Manufacture, microstructure and mechanical properties of W[sbnd]Ta[sbnd]N nano-structured hard films

Abstract

W1−xTaxNy (x=0–0.95) hard films were deposited on Si substrates using reactive direct current magnetron sputtering. The effect of tantalum concentration on phase composition, microstructure, surface morphology, adhesion strength, and hardness of the films has been studied by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy, nano-indenter, and scratch tester. It was found that regardless of tantalum concentration all the W1−xTaxNy films show face centered cubic structure, and form WTaN solid solution. The hardness and Youngs’ modulus of W1−xTaxNy films initially increase and then decrease with increasing tantalum concentration, after passing the maximum value of 38GPa and 360GPa at x=0.31, respectively. The adhesion strength of coating to silicon substrate is in the range of 27–35N, no obvious variation trend of adhesion strength with tantalum concentration was observed.