Permeation of nitrogen in solid nickel and deformation phenomena accompanying internal nitridation

Journal Article · Wed Sep 08 04:00:00 EDT 1999 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(99)00194-9· OSTI ID:684377

Kodentsov, A A; Van Dal, M J.H.; Cserhati, C; Van Loo, F J.J. ^[1]; Daroczi, L ^[2]

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1. Eindhoven Univ. of Technology (Netherlands). Lab. of Solid State and Materials Chemistry
2. Kossuth Lajos Univ., Debrecen (Hungary). Dept. of Solid State Physics

Internal nitridation of Ni alloys containing 5 at.% Cr or 1.5 at.% Ti was studied over the range of 600--700 C in a flowing NH{sub 3} + H{sub 2}-gas mixture. Growth rate of the nitrided zone was found to obey a parabolic law and the nitrogen uptake by the sample is controlled by the nitrogen diffusion in the metal. It was demonstrated that under the experimental conditions used, a classical Wagner`s treatment of the internal precipitation can be applied to describe the nitridation kinetics and obtain permeability constants. Permeability of nickel for nitrogen at the standard pressure of 1 bar was determined to be: N{sub N}{sup {Theta}}{center_dot}D{sub N} = 3.1 {times} 10{sup {minus}11}exp({minus}17,500/T) [m{sup 2}/s]. A volume change associated with the precipitation reaction resulted in a stress gradient between the alloy`s surface and the internal nitridation front. It was observed that stress relief occurred mainly by transport of nickel (solvent metal) to the gas/metal interface. Pipe diffusion-controlled creep was shown to be the dominant stress accommodation mechanism. This mechanism is prevailing because of a large dislocation density generated in the Ni matrix upon the internal precipitation of the semi-coherent nitride particles.

• OSTI ID: 684377
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 11 Vol. 47; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMMONIA
ATOM TRANSPORT
DEFORMATION
DISLOCATIONS
HYDROGEN
KINETICS
NICKEL ALLOYS
NITRIDATION
PRECIPITATION
TEMPERATURE RANGE 0400-1000 K