Vanadium nitride precipitate phase in a 9% chromium steel for nuclear power plant applications

• Published in: Journal of nuclear materials Vol. 374; no. 3; pp. 403 - 412
• Main Authors: Shen, Y.Z., Kim, S.H., Han, C.H., Cho, H.D., Ryu, W.S., Lee, C.B.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-03-2008; Elsevier
• Subjects: Applied sciences; Controled nuclear fusion plants; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; Fuels; Installations for energy generation and conversion: thermal and electrical energy; Nuclear fuels; 75.50.Bb; Nitrides; Air cooling; Nuclear power plant; Vanadium; Chromium; X ray; Steel; Lattice parameters; Nuclear reactor; Crystalline structure
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2007.09.055

Vanadium nitride precipitate phase in a 9% Cr steel was observed and analyzed using transmission electron microscopy and energy dispersive spectroscopy. The steel samples were normalized at 1050 and 1100°C for 1h and then tempered at 750°C for 30min to 5h followed by an air cooling. Through the microdiffraction pattern analyses and energy dispersive X-ray data, two kinds of vanadium nitride precipitates were determined to be (V0.6Nb0.2Cr0.2)N and (V0.45Nb0.45Cr0.1)N with the same fcc crystal structure and different lattice parameters ā=4.070 and 4.232Å, respectively. Lattice parameters estimated for the precipitates regarding the VN phase agree well with the present data from the microdiffraction patterns, indicating that the precipitates do not belong to the VC phase. Observed (V0.45Nb0.45Cr0.1)N precipitates consisted of undissolved particles remaining after a normalizing and the particles newly precipitated during a tempering, whilst, the observed (V0.6Nb0.2Cr0.2)N precipitates were formed during a tempering. These two vanadium nitrides seem to be a stable phase, and not an intermediary phase.