Low-temperature extension of the lehrer diagram and the iron-nitrogen phase diagram
- Cite this article as:
- van Voorthuysen, E.H.D.M., Boerma, D.O. & Chechenin, N.C. Metall and Mat Trans A (2002) 33: 2593. doi:10.1007/s11661-002-0380-2
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Iron layers are nitrided in mixtures of ammonia and hydrogen at low temperatures, using a thin nickel caplayer as a catalyst. In the coordinate field of inverse temperature vs nitriding potential, we determined the boundaries between areas in which the α, γ′, or ε phases are in thermal equilibrium. Using these data, the Fe-N phase diagram is extended from 350 °C to 240 °C and extrapolated down to 200 °C. The α, γ′, and ε phases probably coexist in a triple point in the Lehrer diagram around 214 °C.