On the applicability of isoconversion methods for obtaining the activation energy of reactions with temperature-dependent equilibrium state


Starink, M.J. (1997) On the applicability of isoconversion methods for obtaining the activation energy of reactions with temperature-dependent equilibrium state. Journal of Materials Science, 32, (24), 6505-6512. (doi:10.1023/A:1018655026036).

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Description/Abstract

When the equilibrium state of a reaction depends on the temperature, isoconversion methods for calculating activation energies are no longer valid. In these cases (apparent) activation energies obtained from isoconversion methods vary with temperature and fraction transformed, even if the true activation energy of the thermally activated process is constant. Expressions that describe the influences of the reaction parameters and the equilibrium state on the apparent activation energy are derived. A new method of extrapolating apparent activation energies is introduced that allows the determination of the true activation energy. Verification of this extrapolation method using precipitation in an Al–1 at % Si alloy shows a good correspondence between experiment and calculations. For the Al–1 a t% Si alloy the apparent activation energy can deviate by 30% from the true activation energy of the reaction.

Note: See www.eprints.soton.ac.uk/18822/ for improved analysis.

Item Type: Article
Digital Object Identifier (DOI): doi:10.1023/A:1018655026036
ISSNs: 0022-2461 (print)
Subjects: Q Science > QC Physics
T Technology > TA Engineering (General). Civil engineering (General)
Divisions : University Structure - Pre August 2011 > School of Engineering Sciences
ePrint ID: 21704
Accepted Date and Publication Date:
Status
1 December 1997Published
Date Deposited: 31 Jan 2007
Last Modified: 31 Mar 2016 11:40
URI: http://eprints.soton.ac.uk/id/eprint/21704

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