Structure, mechanical and thermal properties of Ti1−x−y−zAlxTayBzN coatings

Abstract

Multiple alloying is a preferred and practical approach to tailor the properties of TiAlN coatings. Here, we studied the structure, mechanical and thermal properties of Ti1−x−y−zAlxTayBzN coatings by cathodic arc evaporation. Increasing Ta content causes a structural transition from mixed cubic and wurtzite Ti0.35Al0.54Ta0.03B0.08N, Ti0.35Al0.54Ta0.05B0.06N, and Ti0.34Al0.52Ta0.09B0.05N to cubic Ti0.33Al0.51Ta0.13B0.03N and Ti0.33Al0.50Ta0.15B0.02N. This structural change causes an increased hardness, where the maximum hardness of 38.0 ± 0.8 GPa is obtained by Ti0.33Al0.51Ta0.13B0.03N. The cubic Ti0.33Al0.51Ta0.13B0.03N and Ti0.33Al0.50Ta0.15B0.02N coatings reveal higher hardness during the whole annealing range, which reach the peak hardness of 39.3 ± 0.9 and 36.7 ± 1.0 GPa at 1000 °C, respectively. In addition, the oxidation resistance of Ti1-x-y-zAlxTayBzN coatings is closely related to the Ta content. After oxidation of 10 h at 1000 °C, the oxide scale of Ti0.35Al0.54Ta0.05B0.06N, Ti0.34Al0.52Ta0.09B0.05N, Ti0.33Al0.51Ta0.13B0.03N, and Ti0.33Al0.50Ta0.15B0.02N are ∼2.31, ∼1.44, ∼1.23, and ∼ 1.08 μm, respectively, while Ti0.35Al0.54Ta0.03B0.08N has been entirely oxidized.