scholarly journals Phase transformations and properties of concentration-inhomogeneous magnetic materials based on the Fe–30%Cr–27%Co system

2019 ◽  
pp. 82-90
Author(s):  
V. A. Kozvonin ◽  
A. A. Shatsov ◽  
I. V. Ryaposov ◽  
K. N. Generalova ◽  
L. V. Spivak
Keyword(s):  
Solid Solution ◽  
Magnetic Properties ◽  
Magnetic Hysteresis ◽  
Contact Melting ◽  
Thermomagnetic Treatment ◽  
Magnetic Alloy ◽  
Scanning Calorimetry ◽  
Α Phase ◽  
Final Aging ◽  
Α2 Phase

The phase and structural transformations of a powder magnetically hard alloy of the system Fe–30%Cr–27%Co–1%Si–0,07%B with a metastable α1+α2 phase composition, a high content of cobalt, and a high level of magnetic properties were studied. The density and coefficient of variation of the concentration of the main elements of the sintered blanks at the level of deformable analogs are achieved by sintering in the α-phase with contact melting in the presence of a «vanishing» liquid phase formed due to the addition of silicon and boron ferroalloys. A kinetic approach to the development of a competitive hard magnetic alloy with a high proportion of the strongly magnetic phase is proposed. The effect of boron additions on the incubation period of the formation of an undesirable σ-phase and the temperature range of the concentration stratification of the α-solid solution on the strongly magnetic α1-phase and the weakly magnetic α2-phase were established. Optical microscopy, X-ray phase analysis and differential scanning calorimetry were used to determine temperature and time parameters of heat treatment of the alloy, including hardening, thermomagnetic treatment (TMT) and final aging, providing the required combination of Hc and Br by increasing the stability of the metastable α-phase up to 20 minutes in the interval temperatures of spinodal decomposition α → α1 + α2. The greatest increase in magnetic properties after TMT, observed at the 1st and 2nd steps of final aging, is related to the decomposition of the α-solid solution and the formation of subgrain boundaries. Elements of the obtained structure are characterized by submicron and nanometric sizes, which correlate with the research results on deformable alloys based on the Fe – Cr – Co system. The anisotropic α1+α2-structural state achieved by thermomagnetic treatment provided an increase in the magnetic properties of the studied 30H27KSR powder alloy to 30 % and the squareness coefficient of the magnetic hysteresis loop equal to 0,82 .

Structure and properties of Al–Mg mechanical alloys

2003 ◽  
Vol 18 (8) ◽  
pp. 1827-1836 ◽  
Author(s):  
Mirko Schoenitz ◽  
Edward L. Dreizin
Keyword(s):  
Solid Solution ◽  
Energetic Materials ◽  
Amorphous Material ◽  
Bulk Composition ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Β Phase ◽  
Α Phase ◽  
Diffraction Microscopy

Mechanically alloys in the Al–Mg binary system in the range of 5–50 at.% Mg were produced for prospective use as metallic additives for propellants and explosives. Structure and composition of the alloys were characterized by x-ray diffraction microscopy (XRD) and scanning electron microscopy. The mechanical alloys consisted of a supersaturated solid solution of Mg in the α aluminum phase, γ phase (Al12Mg17), and additional amorphous material. The strongest supersaturation of Mg in the α phase (20.8%) was observed for bulk Mg concentrations up to 40%. At 30% Mg, the γ phase formed in quantities detectable by XRD; it became the dominating phase for higher Mg concentrations. No β phase (Al3Mg2) was detected in the mechanical alloys. The observed Al solid solution generally had a lower Mg concentration than the bulk composition. Thermal stability and structural transitions were investigated by differential scanning calorimetry. Several exothermic transitions, attributed to the crystallization of β and γ phases were observed. The present work provides the experimental basis for the development of detailed combustion and ignition models for these novel energetic materials.

Enhanced ferroelectricity and ferromagnetism in La1−xBixCrO3 by Bi3+ substitution

2007 ◽  
Vol 22 (8) ◽  
pp. 2081-2086 ◽  
Author(s):  
H-Y. Guo ◽  
J.I.L. Chen ◽  
Z-G. Ye ◽  
A.S. Arrott
Keyword(s):  
Solid Solution ◽  
Magnetic Properties ◽  
Quantum Interference ◽  
Remanent Polarization ◽  
Magnetic Hysteresis ◽  
Zero Field ◽  
Ferroelectric Hysteresis ◽  
Different Origins ◽  
Zero Field Cooling ◽  
Field Cooling

The ferroelectric and magnetic properties of the perovskite solid solution, (1 − x)LaCrO3–xBiCrO3, have been investigated. While pure LaCrO3 does not show ferroelectric hysteresis even at 77 K, the solid solution of La1−xBixCrO3 with x = 0.1, 0.2, 0.3, and 0.35 displays ferroelectric hysteresis, with the remanent polarization increasing with the increase of the Bi3+ content. Using a superconducting quantum interference device, the magnetization was measured versus temperature under field cooling (FC) and zero field cooling (ZFC) conditions. Magnetic hysteresis has been found in La1−xBixCrO3 (0.1 ⩽ x ⩽ 0.3) below the Néel temperature, TN. With the increase of Bi3+ content, TN decreases, while the magnetization below TN is enhanced. While the ferroelectric and magnetic properties could be due to different origins, the Bi substitution results in both ferroelectric and magnetic enhancements in the (1 − x)LaCrO3–xBiCrO3 solid solutions.

Structural, Thermal, Morphological and Magnetic Properties of Al3+-Doped Nanostructured Spinel Nickel Ferrites

2021 ◽  
Vol 13 (5) ◽  
pp. 794-802
Author(s):  
Sami-ullah Rather ◽  
Abdulrahim Ahmad Al-Zahrani ◽  
Usman Saeed ◽  
O. M. Lemine ◽  
Saad S. A. Al-Shahrani ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Nickel Ferrite ◽  
Crystal Size ◽  
Magnetic Hysteresis ◽  
Exchange Interactions ◽  
Magnetic Hysteresis Loop ◽  
Nominal Composition ◽  
Average Crystal Size ◽  
Scanning Calorimetry ◽  
X Ray

Aluminum–nickel ferrite nanostructure with a nominal composition of NiFe2-xAlxO4 (0 < x < 0.9) was synthesized by heat treatment process by employing polyvinylpyrrolidone (PVP) as a capping operator. The effects of Al3+ substitution on structural, morphological, quantitative, qualitative and magnetic properties were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron microscopy (XPS) and vibrating-sample magnetometry (VSM). Single-phase inverse spinel structure and decrease in average crystal size as Al concentration increases was acknowledged by XRD and EDX characterization. The decrease in average crystal size as Al3+ ions content increases is associated with structural effects of overall crystal size of nanostructure. The development of a thermally stable nickel ferrite above 500 °C was detected by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) measurements. The magnetic hysteresis loop measurements at room temperature (RT) with an ultimate tested magnetic field of 1.8 T shows both saturation and remnant magnetization decreases as content of Al3+ ions substitution increases. The decrease in overall magnetization is due to spin non-collinearity, weakening of magnetocrystalline anisotropy and weak super-exchange interactions.

Structural and Magnetic Hysteresis Properties of Co-Zr Substituted Hexagonal Barium Ferrites

2015 ◽  
Vol 7 (1) ◽  
pp. 1346-1351
Author(s):  
Ch.Gopal Reddy ◽  
Ch. Venkateshwarlu ◽  
P. Vijaya Bhasker Reddy
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Magnetic Hysteresis ◽  
Grain Morphology ◽  
Hexagonal Structure ◽  
Ion Composition ◽  
X Ray Diffraction ◽  
Ceramic Method ◽  
Barium Ferrites ◽  
Xrd Patterns

Co-Zr substituted M-type hexagonal barium ferrites, with chemical formula BaCoxZrxFe12-2xO19 (where x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), have been synthesized by double sintering ceramic method. The crystallographic properties, grain morphology and magnetic properties of these ferrites have been investigated by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM). The XRD patterns confirm the single phase with hexagonal structure of prepared ferrites. The magnetic properties have been investigated as a function of Co and Zr ion composition at an applied field in the range of 20 KOe. These studies indicate that the saturation magnetization (Ms) in the samples increases initially up to the Co-Zr composition of x=0.6 and decreases thereafter. On the other hand, the coercivity (Hc) and Remanent magnetization (Mr) are found to decrease continuously with increasing Co-Zr content. This property is most useful in permanent magnetic recording. The observed results are explained on the basis of site occupation of Co and Zr ions in the samples.

Mechanochemical synthesis of a Mg-Li-Al-H complex hydride

2009 ◽  
Vol 24 (9) ◽  
pp. 2880-2885 ◽  
Author(s):  
Jing Zhang ◽  
Wei Yan ◽  
Chenguang Bai ◽  
Fusheng Pan
Keyword(s):  
Solid Solution ◽  
Hydrogen Storage ◽  
Storage Capacity ◽  
Raw Materials ◽  
Initial Step ◽  
Hydrogen Atmosphere ◽  
Al Alloy ◽  
Hydrogen Storage Capacity ◽  
Scanning Calorimetry ◽  
Complex Hydride

Mg-Li-Al alloy was prepared by ingot casting and then underwent subsequent reactive ball milling. A Mg-Li-Al-H complex hydride was obtained under a 0.4 MPa hydrogen atmosphere at room temperature, and as high as 10.7 wt% hydrogen storage capacity was achieved, with the peak desorption temperature of the initial step at approximately 65 °C. The evolution of the reaction during milling, as well as the effect of Li/Al ratio in the raw materials on the desorption properties of the hydrides formed, were studied by x-ray diffraction and simultaneous thermogravimetry and differential scanning calorimetry techniques. The results showed that mechanical milling increases the solubility of Li in Mg, leading to the transformation of bcc β(Li) solid solution to hcp α(Mg) solid solution, the latter continues to incorporate Li and Al, which stimulates the formation of Mg-Li-Al-H hydride. A lower Li/Al ratio resulted in faster hydrogen desorption rate and a greater amount of hydrogen released at a low temperature range, but sacrificing total hydrogen storage capacity.

Synthesis and magnetic properties of Fe-doped (In1−xHox)2O3 solid solution

2008 ◽  
Vol 59 (4) ◽  
pp. 444-447 ◽  
Author(s):  
K OKADA ◽  
S KOHIKI ◽  
F TSUTSUI ◽  
H SHIMOOKA ◽  
M MITOME ◽  
...  
Keyword(s):  
Solid Solution ◽  
Magnetic Properties

scholarly journals Synthesis, structure and magnetic properties of (Eu1−xMnx)MnO3−δ

RSC Advances ◽  
2017 ◽  
Vol 7 (4) ◽  
pp. 2019-2024 ◽  
Author(s):  
Jianming Deng ◽  
Aimei Yang ◽  
M. A. Farid ◽  
Hao Zhang ◽  
Jian Li ◽  
...  
Keyword(s):  
Solid Solution ◽  
Magnetic Properties ◽  
Solid State ◽  
Solid State Method ◽  
Conventional Solid State Method ◽  
State Method

The solid solution (Eu1−xMnx)MnO3−δ (0 ≤ x ≤ 0.126) has been synthesized using a conventional solid-state method.

Influence of Al Substitution on Magnetocaloric Effect in La0.8-XAlXCe0.2Fe11.4Si1.6 Compounds

2011 ◽  
Vol 399-401 ◽  
pp. 992-996
Author(s):  
Yi Hu ◽  
Shan Dong Li ◽  
Mei Mei Liu ◽  
Jian Peng Wu ◽  
Xin Le Cai ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Turning Point ◽  
Magnetic Transition ◽  
Magnetic Hysteresis ◽  
Doping Content ◽  
Magnetic Entropy ◽  
Al Doping ◽  
Al Substitution ◽  
Knee Point ◽  
Transition Type

The influence of Al doping on the magnetic properties and magnetic entropy changes (ΔSM) of the La0.8-xAlxCe0.2Fe11.4Si1.6(x = 0-0.2) compounds have been investigated around their Curie temperature TC. The incorporation of Al atoms is unfavorable for the formation of the NaZn13-type phase, however, it increases the TCby ~40 K, effectively decreases the magnetic hysteresis loss, and broadens the ΔSM-T curve at expense of the (ΔSM)maxof the compounds. It is also revealed that Al doping content of x = 0.06 is an important composition knee point where the doped Al start to occupy the site of Rare-earth elements, leading to a turning point for the lattice constant, TC, and magnetic transition type.

Microstructure Evolution upon Thermomagnetic Treatment of Soft Magnetic Alloys

2009 ◽  
Vol 152-153 ◽  
pp. 66-69 ◽  
Author(s):  
V.V. Gubernatorov ◽  
T.S. Sycheva ◽  
Irina I. Kositsyna
Keyword(s):  
Electron Microscopy ◽  
Magnetic Properties ◽  
Microstructure Evolution ◽  
Soft Magnetic Materials ◽  
Thermomagnetic Treatment ◽  
Soft Magnetic ◽  
Magnetic Alloys ◽  
Treatment Mode ◽  
Soft Magnetic Alloys ◽  
Microscopy Examination

A new concept is suggested that serves to explain the effects of thermomagnetic treatment. Its validity is proved via measurements of magnetic properties and electron microscopy examination of structure of soft magnetic materials after different treatments. This concept allows one to consciously choose the treatment mode aiming on improvement of magnetic properties of alloys.

scholarly journals Developing a reference material set for the magnetic properties of NdFeB alloy-based hard magnetic materials

2019 ◽  
Vol 15 (1) ◽  
pp. 21-27
Author(s):  
E. A. Volegova ◽  
T. I. Maslova ◽  
V. O. Vas’kovskiy ◽  
A. S. Volegov
Keyword(s):  
Magnetic Properties ◽  
Magnetic Materials ◽  
Permanent Magnets ◽  
Magnetic Loss ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Magnetic Hysteresis Loop ◽  
Magnetic Characteristics ◽  
Hard Magnetic Materials ◽  
Certified Values

Introduction The introduction indicates the need for the use of permanent magnets in various technology fields. The necessity of measuring the limit magnetic hysteresis loop for the correct calculation of magnetic system parameters is considered. The main sources of error when measuring boundary hysteresis loops are given. The practical impossibility of verifying blocks of magnetic measuring systems element-by-element is noted. This paper is devoted to the development of reference materials (RMs) for the magnetic properties of hard magnetic materials based on Nd2Fe14B, a highly anisotropic intermetallic compound.Materials and measuring methods Nd-Fe-B permanent magnets were selected as the material for developing the RMs. RM certified values were established using a CYCLE‑3 apparatus included in the GET 198‑2017 State Primary Measurement Standard for units of magnetic loss power, magnetic induction of constant magnetic field in a range from 0.1 to 2.5 T and magnetic flux in a range from 1·10–5 to 3·10–2 Wb.Results and its discussion Based on the experimentally obtained boundary hysteresis loops, the magnetic characteristics were evaluated, the interval of permitted certified values was set, the measurement result uncertainty of certified values was estimated, the RM validity period was established and the first RM batch was released.Conclusion On the basis of conducted studies, the RM type for magnetic properties of NdFeB alloy-based hard magnetic materials was approved (MS NdFeB set). The developed RM set was registered under the numbers GSO 11059–2018 / GSO 11062–2018 in the State RM Register of the Russian Federation.

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