Hardening of Al thin films by Ti–C doping

Abstract

Amorphous aluminum alloys have been evaluated as suitable thin films for protective coatings. Magnetron sputtering deposition may provide the necessary conditions for preparing such alloys due to its far-from-equilibrium deposition conditions. In this work, Al-Ti-C nanocomposite films were deposited by magnetron sputtering technique using TiC and Al targets. The produced films are mainly composed of Al nanocrystallites embedded into an amorphous matrix. Films effective hardness varied in the 6.4–8.2 GPa range, while their elastic modulus ranged from 109 up to 134 GPa. The higher the TiC/Al target power ratio, the harder the film. Topographic atomic force microscopy (AFM) images showed that films are mainly constituted by unevenly dispersed grains. Also, the dark phase angle fraction calculation derived from the phase angle contrast AFM images could be correlated with the deposited Al–Ti–C films hardness measured by nanoindentation tests; the higher the surface dark phase angle fraction, the harder the Al–Ti–C films.