Influence of growth temperature on microstructure and mechanical properties of nanocrystalline zirconium carbide films

ZrC films were grown on Si (100) substrates using magnetron sputtering where the growth temperature (Ts) was varied from 25 °C to 290 °C. Film/substrate practical adhesion of the ZrC films was determined by scratch testing while hardness, elastic modulus and fracture toughness were measured by nanoindentation. Structures and morphologies of the ZrC films were analyzed using scanning electron microscopy and X-ray diffraction. The results indicate that there exists an optimum growth temperature at Ts=120 °C, at which the film exhibits the best adhesion. In addition, lower growth temperatures result in an increase in hardness and a decrease in modulus, while higher growth temperatures degrade fracture toughness. The film structure reveals a change from columnar to equiaxed nanocrystalline at Ts=290 °C, which has a profound effect on some of the mechanical properties, such as hardness. The mechanism responsible for the nanocrystalline structure is discussed.