Elastic properties of (Ti,Al,Si) N nanocomposite films

(Ti,Al,Si)N films have been prepared by d.c. and rf reactive magnetron sput tering, with Si contents in the range 2-11 at.% and Al contents between 4 a nd 19 at.%. Samples prepared in rotation mode (three magnetrons) presented densities between 4.0 and 4.6 g/cm(3), while samples prepared in static mod e (magnetron with Ti target with small pieces of Si and Al) displayed densi ties mainly in the range 3.0-3.9 g/cm(3). For comparison purposes, the eval uation of Young's modulus was performed by both depth-sensing indentation a nd surface acoustic wave (SAW) techniques. Indentation results revealed sys tematically higher values than those obtained by SAW. These discrepancies m ight be related with the relatively low density of the films. Hardness valu es of approximately 60 GPa were obtained with samples with a composition of approximately 28.5 at.% titanium, 12 at.% aluminium, 9.5 at.% silicon and 50 at.% nitrogen. XRD patterns showed the presence of two different crystal line phases, as in the case of (Ti,Si)N films. One is assigned to TiN phase (lattice parameter of approx. 0.429 nm) and the second, the so-called soli d solution which is developed in situations of low surface mobility, reveal ed a lattice parameter (0.419 nm) slightly lower than that of bulk TiN. (C) 2001 Elsevier Science B.V. All rights reserved.