| Summary: | Ta hard coatings were prepared on PCrNi1MoA steel substrates by direct current magnetron sputtering, and their growth and phase evolution could be controlled by adjusting the substrate temperature (T<sub>sub</sub>) and sputtering power (P<sub>spu</sub>) at various conditions (T<sub>sub</sub> = 200–400 °C, P<sub>spu</sub> = 100–175 W). The combined effect of T<sub>sub</sub> and P<sub>spu</sub> on the crystalline phase, surface morphology, and mechanical properties of the coatings was investigated. It was found that higher P<sub>spu</sub> was required in order to obtain α-Ta coatings when the coatings are deposited at lower T<sub>sub</sub>, and vice versa, because the deposition energy (controlled by T<sub>sub</sub> and P<sub>spu</sub> simultaneously) within a certain range was necessary. At the optimum T<sub>sub</sub> with the corresponding P<sub>spu</sub> of 200 °C-175 W, 300 °C-150 W, and 400 °C-100 W, respectively, the single-phased and homogeneous α-Ta coatings were obtained. Moreover, the α-Ta coating deposited at T<sub>sub</sub>-P<sub>spu</sub> of 400 °C-100 W showed a denser surface and a finer grain, and as a result exhibited higher hardness (9 GPa), better toughness, and larger adhesion (18.46 N).
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