The formation of a solid solution band at the surface of Ti(CN)-based cermets

Ti(CN), a well-known substrate material for cutting tool applications, provides attractive mechanical properties, including excellent strength, hardness, and high temperature stability. Experiments were carried out in order to elucidate the influence of secondary carbides and a variety of atmospheric conditions on the formation of the solid solution band. TaC and WC were used as additives to a Ti(CN)–Ni–Co system, and were processed in vacuum, various nitrogen pressures(2–200 Torr) and in carbon atmosphere. It was found that the addition of TaC facilitated band formation while the WC-containing system served to retard band formation. Of various processing atmospheres, vacuum conditions were the most effective in producing the band by permitting the ready dissolution of Ti(CN) near the sample surface.