graphite and cementite. Inert gases and nitrogen form solid solutions with copper. Phase composition of near-surface layers in Fe is determined. Iron dioxide FeO, a carbon solid solution in iron with fcc lattice γ-Fe, tetragonal martensite and cementite, two iron (III) hydroxide FeOOH modifications, a supersaturated solid solution of nitrogen and nitride Fe4N, solid solutions of inert gases in iron are formed in the diffusion zone. Simultaneous interaction of molybdenum with iron (the anode material) and various gases results in the formation of substitutional solid solutions of iron in molybdenum and molybdenum in iron, a small amount of interstitial solid solutions of nitrogen and carbon in molybdenum and nitrogen in iron, interstitial phases: molybdenum nitrides and carbides and traces of nitrides of iron (Fe4N, Fe2N) and Fe1,9Mo (λ) phases in the form of needles. Treatment of nickel with a nickel anode in the nitrogen medium promotes formation of a solid solution of nitrogen and nitride Ni3N in the matrix with preserved hexagonal symmetry and lattice parameters that are characteristic of this phase under equilibrium conditions. Atoms of oxygen, nitrogen, carbon and argon are present in the interstitial solid solutions in treatment of nickel in ambient air; however, oxides are not found even on the surface (in the layer ~200 nm). Interaction of titanium with atmospheric gases leads to formation of a solid solution of nitrogen, oxygen, carbon, hydrogen and argon in titanium and titanium nitride Ti2N (ε). Simultaneous saturation of the titanium surface with nickel and nitrogen in the interaction zone causes formation of phases in the following order: nickel nitride; a solid solution of nitrogen and titanium in nickel and a solid solution of both alloying elements in titanium.

Interaction of metals and alloys with gas media under spark discharges

The paper studies the penetration of nitrogen, oxygen, hydrogen, carbon, argon and krypton into copper, nickel, molybdenum, titanium, aluminum, iron and different steels under the action of spark discharges in various media based on radioactive indicators using step-by-step radiometric analysis, macro-, micro-, electron-microscopy and activation autoradiography, Mössbauer and Auger spectroscopy, secondary ion-ionic emission, X-ray diffraction and X-ray microanalysis. The study describes distribution features of penetrating atoms and their concentration profiles. Phase composition of near-surface layers is also determined. It is shown that supersaturated solid solutions of iron in copper and copper in iron are formed during simultaneous iron and oxygen penetration in copper and spinel (Fe6Cu3O4)4. Diffusion of iron and carbon results in supersaturated solid solutions of iron and carbon in copper, copper and carbon in iron, graphite and cementite. Inert gases and nitrogen form solid solutions with copper. Phase composition of near-surface layers in Fe is determined. Iron dioxide FeO, a carbon solid solution in iron with fcc lattice γ-Fe, tetragonal martensite and cementite, two iron (III) hydroxide FeOOH modifications, a supersaturated solid solution of nitrogen and nitride Fe4N, solid solutions of inert gases in iron are formed in the diffusion zone. Simultaneous interaction of molybdenum with iron (the anode material) and various gases results in the formation of substitutional solid solutions of iron in molybdenum and molybdenum in iron, a small amount of interstitial solid solutions of nitrogen and carbon in molybdenum and nitrogen in iron, interstitial phases: molybdenum nitrides and carbides and traces of nitrides of iron (Fe4N, Fe2N) and Fe1,9Mo (λ) phases in the form of needles. Treatment of nickel with a nickel anode in the nitrogen medium promotes formation of a solid solution of nitrogen and nitride Ni3N in the matrix with preserved hexagonal symmetry and lattice parameters that are characteristic of this phase under equilibrium conditions. Atoms of oxygen, nitrogen, carbon and argon are present in the interstitial solid solutions in treatment of nickel in ambient air; however, oxides are not found even on the surface (in the layer ~200 nm). Interaction of titanium with atmospheric gases leads to formation of a solid solution of nitrogen, oxygen, carbon, hydrogen and argon in titanium and titanium nitride Ti2N (ε). Simultaneous saturation of the titanium surface with nickel and nitrogen in the interaction zone causes formation of phases in the following order: nickel nitride; a solid solution of nitrogen and titanium in nickel and a solid solution of both alloying elements in titanium.

The Influence of Boroaluminizing Temperature on Microstructure and Wear Resistance in Low-Carbon Steels

This article investigates the possibility of improving the wear resistance of carbon steel 30 by means of boroaluminizing in treatment pastes. Boroaluminizing was conducted in sodium fluoride (as an activator), boron carbide, and aluminum at furnace heating (the latter two components were taken in a ratio of 4 to 1). The treatment was administered for 4 hours in four temperature modes between 950°C and 1,100°C with a 50°C difference between modes. The microstructure, microhardness, and elemental and phase compositions of the boroaluminized layers were investigated. In addition, the wear resistance of the boroaluminized steels was tested. It was established that treatment temperatures of 1,000°C and lower lead to the formation of layered structures consisting of iron aluminides that are mainly located on top of the diffusion layer and iron borides adjacent to the base metal. Moreover, the use of boroaluminizing temperatures over 1,000°C results in the formation of a heterogeneous structure with iron borides FeB and Fe2B evenly distributed in the matrix of aluminum solid solution in iron. This contributes significantly to the mechanical properties of the layer; in particular, it enhances its wear resistance. It was established that the wear resistance of steel 30 significantly improves after treatment at 1,100°C in comparison with temperature modes of 950°C and 1,000°C.

Study of Diffusion Bonding of 45 Steel through the Compacted Nickel Powder Layer

The microstructure of the transition zone and powder spacer, the concentration distribution of chemical elements over the width of the diffusion-bonded joint, and microhardness of 45 steel–compacted Ni powder spacer–45 steel layered composites formed by diffusion bonding have been investigated. It has been shown that the relative spacer thickness χ < 0.06 is optimal for obtaining a high-quality joint has been formed under a compacting pressure of 500 MPa. The solid-state diffusion bonding is accompanied by sintering the nickel powder spacer and the formation of the transition zone between the spacer and steel. The transition zone consists of solid solution of nickel in the α-Fe phase and ordered solid solution of iron in nickel (FeNi3).

Influence of strain rate on ductile versus brittle fracture for ductile cast iron EN-GJS-500-14 in V-notch three-point bending tests

Three point bending tests on V-notched specimens machined from a component cast in EN-GJS 500-14 nodular iron solid solution strengthened by silicon have been carried out. The 3P bending tests were performed at different stroke speeds (10-3 ~ 102 mm/s). The resulting strain rates at the V notch varied in the range of 1·10-4 ~ 5,8 s-1. The fracture surface of 3P bending tests was quantified in terms of ductile and brittle fracture using Scanning Electron Microscope (SEM). EN-GJS 500-14 has an increased brittle behavior with increasing strain rate. Predominately ductile fracture was observed for the strain rates 1·10-4~4·10-2S-1. . At the strain rate of about 1 s-1 more significant change in ductile to brittle fracture is seen. The 3P bending tests at -15°C showed predominately brittle fracture for the strain rates investigated 3,6·10-2 ~ 2,3 s-1.

Photocatalytic degradation of H2S aqueous media using sulfide nanostructured solid-solution solar-energy-materials to produce hydrogen fuel

H2S is a corrosive, flammable and noxious gas, which can be neutralized by dissolving in alkaline media and employed as H2-source by utilizing inside semiconductor-assisted/photochemical reactors. Herein, through a facile hydrothermal route, a ternary nanostructured solid-solution of iron, zinc and sulfur was synthesized in the absence and presence of Ag-dopant, and applied as efficient photocatalyst of hydrogen fuel production from H2S media. The effect of pH on the photocatalyst performance was scrutinized and the maximum activity was attained at pH=11, where HS− concentration is high. BET, diffuse reflectance and photoluminescence studies indicated that the ternary solid-solution photocatalyst, in comparison to its solid-solvent (ZnS), has a greater surface area, stronger photon absorption and less charge recombination, which justify its superiority. Moreover, the effect of silver-dopant on the photocatalyst performance was examined. The investigations revealed that although silver could boost the absorption of photons and increase the surface area, it could not appreciably enhance the photocatalyst performance due to its weak influence on retarding the charge-recombination process. Finally, the phenomenon was discussed in detail from mechanistic viewpoint.