Characteristics of material surfaces modified using plasma-enhanced ion beams

Plasma-enhanced ion beams are used for the surface modification of carbon steel, stainless steel, and Al alloys samples. The morphology and the microstructure of the treated surfaces of the samples is examined with an optical microscope and a scanning electron microscope. Microhardness is measured on both the treated surfaces as well as the cross-sections. Indications are that during the ion bombardment craters are formed and surface melting is produced on the sample surfaces. The effect of the ion bombardment is limited to the surface layer of the samples. The density, size and distribution of the craters formed on the irradiated surfaces are related to the current density and the ion energy. Larger sized craters tend to be associated with higher ion beam energies. For the ion beam energies used in this study, there is a threshold current density for crater formation and surface melting. Some possible mechanisms for the crater formation and effects of the ion beam parameters are discussed.