Nanoindentation investigation of Ti-TiN and Al-Al2O3multilayers

The aim of this study is to correlate the mechanical properties of Ti-TiN and Al-Al 2 O 3 multilayers with their structural properties. For the Ti-TiN system, the hardness increases with decreasing period thickness to go beyond the rule-of-mixture value for samples with period thickness A ≤ 5nm. The maximum hardness, 1.6 times higher than the rule of mixture value, is obtained for A = 2.5nm. For Al-Al 2 O 3 system, the hardness shows no significant change when varying the period thickness. These results are well correlated with the microstructure investigated by X-Ray Reflectometry and High Resolution Scanning Electron microscopy. These techniques show that the modulation of composition of Ti-TiN multilayers exists for all the period thickness and that, it is less pronounced in the case of Al-Al 2 O 3 system.