MICROSTRUCTURES OF TIN AND TI2N DEPOSITS PREPARED BY ACTIVATED REACTIVE EVAPORATION

Titanium nitride has an important application as a coating on cutting tools to extend their lifetime. In this study various phases in the Ti-N system were deposited by the activated reactive evaporation process. The influence of process variables-evaporation rate, N2 partial pressure and deposition temperature-on the phases present, their morphology and hardness, was studied using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. As the ratio of the evaporation rate of titanium to the partial pressure of N2 decreases, the deposit changes from titanium to Ti2N to TiN including two-phase mixtures. As the deposition temperature is increased the grain size increases markedly, from about 0.5 μm at 550 °C to 20 μm at 1000 °C, and the grain morphology changes from a faceted to a smooth topography. The hardness of the deposit is influenced primarily by the presence of the Ti2N phase which produces the highest hardness levels. © 1979.