Microstructure and hardness of nanocrystalline Ti1−x−yAlxSiyN thin films

The relationship between the microstructure and the hardness of Ti1−x−yAlxSiyN nanocomposite thin films was investigated using X-ray diffraction and high-resolution electron microscopy. It was found that a high hardness is accompanied by a partial crystallographic coherence of the nanocrystalline domains. The degree of crystallographic coherence depends strongly on the chemical composition and microstructure of the nanocomposites. The silicon present in the thin films creates an amorphous phase, which in excess obstructs the crystallographic coherence and the creation of coherent lattice strains. Consequently, an excess of silicon decreases the hardness of the Ti–Al–Si–N nanocomposites.