Microstructure of plasma nitrided layers on aluminium

Plasma immersion ion implantation (PI3) treatment was performed on aluminium for surface nitriding. Glow discharge optical spectroscopy (GDOS) was used to estimate the penetration depth of nitrogen. Transmission electron microscopy (TEM) was used to reveal the structure and composition of nitrided layers and that of the interface. The microstructural analysis was performed using thin foils from the cross-sections of nitrided samples. The crystallographic phases were identified by electron diffraction. It is shown that the formation of AlN is strongly correlated to the plasma treatment parameters. The structure of the surface layers and the substrate material beneath the interface depends on the plasma treatment conditions: treatment time, energy and accelerating voltage.