Structure of Al–Ni intermetallic composite layers produced on the Inconel 600 by the glow discharge enhanced-PACVD method

The Plasma Assisted Chemical Vapor Deposition (PACVD) treatment conducted under glow discharge conditions in an atmosphere of trimethylaluminum vapors applied to an Inconel 600 substrate yielded composite surface layers built of intermetallic phases of the Al–Ni system with the outer zone composed of aluminum oxides. Such layers have very advantageous performance properties, such as high hardness, good corrosion and frictional wear resistance and, good adherence to the substrate.The present study is dedicated to microstructure characterization of the layers. The layers were examined using a variety of methods. Based on the results of these examinations, the microstructure of the composite layers was described as a multizone one with an outer Al2O3 zone, an intermediate AlNi3 + Al2O3 zone and a diffusion zone of type Ni(Al,Cr,Fe) + AlNi3 + Cr7C3. The mechanism of layer formation as well as the correlation between the microstructure and the observed improvement of the surface properties of the Inconel 600 alloy are discussed.