Hard nanocomposite coatings prepared by magnetron sputtering

Magnetron sputtering is a very efficient method for a production of nanocomposite films. The nanocomposite films are formed in consequence of a combined action of four processes: (1) low-energy ion bombardment, (2) element mixing, (3) substrate heating and (4) energy released or consumed during the film formation. This article reviews the present state of the art in the field of sputtered hard and superhard nanocomposite films. Special attention is devoted to mechanical properties of hard nanocomposite coatings and open problems in their formation and characterization. Two problems are discussed in detail: (i) the correlation between hardness, grain size and microstrain and (ii) the correctness of the evaluation of mechanical quantities from microindentation measurements. Trends of next development of hard and superhard nanocomposite coatings are outlined.