Calorimetric study of β-relaxation in an amorphous alloy: An experimental technique for measuring the activation energy for shear transformation

2014 ◽  
Vol 44 ◽  
pp. 116-120 ◽  
Author(s):  
Jae-Chul Lee
Keyword(s):  
Activation Energy ◽  
Amorphous Alloy ◽  
Experimental Technique ◽  
Calorimetric Study ◽  
Shear Transformation ◽  
Β Relaxation

Non—Isothermal Differential Scanning Calorimetry Studies on Nanocrystallization Kinetics of Fe81Si3.5B13.5C2 Amorphous Alloy

2011 ◽  
Vol 688 ◽  
pp. 180-185
Author(s):  
Yu Zhang ◽  
Wei Lu ◽  
Biao Yan ◽  
Yu Xin Wang ◽  
Ying Yang
Keyword(s):  
Activation Energy ◽  
Differential Scanning Calorimetry ◽  
Amorphous Alloy ◽  
Three Dimensional ◽  
Crystallization Mechanism ◽  
Scanning Calorimetry ◽  
Average Value ◽  
Initial Stage ◽  
Friedman Method ◽  
Kinetics Of

The nanocrystallization kinetics of the Fe81Si3.5B13.5C2amorphous alloy was investigated by differential scanning calorimetry (DSC). The apparent activation energy Ea, as well as the nucleation and growth kinetic parameters has been calculated by Kissinger and Ozawa methods. The changeable activation energy Eawith crystalline fraction α was obtained by the expended Friedman method without assuming the kinetic model function, and the average value of Eawas 364±20 kJ/mol. It was shown that the crystallization mechanism of initial stage (0<α<0.7) of the transformation was bulk crystallization with two and three dimensional nucleation graining growth which was controlled by diffusion. For the middle stage (0.7<α<0.9), the crystallization mechanism is surface crystallization with one dimensional nucleation graining growth at a near-zero nucleation rate. In the final stage(α>0.9)，the local Avrami exponents rose anomalously from 1.4 to about 2.0.

Ti50Fe25Ni25 Amorphous Alloy Prepared by Mechanical Alloying

2011 ◽  
Vol 327 ◽  
pp. 76-80
Author(s):  
Yu Ying Zhu ◽  
Qiang Li ◽  
Yun Hua He ◽  
Ge Wang ◽  
Xing Hua Wang
Keyword(s):  
Activation Energy ◽  
Amorphous Alloy ◽  
Mechanical Alloying ◽  
High Energy ◽  
Structural Features ◽  
Liquid Region ◽  
X Ray Diffraction ◽  
Crystallization Peak ◽  
Activation Energy Of Crystallization ◽  
Amorphous Alloy Powder

A new ternary Ti-based amorphous alloy, Ti50Fe25Ni25, is prepared by the mechanical alloying. The milling is performed in a high-energy planetary ball mill under argon atmosphere. Fully Ti50Fe25Ni25amorphous alloy powder is obtained after milled 160h. The milling speed is 300rpm and the weighs ratio of ball to powder is 10:1. The structural features are studied by X-ray diffraction and field emission scanning electron microscope, and the thermal stability is investigated by a differential scanning calorimeter. The super-cooled liquid region of the amorphous alloy increases from 98K to 119K as the heating rate increasing from 10K/min to 40K/min. The effective activation energy of crystallization is estimated with modified Kissinger’s plot. The initial crystallization activation energyEx1and the first crystallization peakEp1are 155.9KJ/mol and 188.5KJ/mol, respectively.

scholarly journals Accuracy in the experimental calorimetric study of the crystallization kinetics and predictive transformation diagrams: Application to a Ga–Te amorphous alloy

1998 ◽  
Vol 13 (3) ◽  
pp. 744-753 ◽  
Author(s):  
N. Clavaguera ◽  
M. T. Clavaguera-Mora ◽  
M. Fontana
Keyword(s):  
Amorphous Alloy ◽  
Primary Crystallization ◽  
Continuous Heating ◽  
Differential Scanning Calorimetric ◽  
Nominal Composition ◽  
Base Line ◽  
Calorimetric Study ◽  
Calorimetric Data ◽  
Scanning Calorimetry ◽  
Transformation Diagrams

The uncertainties inherent to experimental differential scanning calorimetric data are evaluated. A new procedure is developed to perform the kinetic analysis of continuous heating calorimetric data when the heat capacity of the sample changes during the crystallization. The accuracy of isothermal calorimetric data is analyzed in terms of the peak-to-peak noise of the calorimetric signal and base line drift typical of differential scanning calorimetry equipment. Their influence in the evaluation of the kinetic parameter is discussed. An empirical construction of the time-temperature and temperature-heating rate transformation diagrams, grounded on the kinetic parameters, is presented. The method is applied to the kinetic study of the primary crystallization of Te in an amorphous alloy of nominal composition Ga20Te80, obtained by rapid solidification.

The activation energy and kinetic of the nanocrystallization process of Al 85 Ni 9 Nd 4 Co 2 amorphous alloy

2009 ◽  
Author(s):  
V.A. Serban ◽  
C. Codrean ◽  
C. Opris ◽  
D. Utu ◽  
M. Lita
Keyword(s):  
Activation Energy ◽  
Amorphous Alloy

Kinetics Study on Non-Isothermal Crystallization of Amorphous Alloy Mg65Cu15Ag10Y10

2011 ◽  
Vol 413 ◽  
pp. 432-438
Author(s):  
Xiao Jun Wang ◽  
Tian Dong Xia ◽  
Xue Ding Chen
Keyword(s):  
Activation Energy ◽  
Amorphous Alloy ◽  
Heating Rate ◽  
Volume Fraction ◽  
Strong Dependence ◽  
Continuous Heating ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Local Activation ◽  
Local Activation Energy

The crystallization kinetics of amorphous alloy Mg65Cu15Ag10Y10has been studied by differential scanning calorimetry in the mode of continuous heating annealing. It is found that both DSC curves and activation energy show a strong dependence on the heating rate. The activation energy for crystallization are determined as 186.1 and 184.4 KJ mol−1for the heating rates β=5-20 Kmin−1, and 107.5 and 110.0 KJmol−1for the heating rates β=20-80Kmin−1, when using the Kissinger equation and the Ozawa equation, respectively. Local activation energy at any volume fraction crystallized was obtained by the general Ozawa's isoconversional method. The average value of local activation energy for heating rates ranging from 5 to 20Kmin−1is 180.9 KJ mol−1and for heating rates ranging between 20 and 80Kmin−1is 110.2 KJ mol−1. Using the Suriñach curve fitting procedure, the kinetics mode was specified. The JMA kinetics is manifested as a rule in the early stages of the crystallization. The JMA exponent,n, initially being larger than 4 and continuously decreases to about 2 along with the development of crystallization. The NGG-like mode dominates in the advanced stages of the transformation. These two modes are mutually independent. The proportion between the JMA-like and the NGG-like modes is related to the heating rate.

A correlation method for determination of crystallization mechanism and activation energy of amorphous alloy

1998 ◽  
Vol 29 (1) ◽  
pp. 149-151 ◽  
Author(s):  
Dejiu Shen ◽  
Yulin Wang ◽  
Guanzhong Xing ◽  
Liyang Li ◽  
Zhongyi Shen
Keyword(s):  
Activation Energy ◽  
Amorphous Alloy ◽  
Correlation Method ◽  
Crystallization Mechanism
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