Permeation of nitrogen in solid nickel and deformation phenomena accompanying internal nitridation
- Eindhoven Univ. of Technology (Netherlands). Lab. of Solid State and Materials Chemistry
- 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, Vol. 47, Issue 11; Other Information: PBD: 8 Sep 1999
- Country of Publication:
- United States
- Language:
- English
Similar Records
Internal nitridation of nickel-base alloys. Part 1: Behavior of binary and ternary alloys of the Ni-Cr-Al-Ti system
Internal-nitriding behavior of Ni-V and Ni-3Nb alloys