Authors: Supriya Kasyap Ashmi T Patel Arun Pratap
Publish Date: 2014/04/16
Volume: 116, Issue: 3, Pages: 1325-1336
Abstract
The study of crystallization kinetics of amorphous alloys has been a matter of great interest for material researchers for past few decades since it provides information about the kinetic parameters ie activation energy of crystallization and the frequency factor These kinetic parameters can be calculated by modelfree isoconversional methods Isoconversional methods allow calculating the activation energy as a function of degree of conversion α Hence these methods provide accurate results for multistep processes like crystallization Modelfree methods are categorized as linear and nonlinear isoconversional methods Linear methods are further classified as linear differential and linear integral isoconversional methods In present work we have used these isoconversional methods to study the effect of nonlinear heating rate employed by modulated differential scanning calorimetry MDSC on the nonisothermal crystallization kinetics of Ti20Zr20Cu60 metallic glass For Ti20Zr20Cu60 MDSC curves clearly indicate a twostep crystallization process Both crystallization peaks were studied based on the modified expressions for isoconversional methods by nonlinear heating rate The term corresponding to nonlinearity comes out to be A T ω/2β2 The effect of nonlinear heating rate on measurement of kinetic parameters by isoconversional methods is studied The activation energy of crystallization is calculated for Ti20Zr20Cu60 metallic glass for various degrees of conversion by linear integral isoconversional methods ie Ozawa–Flynn–Wall Kissinger–Akahira–Sunose and also with Friedman method which is a linear differential isoconversional methodThe authors want to thank Institute of Material Research Tohoku University Sendai Japan for providing the sample Sincere thanks are due to Dr K N Lad for useful discussions The authors are thankful to IUC for DAE Facility at Indore for providing modulated DSC equipment to carry out this work One of the authors Supriya Kasyap is grateful to the Department of Science and Technology DST Government of India for providing financial assistance under the DSTPURSE Fellowship Scheme
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