Influence of bipolar pulsed DC magnetron sputtering on elemental composition and micro-structure of Ti-Al-Y-N thin films

Based on X-ray diffraction and transmission electron microscopy studies we reveal that DC magnetron sputtering (DC-MS) from Ti0.49Al0.49Y0.02 compound targets in Ar-N2 atmosphere results in the formation of mixed cubic-hexagonal structured (Ti1 − xAlx)1 − yYyN films, whereas the cubic structure can be stabilized by employing bipolar pulsed magnetron sputtering. This can be correlated to an increase in the Ti/Al ratio of the film and increased ion bombardment with increasing pulse duration, triggered by increases in the plasma electron temperature and ion fluxes. For pulsed DC-MS with 80 kHz and increasing pulse duration from 0 (DC-MS) to 4976 ns the composition of the coatings changes from Ti0.41Al0.57Y0.02N to Ti0.46Al0.52Y0.02N and the structure from a mixed cubic-hexagonal to a single-phase cubic, resulting in hardness increases from 23.5 to 34.6 GPa, respectively.