scholarly journals Non-Isothermal Crystallization Kinetics of Co67Fe4Cr7Si8B14 Amorphous Alloy

2012 ◽  
Vol 706-709 ◽  
pp. 1311-1317 ◽  
Author(s):  
S.A. Hasheminezhad ◽  
M. Haddad-Sabzevar ◽  
S. Sahebian
Keyword(s):  
Activation Energy ◽  
Amorphous Alloy ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Frequency Factor ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Kinetics Parameters ◽  
Isothermal Crystallization Kinetics ◽  
Kinetics Of

Non-isothermal crystallization kinetics of Co67Fe4Cr7Si8B14amorphous ribbons was studied by differential scanning calorimetry (DSC) technique under 10, 20, 30, 40 and 80 °Cmin-1heating rates. It is found that Co67Fe4Cr7Si8B14amorphous alloy exhibits two-stage crystallization on heating. The two crystallization peaks shift to higher temperatures with increasing heating rate. The apparent activation energies (EC) for the first stage of crystallization were determined as 443.44 and 434.47 kJmol-1by using the Kissinger and Ozawa equations, respectively. Frequency factor (A) estimated to be 1.084×1026s-1using Kissinger equation. Kinetics parameters such as Crystallization exponent (n) and dimensionality of growth (Ndim) were determined using JMA (Johnson-Mehl-Avrami) method. Details of the nucleation and growth behaviours during the non-isothermal crystallization were studied in terms of local activation energy EC(x) by the OFW (Ozawa, Flynn and Wall) method. Also the activation energy for nucleation (En) and growth (Eg) separately estimated.

Non-Isothermal Crystallization Kinetics of Mg61Zn35Ca4 Glassy Alloy

2017 ◽  
Vol 898 ◽  
pp. 657-665
Author(s):  
Dao Zhang ◽  
Wang Shu Lu ◽  
Xiao Yan Wang ◽  
Sen Yang
Keyword(s):  
Activation Energy ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Melt Spinning ◽  
Glassy Alloy ◽  
Heating Rates ◽  
Isothermal Crystallization Kinetics ◽  
Complex Process ◽  
Activation Energy Of Crystallization ◽  
Kinetics Of

The non-isothermal crystallization kinetics of Mg61Zn35Ca4 glassy alloy prepared via melt-spinning were studied by using isoconversion method. The crystalline characterization of Mg61Zn35Ca4 was examined by X-ray diffraction. Different scanning calorimeter was used to investigate the non-isothermal crystallization kinetics at different heating rates (3-60 K/min). The calculated value of Avrami exponent obtained by Matusita method indicated that the crystalline transformation for Mg61Zn35Ca4 is a complex process of nucleation and growth. The Kissinger-Akahira-Sunose method was used to investigate the activation energy. The activation energy of crystallization varies with the extent of crystallization and hence with temperature. The Sestak-Berggren model was used to describe the non-isothermal crystallization kinetics.

Effect of Hyperbranched Polymer on Crystallization Kinetics of Isotactic Polypropylene

2012 ◽  
Vol 535-537 ◽  
pp. 1142-1145
Author(s):  
Guang Tian Liu ◽  
Jing Lei
Keyword(s):  
Activation Energy ◽  
Crystallization Kinetics ◽  
Isotactic Polypropylene ◽  
Isothermal Crystallization ◽  
Hyperbranched Polymer ◽  
Crystallization Rate ◽  
Crystallization Activation Energy ◽  
Scanning Calorimetry ◽  
Isothermal Crystallization Kinetics ◽  
Kinetics Of

In this paper, the isothermal crystallization kinetics of isotactic polypropylene (iPP) and iPP with 5% hyperbranched polymer (HBP) added had been investigated by differential scanning calorimetry (DSC). The results show that a small addition of HBP affects the crystallization behavior of iPP. During isothermal crystallization, the crystallization rate of the blend is higher than those of iPP remarkably. An increase in the Avrami exponent may be attributed to the fractal structure of hyperbranched polymer. The crystallization activation energy is estimated by the Friedman equation, the results show that the activation energy decreases remarkably by addition of HBP and the crystallization rate of the blend is more sensitive to temperature than that of iPP.

Study of the crystallization kinetics of a Zr57Cu15.4Ni12.6Al10Nb5 amorphous alloy

2020 ◽  
Vol 111 (10) ◽  
pp. 849-856
Author(s):  
Hui E. Hu ◽  
Zhou Lu ◽  
Xiao Hong Su ◽  
Jing Xin Deng
Keyword(s):  
Amorphous Alloy ◽  
Crystallization Kinetics ◽  
Nucleation Rate ◽  
Isothermal Crystallization ◽  
Growth Process ◽  
Exothermic Peak ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Isothermal Crystallization Kinetics ◽  
Diffusion Controlled

Abstract The non-isothermal crystallization kinetics with heating rates ranging from 10 K s-1to 80 K s-1and the isothermal crystallization kinetics during annealing from the glass transition temperature to the crystallization onset temperature of a Zr57Cu15.4Ni12.6Al10Nb5 amorphous alloy were studied in detail using X-ray diffraction and differential scanning calorimetry. During non-isothermal crystallization, it is more difficult to nucleate than to grow, and the crystallization resistance increases first and then decreases. During isothermal crystallization of the alloy from 713- 728 K, there are two exothermic peaks corresponding to a diffusion-controlled growth process with decreasing nucleation rate and increasing nucleation rate. From 733- 748 K, only one exothermic peak appears, and the growth process is controlled by the interface with decreasing nucleation rate. Isothermal crystallization is a process in which the crystallization resistance increases. The resistance of isothermal crystallization is less than that of non-isothermal crystallization.

scholarly journals Thermal Properties and Non-Isothermal Crystallization Kinetics of Poly (δ-Valerolactone) and Poly (δ-Valerolactone)/Titanium Dioxide Nanocomposites

Crystals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 452 ◽  
Author(s):  
Waseem Saeed ◽  
Abdel-Basit Al-Odayni ◽  
Abdulaziz Alghamdi ◽  
Ali Alrahlah ◽  
Taieb Aouak
Keyword(s):  
Titanium Dioxide ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Three Dimensional ◽  
Degree Of Crystallinity ◽  
Simultaneous Occurrence ◽  
Scanning Calorimetry ◽  
Isothermal Crystallization Kinetics ◽  
The Stability ◽  
Kinetics Of

New poly (δ-valerolactone)/titanium dioxide (PDVL/TiO2) nanocomposites with different TiO2 nanoparticle loadings were prepared by the solvent-casting method and characterized by Fourier transform infra-red, differential scanning calorimetry, X-ray diffraction and scanning electron microscopy, and thermogravimetry analyses. The results obtained reveal good dispersion of TiO2 nanoparticles in the polymer matrix and non-formation of new crystalline structures indicating the stability of the crystallinity of TiO2 in the composite. A significant increase in the degree of crystallinity was observed with increasing TiO2 content. The non-isothermal crystallization kinetics of the PDVL/TiO2 system indicate that the crystallization process involves the simultaneous occurrence of two- and three-dimensional spherulitic growths. The thermal degradation analysis of this nanocomposite reveals a significant improvement in the thermal stability with increasing TiO2 loading.

Morphology, Crystalline Structure and Isothermal Crystallization Kinetics of Polybutylene Terephthalate/Montmorillonite Nanocomposites

2005 ◽  
Vol 13 (1) ◽  
pp. 61-71 ◽  
Author(s):  
Defeng Wu ◽  
Chixing Zhou ◽  
Xie Fan ◽  
Dalian Mao ◽  
Zhang Bian
Keyword(s):  
Activation Energy ◽  
Crystallization Kinetics ◽  
Crystallization Temperature ◽  
Isothermal Crystallization ◽  
Polymer Chains ◽  
Isothermal Crystallization Kinetics ◽  
Clay Particles ◽  
Nucleation Sites ◽  
Kinetics Of ◽  
Montmorillonite Nanocomposites

The melt intercalation method was employed to prepare poly(butylene terepathalate)/montmorillonite nanocomposites, and their microstructure was characterized by wide angle X-ray diffraction and transmission electron microscopy. The XRD results showed that the crystalline plane such as (010), (111), (100) was smaller than that of pristine PBT, which indicates that the crystallite size of PBT in the nanocomposites could be diminished by adding clay. Moreover, the isothermal crystallization kinetics of PBT and PBT/MMT nanocomposites was investigated by differential scanning calorimetry (DSC). During isothermal crystallization, the development of crystallinity with time was analysed by the Avrami equation. The results show that very small amounts of clay dramatically increased the rate of crystallization and high clay concentrations reduced the rate of crystallization at the low crystallization temperatures. At low concentrations of clay, the distance between dispersed platelets was large so it was relatively easy for the additional nucleation sites to incorporate surrounding polymer, and the crystal nucleus was formatted easily. However, at high concentrations of clay, the diffusion of polymer chains to the growing crystallites was hindered by large clay particles, despite the formation of additional nucleation sites by the clay layers. At the higher crystallization temperature, the crystallization of the nanocomposites was slower than that of the pure PBT under the experimental conditions, which means that with the increase in chains mobility at the high crystallization temperature, the crystal nuclei are harder to format, and the hindering effect of clay particles on the polymer chains was stronger than the nucleating effect of the layers. In addition, the activation energies of crystallization for PBT and its nanocomposites were calculated by the Arrhenius relationship, and the results showed that the nanocomposites with a low clay content had the lower activation energy values than PBT, while high amounts of clay increased the activation energy of PBT.

Non-isothermal crystallization kinetics of FeZrB amorphous alloy

2011 ◽  
Vol 522 (1-2) ◽  
pp. 166-172 ◽  
Author(s):  
L.H. Kong ◽  
Y.L. Gao ◽  
T.T. Song ◽  
G. Wang ◽  
Q.J. Zhai
Keyword(s):  
Amorphous Alloy ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Isothermal Crystallization Kinetics ◽  
Kinetics Of

Crystallization kinetics of amorphous Ga–Sb–Te chalcogenide films: Part I. Nonisothermal studies by differential scanning calorimetry

2004 ◽  
Vol 19 (10) ◽  
pp. 2929-2937 ◽  
Author(s):  
Chain-Ming Lee ◽  
Yeong-Iuan Lin ◽  
Tsung-Shune Chin
Keyword(s):  
Activation Energy ◽  
Differential Scanning Calorimetry ◽  
Crystallization Kinetics ◽  
Crystallization Temperature ◽  
Ternary Phase Diagram ◽  
Film Deposition ◽  
Rate Dependency ◽  
Scanning Calorimetry ◽  
Kinetics Parameters ◽  
Kinetics Of

Nonisothermal crystallization kinetics of amorphous chalcogenide Ga–Sb–Te films with compositions along the pseudo-binary tie-lines connecting Sb7Te3−GaSb and Sb2Te3–GaSb of the ternary phase diagram were investigated by means of differential scanning calorimetry. Powder samples were prepared firstly by film deposition using a co-sputtering method; the films were then stripped from the substrate. The activation energy (Ea) and rate factor (Ko) were evaluated from the heating rate dependency of the crystallization temperature using the Kissinger method. The kinetic exponent (n) was deduced from the exothermic peak integrals using the Ozawa method. The crystallization temperature (Tx = 181 to 327 °C) and activation energy (Ea= 2.8 to 6.5 eV) increased monotonically with increasing GaSb content and reached a maximum value in compositions located at the vicinity of GaSb. The kinetic exponent is temperature dependent and shows higher values in the SbTe-rich compositions. Promising media compositions worthy of further studies were identified through the determined kinetics parameters.

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