Properties Of Ribbons Research Articles

Combined experimental and DFT studies of Co82Zr12V6-xBx melt-spun ribbons to investigate structure and magnetic properties

For the development of rare-earth free permanent magnets with better performance to cost ratio, V and B dopings were employed to enhance the hard magnetic properties of Zr-Co-V-B alloys. The effect of V and B microalloying additions on the magnetic properties, phase stability and microstructure of the metastable Co5Zr phase have been investigated with experimental measurements together with first principles based on the DFT (Density Functional Theory) calculations. This study also investigates the effects of annealing at different temperatures on the intrinsic and extrinsic magnetic properties of Co82Zr12V6-xBx melt-spun ribbons. Rapidly solidified Co82Zr12V6-xBx (x = 1, 2, 3) alloy ribbons were produced by melt-spinning. For as-spun Co82Zr12V6-xBx (x = 1, 2, 3) ribbons, the coercivityHcdecreases from 2.34 kOe to 0.008 kOe with an increasing × value from 1 to 3.The amorphous alloy ribbons were annealed in a vacuum furnace at a series of temperatures of 600 °C, 650 °C, 700 °C and 750 °C each for 30 min. The XRD analysis showed the presence of two soft magnetic phases (fcc-Co and Co23Zr6), accompanied with a hard phase Co5Zr in ribbons thus leading to the desired hard/soft structure and the amount of both (hard and soft) phases increased with the annealing temperature. Coercivity was found to increase upon annealing treatment. The phase stabilities of the Co82Zr12V6-xBx ribbons were calculated from the total energy by the DFT calculations in this work. The calculated magnetic anisotropy energies have been compared to that of experimental coercivity values. Annealed sample Co82Zr12V5B1 showed the maximum coercivity value of 3.58 kOe due to the formation of a high volume fraction of hard magnetic phase (Co5Zr) and evenly distributed finer grains throughout the matrix. However, annealing under the same conditions resulted in lower coercivity of about 0.088 kOe and 1.61 kOe for Co82Zr12V3B3 and Co82Zr12V4B2 samples, respectively. Although sample Co82Zr12V4B2 exhibited higher remanence (42.80 emu/g) and maximum magnetization value with the applied field of 17 kOe (i.e. M17 = 77.70 emu/g) compared to Co82Zr12V3B3 sample.

The effect of the Mo addition on the magnetic properties and phase constituents of the Ce-(FeCo)–B ribbons

The effect of molybdenum (Mo) addition on the magnetic properties and phase constituents of Ce14Fe78-xMoxCo2B6 (x = 0–1.25 at %) ribbons has been investigated. The investigated ribbons have been prepared by melt spinning technique at different velocities. Samples were studied in as-cast state and after annealing. The results reveal that the addition of Mo in Ce14Fe78-xMoxCo2B6 ribbons and the subsequent annealing improves the magnetic properties. Mo acts as inhibitor of the growth of crystalline grains and reduces the volume fraction of the undesirable non-magnetic phases. As a result, the coercivity of Ce14Fe78-xMoxCo2B6 ribbons increases with the increase of Mo content from x = 0 to x = 1.25 at%, while the remanence remains unchanged up to 0.75 at% Mo content and after this value slightly decreases. Analysis of the δM curves showed that a suitable content of Mo improves the exchange coupling interaction. The optimum magnetic properties, i.e. coercivity, Hc = 6.1 kOe, remanence (Br) = 5.2 kG and energy density (BH)max = 4.92 MGOe, were obtained in ribbons with 1.0 at% Mo. The addition of Mo lead to an improvement of the magnetic properties of CeFeB-based ribbons making them good candidate precursors for the preparation of permanent magnets without heavy critical rare earths.

Effects of the Severe Plastic Deformation on the Magnetic Properties of Zr13Co87 Ribbons

Effects of the Severe Plastic Deformation on the Magnetic Properties of Zr13Co87 Ribbons

Thermoelectric properties of a diamond ribbon subjected to a transverse magnetic field

To manufacture an efficient thermoelectric device at the nanoscale and to get its controlled performance, we suggest a finite-width diamond ribbon in the presence of a perpendicular magnetic field. Contemplating the asymmetry in transmission function in a narrow conducting channel, the possibility of a gap around the energy band center in the presence of a magnetic field is discussed here. The eigenvalue spectrum and band structures show several interesting features. The different thermoelectric quantities are evaluated following the Landauer prescription. We show that the gap is tunable by controlling the strength of the magnetic field. Near the edge of the gap, our results exhibit a favorable thermoelectric response. We believe that our analysis of the proposed model can be experimentally tested in the laboratory and hope our study helps to construct an efficient thermoelectric device at the mesoscopic level.

Effect of dopants on magnetic and magnetoimpedance properties of rapidly solidified FeCoBM (M = Al, Cu and Si) ribbons

In this work magnetic properties, magnetoimpedance (MI) and field sensitivity (η) of rapidly solidified (Fe0.7Co0.3)80B19M1 (M = B, Al, Si & Cu) ribbons have been investigated in the frequency range 0.5 – 13 MHz. Present study shows replacement of boron (B) by a nonmagnetic element (Al, Si or Cu) can alter the thermal stability, soft magnetic and magnetoimpedance properties of the (Fe0.7Co0.3)80B20 ribbons. It is found that saturation magnetization reaches the largest value for Cu-containing sample and the smallest value for Al-containing sample. The MI studies show maximum MI ratios 30% at 5 MHz, 23% at 7 MHz, 26% at 3 MHz and 39% at 4 MHz for M = B, Al, Si & Cu respectively. Variation of MI with external magnetic field shows single peak behavior of Al-content ribbon over the entire frequency range, whereas for all other samples single peak converted to double peak at higher frequency, which indicates existence of stronger longitudinal magnetic anisotropy in Al-containing ribbon. The MI variation with magnetization, M and damping constant, α is also validated through numerical simulations using standard electrodynamics models. Present study reveals that the variations of MI response are associated with formation of soft magnetic phase and development of anisotropy with replacement of B by an additional element.

Phase formation and magnetic properties of (Nd1−xYx)14Fe80B6 melt-spun ribbons

Phase formation and magnetic properties of (Nd1−xYx)14Fe80B6 (x = 0.1–0.8) alloys were investigated experimentally by x-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The phase structure analysis reveals that the as-cast (Nd1−xYx)14Fe80B6 alloys were made of 2:14:1 phase with tetragonal Nd2Fe14B-tpyed structure, REFe2 and α-Fe phases, while the melt-spun ribbons are composed of 2:14:1 phase and α-Fe Phase. Based on the magnetic measurements, the remanence (Br), the coercivity (Hcj), the maximum magnetic energy product ((BH)max) and the Curie temperatures (Tc) of (Nd1−xYx)14Fe80B6 ribbons reduces gradually with increasing Y substitution. The relatively high coercivity (6.75 kOe) of (Nd0.4Y0.6)14Fe80B6 ribbon with high Y substitution was achieved, which indicates that good magnetic properties of Nd–Y–Fe–B ribbons would be obtained through the design of alloy composition and phase formation.

Comparative study of structural and magnetic properties of ribbon and bulk Ni55Fe19Ga26 Heusler alloy

The influence of the fabrication method on the magnetostructural properties of a Ni55Fe19Ga26 Heusler alloy, obtained both as a ribbon, by melt-spinning, and as a pellet, by arc-melting, has been analyzed. It has been found that, while the arc-melting technique leads to the precipitation of the gamma phase and to a non-modulated martensite structure, the alloy prepared by melt-spinning presents a fully 14M modulated martensitic structure at room temperature. The tetragonal non-modulated martensite in the arc-melted bulk sample transforms into the 14M structure after a long thermal treatment (at 1073 K for 24 h) and subsequent quenching. Characteristic temperatures of the martensitic transformation are higher for melt-spun ribbons than for bulk sample, due to the precipitation of the gamma phase and consequent different martensite composition. However, while the martensitic transformation temperature is practically constant in the case of the bulk sample, it changes by ~ 150 K in the case of the ribbon sample submitted to the same thermal treatment applied to bulk samples. Finally, it was found that the martensitic transformation occurs in the paramagnetic regime of both types of samples.

Thermoelastic Properties and Elastocaloric Effect in Rapidly Quenched Ribbons of Ti2NiCu Alloy in the Amorphous and Crystalline State

The thermoelastic properties and the elastocaloric effect (ECE) were studied in rapidly quenched ribbons of the Ti2NiCu alloy samples in amorphous and crystalline states under periodic mechanical tension with a frequency of up to 50 Hz. In the amorphous samples, elastic behavior is observed, described by Hooke’s law, with a high coefficient of thermal expansion α = 1.7 × 10−4 K−1. Polycrystalline ribbons of the Ti2NiCu alloy have the classical shape memory effect (SME), the temperatures of the forward and reverse thermoelastic martensitic transitions being Ms = 345 K, Mf = 325 K, As = 332 K, and Af = 347 K and the coefficient of the dependence of the transition temperature on mechanical stress being β = 0.12 K/MPa. The experimentally measured value of the adiabatic temperature change under the action of mechanical stress (ECE) in the amorphous state of the alloy at room temperature (Tr = 300 K) was ΔT = −2 K, with a relative elongation of ε = 1.5% and a mechanical stress of σ = 243 MPa. For crystalline samples of Ti2NiCu alloy ribbons, the ECE is maximum near the completion temperature of the reverse thermoelastic martensitic transformation Af, and its value was 21 K and 7 K under cyclic mechanical loads of 300 and 100 MPa, respectively. It is shown that the ECE value does not depend on the frequency of external action in the range from 0 to 50 Hz. The specific power of the rapidly quenched ribbon was evaluated as a converter of thermal energy at an external mechanical stress of 100 MPa; its value was 175 W/g at a frequency of 50 Hz. The thermodynamic model based on the Landau theory of phase transitions well explains the properties of both amorphous ribbons (reverse ECE) and alloy ribbons with EPF (direct ECE).

Improving the Bs and soft magnetic properties of Fe-based amorphous ribbons by manipulating the surface crystallization behavior

Improving the Bs and soft magnetic properties of Fe-based amorphous ribbons by manipulating the surface crystallization behavior

Strain gages based on gallium arsenide whiskers

Strain-resistant properties of GaAs whiskers and ribbons of p- and n-type conductivity with various length (0.3–7 mm) and diameter (10–40 μm) have been investigated in a wide range of temperatures. Strain gages based on heavily doped p-type conductivity GaAs whiskers have linear deformation characteristics and a weak temperature dependence of strain sensitivity in the temperature range from –20 to +3500 °C. The temperature coefficient of resistance (TСR) of not fixed strain gages is about +(0.12–0.16)% × grad–1. The temperature coefficient of strain sensitivity is –0.03 % × deg–1 in the temperature range –120+800 °C. Strain gages based on n-type GaAs ribbons are characterized by high flexibility and high strain sensitivity. They are capable up to +4000 °C and can be used to measure deformations on curved surfaces at high temperatures. TСR of not fixed strain gages is –0.01 +0.03 % × grad–1. The temperature coefficient of strain sensitivity is –0.16% × deg–1 in the temperature range –120 ... +4000 °С.

Microstructure and Its Effect on the Magnetic, Magnetocaloric and Magnetostrictive Properties of Tb55Co30Fe15 Glassy Ribbons.

In the present work, the microstructure and its effect on the magnetic, magnetocaloric, and magnetoelastic properties of the Tb55Co30Fe15 melt-spun ribbon were investigated. The ribbon exhibits typical amorphous characteristics in its X-ray diffraction examination and differential scanning calorimetry measurement. However, the magnetic properties of the ribbon indicate that the ribbon is inhomogeneous in the nanoscale, as ascertained by a high-resolution electron microscope. Compared to the Tb55Co45 amorphous alloy, the Tb55Co30Fe15 ribbon shows poor magnetocaloric properties but outstanding magnetostriction. A rather high value of reversible magnetostriction up to 788 ppm under 5 T was obtained. The mechanism for the formation of nanoparticles and its effect on the magnetocaloric and magnetostrictive properties were investigated.

The role of quenched-in disorder in polycrystalline bulk and melt-spun ribbons of Ni50Mn29Ga21

ABSTRACT Investigations on the properties of polycrystalline bulk and melt-spun ribbons of composition Ni50Mn29Ga21 are contrasted. Both samples are subjected to quenching after melting and then were homogenized at the same temperature. Though the electron per atom ratio is unchanged, the quenched-in disorder has caused the structural and magnetic transformations to occur in close proximity in the ribbon giving rise to magnetic entropy change of –9.2 J/kg-K at the martensitic transformation. The bulk alloy showed significantly high magnetic field-induced strain of 0.7% at 5 kOe magnetic field and an apparent compressive strain of 5.3% at 40 MPa compression stress, without training the sample. Large grain size and micro-twinning are observed in the bulk, while nano-scale twinning is seen in the ribbon. The variations in the process altered the degree of ordering, which modified the transformation temperatures, the crystal structure, the microstructures of the ribbon and the mechanical properties of the bulk specimen significantly.

Electron magnetic resonance study of the Ni47Co3Mn35.5In14.5 ribbons

In this paper, the electron magnetic resonance (EMR) of Ni47Co3Mn35.5In14.5 alloy in ribbon and powder form are investigated. The EMR spectra for ribbons were registered within the temperature ranges 4 K ⩽T⩽100 K and 140 K ⩽T⩽380 K and for powdered ribbon within the temperature range 140 K ⩽T⩽380 K. Additionally, the magnetic properties of ribbon were also studied by using vibrating sample magnetometer (VSM) in the temperature range of 85 K ⩽T⩽400 K. At high temperature, the EMR signal consist of a single, asymmetric line. The temperature dependence of the inverse integrated intensity exhibits a Curie–Weiss like behaviour and Curie temperature (TC) determined from VSM equals 333 K. Below TC for ribbon sample the low field microwave absorption (LFMA) line was observed. The EMR spectra recorded for the powder sample are of a different shape than those for the ribbon sample. The powdering causes an increase of the effective skin depth, and the high-temperature lines lose asymmetric character. The Curie temperature is shifted relative to Curie temperature determined for the ribbon sample, but the structural phase transition is preserved.

Coercivity development in MnAl ribbons by microstructural modifications achieved through cold-rolling process

MnAl ribbons have been successfully nanostructured by applying cold-rolling. The use of this mechanical process deforms the as-spun ribbons and increases the density of defects in the material. The microstructural characterization of the cold-rolled samples has been performed by SEM and XRD and has allowed studying the evolution of the surface of the ribbons with the number of the passes increasing. These microstructural changes, in addition to the crystallization of β-phase during the annealing step, have successfully modified the magnetic properties of the as-spun ribbons, raising the coercivity from 1.5 to 3.5 kOe. Remarkably, this large increase in coercivity is accompanied by only an 8% decrease in remanence by comparison with that of the starting ribbons, achieving values above 35 emu/g for all the cold-rolled and annealed samples.

Evolution of Shear Bands in the Structure of a Zirconium-Based Amorphous Alloy during Rolling at Different Temperatures

The effects of rolling with different reductions at room temperature, a temperature of 300°C, and the temperature of boiling of liquid nitrogen on the surface structure of the Zr62.5Cu22.5Fe5Al10 alloy on the evolution of shear bands and microhardness of this alloy have been investigated. Scanning electron microscopy, transmission electron microscopy, and X-ray structural analysis methods were used to study the changes in the structure after mechanical processing. To study the effect of rolling on the mechanical properties of ribbons, the Vickers microhardness is measured. Based on the results, conclusions on the hardness changes depending on the mode of rolling of the Zr62.5Cu22.5Fe5Al10 alloy ribbons are drawn. It is found that after rolling, the microhardness of the ribbons decreases with an increase in the degree of deformation at both room temperature and elevated and lowered temperatures, which is associated with the formation of shear bands in the structure and an increase in the amount of free volume (the greater the volume, the greater the degree of deformation). The microhardness of the alloy decreases to the greatest extent upon rolling at the temperature of liquid nitrogen.

The surface and bulk properties of CuO ribbons and ZnO particles mixture using physical adsorption and gamma ray attenuation techniques

AbstractIn the present work, we investigate the surface, and bulk structural properties of composite cupric oxide ribbons, and zinc oxide particles. The composites are synthesized using the technique of solution combustion. Crystallographic phases are confirmed using the x‐ray diffraction technique and proved the formation of monoclinic cupric oxide and hexagonal zinc oxide crystallites. Scanning electron microscope and high‐resolution transmission electron microscope are used to examine the morphology of the prepared materials. Composite mixtures of raw particles cupric oxide and zinc oxide are used as benchmark morphologically‐alike composite materials. The specific surface area values of the studied materials are investigated using nitrogen gas adsorption at 77 K while the spectroscopic gamma ray attenuation is used to determine the effective density of the different samples. Zinc oxide particles are dispersed on cupric oxide ribbons and cause nonlinear dependence of the specific surface area and density on the composition ratio due to the physical contact between particles, especially at the voids and the nodes of the fibrous ribbons network.

Effect of heat treatment on magnetic properties of nanocomposite Nd-lean Nd7Fe73B20 ribbons

Effect of heat treatment on magnetic properties of nanocomposite Nd-lean Nd7Fe73B20 ribbons

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 / 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.

Magnetic properties of (Sm,Zr)Fe5 alloys and their nitrides

In this study, magnetic properties of (Sm,Zr)Fe5 melt-spun ribbons and their nitrogenated specimens were examined. The as-annealed (Sm,Zr)Fe5 melt-spun ribbons showed a coercivity of around 1.3 kOe, but it was found that their nitrogenation increased the coercivity. A high coercivity of 11.4 kOe was achieved in the (Sm0.7Zr0.3)Fe5 melt-spun ribbon when nitrogenated at 713 K for 20 h. Microstructural studies revealed that the nitrogenated specimen consisted of fine grains with an average diameter of 20 nm. XRD studies revealed that the nitrogenated specimen contained a small amount of the α-Fe phase together with the (Sm,Zr)Fe5 phase.

Effect of annealing on the structure and magnetic properties of SmCo5-based ribbons with Al-Cu-Fe addition

Al-Cu-Fe alloying addition can simultaneously improve the coercivity and magnetization of the as-spun SmCo5-based ribbons, the annealing process can further improve the hard-magnetic properties of ribbons. In this paper, SmCo5 + 3 wt% Al82.8Cu17Fe0.2 ribbons melt-spun at 40 m/s were annealed at 500 – 700 °C for 30 min. It is found the annealing improves the crystallinity of the grains, changes the phase composition and microstructure, especially the distribution of Sm(Co, M)7 phase. By doping 3% Al82.8Cu17Fe0.2 alloy and annealing at 600 °C for 30 min, the SmCo5-based ribbons obtain ultra-high coercivity of 26.8 ± 3.3 kOe. The reason for the maximum coercivity at 600 °C can be attributed to the high content of Sm(Co, M)5 grains, improved crystallinity of the grains, and the refinement of the grains.