Plasma assisted nitriding of Inconel 690

Inconel 690 is a nickel base alloy with a broad range of application such as nuclear reactor technology. A low temperature plasma assisted nitriding treatment is expected to improve the tribological properties without changing the corrosion resistance of this alloy. The nitrided case is constituted of two or three distinct layers depending on the plasma reactivity. These layers are, respectively, associated to three different metastable f.c.c. nitrogen solid solutions denoted γN1, γN2 and γN3. A parabolic rate constant and an apparent action energy are determined and compared to other values taken from the literature. Dislocation and stacking fault generated in the nitrided layer are expected to play a key role in the nitriding mechanisms of Inconel 690.