Effects of Pulse Bias Duty Cycle on Composition, Structure and Hardness of Ti-Cu-N Nanocomposite Films Deposited by Pulse Biased Arc Ion Plating

Hard nanocomposite Ti-Cu-N films were deposited on high-speed-steel (HSS) substrates by pulse biased arc ion plating with a single multi-component Ti-Cu (88/12 at%) alloyed target. The effects of pulse bias duty cycle on the elemental content, structure and mechanical properties of the deposited films were investigated. The Cu atom content of the Ti-Cu-N films was analyzed using an electron probe microanalyzer (EPMA). The structure of the films was determined by X-ray diffraction (XRD) and their hardness and elastic modulus were measured using a nanoindenter. Under pulse bias voltages of -300V and -600V, the Cu content decreased with an increase in the duty cycle from 10% to 50%. The XPS spectra of Cu 2p for the Ti-Cu-N films showed that only pure metallic Cu was present. With an increase in the pulse duty cycle from 30% to 50%, the diffraction peaks of TiN in the preferred orientations (111) and (220) were observed, for pulse bias voltages of -300 V and -600V, respectively. Furthermore, no obvious sign of the metallic copper phase was observed in the XRD patterns. Under both pulse bias voltages of -300 V and -600 V, the value of hardness showed first an increase and then a decrease with an increase in the duty cycle from 10% to 50%. The maximum hardness value observed was 31.5 GPa, which was obtained for a 30% duty cycle under a pulse bias voltage of -600 V.