scholarly journals Structure of Alloys for (Sm,Zr)(Co,Cu,Fe)Z Permanent Magnets: First Level of Heterogeneity

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3893 ◽  
Author(s):  
Andrey G. Dormidontov ◽  
Natalia B. Kolchugina ◽  
Nikolay A. Dormidontov ◽  
Yury V. Milov
Keyword(s):  
Phase Composition ◽  
Quantitative Analysis ◽  
Chemical Composition ◽  
Permanent Magnets ◽  
Composition Range ◽  
Structural Phase ◽  
High Coercivity ◽  
Structural Components ◽  
Structural Formation ◽  
Hysteretic Properties

An original vision for the structural formation of (Sm,Zr)(Co,Cu,Fe)Z alloys, the compositions of which show promise for manufacturing high-coercivity permanent magnets, is reported. Foundations arising from the quantitative analysis of alloy microstructures as the first, coarse, level of heterogeneity are considered. The structure of the alloys, in optical resolutions, is shown to be characterized by three structural phase components, which are denoted as A, B, and C and based on the 1:5, 2:17, and 2:7 phases, respectively. As the chemical composition of alloys changes monotonically, the quantitative relationships of the components A, B, and C vary over wide ranges. In this case, the hysteretic properties of the (Sm,Zr)(Co,Cu,Fe)Z alloys in the high-coercivity state are strictly controlled by the volume fractions of the A and B structural components. Based on quantitative relationships of the A, B, and C structural components for the (R,Zr)(Co,Cu,Fe)Z alloys with R = Gd or Sm, sketches of quasi-ternary sections of the (Co,Cu,Fe)-R-Zr phase diagrams at temperatures of 1160–1190 °C and isopleths for the 2:17–2:7 phase composition range of the (Co,Cu,Fe)–Sm–Zr system were constructed.

scholarly journals Structure of Alloys for (Sm,Zr)(Co,Cu,Fe)z Permanent Magnets: III. Matrix and Phases of the High-Coercivity State

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7762
Author(s):  
Andrey G. Dormidontov ◽  
Natalia B. Kolchugina ◽  
Nikolay A. Dormidontov ◽  
Mark V. Zheleznyi ◽  
Anna S. Bakulina ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Domain Structure ◽  
Structural Component ◽  
Permanent Magnets ◽  
Phase State ◽  
Volume Fraction ◽  
Heat Treatments ◽  
High Coercivity ◽  
Structural Components ◽  
The Matrix

Observations of the surface domain structure (Kerr-effect), optical metallography, scanning electron microscopy (SEM-SE), and electron microprobe analysis (EPMA-SEM), measurements of major and minor magnetic hysteretic loops were used to study pseudo-single-crystal samples of (Sm,Zr)(Co,Cu,Fe)z alloys subjected to heat treatments to the high-coercivity state, which are used in fabricating sintered permanent magnets. Correlations between the chemical composition, hysteretic properties, structural components, domain structure, and phase state were determined for the concentration ranges that ensure wide variations of 4f-/4d-/3d-element ratio in the studied samples. The phase state formed by collinear and coherent phase components determines the high coercive force and ultimate magnetic hysteresis loops of the pseudo-single crystals. It was found that the 1:5 phase with the hexagonal structure (P6/mmm) is the matrix of the alloys for (Sm,Zr)(Co,Cu,Fe)z permanent magnets; the matrix undergoes phase transformations in the course of all heat treatments for the high-coercivity state. The heterogeneity observed with optical magnifications, namely, the observation of main structural components A and B, is due to the alternation, within the common matrix, of regions with modulated quasi-spherical precipitates and regions with hexagonal bipyramids (cellular phase) although, traditionally, many investigators consider the cellular phase as the matrix. It is shown that the relationship of volume fractions of structural components A and B that account for more than 0.9 volume fraction of the total, which is due to the integral chemical composition of the alloys, determines the main hysteretic performances of the samples. The Zr-rich phases, such as 5:19, 2:7, and 6:23, and a structural component with the variable stoichiometry (Sm(Co,Cu,Fe)3.5–5) that is almost free of Zr and contains up to 33 at% Cu, were found only within structural component A in quantities sufficient for EPMA analysis.

The Structure of Coatings Obtained in a ZnAl23Si Bath by the Batch Hot Dip Method

2015 ◽  
Vol 226 ◽  
pp. 155-160 ◽  
Author(s):  
Henryk Kania
Keyword(s):  
Phase Composition ◽  
Chemical Composition ◽  
Growth Kinetics ◽  
Coating Thickness ◽  
Silicon Steel ◽  
Structural Components ◽  
Uniform Thickness ◽  
External Layer ◽  
Structure Of Coatings ◽  
Kinetics Of

In the paper the results of tests on obtaining ZnAl23Si coatings on low-silicon steel by use of the batch hot dip method have been presented. The growth kinetics of coatings obtained in a ZnAl23 bath with the content of 1% and 2% of Si has been defined. The structure has been developed, the chemical composition of particular structural components of the coating and its phase composition have been established. It has been determined that coatings obtained in the ZnAl23Si bath are continuous and they have uniform thickness. The presence of silicon in the bath allows to reduce excessive coating thickness. The coating is composed of an external layer which is formed by the bath components and of a diffusion layer of the intermetallic FeAl3phase.

scholarly journals Structure of Alloys for (Sm,Zr)(Co,Cu,Fe)z Permanent Magnets: II. Composition, Magnetization Reversal, and Magnetic Hardening of Main Structural Components

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5426
Author(s):  
Andrey G. Dormidontov ◽  
Natalia B. Kolchugina ◽  
Nikolay A. Dormidontov ◽  
Yury V. Milov ◽  
Alexander S. Andreenko
Keyword(s):  
Phase Transformations ◽  
Domain Structure ◽  
Magnetization Reversal ◽  
Permanent Magnets ◽  
Hysteresis Loops ◽  
Total Sample ◽  
High Coercivity ◽  
Metallographic Analysis ◽  
Structural Components ◽  
Slow Cooling

Experimental series of alloys for (Sm,Zr)(Co,Cu,Fe)Z permanent magnets are presented in the concentration ranges that provide wide variations of (4f)/(4d)/(3d) ratios of comprising elements. Optical metallographic analysis, observation of the surface domain structure upon magnetization reversal (Kerr effect), electron microprobe analysis, and measuring the major hysteresis loops of samples at different stages of heat treatment are used to study processes related to the development of the highly coercive state of these samples. It was found that the volume fractions of two main structural components A and B, which comprise 90% of the total sample volume, rigorously control the coercivity at all stages of thermal aging. At the same time, structural components A and B themselves in samples being in the high-coercivity state differ qualitatively and quantitatively in the chemical composition, domain structure and its development in external magnetic fields and, therefore, are characterized by different morphologies of the phases comprising the structural components. Two stages of phase transformations in the sample structure are observed. During isothermal annealing, the cellular structure develops within the B component, whereas, during stepwise (slow) cooling or quenching from the isothermal aging temperature to 400 °C, a phase structure evolves within both the cell boundaries in B and the structural component A. The degree of completion of the phase transformations within micro- and nano-volumes of the components determines the ultimate hysteretic characteristics of the material.

Structure and Magnetic Properties of Heat-Resistant Sm(Co0.796−xFe0.177CuxZr0.027)6.63 Permanent Magnets with High Coercivity

JOM ◽  
2018 ◽  
Vol 71 (2) ◽  
pp. 559-566 ◽  
Author(s):  
A. G. Popov ◽  
V. S. Gaviko ◽  
V. V. Popov ◽  
O. A. Golovnia ◽  
A. V. Protasov ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Permanent Magnets ◽  
High Coercivity ◽  
Heat Resistant

scholarly journals DEVELOPMENT OF A TECHNOLOGICAL PROCESS FOR MANUFACTURING WELDED STRUCTURES

2021 ◽  
Vol 4 (5) ◽  
pp. 35-44
Author(s):  
R. El'cov
Keyword(s):  
Phase Composition ◽  
Laser Welding ◽  
Strain Amplitude ◽  
Welded Joints ◽  
Structural Phase ◽  
Diagnostic Methods ◽  
Aluminum Lithium ◽  
Aluminum Lithium Alloys ◽  
First Time ◽  
Lithium Alloys

the main goal of this article is to obtain welded permanent joints of modern thermally hardened aluminum and aluminum-lithium alloys made by laser welding, having mechanical characteristics (temporary tensile resistance, yield strength, elongation at break) and structural-phase composition close to or equal to the base alloy. It is shown for the first time that by controlling the parameters of heat treatment of samples with a welded joint of all studied aluminum-lithium alloys, it is possible to purposefully influence the formation of the specified mechanical properties of the weld by changing the structural and phase composition of the weld. The evolution of the struc-tural and phase composition of welded joints of thermally hardened aluminum and aluminum-lithium alloys has been investigated using modern independent diagnostic methods: for the first time, the use of synchrotron radia-tion diffractometry in combination with high-resolution transmission, scanning electron and optical microscopy. The dependences of the increment of deformation under cyclic loading with amplitudes exceeding the elastic limit on temperature are established. For untreated welded joints, it was found that at +85 C, the inhomogeneity of the deformation increment increases, and its speed increases by 8 times for alloy 1461, 5 times for alloy 1420 and 1.5 times for alloy 1441. At a temperature of -60 0C, alloys 1420 and 1461 have hardening stages, during which the value of deformation decreases at given boundary stress values. At +20 0C, there is a uniform increment of defor-mation and an increase in the amplitude of deformation with an increase in the amplitude of stress. At +85 0C, the strain amplitude does not change with increasing stress amplitude, its value is 0.55-0.5 of the strain amplitude at +20 0C. Based on the research results, technological techniques have been developed that allow obtaining me-chanical characteristics and structural-phase compositions of welded joints close to the main alloy during laser welding of aviation thermally hardened aluminum and aluminum-lithium alloys of the Al-Mg-Cu. Al-Mg-Li, Al-Cu-Mg-Li, Al-Cu-Li systems.

scholarly journals Effect of Nickel Equivalent on Austenite Transition Ratio in Ni-Mn-Cu Cast Iron

2013 ◽  
Vol 13 (2) ◽  
pp. 53-58 ◽  
Author(s):  
A. Janus ◽  
A. Kurzawa
Keyword(s):  
Cast Iron ◽  
Chemical Composition ◽  
Chemical Analysis ◽  
Wall Thickness ◽  
Brinell Hardness ◽  
Austenite Decomposition ◽  
Structural Components ◽  
Microscopy Image ◽  
Image Analyser ◽  
Nickel Equivalent

Abstract Determined was quantitative effect of nickel equivalent value on austenite decomposition degree during cooling-down castings of Ni-Mn- Cu cast iron. Chemical composition of the alloy was 1.8 to 5.0 % C, 1.3 to 3.0 % Si, 3.1 to 7.7 % Ni, 0.4 to 6.3 % Mn, 0.1 to 4.9 % Cu, 0.14 to 0.16 % P and 0.03 to 0.04 % S. Analysed were castings with representative wall thickness 10, 15 and 20 mm. Scope of the examination comprised chemical analysis (including WDS), microscopic observations (optical and scanning microscopy, image analyser), as well as Brinell hardness and HV microhardness measurements of structural components.

scholarly journals Structural, electrical and magnetic behaviour of undoped and nickel doped nanocrystalline bismuth ferrite by solution combustion route

2015 ◽  
Vol 9 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Kakali Sarkar ◽  
Soumya Mukherjee ◽  
Siddhartha Mukherjee
Keyword(s):  
Crystallite Size ◽  
Bismuth Ferrite ◽  
Structural Phase ◽  
Average Crystallite Size ◽  
Magnetic Behaviour ◽  
Solution Combustion ◽  
Chemical Route ◽  
Structural Formation ◽  
Xrd Diffraction ◽  
The Matrix

Multiferroic bismuth ferrite (BFO) and Ni-doped bismuth ferrites, with perovskite structure, were synthesized by chemical route at the temperatures ranging from 500 to 600 ?C in controlled atmosphere. The structural phase analysis of materials was identified by XRD and crystallite size was calculated from the half width measurement of the well defined major XRD diffraction peak. Average crystallite size was calculated by applying Scherrer?s formula and found to have values in the range from 14 to 35 nm. FESEM was used to evaluate the morphology and structural formation of nanocrystallite grains, while EDX confirmed elemental composition including the presence of dopant in the matrix. Dielectric properties and effect of electric field on polarization behaviour were studied for both undoped and Ni-doped BFO. Doping shows a clear change in ferroelectric behaviour. Antiferromagnetic nature of bulk bismuth ferrite transforms to superparamagnetic strong ferroelectric nature for both undoped and nickel doped nanocrystalline bismuth ferrite due to its close dimension of crystallite size with magnetic domains leading to break-down of frustrated spin cycloidal moment. The superparamagnetism behaviour is more pronounced for the nickel doped BFO though magnetic saturation is slightly higher for the undoped nanocrystalline bismuth ferrite.

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