Effects of C/Si ratios on structures and behaviors of NbSiCN nanocomposite films synthesized by reactive magnetron sputtering

Abstract

A variety of quarternary NbSiCN nanocomposite films, which with the different Si and Ni contents, are deposited on Si (100) substrates by the reactive magnetron sputtering. The X-ray diffraction, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, nanoindentation techniques, and substrate curvature methods were used to research the effects of C/Si contents ratio on the microstructures and mechanical behaviors of the NbSiCN nanocomposite films. The fabrication of the NbSiCN nanocomposite film can be described as a two-way doped mechanism. When the C/Si content ratio was 1: 4 or 3:2, the films showed the best crystallinity with the pronounced preferential (111) and (200) orientations, respectively. Meanwhile, the corresponding Nb20Si4C1N and Nb20Si2C3N presented two equally-low values of average crystallite sizes and obvious optimal mechanical properties. The first-principles calculation was utilized to obtain Young's modulus of the interfacial layer, which was difficult to obtain the values by experiments. The combined effects of the modulus-difference and alternating-stress-field strengthening mechanisms, and Hall-Petch relationship produce the hardness effect of the NbSiCN nanocomposite film, which is composed of the interfacial layer of numerous compounds.