Early stages during plasma nitriding of pure iron
- Inst. Tecnologico y de Estudiuos Superiores de Monterrey, Atizapan (Mexico)
The sequence of nitride formation during the early stages of plasma nitriding of pure iron was studied by optical microscopy, SEM, TEM and x-ray diffraction. Plasma nitriding at {approximately}490 C in a 25 vol.%H{sub 2} + 75 vol.%N{sub 2} mixture starts with the formation of {gamma}{prime}-Fe{sub 4}N after 40s. Once {gamma}{prime} nucleates, it mainly spreads laterally due to diffusion shortcuts in the discontinuous surface nitride layer. Before {gamma}{prime} is continuous on the surface, {epsilon} nucleates on top of it shortly after 40S. Epsilon is then observed to grow, both inwardly and laterally along with {gamma}{prime}. A compact {gamma}{prime}/{epsilon} bilayer forms on the surface at around 100s. The kinetics of nucleation, growth and compactation of the nitrides observed in the present work was significantly more rapid than in any of the nitriding process reported in the literature, including plasma nitriding. The acceleration of the nitriding kinetics in the early stages of plasma nitriding may be attributed to enhanced diffusion resulting from a high nitrogen flux from the plasma atmosphere. The results presented are consistent with the findings of a companion work on modeling the kinetics of nitride layer growth.
- OSTI ID:
- 389747
- Report Number(s):
- CONF-951222-; ISBN 0-87170-561-3; TRN: IM9646%%32
- Resource Relation:
- Conference: International conference on carburizing and nitriding with atmospheres, Cleveland, OH (United States), 6-8 Dec 1995; Other Information: PBD: 1995; Related Information: Is Part Of 1995 Carburizing and nitriding with atmospheres: Conference proceedings; Grosch, J. [ed.] [Technical Univ. of Berlin (Germany)]; Morral, J. [ed.] [Univ. of Connecticut, Storrs, CT (United States)]; Schneider, M. [ed.] [Timken Co., Inc., Canton, OH (United States)]; PB: 403 p.
- Country of Publication:
- United States
- Language:
- English
Similar Records
Real-Time Synchrotron X-ray Studies of Low- and High-temperature Nitridation of c-plane Sapphire
Study of microstructure of low-temperature plasma-nitrided AISI 304 stainless steel