The correlation between structural relaxation process and the change in magnetic permeability of the Fe73.5Cu1Nb3Si15.5B7 amorphous alloy under the thermal influence

In this study it was investigated influence of temperature and frequency on permeability, coercivity and power loses of Fe81B13Si4C2 amorphous alloy. Magnetic permeability measurements performed in nonisothermal and isothermal conditions was confirmed that efficient structural relaxation was occurred at temperature of 663 K. This process was performed in two steps, the first one is kinetic and the second one is diffuse. Activation energies of these processes are: Ea1 = 52.02 kJ/mol for kinetic and Ea2 = 106.9 kJ/mol for diffuse. It was shown that after annealing at 663 K coercivity decrease about 30% and therefore substantial reduction in power loses was attained. Investigated amorphous alloy satisfied the criteria for signal processing devices that work in mean frequency domain.

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Correlation between isothermal expansion and functional properties change of the Fe81B13Si4C2 amorphous alloy

Science of Sintering ◽

10.2298/sos0903283k ◽

2009 ◽

Vol 41 (3) ◽

pp. 283-291 ◽

Cited By ~ 5

Author(s):

A. Kalezic-Glisovic ◽

V.A. Maricic ◽

D.A. Kosanovic ◽

S. Djukic ◽

R. Simeunovic

Keyword(s):

Thermal Expansion ◽

Magnetic Susceptibility ◽

Amorphous Alloy ◽

Relaxation Process ◽

Functional Properties ◽

Structural Relaxation ◽

Structural Changes ◽

Process Time ◽

Second Stage ◽

Isothermal Expansion

The structural changes effect on functional properties of ribbon shaped samples of the Fe81B13Si4C2 amorphous alloy during annealing process was investigated in this paper. Differential scanning calorimetry method has shown that this alloy crystallizes in one stage, in temperature range from room temperature up to 700?C. Structural relaxation process was investigated by sensitive dilatation method in nonisothermal and isothermal conditions. It has been shown that structural relaxation process occurs in two stages by measuring thermal expansion at constant temperatures of t1=420?C, t2 = 440?C and t3 = 460?C. The first stage is characterized by linear logarithmic dependence of thermal expansion upon time at constant temperature. The second stage of structural relaxation process is characterized by linear dependence of isothermal expansion upon the square root of process time. These results imply that the first stage of structural relaxation process is a rapid kinetic process, while the second stage of structural relaxation process is a slow diffusion process. The rate constants k11 = 2,27?10- 3 s-1, k12 = 2,79?10-3 s-1, k13 = 3,6?10-3 s-1, k21 = 0,67?10-4 s-1, k22 = 3,72?10-4 s-1, k23 = 21,53?10-4 s-1 and activation energies E1 = 48,64 kJ/mol and E2 = 366, 23 kJ/mol were determined for both stages of structural relaxation process. The distinct correlation between structural relaxation process and magnetic susceptibility relative change was determined by thermomagnetic measurements. It has been shown that magnetic susceptibility can be increased by up to 80%, by convenient annealings after structural relaxation process, at magnetic field intensity of 8 kA/m.

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Structural Disordering and Relaxation Process in an Amorphous Alloy

Korean Journal of Metals and Materials ◽

10.3365/kjmm.2011.49.11.823 ◽

2011 ◽

Vol 49 (11) ◽

Keyword(s):

Amorphous Alloy ◽

Relaxation Process ◽

Structural Disordering

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The effect of structural changes during sintering on the electric and magnetic traits of the Ni96.7Mo3.3 alloy nanostructured powder

Science of Sintering ◽

10.2298/sos0902175r ◽

2009 ◽

Vol 41 (2) ◽

pp. 175-184 ◽

Cited By ~ 7

Author(s):

L. Ribic-Zelenovic ◽

M. Spasojevic ◽

A. Maricic ◽

M.M. Ristic

Keyword(s):

Electrical Resistivity ◽

Magnetic Permeability ◽

Structural Relaxation ◽

Crystalline Phase ◽

Structural Changes ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

Fcc Lattice ◽

Lower Permeability ◽

Structural Powder

Ni96.7Mo3.3 powder was electrochemically obtained. An X-ray diffraction analysis determined that the powder consisted of a 20% amorphous and 80% crystalline phase. The crystalline phase consisted of a nanocrystalline solid nickel and molybdenum solution with a face-centred cubic (FCC) lattice with a high density of chaotically distributed dislocations and high microstrain value. The scanning electronic microscopy (SEM) showed that two particle structures were formed: larger cauliflower-like particles and smaller dendriteshaped ones. The thermal stability of the alloy was examined by differential scanning calorimetry (DSC) and by measuring the temperature dependence of the electrical resistivity and magnetic permeability. Structural powder relaxation was carried out in the temperature range of 450 K to 560 K causing considerable changes in the electrical resistivity and magnetic permeability. Upon structural relaxation, the magnetic permeability of the cooled alloy was about 80% higher than the magnetic permeability of the fresh powder. The crystallisation of the amorphous portion of the powder and crystalline grain increase occurred in the 630 K to 900 K temperature interval. Upon crystallisation of the amorphous phase and crystalline grain increase, the powder had about 50% lower magnetic permeability than the fresh powder and 3.6 times lower permeability than the powder where only structural relaxation took place.

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Structural Relaxation Process in CuHfTi Amorphous Alloys

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.283-286.533 ◽

2009 ◽

Vol 283-286 ◽

pp. 533-538 ◽

Cited By ~ 1

Author(s):

Kazumasa Yamada ◽

N. Shinagawa ◽

M. Sogame ◽

I.A. Figueroa ◽

Hywel A. Davies ◽

...

Keyword(s):

Activation Energy ◽

Relaxation Process ◽

Structural Relaxation ◽

Amorphous Alloys ◽

Melt Spinning ◽

Amorphous Materials ◽

Ternary Alloys ◽

Relaxation Processes ◽

Scanning Calorimetry ◽

Structure Relaxation

The aim of this research is to clarify a quantitative evaluation in the structural relaxation processes focusing on the activation energy in Cu based amorphous alloys. The activation energy for structural relaxation process in a metal type amorphous CuHfTi ternary alloys, with cross sections of typically 0.03 mm x 2.0 mm, prepared by chill-block melt spinning has been investigated by Differential Scanning Calorimetry (DSC) with a cyclically heating technique. Activation energies for structural relaxation with a spatial quantity in amorphous materials have been discussed by use of a relaxed ratio function that depends on annealing temperature and time. In the present work, the distributions for the Activation Energy Spectrum (AES) were observed almost 152 kJmol-1 (1.58 eV). Another result has been also established that the “reversible” AES model energy distribution though the cyclically structure relaxation occurs even in amorphous Cu60Hf20Ti20 alloy.

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