Structure of improved tribological properties of V–5at.%Ti alloys by nitrogen implantation at low energy

The aim of the present work was to study the morphological, structural, and chemical analysis as a function of depth in vanadium alloys with a 5 at.% of titanium implanted at 673 K with 1.2 keV N+ ions, by transmission electron microscopy (TEM), glow discharge (GD) analysis, and x-ray photoemission spectroscopy. These results are correlated with those of previously published nanoindentation tests, and the species and chemical states responsible for the increase in hardness are identified. The maximum increase in hardness corresponds to the highest N concentration, measured by both photoemission spectroscopy and GD. In addition, the thickness of the layer (≈1000 nm), where structural modifications are observed using TEM, can also be directly correlated with the thickness of the implanted layer, where an incremental increase in hardness has previously been measured. These findings support the conclusion that the formation of vanadium and titanium nitride/oxynitrides (–N–O,–O–N–H) compounds are responsible for the increased hardness of these V–5at.% Ti samples implanted with N at low ion energy and high sample temperature.