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Thermodynamics of Congruent Oxidation

Jacob, KT and Adharsh, R (2012) Thermodynamics of Congruent Oxidation. In: HIGH TEMPERATURE MATERIALS AND PROCESSES, 31 (4-5). pp. 395-403.

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Official URL: http://dx.doi.org/10.1515/htmp-2012-0072

Abstract

Congruent oxidation occurs when an alloy oxidizes at constant oxygen chemical potential and temperature to an oxide in which the ratio of metallic components is the same as in the alloy. In alloys that undergo congruent oxidation concentration gradients near the surface are minimized. In this work thermodynamic conditions for congruent oxidation of binary and ternary alloys are formulated using the regular solution model to describe thermodynamic mixing properties. The conditions under which congruent oxidation can occur are identified. Congruent oxidation of a binary alloy X-Y will occur only if difference in oxygen potential for the oxidation of the two pure metals is less than twice the difference in regular solution parameters for the oxide and alloy phases (Omega(O)-Omega(A)). In the case of ternary alloys, congruency requirements for both two-phase and three-phase equilibria are discussed. Since the conditions for congruent oxidation of ternary alloy X-Y-Z depends on many parameters, the effect of systematic variation of the binary sets of regular solution parameters on the congruent composition is explored by numerical solution of the governing equations.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to WALTER DE GRUYTER & CO, GERMANY
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Depositing User: Francis Jayakanth
Date Deposited: 21 Dec 2012 03:42
Last Modified: 21 Dec 2012 03:42
URI: http://eprints.iisc.ac.in/id/eprint/45490

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