E.Kusano, M.Matsui, Y.Sawahira, N.Kikuchi, A.Kinbara, Kanazawa Institute of Technology, AMS R&D Center. 3-1 Yatsukaho, Matto, Ishikaka 924-0838, Japan.

TEL +81-76-274-9257 FAX +81-76-274-9251, e-mail:kusano@neptune.kanazawa-it.ac.jp

Hardness enhancement of V/VN multilayer films by a nano-modulated structure has been studied. The films were deposited on aluminosilicate glass substrate by reactive-gas flow rate modulation sputtering. The film thickness was 500nm including a 100nm-thick glue layer of VOx/V. The modulation period was varied from 10nm to 80nm by changing the reactive-gas flow rate modulation period. The maximum microhardness of 18GPa was obtained at a modulation period of 12nm. For further increase in the modulation period, the film hardness decreased. The dissipated energy obtained from the load-displacement curve of nanoindentation decreased drastically for a low modulation period compared to that of the monolithic VN film, while the elastic energy was independent of the modulation period. This result implies that the film becomes plastically harder at a small modulation period, yielding a high microhardness.