The modulation structure induced changes in mechanical properties of TiAlN/Al2O3 multilayers

TiAlN/Al2O3 multilayers which had different separate layer thickness of TiAlN or Al2O3 were synthesized by sputtering Ti3Al and Al2O3 targets with N2 and Ar gases. The influence of modulation periods and modulation ratios on structure and properties of TiAlN/Al2O3 multilayers was investigated using scanning electron microscopy, X-ray diffraction, X-ray Photoelectron Spectroscopy, surface profiler, and nanoindenter. Compared to TiAlN layer with only (2 0 0) preferred orientation, TiAlN/Al2O3 multilayers were crystallized with orientations in the TiAlN (1 1 1), TiAlN (2 2 2) and AlN (1 0 0). Besides, weak Al2O3 (0 2 2) orientation is observed, when modulation period is 8.9 nm. The maximum hardness about 36.6 GPa was obtained at modulation period of 10.4 nm and modulation ratio of 10:1. The hardness and the toughness of TiAlN/Al2O3 multilayers increase as individual TiAlN layer thickness increases.