ZrN/Cu nanocomposite film - a novel superhard material

This article reports on the structure and hardness of ZrCu-N films prepared by de reactive magnetron sputtering of a ZrCu alloyed target in a mixture of Ar + N-2 using a round planar unbalanced magnetron of diameter 100 mm. It was found that there is a strong correlation between the structure of the film and its hardness. The hard (< 40 GPa) ZrCu-N films are characterized by many weak reflections from poly-oriented ZrN and Cu grains. In contrast, the superhard (greater than or equal to 40GPa) ZrCu-N films are characterized by a strong reflection from ZrN grains with a dominate ZrN(111) orientation and no reflections from Cu. The superhard ZrCu-N films with a hardness of 54 GPa are nc-ZrN/Cu nanocomposite films composed of strongly oriented ZrN grains surrounded by a thin layer of Cu. These films exhibit a high elastic recovery of about 80% (determined by a microhardness tester) and contain approximately 1-2 wt.% Cu. The superhard nc-ZrN/Cu nanocomposite films represent a new class of superhard materials of the type nc-MeN/metal. (C) 1999 Elsevier Science S.A. All rights reserved.