Influence of niobium addition on structure and mechanical properties of W-Nb-N coatings

W-Nb-N coatings with Nb content ranging from 0 to 13.2 at.% were deposited by reactive magnetron sputtering technique. The influence of Nb content on the structure and mechanical properties was investigated. The results show that Nb atoms substitute W atoms forming the solid solution W-Nb-N. All the coatings exhibit a single-phase face-centered cubic (fcc) structure and the preferred orientation changes from (200) to (111) with Nb addition. The grain size of W-Nb-N coatings decreases with the increase of Nb content. The hardness and elastic modulus of W-Nb-N coatings increase gradually from 28.0 GPa to 320 GPa at 0 at.% Nb to 36.0 GPa and 386 GP at 13.2 at.% Nb, respectively. The adhesion between coatings and Si substrate also could be improved by Nb addition.