Influence of yttrium addition on microstructure and mechanical properties of ZrN coatings

ZrYN coatings with various yttrium contents (0 to 15 at.% in the targets) are deposited from zirconium yttrium composite targets using DC magnetron sputtering. The effect of varying amounts of yttrium addition on the microstructure and mechanical properties of ZrN coatings has been studied. The results reveal that yttrium atoms substitute zirconium atoms in Zr–N lattice forming the solid solution ZrYN coatings. The preferred orientation changes from (200) to (111) with yttrium addition, while the grain sizes are approximately the same. The indentation hardness of the ZrYN coatings first increases from 19.7 GPa to 24.1 GPa with increasing yttrium content up to 5 at.% and is followed by a decrease to 20.9 GPa with a further increase in yttrium content. Scratch test shows that yttrium addition has a beneficial effect on the adhesion of the ZrYN coatings with the critical load increasing from 2.8 N for the ZrN coating to 7.6 N for the ZrYN coating (yttrium content 10 at.%).