Magnetic Transformation Temperatures Research Articles

Calorimetric Studies of Phase Transformations in the La<sub>1 – x</sub>Y<sub>x</sub>Mn<sub>2</sub>Si<sub>2</sub> System

Differential scanning calorimetry (DSC) is used to determine the magnetic phase transformation temperatures of the La1 – xYxMn2Si2 (x = 0–1) alloys. For the compositions with х from 0 to 0.3, the temperature dependences of DSC signal exhibit λ-like endothermic effects observed near 300 K, which are related to the magnetic phase transition from the ferromagnetic to layered antiferromagnetic structure, and weak anomalies, which are observed in a temperature range of from 458 K for the composition with х = 0 to 323 К for the composition with х = 0.3 upon disordering of the layered antiferromagnetic structure. A clear endothermic peak corresponding to the disordering of interplane antiferromagnetic layered structure was found for the YMn2Si2. The data obtained are used to construct the magnetic phase diagram of the La1–xYxMn2Si2 system in a temperature range of 270–600 К. The differential scanning calorimetry is shown can be successfully used for the determination of temperatures of various magnetic phase transformations in rare-earth intermetallic compounds.

The effect of hydrogenation on the electrophysics and magnetic characteristics of dysprosium

The effect of hydrogenation from the gas phase on the change in the character of the temperature dependence of the electrical resistivity ρ(T) in the range of 77–300 K and the temperatures of phase magnetic transformations (Curie temperature TC and Néel temperature TN) of dysprosium was studied. It follows from the experimental data and their analysis that, within the framework of the indirect exchange ideas, the decreases in TC, TN and the contribution to ρ(T) related to electron scattering in the paramagnetic phase are interrelated. It has been suggested that hydrogenation effects may be related to changes in microscopic parameters: a decrease in the density of states at the Fermi level, an increase in the Fermi energy, and a decrease in the effective mass of carriers and the s-f exchange parameter.

Ordering mechanism and kinetics in Ni2Mn1−xCuxGa ferromagnetic shape memory alloys

The effect of atomic order on the martensitic and magnetic transformations undergone by Ni2Mn1−xCuxGa ferromagnetic shape memory alloys has been investigated. Different degrees of order have been induced by performing selected thermal treatments, and it has been found that, although both the structural (martensitic) and magnetic transformation temperatures increase with the improvement of the atomic order, each of these temperatures evolve with different kinetics. Reinforcing this result, during post–quench heating of Ni2Mn1−xCuxGa alloys two consecutive DSC exothermic peaks are observed, while the ternary Ni–Mn–Ga, Co–doped Ni–Mn–Ga and even Cu–doped Ni–Mn–Ga alloy when Cu replaces Ni show a single peak. The kinetics of the post–quench ordering processes have been studied using the Kissinger’s method, and two different activation energies have been obtained: 1.16 eV for the process that is common to all alloys and 1.35 eV for the one that is only observed in Ni2Mn1−xCuxGa alloys. The former, responsible for the change in Curie temperature, is attributed to the improvement of L21 order mainly due to Mn diffusion; for the second, which underlies the rise of martensitic transformation temperatures, diffusion of Cu atoms, misplaced in the Ni sublattice after quench, towards their most favourable sites in the Mn sublattice is proposed as the responsible mechanism.

Martensitic Transformation and Magnetocaloric Effect in Co-Doped Ni–Mn–In Ferromagnetic Shape Memory Alloy

In this work, we present the detailed results of magnetic, structural, and magnetocaloric measurements in Ni-Mn-In-based Heusler alloys, namely, Ni <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">51</sub> Mn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">32.8</sub> In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">16.2</sub> , Ni <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">50.2</sub> Mn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">33.6</sub> In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">16.2</sub> , and Ni <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">51</sub> Mn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">33.4</sub> In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15.6</sub> . The characteristics of magnetostructural coupling play an important role in the magnetic field-driven behavior of these alloys. A small variation in the stoichiometry composition broadens the magnetic entropy change curve and shifts the critical temperatures by as much as 48 K. The effect of cobalt doping on the magnetic, structural, and magnetocaloric properties in these multifunctional alloys is investigated through characterizing Ni <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">50</sub> Co <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Mn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">35</sub> In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sub> and Ni <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">45</sub> Co <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> Mn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">37</sub> In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sub> samples. Cobalt doping affects the martensitic and magnetic transformation temperatures and enhances the ferromagnetic properties of the parent austenitic phase. Therefore, the magnetization change accompanying the martensitic transformation is significantly improved, resulting in a large magnetic entropy change of 21.6 J kg <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> at 1.5 T. Additionally, Co doping broadens the operating temperature window to 21 K around room temperature. Consequently, a significant effective refrigeration capacity of 254 J kg <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> for 1.5 T is obtained which is comparable or even superior to that of the high-performance, though expensive, rare-earth-based magnetocaloric refrigerants. The high performance, low cost, nontoxicity, and tunability make these alloys of great interest and promising prospect for an affordable magnetic refrigeration system.

Large refrigeration capacity in a Ni48Co1Mn37In14 polycrystalline alloy with low thermal hysteresis

For Ni–Mn–In based alloys, simultaneously achieving large magnetic field-induced transformation temperature shift and low thermal hysteresis is of vital significance to obtain significant magnetocaloric properties. In this work, we employ low content Co doping to tune the magnetostructural transformation parameters and demonstrate large inverse magnetocaloric effect in a Ni48Co1Mn37In14 alloy. It is shown that 1% Co doping confers a strong magnetic field dependence of transformation temperature, i.e., 7.2 KT−1, giving rise to a wide refrigeration temperature window of 34 K under the magnetic field change of 5 T. Together with relatively low thermal hysteresis, i.e., ~8 K, giant effective refrigeration capacity up to 284 Jkg−1 is achieved under the magnetic field change of 5T. The present work is expected to offer some instructions for the design of Ni–Mn-based alloys with excellent magnetocaloric properties.

Variation of the Curie Temperature in Porous Materials

The dependence of the temperatures of magnetic phase transformations in porous ferromagnetic materials on the geometric characteristics (volume and shape) of pores and their distribution in a particular material has been studied. The geometric features of nanopores have been characterized by their effective pore radius and form factor (deviation of the pore shape from spherical). Estimations indicate that it is possible to obtain macroscopic samples of porous materials with decreased Curie temperatures, which can be further reduced in the case of complicated shapes of pores. These results were obtained in the framework of a cohesive model in application to pure porous nickel and cobalt.

Significant enhancement of magnetocaloric effect in a NiMnCuGa Heusler alloy through textural modification

Magnetocaloric materials are of increasing interest to bring magnetic refrigeration to everyday households and drastically impact the energy demands for temperature control devices. In this work, a polycrystalline Heusler alloy of composition Ni2Mn0.76Cu0.24Ga with coinciding structural and magnetic transformation temperatures was subjected to compressive stress assisted thermal cycling (SATC) to enhance the magnetic properties by inducing a preferred orientation in the martensite. Isofield magnetization measurements showed a sharpening of the transformation between ferromagnetic martensite and paramagnetic austenite due to SATC. In isothermal magnetization measurements, SATC was seen to increase the magnetostructural coupling. With a 2 T applied magnetic field, the magnetocaloric effect (MCE) increased from ∼10 to ∼25 J/kg K and the refrigeration capacity (RC) almost doubled due to SATC. Heat capacity measurements were largely unaffected by SATC. The change in adiabatic temperature was estimated by using Cp and change in magnetic entropy (ΔSM) calculations. SATC was seen to increase ΔTad from ∼1.2 K to 2 K for an applied magnetic field of 2 T. Neutron diffraction measurements revealed highly textured martensite in the as received state that rotated to a more ideal preferred orientation after SATC that enhanced the magnetostructural transformation; and thus, improving the MCE and ΔTad.

The effect of Co and Ce codoping in CuIn0.9CexCo0.1−xTe2

The codoped dilute magnetic semiconductor CuIn0.9CexCo0.1−xTe2 has been successfully prepared by arc melting and vacuum solid-state reaction technologies. CuIn0.9CexCo0.1−xTe2 crystallizes into body centered tetragonal structure with a space group of I4¯2d. The codoping of Co and Ce induces the room temperature ferromagnetism in CuIn0.9CexCo0.1−xTe2. The magnetization of CuIn0.9CexCo0.1−xTe2 are enhanced by codoping Ce and Co into CuInTe2, which is ascribed to the exchanging interaction between 4f electron of Ce and 3d electron of Co. Magnetic measurements show that Co influences mainly on the saturation magnetic moment of CuIn0.9CexCo0.1−xTe2. The high doping ratio of Co and Ce is beneficial for increasing saturation magnetization and the magnetic transformation temperature. Codoping Ce and Co into CuInTe2 can adjust the light absorption bandgap from 0.92 eV to 1.08 eV, which is slightly higher than that of CuInTe2. It shows that the light absorption bandgap can be refined by controlling Co/Ce ratio for the potential application of solar cell material.

Effect of Chromium Substitution for Iron on the Magnetic and Structural Properties of (TmxPr1– x)2Fe17

The (TmxPr1 – x)2Fe17 and (TmxPr1 – x)2Fe16.5Cr0.5 compounds crystallize with the formation of the rhombohedral Th2Zn17-type structure for the compositions with x = 0–0.4 and the hexagonal Th2Ni17-type structure for the compositions with x = 0.8–1 and x = 0.75–1, respectively. Both structures coexist in the (TmxPr1 – x)2Fe17 and (TmxPr1 – x)2Fe16.5Cr0.5 compounds with x = 0.5–0.75 and x = 0.5–0.6, respectively. The (TmxPr1 – x)2Fe17 compositions with 0 < x < 0.6 are ferrimagnets; at x = 0.6–1, additionally a high-temperature helical magnetic state is realized. The substitution of chromium for iron leads to the transformation of the helimagnet to ferrimagnet; in this case, the difference between the Curie temperatures of rhombohedral and hexagonal phases is unexpectedly high (25–28 К). For the composition with x = 0.8, the Curie and Neel temperatures and the ferrimagnet–helimagnet transformation temperature are minimum, and the microdeformations are maximum. The overlap of two peaks in –ΔSM(T), which correspond to the magnetic entropy change at two magnetic phase transformation temperatures, favors the realization of the higher cooling capacity of the two-phase compositions as compared to that of neighboring single-phase compositions.

Magnetic properties and magnetocaloric effects of Gd65(Cu,Co,Mn)35 amorphous ribbons

The magnetic phase transition and magnetocaloric effects of Gd65(Cu,Co,Mn)35 amorphous ribbons were investigated. The increased Mn substitution for Co or Mn substitution for Cu led into a higher second-order magnetic phase transformation temperature, near 200 K in all ribbons. Under the field change of 7 T, a maximum entropy change (ΔSmmax) of 6 J kg−1 K−1 was achieved in Gd65Cu10Co20Mn5 ribbon and slightly dependent on the compositions. With varied composition, a full width at half of ΔSmmax was greatly widened to be over than 180 K for Gd65Cu15Co10Mn10 ribbon. The refrigeration capacity was also greatly enhanced to 1000 J kg−1 for Gd65Cu20Co10Mn5 ribbon, which was even excellent compared with other Gd-based amorphous systems.

Effect of Cobalt on the Crystal Structure and Magnetism of Electron-Doped Sr0.8Ce0.2MnO3 Oxide

The Sr0.8Ce0.2Mn1 – yCoyO3 – δ (y = 0.2, 0.3, 0.4, 0.5, and 0.6) complex oxides with the perovskite structure obtained from simple oxides by the solid–state reaction technique have been examined using structural analysis and magnetic measurements. Substitution of Co for Mn in the dilute Sr0.8Ce0.2MnO3 antiferromagnet with a Neel temperature of TN = 210 K leads to a decrease in the degree of tetragonal distortion of the crystal structure and transition to the cubic cell. The degeneracy of the antiferromagnetic interaction (TN = 138 K at y = 0.2) observed at the first stage of the substitution of Co for Mn changes for its gradual enhancement with an increase in the magnetic transformation temperature up to 239 K at y = 0.6. An increase in the Co content weakens the competition between the ferromagnetic and antiferromagnetic couplings and reduces the temperature of the transition to the spin-glass-like state. The magnetic inhomogeneity and formation of Co2+–Mn4+ ferromagnetic clusters in Sr0.8Ce0.2Mn0.4Co0.6O2.69 at 140 K have been observed.

A Study of Phase Transformations in High-Chromium Ferritic-Martensitic Steels by Magnetometry

Phase transformations in high-chromium ferritic-martensitic steels are studied using magnetometric analysis of the magnetic field. A designed, certified and experimentally tested facility for measuring the magnetic permeability of small (pea-size) specimens is described. The facility makes it possible to determine the temperatures of magnetic transformations and, in some cases, the thermal effects of phase transformations. Examples of application of the developed method for determining the characteristics mentioned are given and used to plot diagrams of isothermal transformation of supercooled austenite. An analysis of pairs “mechanical properties – parameters of diagrams of isothermal transformation” is performed, and the dependences obtained are analyzed. The formulated features of the parameters of the diagrams of isothermal decomposition may be used for developing high-chromium ferritic-martensitic steels with high refractoriness. The limits of the applicability of the developed methods and of the used facility are presented.

Влияние кобальта на кристаллическую структуру и магнетизм электрон-допированного оксида Sr-=SUB=-0.8-=/SUB=-Ce-=SUB=-0.2-=/SUB=-MnO-=SUB=-3-=/SUB=-

AbstractThe Sr_0.8Ce_0.2Mn_1 – _ y Co_ y O_3 – δ ( y = 0.2, 0.3, 0.4, 0.5, and 0.6) complex oxides with the perovskite structure obtained from simple oxides by the solid–state reaction technique have been examined using structural analysis and magnetic measurements. Substitution of Co for Mn in the dilute Sr_0.8Ce_0.2MnO_3 antiferromagnet with a Néel temperature of T _N = 210 K leads to a decrease in the degree of tetragonal distortion of the crystal structure and transition to the cubic cell. The degeneracy of the antiferromagnetic interaction ( T _N = 138 K at y = 0.2) observed at the first stage of the substitution of Co for Mn changes for its gradual enhancement with an increase in the magnetic transformation temperature up to 239 K at y = 0.6. An increase in the Co content weakens the competition between the ferromagnetic and antiferromagnetic couplings and reduces the temperature of the transition to the spin-glass-like state. The magnetic inhomogeneity and formation of Co^2+–Mn^4+ ferromagnetic clusters in Sr_0.8Ce_0.2Mn_0.4Co_0.6O_2.69 at 140 K have been observed.

Effect of upsetting deformation temperature on the formation of the fine-grained cast alloy structure of the Ni–Mn–Ga system

The plastic behavior during deformation by upsetting and its effect on the microstructure in the polycrystalline Ni2.19Fe0.04Mn0.77Ga alloy are studied. The temperatures of martensitic and magnetic phase transformations were determined by the method for analyzing the temperature dependence of the specific magnetization as M F = 320 K, A S = 360 K, and T C = 380 K. Using differential scanning calorimetry, it is shown that the phase transition from the ordered phase L21 to the disordered phase B2 is observed in the alloy during sample heating in the temperature range of 930–1070 K. The melting temperature is 1426 K. An analysis of the load curves constructed for sample deposition at temperatures of 773, 873, and 973 K shows that the behavior of the stress–strain curve at a temperature of 773 K is inherent to cold deformation. The behavior of the dependences for 873 and 973 K is typical of hot deformation. After deforming the alloy, its microstructure is studied using backscattered scanning electron microscopy. Plastic deformation of the alloy at study temperatures results in grain structure fragmentation in the localized deformation region. At all temperatures, a recrystallized grain structure is observed. It is found that the structure is heterogeneously recrystallized after upsetting at 973 K due to the process intensity at such a high temperature. The alloy microstructure after plastic deformation at a temperature of 873 K is most homogeneous in terms of the average grain size.

The effect of Sn content on mechanical, magnetization and shape memory behavior in NiMnSn alloys

The effects of the composition alteration on the magnetization and shape memory behavior of Ni50Mn40-xSn10+x (x = 0, 1, 2, 3) alloys were systematically investigated by thermal, magnetic and mechanical experiments. Phase transformation from ferromagnetic austenite to weakly magnetic martensite was observed during thermal cycling under magnetic field and transformation temperatures were decreased with increasing Sn (or decreasing Mn). Moreover, the saturation magnetization of martensite increased with Sn content. Ni50Mn40Sn10 showed the recoverable strain of 2.1% during thermal cycling under 300 MPa and the reversible superelastic strain of 2% at 190 °C. Mechanical experiments exhibited that the largest compressive deformation of about 7% at 650 MPa occurred in Ni50Mn39Sn11 while Ni50Mn40Sn10 had fractured at 4% and 390 MPa at room temperature.

The magneto-structural transition in Mn1−xFexCoGe

Large refrigeration capacities, between 212(30) J kg−1 and 261(40) J kg−1 for a magnetic field change from 0 T to 5 T, were obtained in Mn1−xFexCoGe (x = 0.01, 0.02, 0.03 and 0.04) compounds. A partial magnetic phase diagram has been derived on the basis of magnetic transition and martensitic transformation temperatures determined from differential scanning calorimetry (200 K to 450 K), variable temperature x-ray diffraction (20 K to 310 K) and magnetisation measurements (5 K to 340 K; 0.01 T). Mn1−xFexCoGe compounds with compositions in the range x = 0.01 to 0.03 exhibit magneto-structural transitions. Neutron diffraction experiments were carried out on the Mn0.98Fe0.02CoGe sample over the temperature range of 5 K to 450 K. The diffraction patterns were analysed based on irreducible representation theory which confirms a ferromagnetic structure in the sample with an atomic magnetic moment of 3.7(1)μB at 5 K on the Mn sublattice, oriented along the orthorhombic c axis. More significantly, a magneto-structural transition around TM ~ 297(1) K with a full width at half maximum of 29 K is demonstrated directly via neutron diffraction. Larger magnetic entropy changes are obtained for the Mn1−xFexCoGe (x = 0.01, 0.02 and 0.03) samples than for Mn0.96Fe0.04CoGe which has separate structural and magnetic transitions. In addition, it is noted that standard Arrott plots do not provide unambiguous insight to the nature of the magneto-structural transition in the Mn1−xFexCoGe compounds.

Microstructure, hyperfine interaction and magnetic transition of Fe-25%Ni-5%Si-x%Co alloys

Morphological and magnetic properties in Fe-25%Ni-5%Si-x%Co (x = 0, 10, 15) alloys are investigated. Scanning electron microscopy (SEM), Mossbauer spectroscopy and AC magnetic susceptibility measurements are used to determine the physical properties of alloys. The martensite morphology changed depending on the Co content. The Mossbauer study shows that the volume fraction and hyperfine field of martensite increases while isomer shift values decrease with increasing Co content. On the other hand; AC susceptibility results showed that; Co is an effective element which can be used to control both the magnetic transition and martensitic transformation temperatures.

Magnetic field and stress Induced strain in CoNiAl Ferromagnetic Shapememory Alloy

Ferromagnetic shapememory alloys (FSMAs) are versatile and best materials for the application as sensors and actuators due to their smart behavior and faster response than the ordinary SMAs. Because of the ductility induced by the gamma phase precipitates and large range of martensitic and magnetic transformation temperatures CoNiAl FSMA is getting more importance and study of it is more interesting. We have made a CoNiAl alloy with the composition Co35Ni35Al30 by arc melting method. The sample was annealed at 1200°C/24h and quenched in water. It was characterized by XRD, SEM EDAX, DSC, and magnetization. From the XRD and SEM, the sample possesses two phases at room temperature (both β and γ). The Single phase (β) Co35Ni35Al30 alloy shows very sharp martensitic transition, but has extremely low ductility at room temperature. The presence of γ solid solution (disordered F.C.C. structure) as a second phase in the CoNiAl system renders the β-phase ductile at room temperature and makes it useful for practical applications. The transformation temperatures of the present CoNiAl alloy were obtained from DSC and four probe measurements. These were found to be TMs = 175 K, TMf = 153 K, TAs = 185 K and TAf = 205 K and Tc(β) = 225 K The magnetic field induced strain was measured at room temperature using NI 6210 data logger. M-H Curves at different temperatures (80 K, 150 K, 175 K, 200 K, 250 K, 300 K, 350 K and 400 K) were recorded using VSM. Stress induced strain at different stress levels was studied by Vibrating reed method (VBR). In the present paper we are presenting the magnetic field induced strain and stress induced strain near the martensitic transformation temperature of the sample. How the sample strain in the presence of magnetic field strength and stress level affect the behaviour of the sample in the vicinity of the martensitic transformation temperature.

Thermodynamics of Pd–Mn phases and extension to the Fe–Mn–Pd system

A thermodynamic description of the Pd–Mn system and the extension to the Fe–Pd–Mn system is developed within the framework of the CALPHAD approach. Thermodynamic data of the Pd–Mn system are critically reviewed and parameters of thermodynamic phase descriptions are optimized by selective combination of experimental data from the literature as well as published and new first-principles results. Phase diagram data are obtained from published microscopic and x-ray analysis. A previous calorimetric study and density functional theory results deliver enthalpies of formation of intermetallic Pd–Mn phases, and assessed Mn-activities are compared with experimental data derived from electromotive force and isopiestic experiments. A large difference between calorimetric high-temperature CALPHAD-assessed and first-principles enthalpies at 0K of the PdMn-B2 phase is revealed and discussed. For the extension to the Fe–Mn–Pd system, thermodynamic descriptions of Pd–Fe intermetallics are revised using recent experimental and theoretic thermodynamic standard data and measured temperatures of magnetic transformations from the literature. A comprehensive thermodynamic standard data set of the intermetallic phases PdMn-B2, PdMn-L10, Pd5Mn3, Pd2Mn, Pd3Mn-D023, Pd3Mn-L12, Pd3Fe-L12, and PdFe-L10 is proposed. A set of experimental data of Fe-solubility in PdMn-L10, the phase compositions of the L10-phase in equilibrium with austenite, and the observed austenite+liquid equilibrium is used for extensions of model descriptions to ternary Fe–Mn–Pd. Heat-treated Fe-rich Fe–Mn–Pd alloys containing 5–20wt% Mn and 1–10wt% Pd reveal considerable stabilization of the tetragonal PdMn-L10 by dissolved Fe leading to an increase of the solvus temperature by more than 650K relative to pure PdMn-L10. Assessed isothermal sections of the ternary Fe–Mn–Pd system are presented.

Magnetic properties and structure of nanocrystalline FINEMET alloys with various iron contents

The effect of the composition and annealing temperature on the structure and magnetic properties of soft magnetic nanocrystalline Fe-Cu-Nb-Mo-Si-B alloys has been studied. An increase in the iron content compared to that in the traditional FINEMET alloy is shown to allow one to increase the magnetic induction by 18% at a coercive force of no less than 6 A/m. It has been found that, along with the amorphous phase, rapidly quenched ribbons of alloys enriched in Fe contain crystalline α-Fe-based phase precipitates, the (100) crystallographic directions of which are perpendicular to the ribbon plane. Thermomagnetic analysis and differential scanning calorimetry were used to determine the temperatures of structural and magnetic phase transformations of the alloys with different iron contents. It was found that the separation of amorphous phase into areas of different compositions precedes the precipitation of nano-sized soft magnetic Fe-Si phase grains in the rapidly quenched iron-enriched ribbons.