Solubility in Austenite of Carbon from Carbon and of Carbon from Iron-Carbide

Authors

H. L. MaxwellFollow
Anson HayesFollow

Document Type

Research

Abstract

For the well-established equilibria: (1) Fe₃C+CO₂ ⇔ 3Fe+2CO + Δ H₁ (2) C + CO₂ ⇔ 2CO + Δ H₂ (3) [C]₁ + CO₂ ⇔ 2CO (4) [C]₂ + CO₂ ⇔ 2CO (5) [C] + CO₂ ⇔ 2CO

Where [C] = concentration of dissolved carbon in austenite, [C]₁ = saturated value of carbon from carbon, [C]₂= saturated value of carbon from iron carbide, and K₁, K₂, K₃... are the gaseous equilibrium constants for these reactions. Thermodynamics demands K₂ = K₄, K₂ = K₃ and that K₅ is a function of the concentration of carbon in austenite. Since iron-carbon alloys graphitize down to some 0.9% combined carbon or less, Fe₃C is metastable with respect to carbon from 720° to 1130°C. Since the heat of formation of Fe₃C is -15100 calories, it follows from the equation (d/dT) (Log K) = ΔH/RT² and from the metastability of Fe₃C that the carbon solubility line of the iron-carbon diagram lies to the left of the cementite solubility line and has a greater slope.

Publication Date

1924

Journal Title

Proceedings of the Iowa Academy of Science

Volume

31

Issue

1

First Page

284

Last Page

284

Copyright

©1924 Iowa Academy of Science, Inc.

Language

en

File Format

application/pdf

Recommended Citation

Maxwell, H. L. and Hayes, Anson (1924) "Solubility in Austenite of Carbon from Carbon and of Carbon from Iron-Carbide," Proceedings of the Iowa Academy of Science, 31(1), 284-284.
Available at: https://scholarworks.uni.edu/pias/vol31/iss1/73