Machining Performance of Sputter-Deposited (Al0.34Cr0.22Nb0.11Si0.11Ti0.22)50N50 High-Entropy Nitride Coatings

TLDR

The study aimed to evaluate the thermal stability, adhesion strength, and cutting performance of (Al₀.₃₄Cr₀.₂₂Nb₀.₁₁Si₀.₁₁Ti₀.₂₂)₅₀N₅₀ high‑entropy nitride coatings. Thermal stability was assessed by annealing at 900 °C and 1000 °C in air and vacuum, while adhesion was measured via Rockwell C indentation and scratch tests, and cutting performance was evaluated through milling tests comparing flank wear against TiN and TiAlN coated inserts. The coatings exhibited a hardness of 36 GPa that decreased only to 33 GPa after 900 °C annealing, maintained phase and microstructure integrity up to 1000 °C, showed strong adhesion to WC/Co substrates, and produced significantly lower flank wear than commercial TiN and TiAlN coatings, indicating strong potential for hard‑coating applications.

Abstract

(Al0.34Cr0.22Nb0.11Si0.11Ti0.22)50N50 high-entropy nitride coatings prepared by reactive magnetron sputtering have been proved to have high hardness and superior oxidation resistance. Their thermal stability, adhesion strength, and cutting performance were investigated in this study. Hardness of the coating is 36 GPa, which only decreases slightly to 33 GPa after 900 °C annealing either in air or in vacuum for 2 h. No significant change in phase and microstructure were detected after annealing at 1000 °C. Rockwell C indentation and scratch tests shows that Ti interlayer provides a good adhesion between the nitride film and WC/Co substrates. In various milling tests, inserts coated with (Al0.34Cr0.22Nb0.11Si0.11Ti0.22)50N50 have evidently smaller flank wear depth than commercial inserts coated with TiN and TiAlN, even with their smaller thickness. Therefore, the (Al0.34Cr0.22Nb0.11Si0.11Ti0.22)50N50 coating has great potential in hard coating applications.