Hot-pressed Ti-Al targets for synthesizing Ti 1− xAl xN films by the arc ion plating method

Abstract

Ti and Al powders were mixed with identical atomic ratios and hot-pressed at 650, 800, 950, 1100 and 1250°C, respectively, for the use of targets in the arc ion plating (AIP) method. As the sintering temperatures increased, the target density monotonously increased and the porosity correspondingly decreased. Chemical analysis by X-ray diffraction indicated that pure Ti and Al phases decreased and intermetallics such as TiAl 3 and Ti 3Al phases were formed at 800–950°C. Over 950°C, the amount of the intermetallics decreased and finally TiAl phase was formed. Next, the Ti-Al targets were arc-discharged in nitrogen plasma and Ti 1− x Al x N films were deposited on mirror-polished cemented carbide substrates. The targets with lower density, sintered at 650 and 800°C, did not easily trigger and keep stable arc-discharge during the deposition. As a result, synthesized Ti 1− x Al x N films had a larger number and size of droplets which were not only circular but were also irregular shapes. Although microstructures of Ti–Al targets were quite different, all films mostly consisted of Ti 0.5Al 0.5N with the NaCl structure and similar hardness with approximately 3000 HV. Further, all Ti 0.5Al 0.5N films had the same columnar cross-sectional structures and the growth rate was approximately 17 μm/h.