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BY-NC-ND 3.0 license Open Access Published by De Gruyter November 23, 2012

Thermodynamics of Congruent Oxidation

  • K.T. Jacob EMAIL logo and R. Adharsh


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 (Ω0 − ΩA). 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.

Department of Materials Engineering, Indian Institute of Science, Bangalore 560012, India

Received: 2012-04-12
Accepted: 2012-07-09
Published Online: 2012-11-23
Published in Print: 2012-10-30

©[2012] by Walter de Gruyter Berlin Boston

This article is distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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