Study of the Effect of Boron Concentration on Magnetic and Structural Properties of Nd 7.5 Pr 2.5 Fe 90-x B x Melt-Spun Alloys (original) (raw)
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Metals
In this work, we report a systematic study on the microstructure evolution of rapid solidified Fe91−xZr5Nb4Bx alloys (x = 10, 15, 20, 25, 30 at%) under melt-spinning conditions. Mechanical and magnetic properties are also evaluated. X-ray diffraction patterns indicate that the microstructure across the compositional series consists of an amorphous matrix with partial crystallization when boron concentration is increased. These features were identified by transmission electron microscopy (TEM). The radial distribution function (RDF) affords to resolve the nearest-neighbor configuration. The tensile and microhardness properties were measured to correlate the microstructural evolution with boron content. On the other hand, the magnetic properties of these alloy series were determined by vibrating sample magnetometry (VSM); the saturation magnetization and Curie temperature showed an increasing tendency when increasing the boron content, reaching values up to 110 Am2kg−1 and 465 K, resp...
Magnetic properties of ND Rich Melt-Spun ND-FE-B alloy
Science of Sintering, 2005
As a part of these experimental investigations of melt-spun Nd-Fe-B alloy with Nd rich content in relation to Nd 2 Fe 14 B prepared by rapid quenching process for optimally selected cooling rate and heat treatment, the influence of the chosen chemical composition on magnetic properties was observed. The results of X-ray diffraction, Mössbauer spectroscopy phase analysis and magnetic measurement of investigated melt-spun Nd 14.5 Fe 78.5 B 7 alloy are presented to bring some new information concerning the relation between their structure and magnetic properties.
Magnetic properties and synthesis conditions of Nd2Fe23B3 melt-spun alloy
Journal of Magnetism and Magnetic Materials, 2007
The formation of amorphous and crystalline state of the Nd 2 Fe 23 B 3 alloy from melt-spun ribbon is presented. The synthesis conditions are investigated combining DSC, X-ray diffraction and thermomagnetic analysis. The thermomagnetic analysis is found to be very useful to optimize the synthesis process. Comparison of these results enables to discuss the thermal stability of both the amorphous and crystalline phases. It is found that the onset temperature of the α-iron formation is significantly smaller than the Nd 2 Fe 23 B 3 crystallization temperature. Magnetization measurements have also been carried out on the as spun ribbon and the crystalline Nd 2 Fe 23 B 3 sample. The crystalline phase is found to exhibit a much larger Curie temperature than the amorphous one as well as a larger saturation magnetization.
Metals, 2019
The structural transformations and magnetic property changes of the Nd16.2FebalCo9.9Ga0.5B7.5 (SG1, SG2) and Nd15.0FebalGa2.0B7.3 (SG3) nanocomposite alloys obtained by melt spinning in the as-quenched state and after annealing at a temperature range of 560–650 °C for 30 min were studied. The methods used were X-ray diffraction analysis, magnetic property measurements, TEM studies, X-ray fluorescence analysis and Mössbauer spectroscopy. Amorphous phase and crystalline phase Nd2Fe14B (P42/mnm) were observed in the alloy after melt spinning. The content of the amorphous phase ranged from 20% to 50% and depended on the cooling rate. Annealing of the alloys resulted in amorphous phase crystallization into Nd2Fe14B and led to the increased coercivity of the alloys up to 1840 kA/m (23.1 kOe) at 600 °C annealing for 30 min. The alloy with the maximum coercivity had a grain size of the Nd2Fe14B phase ≈50–70 nm with an Nd-rich phase between grains.
On the microstructure and the recrystallization procedure of melt-spun Nd7.5Fe84.8Ti7.7−xNbx alloys
Journal of Magnetism and Magnetic Materials, 2003
The microstructure of melt-spun Nd 7.5 Fe 84.8 Ti 7.7Àx Nb x alloys, as well as the structural changes taking place during their heating, were studied with the aid of TEM, XRD and magnetic measurements. The microstructure of the ribbons consists of nanocrystallites of Fe-Nd intermetallic compounds. The size of the nanocrystallites decreases with increase of the Nb concentration. No Nb was found to be present in the intermetallic Fe-Nd compounds, either in the as-spun ribbons, or in samples which had undergone any kind of heat treatment. During the heating of alloys, the processes taking place with the increase of temperature are: (a) decomposition of the crystallites of the Fe-Nd intermetallic compounds, (b) crystallization of BCC Fe and of the metastable compound NdFe 7 and (c) formation of the compounds NdFe 11 Ti or Nd 2 Fe 17 and Fe 2 Nb. r
Crystallization and magnetic properties of melt-spun neodymium-iron alloys
Journal of Magnetism and Magnetic Materials, 1981
The magnetic and crystallization properties of melt-spun Ndr _xFe, alloys are reported. By using high purity constituents and an extremely fine orifice (loo-150 pm), amorphous alloys were prepared over the interval 0.4 G x < 0.8. Their magnetic properties, taken between 20-850 K in fields up to 95 kOe, are interpreted on the basis of a sperimagnetic structure; at high field the alloys form collinear ferromagnetic structures. Room temperature coercivities of the amorphous alloys are relatively low (1.5-2.0 kOe) but increase substantially at reduced temperatures; at 20 K, a maximum coercivity of 52 kOe was found for a Ndo.4Feo.e alloy. X-ray diffraction indicates that the melt-spun alloys crystallize by the precipitation of Nd metal and an unidentified Nd-Fe phase. Changes in magnetization and coercivity during crystallization are reported.
Scripta Materialia, 2017
The structural and magnetic properties of amorphous Fe 87 − y B 13 Cu y (y = 0 to 1.5) annealed with a range of heating rates (α) up to 150 K/s were investigated. The lowest coercivity (H c) for Fe 87 B 13 after crystallization shows a dramatic decrease from 174 A/m to 6.7 A/m when α is increased from 1.7 K/s to 150 K/s. The coercivity of Fe 87 − y B 13 Cu y annealed at 150 K/s is reduced by Cu addition and H c = 3.0 A/m is obtained at y = 1.5. Nanostructures with a grain size of 15 to 20 nm were evident in transmission electron micrographs from these rapidly annealed alloys.
Structure , Phase Composition and Thermomagnetic Behavior of Nd 14 Fe 79 B 7 Alloy
2007
The results of investigation of the influence of phase composition and microstructure on the magnetic properties of rapid quenched (R/Q) Nd14Fe79B7 alloy are presented and discussed. Thermomagnetic behavior of investigated alloy has been studied by measurement of themomagnetic curves (TM) in temperature interval 20–800C. Phase composition and grain size of investigated alloy in optimized magnetic state and state after the thermomagnetic measurements were determined using the X-ray diffraction analysis (XRD). Based on X-Ray diffraction data mean grain size of identified phases was determined by size-strain analysis using the FullProf computer program. The investigation by transmission electron microscope (TEM) was done as a confirmation of mean grain size. The substantial difference between the state with optimized magnetic properties and the state after the decomposition, induced by the TM measurements, was illustrated by the corresponding hysteresis loops obtained by measurements o...
Structural, Magnetic and Mechanical Properties of Nd16 (Fe76−xCox)B8 0 ≤ x ≤ 25 Alloys
Applied Sciences
In this work, the structural, magnetic and mechanical properties of Nd16Fe76−xCoxB8 alloys with a varying Co content of x = 0, 10, 20 and 25 were experimentally investigated by X-ray diffraction (XRD), Mössbauer spectrometry (MS) and vibrating sample magnetometry (VSM) at room temperature (RT), and microhardness tests were performed. The system presented hard Nd2Fe14B and the Nd1.1Fe4B4 phases for samples with x = 0; when the concentration increased to x = 20 and 25, the CoO phase appeared. All MS data showed ferromagnetic behavior (eight sextets: sites 16k1, 16k2, 8j1, 8j2, 4c, 4e, sb) associated with the hard and soft magnetic phases, and one paramagnetic component (doublet: site d) associated with the minority Nd1.1Fe4B4 phase, which was not identified by XRD. All samples were magnetically hard and presented hard magnetic behavior. The increase of Co content in these samples did not improve the hard magnetic properties but increased the critical temperature of the system and decr...