This is to confirm that the thesis entitled "Influence of Annealing Temperature on Magnetization and Initial Permeability of Fe-Ni Based Amorphous Ribbons" has been carried out in partial fulfillment of the requirements for M. Fe-Ni-B amorphous ribbons with different Annealing Temperatures 69 5.1 .4 Frequency dependence of the imaginary part of the complex permeability.
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Frequency dependence of the imaginary part of the initial permeability of amorphous ribbons for different annealing temperatures with composition Fe3oNi50B20 at a constant annealing time of 1 hour. Fig.5.23 Real part temperature dependence of complex initial permeability of Fe4oNi40B20 ribbon at different annealing temperatures for a constant annealing time of 1 hour.
INTRODUCTION
INTRODUCTION
- Introduction
- The Aim and Objectives of the Present Work
- Reason for Choosing this Research Work
- Application of Amorphous Ribbons
- Review of research Work
- Outline of the Thesis
In the present work, an attempt is made to describe the unusual nature of the thermodynamic parameters in amorphous bands using a theoretical model developed by B. The behavior of the amorphous Fe-based band is very different from Co-based bands.
PREPARATION OF AMORPHOUS RIBBONS
Introduction
Amorphous states of pure metals like Fe, Co, Ni etc can only be obtained at a very low temperature. Recently, the metalloids in TM - M glass are prepared by non-magnetic metals such as Zr, Hf.
The Structure of an Amorphous Alloy
A metallic glass is distinguished from a liquid or a solid, due to its deviation from thermodynamic equilibrium, while both a melt and the corresponding crystalline phase have a minimum free energy, while an amorphous material, due to its non-equilibrium state, has a higher free energy . energy. Free energy as a function of temperature for a crystalline solid, an amorphous solid and a liquid is shown in Fig.
Conditions for Forming Amorphous Material
01 2.4 Conditions Necessary for Preparing Amorphous Materials
- Preparation Technique of Amorphous Ribbon
- The Atomic Deposition Methods
- The Fast Cooling of the Melt
- Master alloy Preparation
- Rapid Quenching Method
- Experimental details of the Preparation of Amorphous Ribbon
- Important Factors to Control the Thickness of Ribbons
- Factors Contributing to Glass Formation
- Examining the Amorphous Ribbon
Care must be taken to ensure that the ribbon does not remain in contact with the surface of the roller for a full revolution and is struck from behind. A single parameter expressing the glass formation tendency is the ratio of the glass transition temperature to the melting temperature, defined as reduced glass transition temperature.
THEORETICAL ASPECTS
- Amorphous Alloy or Metallic Glass
- Nature and Formation of amorphous Alloys
- Factors Contributing to Glass Formation and Stability
- Structure and Microstructure of Amorphous and Nanocrystalline Alloys
- Stability of the Amorphous Nanocrystalline Materials
- Annealing Effects in Amorphous Alloy
- Initial Permeability of Amorphous Ribbons
- Theories of Permeability
- Measurement of Initial Permeability
- Relative permeability
- High Frequency Behavior and Losses
Melt viscosity, glass transition temperature (Tg) and homogeneous nucleation rate belong to the kinetic parameters. A single parameter that expresses the glass formation tendency is the ratio of the glass transition temperature to the melting temperature, defined as The composition of amorphous alloys most favorable for glass formation is close to eutectic, i.e. the composition in which taxes from the liquid state to the solid state occur immediately without passing through the mixed liquid plus solid phase.
Since, an energy loss of this type increases in proportion to frequency square in the high frequency range.
W aBBfY
Magnetic Dipole Moments and Magnetization
- Magnetization of the Amorphous Ribbons
- Ferromagnetic ordering (Curie) Temperatures
The exchange integral also varies at each point due to the different interatomic distance and the overlap of the electronic wave functions. The moments of most amorphous alloys are lower than those of the pure crystalline transition metal they contain. Moments are lower due to the change in the local chemical environment provided by the presence of metalloids.
Exchange replaces the molecular field Weiss constant in the mean field theory of ferromagnetism to account for the temperature dependence of magnetization.
Thermal Treatment of the Amorphous Ribbon
Annealing
- Stages
- Setup and Equipment
The interior of the oven is large enough to place the workpiece in a position that allows maximum exposure to the circulating heated air. After the annealing process has been successfully completed, the workpieces are sometimes left in the oven so that the parts can undergo a controlled cooling process. While some workpieces are left in the oven for controlled cooling, other materials and alloys are removed from the oven.
After being removed from the furnace, the workpieces are often rapidly cooled in a process known as blushharding.
Impedance Analyzer
- Preparation of the Samples for Complex Permeability Measurement
- Components of Complex Permeability Measurements
- Real and Imaginary Components of Complex Permeability
The sweep capabilities of the built-in frequency synthesizer and dc bias source allow fast and accurate measurements. However, the cross-section of the amorphous ribbon core to be measured may need to be kept small to avoid dimensional resonance phenomena. The thickness of the separate wire stands is adjusted in the measurement frequency of approximately 13MHz.
Determination of permeability usually involves measurements of the change in self-inductance of a coil in the presence of the magnetic core.
Curie Temperature
If we have an ideal lossless air coil with inductance L, by inserting a magnetic core with permeability p, the inductance will be pL0. The complex impedance Z of this coil will then be expressed as
Inductance Analyzer
- Curie Temperature determination from temperature dependence of ac permeability
4.2, the circuit consists of two parts. The primary part consists of a low frequency generator, a multimeter and a resistor in series. An alternating current i flowing through the primary of the annular toroidal sample produces a magnetizing field. Where N1 is the total number of turns in the primary of the toroidal ring and d is given by the, d 1+d 2.
If the heating rate is too fast, then the sample temperature may not follow the temperature inside the oven and there may be misleading information about the sample temperature.
Magnetization Measurement Techniques
- Vibration Sample Magnetometer
- The Principle of Vibration Sample Magnetometer
- Electronic Circuits of the VSM
- Sensitivity limits
- Stability Tests Differential Measurements
- Vibration Amplitude
- Image Effects
- Vibration Frequency
- Vibration problems
Thus, only the moment determines the amplitude of the signal at the output of the differential amplifier. Thus, the output of the Lock-in amplifier is proportional to the magnetic moment of the sample avoiding only any frequency noise other than that of the signal. The main sources of noise are the Johnson noise of the wire used for the pickup coils and the magnetic responses of the sample holder, which superimposes unwanted signals in phase with the desired signal.
Corrections for the small magnetic contribution of the sample holder can then be made by measurements with the sample removed.
RESULTS AND DISCUSSION
Dynamic Magnetic Properties of Fe-Ni Based Amorphous Ribbons
- Initial permeability of as-cast Fe-Ni-B Amorphous Ribbons
- Complex Permeability of the Fe-Ni-B Amorphous Ribbons
- Frequency Dependence of the Real part of the Complex Permeability Fe-Ni-B Amorphous Ribbons with Different Annealing Temperatures
5.1. The real part of the complex permittivity depends on the applied field and shows that the dispersion depends on the frequency as shown in the figure. But the real part of the complex permeability is independent of the applied field and shows a dispersion at -1O5Hz, shown in Fig. Figure 5.3 Frequency dependence of the real part of the initial permeability of the amorphous strip for different fields with the composition of FeNi3oB20 at a constant annealing time of 1 hour (a) x=20.
Fig-5.7 to Fig-5.10 show frequency dependence of the real part of initial permeability for different annealing temperatures at constant annealing time 1 hour.
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Frequency Dependence of Imaginary Part of the Complex Permeability of Fe-Ni-B Amorphous Ribbons with Different
The imaginary part of the complex permeability (ji") at a constant annealing time of one hour with different annealing temperatures in the frequency range I kHz to 1 3 MHz is shown in the figure. Figure 5.13 Frequency dependence of the imaginary part of the permeability of amorphous strips for different annealing temperatures with the composition Fe.10Ni40B20 at a constant] hourly annealing time Figure 5.14 Frequency dependence of the imaginary part of the initial permeability of amorphous strips for different annealing temperatures with the composition of Fe30Ni50B20 at a constant 1 hour.
Fig.5.15 Frequency dependence of the imaginary part of the permeability of amorphous bands for different annealing temperatures with composition Fe20N6132() at a constant 1 hour annealing time.
Relative Quality Factor of Fe-Ni-B Amorphous Ribbons with Different Annealing Temperatures
It is well known that amorphous ribbons with optimal annealing exhibit minimal loss and a very high relative quality factor, A of the order of 3.4 x 104. The high relative quality factor and low loss factor of the ribbons indicate that this may be useful as a soft magnetic material. The increase of the loss factor with the annealing temperature indicates that a longer annealing time results in further growth of the crystallites and their stability.
The loss factor arises due to the eddy current loss as well as to the phase leg of the spin orientation with respect to the external field.
- Annealing Temperature Effects on Curie Temperature Measurements of Fe-Ni-B Amorphous Ribbons
Because the longer time initiates nucleation of crystallites, which inhibits the determination of T of the perfect amorphous state. This can be determined by the temperature dependence of the material's inherent anisotropy. The dependence of Tc on the composition and nature of the metalloids is not very systematic.
It is explained as a result of the weakening of the exchange interaction between the magnetic atoms due to the replacement of the Fe atom with Ni atoms.
Specific Magnetization Measurements of Fe-Ni—B Amorphous Ribbons
- Effect of Annealing Temperature on Specific Magnetization of Fe-Ni—B Amorphous Ribbons at Room Temperature
Fig.5.28 Specific magnetization versus magnetic field of Fe50Ni3oB2o ribbon at different annealing temperatures for a constant annealing time of 1 hour. Fig.5.29 Specific magnetization versus magnetic field of Fe40Ni4oB2o ribbons at different annealing temperatures for a constant annealing time of 1 hour. Fig.5.30 Specific magnetization versus magnetic field of Fe30Ni50B2o ribbons at different annealing temperatures for a constant annealing time of 1 hour.
Figure 5.3 1 Specific magnetization versus magnetic field of Fe20Ni601320 strip at different annealing temperatures for a constant annealing time of 1 hour.
CONCLUSIONS
CONCLUSIONS
Conclusions
These effects contribute to an increase in the real part of the permeability, but at the same time the imaginary component is also influenced, especially by eddy current effects. For all ribbon alloy systems, the saturation-specific magnetization depends on the atomic magnetic moments of the constituent 3D transition moment. The effect of the glass-forming materials is explained as due to the transfer of p-electron to the 3D band.
The annealing temperatures are chosen to partially remove the pinning centers of the domain walls and thereby improve the magnetic softness of these bands.
Petrakovskii; "Amorphous Magnetic Materials", Institute of Physics of the Siberian Branch of the Academy of Sciences of the USSR Kragnoyarsky USP. Asgar; "Study of Complex Permeabilities of Amorphous Magnetic Strip Fe82SigB10 and Their Dependence on Thermal Annealing and Frequency"; Jahangirnagar University, Journal of Science;. Kinetics of atomic and magnetic ordering of Co-based amorphous ribbons under the influence of iron substitution";.
Sikder; 'the influence of glass-forming material on the atomic and magnetic arrangement of Fe-based metallic glass'; Indian J.
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5.10] Siba Pada Mondal; "Study of nanocrystal formation in Fll'.JEMET metallic glasses and their magnetic properties". Balong; "Saturation Magnetization and Amorphous Curie Point Charge During the Early Phase of the Amorphous Nanocrystalline Transformation of a FINEMET-Type Alloy": J.
