Reactive magnetron sputtering of Inconel 690 by Ar–N2 plasma

M and M–N coatings, where M is nearly the metal composition of Inconel 690 (57 at.% Ni, 32 at.% Cr, 9.5 at.% Fe…) were sputter-deposited on glass and steel substrates in pure argon and in Ar–N2 mixtures using a round planar magnetron. The influence of nitrogen gas flow rate inlet in argon on chemical composition and microstructure was studied. The as-deposited (T < 100 °C) M–N films containing up to 30 at.% nitrogen are a nanocrystalline supersaturated face cubic centered (fcc) solid solution (γN). The pure metallic films have a pronounced<111>fcc crystallographic texture, while the M–N films exhibit a strong<100>fcc crystallographic texture. The effect of temperature on the microstructure of M–N films was studied by increasing the substrate temperature during preparation and by tempering of an as-deposited M–N films. For M–N films prepared at 400 °C, the X-ray diffraction analysis reveals a magnetic γ phase with a very low nitrogen content, while electron probe microanalysis gives an overall high nitrogen content in the layer (up to 25 at.%). It is concluded that the layers consist of two phases when prepared or tempered at high temperature (T > 400 °C): an fcc CrN nitride and a γ (Ni,Fe,Cr) depleted in nitrogen.