Influence of nitrogen implantation on the high temperature oxidation of titanium-base alloys

Nitriding is one of the important surface modifications used to enhance corrosion resistance of materials in addition to improving wear resistance due to high hardness of the nitrided surface. However, its effect depends not only on the nature of the materials but also on the treating and environmental conditions. In the present investigation, the influence of nitrogen implantation on the high temperature oxidation of titanium-base alloys, IMI 834, Ti–Al–Nb and Ti–Al–Nb–Mo, has been studied at 800 and 900 °C. Nitriding enhances the oxidation resistance of titanium-base alloys. However, the influence of nitriding is found to depend on the nature and concentration of alloying elements present in the titanium-base alloys. It is also found that the nitriding effect is fluence and temperature dependent. The oxidation resistance of all the titanium-base alloys was enhanced considerably for the initial 20 h. After prolonged exposure, the effect of nitriding was nullified in the case of IMI 834, had no effect on TiAlNb and a significant effect on TiAlNbMo. XRD was used to identify the phases, and SEM and EDS to study the morphology of oxides scales and their compositions formed during high temperature exposure. Metallography and EPMA were used to study the cross sections and elemental distribution after oxidation.