Abstract
Ti-Al films with various compositions were prepared by the ion plating method. Compositions of the films were controlled by selecting the experimental conditions of ion plating. The properties of films, such as the homogeneity of composition, structural phases and microhardness, were investigated by Auger electron spectroscopy, X-ray diffraction and hardness measurements.
It was found that the hardness of the as-deposited films showed a maximum at the stoichiometric composition of 50 at%Al and its composition dependence was similar to that of a rapidly solidificated bulk alloy. The films were implanted with 150 keV nitrogen ion N2+ at room temperature to doses from 2×1021 to 1.7×1022 ions/m2. After the nitrogen ion implantation the hardness of the films increased about 2-3 times that of the unimplanted state and its composition dependence changed to exhibit a minimum at the stoichiometric composition of 50 at%Al. The maximum concentration of implanted nitrogen in the Ti-rich films reached about 50 at%, and decreased to 30% for the Al-rich films. In the nitrogen implanted films, nitrides such as AlN and Ti2N were formed and neither TiN nor Ti2AlN were observed. Corrosion resistance of the films was improved markedly by a nitrogen dose of more than 2×1021 ions/m2.
