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

2009 ◽  
Vol 41 (3) ◽  
pp. 283-291 ◽  
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.

Local atomic structural changes on structural relaxation in a Pd82Si18 amorphous alloy

1994 ◽  
Vol 179-180 ◽  
pp. 479-482 ◽  
Author(s):  
Kazunori Anazawa ◽  
Tadakatsu Ohkubo ◽  
Yoshihiko Hirotsu
Keyword(s):  
Amorphous Alloy ◽  
Structural Relaxation ◽  
Structural Changes

scholarly journals Influence of structural changes on electrical and magnetic properties of the Co84Fe5,3Si8,5B2,2 amorphous alloy

2005 ◽  
Vol 37 (3) ◽  
pp. 231-235 ◽  
Author(s):  
S.R. Djukic ◽  
Radojko Simeunovic ◽  
Aleksa Maricic
Keyword(s):  
Activation Energy ◽  
Amorphous Alloy ◽  
Relaxation Process ◽  
Structural Changes ◽  
Crystallization Process ◽  
State Density ◽  
Annealing Process ◽  
Scanning Calorimetry ◽  
Electrical And Magnetic Properties ◽  
Electronic State Density

The crystallization process of the Co84Fe5.3Si8.5B2.2 amorphous alloy examined by differential scanning calorimetry (DSC) exhibits three exothermal steps at Tcr1=649K, Tcr2=800K, and Tcr3=838K. The rate constants of the first relaxation process (determined at 598K and 623K) are k1=5*10-4 s and k2=8*10-4 s and the corresponding activation energy Ea1=26.23 kJ/mol. The data for the relaxation process before the second crystallization step (determined at 683K and 713K) are k3=14.5*10-4 s and k4=17.5*10-4 s and the corresponding activation energy Ea2=60.0 kJ/mol. The process of structural relaxation in non-isothermal and isothermal conditions was studied by analysis of the results of measurements of the thermo electromotive force (TEMF). From the change of the temperature coefficient of TEMF that follows each annealing process, the relative electronic state density changes at the Fermi level were determined: ?N21/N2=5,45%, ?N22/N2=5,76%, ?N23/N2=7,57% and ?N24/N2=9,85%.

scholarly journals The Structure and Magnetic Properties of Rapidly Quenched Fe72Ni8Nb4Si2B14 Alloy

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 5
Author(s):  
Lukasz Hawelek ◽  
Tymon Warski ◽  
Patryk Wlodarczyk ◽  
Marcin Polak ◽  
Przemyslaw Zackiewicz ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Relaxation Process ◽  
Glassy State ◽  
Diffraction Method ◽  
Soft Magnetic Materials ◽  
Process Time ◽  
Complex Permeability ◽  
Soft Magnetic ◽  
Conventional Heat Treatment ◽  
Glass Relaxation

The complex structural and magnetic studies of the annealed rapidly quenched Cu-free Fe72Ni8Nb4Si2B14 alloy (metallic ribbons form) are reported here. Based on the calorimetric results, the conventional heat treatment process (with heating rate 10 °C/min and subsequent isothermal annealing for 20 min) for wound toroidal cores has been optimized to obtain the least lossy magnetic properties (for the minimum value of coercivity and magnetic core losses at 50 Hz). For optimal conditions, the complex permeability in the 104–108 Hz frequency range together with core power losses obtained from magnetic induction dependence up to the frequency of 400 kHz was successfully measured. The average and local crystal structure was investigated by the use of the X-ray diffraction method and the transmission electron microscopy observations and proved its fully glassy state. Additionally, for the three temperature values, i.e., 310, 340 and 370 °C, the glass relaxation process study in the function of annealing time was carried out to obtain a deeper insight into the soft magnetic properties: magnetic permeability and cut-off frequency. For this type of Cu-free soft magnetic materials, the control of glass relaxation process (time and temperature) is extremely important to obtain proper magnetic properties.

The Study of Underfill Epoxy Hardness in Reducing Curing Process Time for Flip Chip Packaging

2011 ◽  
Vol 462-463 ◽  
pp. 1194-1199
Author(s):  
Zainudin Kornain ◽  
Azman Jalar ◽  
Rozaidi Rashid ◽  
Shahrum Abdullah
Keyword(s):  
Thermal Expansion ◽  
Flip Chip ◽  
Ball Grid Array ◽  
Process Time ◽  
Curing Process ◽  
Curing Time ◽  
Hold Temperature ◽  
Flip Chip Packaging ◽  
Time Cycle ◽  
The Impact

Underfilling is the vital process to reduce the impact of the thermal stress that results from the mismatch in the co-efficient of thermal expansion (CTE) between the silicon chip and the substrate in Flip Chip Packaging. This paper reported the pattern of underfill’s hardness during curing process for large die Ceramic Flip Chip Ball Grid Array (FC-CBGA). A commercial amine based underfill epoxy was dispensed into HiCTE FC-CBGA and cured in curing oven under a new method of two-step curing profile. Nano-identation test was employed to investigate the hardness of underfill epoxy during curing steps. The result has shown the almost similar hardness of fillet area and centre of the package after cured which presented uniformity of curing states. The total curing time/cycle in production was potentially reduced due to no significant different of hardness after 60 min and 120 min during the period of second hold temperature.

THERMAL INVESTIGATION OF SiO2-Bi2O3 HEAVY METAL GLASSES

2005 ◽  
Vol 19 (20) ◽  
pp. 3293-3299 ◽  
Author(s):  
V. SIMON ◽  
M. TODEA ◽  
S. SIMON
Keyword(s):  
Thermal Analysis ◽  
Heavy Metal ◽  
Differential Thermal Analysis ◽  
Silicon Dioxide ◽  
Melting Temperature ◽  
Structural Relaxation ◽  
Structural Changes ◽  
Glass Stability ◽  
Thermal Investigation ◽  
Metal Glasses

Structural changes induced by temperature rising in binary silico-bismuthate glasses are investigated by differential thermal analysis. Several exothermic peaks are recorded for all samples. Progressive substitution of Bi 2 O 3 by SiO 2 contributes to the structural relaxation of vitreous network and leads to diminishing of the melting temperature, even as SiO 2 content reaches 40 mol%. Glass stability is enhanced by addition of silicon dioxide.

scholarly journals Specific heat, magnetic susceptibility, resistivity and thermal expansion of the superconductorZrB12

2005 ◽  
Vol 72 (2) ◽  
Author(s):  
R. Lortz ◽  
Y. Wang ◽  
S. Abe ◽  
C. Meingast ◽  
Yu. B. Paderno ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Magnetic Susceptibility ◽  
Specific Heat

scholarly journals The effect of temperature and frequency on magnetic properties of the Fe81B13Si4C2 amorphous alloy

2011 ◽  
Vol 43 (2) ◽  
pp. 175-182 ◽  
Author(s):  
S. Djukic ◽  
V. Maricic ◽  
A. Kalezic-Glisovic ◽  
L. Ribic-Zelenovic ◽  
S. Randjic ◽  
...  
Keyword(s):  
Signal Processing ◽  
Magnetic Properties ◽  
Amorphous Alloy ◽  
Frequency Domain ◽  
Magnetic Permeability ◽  
Structural Relaxation ◽  
Substantial Reduction ◽  
Effect Of Temperature ◽  
Influence Of Temperature ◽  
Mean Frequency

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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