Hard and superhard nanocomposite Al-Cu-N films prepared by magnetron sputtering

The article reports on structure, mechanical properties and macrostress of Al-Cu-N films deposited by reactive sputtering using a dc unbalanced magnet ron equipped with a round planar aluminum target fixed to the magnetron cat hode with a copper ring. A systematic investigation of sputtered films show ed that: (i) Al-Cu-N is a new nanocomposite material which can form superha rd (> 40 GPa) coatings with a maximum microhardness of approximately 48 GPa ; (ii) Al-Cu-N can easily form a very fine-grained material; (iii) the size of grains decides on the macrostress in Al-Cu-N films; the Al-Cu-N films c omposed of grains with the average size of 9.5 nm exhibit a low (< 0.5 GPa) macrostress and, on the contrary, the Al-Cu-N films composed of larger (> 10 nm) grains exhibit large macrostress of several GPa; and (iv) the macros tress in Al-Cu-N films can be varied from tension to compression by the var iation of the energy delivered to the growing film, i.e. by the ion bombard ment and the substrate heating. The relationships between microhardness, H, Young's modulus, E, and elastic recovery, W-e evaluated from loading/unloa ding curves measured using the microhardness tester Fisherscope H 100 are a lso given. (C) 2001 Elsevier Science B.V. All rights reserved.