scholarly journals Investigation of the Critical Behavior, Magnetocaloric Effect and Hyperfine Structure in the Fe72Nb8B20 Powders

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4476
Author(s):  
Safia Alleg ◽  
Thaounza Chabi ◽  
Nadia Bensebaa ◽  
Joan Saurina ◽  
Lluisa Escoda ◽  
...  
Keyword(s):  
Amorphous Phase ◽  
Magnetic Measurements ◽  
Mean Field ◽  
Entropy Change ◽  
Mössbauer Spectrometry ◽  
Mechanically Alloyed ◽  
Scanning Calorimetry ◽  
Mean Field Model ◽  
Mossbauer Spectrometry ◽  
Ferromagnetic Interactions

Microstructure as well as magnetic, thermal and magnetocaloric properties of the mechanically alloyed Fe72Nb8B20 powders have been investigated by means of Mössbauer spectrometry, differential scanning calorimetry (DSC), and magnetic measurements. The Mössbauer spectrometry results showed the formation of nanostructured Fe(B) and Fe(Nb) solid solutions, Fe2B boride, and an amorphous phase. The endothermic and exothermic peaks that are observed in the DSC curves might be related to the Curie temperature, and the crystallization of the amorphous phase, respectively. The critical exponent values around the magnetic phase transition of the amorphous phase (TC = 480 K), are deduced from the modified Arrott plots, Kouvel−Fisher curves and critical isotherm examination. The calculated values (β = 0.457 ± 0.012, γ = 0.863 ± 0.136 and δ = 3.090 ± 0.004) are near to those of the mean field model, revealing a dominating role of magnetic order arising due to long-range ferromagnetic interactions, as the critical exponents are mean-field-like. The maximum entropy change and the refrigerant capacity values are 1.45 J/kg·K and 239 J/kg, respectively, under a magnetic field of 5 T.

Thermomagnetic Properties and Magnetocaloric Effect of R2Fe17C (R=Dy, Nd, Tb, Gd, Pr, Ho, Er) Compounds

2018 ◽  
Vol 1 (1) ◽  
pp. 268-278
Author(s):  
Ahmed Nagy ◽  
Samy H. Aly ◽  
Sherif Yehia ◽  
Tareq Hammad
Keyword(s):  
Magnetocaloric Effect ◽  
Mean Field ◽  
Entropy Change ◽  
Field Analysis ◽  
Magnetic Phase Transitions ◽  
Mean Field Model ◽  
Magnetocaloric Properties ◽  
The Mean ◽  
Thermomagnetic Properties ◽  
Critical Temperature Tc

We present a mean-field analysis, using the two-sublattice model, for the thermomagnetic and magnetocaloric properties of the R2Fe17C compounds, where R=Dy, Nd, Tb, Gd, Pr, Ho, Er and C is carbon.   The dependence of magnetization, magnetic heat capacity, magnetic entropy and isothermal entropy change ∆Sm, are calculated for magnetic fields up to 5T and for temperatures up to 700 K . Direct magnetocaloric effect is present for all compounds with maximum ∆Sm between 6.13-10.95 J/K. mole for an applied field change of 5T. It is found that Pr2Fe17C compound has the highest  ∆Sm of 10.95 J/K. mole at ∆H=5T and Tc=375 K. The inverse MCE is found in ferrimagnetic compounds, e.g. Gd2Fe17C, with ∆Sm= J/K mol at critical temperature Tc=623K and ∆Sm=  J/K mol at Neel temperature TN=136 K.  The calculated Arrott plots confirmed that the magnetic phase transitions in these compounds are of second order. The mean-field model proves its suitability for calculating the properties of the compounds under study.

Solid State Amorphization of Ti60Si40 Alloy via Mechanical Alloying

2021 ◽  
Vol 876 ◽  
pp. 7-12
Author(s):  
Petr Urban ◽  
Fátima Ternero Fernández ◽  
Rosa M. Aranda Louvier ◽  
Raquel Astacio López ◽  
Jesus Cintas Físico
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Mechanical Alloying ◽  
Amorphous Phase ◽  
Milling Time ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Heating Up

The effect of milling time on the microstructure evolution and formation of amorphous phase of Ti60Si40 alloy produced by mechanical alloying (MA) has been investigated. Laser diffraction, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Differential Scanning Calorimetry (DSC) were employed to characterize the particle size, morphology and structure of mechanically alloyed Ti60Si40. When the milling time is increased to 20 h, the particle size decreases from 23.7 to 4.7 μm, the shape of the particles changes to spherical and the crystalline structure is transformed into an amorphous phase. The amorphous Ti60Si40 alloy is stable when heating up to 750oC. Above this temperature, the cold crystallization of the intermetallic compounds Ti5Si3 and/or Ti5Si4 begins.

Mechanical alloying of Fe and V powders: Intermixing and amorphous phase formation

1989 ◽  
Vol 4 (6) ◽  
pp. 1450-1455 ◽  
Author(s):  
B. Fultz ◽  
G. Le Caür ◽  
P. Matteazzi
Keyword(s):  
Chemical Composition ◽  
Mechanical Alloying ◽  
Ball Milling ◽  
Amorphous Phase ◽  
Phase Formation ◽  
Mössbauer Spectrometry ◽  
Microstructural Changes ◽  
X Ray ◽  
Mossbauer Spectrometry ◽  
Amorphous Phase Formation

Mössbauer spectrometry and x-ray diffractometry were used to characterize the microstructural changes that occurred during the mechanical alloying of Fe and V powders, After 3 h of essentially no interatomic intermixing, an Fe–V alloy began to form. At first the chemical composition of this alloy was highly inhomogeneous, having large variations over distance scales of less than 100 Å. After about 24 h of ball milling, the alloy homogenized and then became at least partly amorphous.

scholarly journals Influence of the Quenching Rate on the Structure and Magnetic Properties of the Fe-Based Amorphous Alloy

2016 ◽  
Vol 61 (1) ◽  
pp. 439-444 ◽  
Author(s):  
M. Nabiałek
Keyword(s):  
Magnetic Properties ◽  
Amorphous Alloy ◽  
Magnetic Measurements ◽  
Mössbauer Spectrometry ◽  
X Ray Diffraction ◽  
Quenching Rate ◽  
X Ray ◽  
Transmission Electron ◽  
Mossbauer Spectrometry ◽  
Diffraction Patterns

This paper presents the results of investigations into the structure, microstructure and magnetic properties of Fe61Co10Y8W1B20 amorphous alloy. The alloy samples were in two physical forms: (1) plates of approximate thickness 0.5 mm (so-called bulk amorphous alloys) and (2) a ribbon of approximate thickness 35 μm (so-called classic amorphous alloy). The investigations comprised: X-ray diffractometry, Mössbauer spectrometry, transmission electron microscopy, and selected magnetic measurements; all of the investigations were carried out on samples in the as-quenched state. Analysis of the obtained SEM and TEM images, X-ray diffraction patterns, Mössbauer spectrometry results and measurements of the magnetisation in a high magnetic field facilitated collectively the detailed description of the structure of the investigated alloy, which was found to depend on the quenching speed.

scholarly journals Investigation of magnetic phase transition and magnetocaloric effect of (Ni,Co)-Mn-Al melt-spun ribbons

2018 ◽  
Vol 185 ◽  
pp. 05001
Author(s):  
Yen Nguyen ◽  
Mai Nguyen ◽  
Quang Vu ◽  
Thanh Pham ◽  
Victor Koledov ◽  
...  
Keyword(s):  
Phase Transition ◽  
Magnetocaloric Effect ◽  
Magnetic Phase Transition ◽  
Magnetic Phase ◽  
Mean Field ◽  
Entropy Change ◽  
Soft Magnetic Materials ◽  
Critical Parameters ◽  
Mean Field Model ◽  
Diffraction Patterns

Magnetic phase transition, magnetocaloric effect and critical parameters of Ni50-xCoxMn50-yAly (x = 5 and 10; y = 17, 18 and 19) rapidly quenched ribbons have been studied. X-ray diffraction patterns exhibit a coexistence of the L21 and 10M crystalline phases of the ribbons. Magnetization measurements show that all the samples behave as soft magnetic materials with a low coercive force less than 60 Oe. The shape of thermomagnetization curves considerably depends on Co and Al concentrations. The Curie temperature (TC) of the alloy ribbons strongly increases with increasing the Co concentration and slightly decreases with increasing the Al concentration. The Ni45Co5Mn31Al19 and Ni40Co10Mn33Al17 ribbons reveal both the positive and negative magnetocaloric effects. Under magnetic field change (ΔGH) of 13.5 kOe, the maximum magnetic entropy change (|ΔSm|max) of the Ni45Co5Mn31Al19 ribbon is about 2 and -1 J·kg−1·K−1 for negative and positive magnetocaloric effects, respectively. Basing on Arrott - Noakes and Kouvel - Fisher methods, critical parameters of the Ni45Co5Mn31Al19 ribbon were determined to be TC ≈ 290 K, β ≈ 0.58, γ ≈ 0.92 and δ ≈ 2.59. The obtained values of the critical exponents indicate that the magnetic order of the alloy ribbon is close to the mean-field model.

scholarly journals Tunable magnetocaloric effect in amorphous Gd-Fe-Co-Al-Si alloys

2022 ◽  
Author(s):  
Natalia Lindner ◽  
Zbigniew Śniadecki ◽  
Mieszko Kołodziej ◽  
Jean-Marc Grenèche ◽  
Jozef Marcin ◽  
...  
Keyword(s):  
Magnetocaloric Effect ◽  
Mean Field ◽  
Magnetic Behavior ◽  
Entropy Change ◽  
X Ray Diffraction ◽  
Mean Field Model ◽  
Melt Spun ◽  
Parent Alloy ◽  
The Mean ◽  
The Magnetic Field

AbstractA magnetocaloric effect with wide tunability was observed in melt-spun amorphous Gd65Fe15-xCo5+xAl10Si5 (x = 0, 5, 10) alloys of different Fe/Co ratios. Their magnetic properties were compared with those of the previously investigated parent alloy Gd65Fe10Co10Al15. The glassy structure of the melt-spun samples was confirmed by X-ray diffraction (XRD) and 57Fe Mössbauer spectrometry. Their Curie temperatures (TC) were between 155 and 195 K and increased significantly with decreasing Co content. The highest value of the magnetic entropy change ΔSM = − 6.8 J/kg K was obtained for Gd65Fe5Co15Al10Si5, when the magnetic field was increased from 0 to 5 T. Refrigerant capacity (RC) takes values close to 700 J/kg for the whole series of the alloys. The occurrence of the second-order phase transition and the conformity of the magnetic behavior with the mean field model were concluded on the basis of the analysis of the universal curves and the values of the exponent n (ΔSM ∝ Hn). Graphical abstract

Crystallisation of Amorphous Al60Fe20Ti15Ni5 Alloy Produced by Mechanical Alloying

2010 ◽  
Vol 163 ◽  
pp. 243-246 ◽  
Author(s):  
Marek Krasnowski ◽  
Tadeusz Kulik
Keyword(s):  
Mechanical Alloying ◽  
Amorphous Phase ◽  
High Energy ◽  
Lattice Parameter ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Elemental Powder Mixture

In the present work, an elemental powder mixture of Al60Fe20Ti15Ni5 (at.%) was mechanically alloyed in a high-energy ball mill. The phase transformations occurring in the material during milling were studied with the use of X-ray diffraction. The results obtained show that an amorphous phase was formed during performed mechanical alloying process. Thermal behaviour of the milling product was examined by differential scanning calorimetry. It was found that amorphous phase crystallised above 540 °C when a heating rate of 40 °C/min was applied. On the basis of X-ray diffraction results, crystallisation product was identified as a cubic phase with the lattice parameter a0 = 11.856 Å, isomorphic with the 2 (Al2FeTi, fcc structure D8a) phase. The mean crystallite size of the crystallised 2 phase was 19 nm.

X-ray diffraction, Mössbauer spectrometry and thermal studies of the mechanically alloyed (Fe 1−x Mn x ) 2 P powders

2018 ◽  
Vol 29 (2) ◽  
pp. 257-265 ◽  
Author(s):  
S. Alleg ◽  
A. Brahimi ◽  
S. Azzaza ◽  
S. Souilah ◽  
M. Zergoug ◽  
...  
Keyword(s):  
Thermal Studies ◽  
Mössbauer Spectrometry ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray ◽  
Mossbauer Spectrometry

Effect of Co substitution on the martensitic transformation and magnetocaloric properties of Ni50Mn35−xCoxSn15

2013 ◽  
Vol 28 (S1) ◽  
pp. S22-S27 ◽  
Author(s):  
F.S. Liu ◽  
Q.B. Wang ◽  
S.P. Li ◽  
W.Q. Ao ◽  
J.Q. Li
Keyword(s):  
Martensitic Transformation ◽  
Diffraction Analysis ◽  
Powder Diffraction ◽  
Magnetic Entropy Change ◽  
Magnetic Measurements ◽  
Entropy Change ◽  
Valence Electron Concentration ◽  
Magnetic Entropy ◽  
Scanning Calorimetry ◽  
X Ray

Martensitic transformation and magnetic entropy change in Co substituted Ni50Mn35−xCoxSn15 (x = 0, 1.0, 1.5, 2.0, and 3.0) Heusler alloys have been investigated by X-ray powder diffraction analysis, differential scanning calorimetry, and magnetic measurements. X-ray diffraction analysis reveals that the Ni50Mn35−xCoxSn15 alloys have L21 Heusler structure at room temperature. The phase decomposition of the sample with x = 3.0, after annealing 48 h at 1173 K, is confirmed by both X-ray powder diffraction analysis and energy-dispersive x-ray spectroscopy in scanning electron microscopy. With the increase of the Co content from 0 to 2.0, the martensitic transformation temperature TM increases from 185 to 245 K, which is in good agreement with the rule of valence electron concentration e/a-dependence of TM. The magnetic entropy change ∆SM is investigated in the vicinity of the martensitic transformation.

Sign in / Sign up

Export Citation Format

Share Document