Effect of Nitrogen Partial Pressure on the Structural, Mechanical, and Electrical Properties of (CrHfNbTaTiVZr)N Coatings Deposited by Reactive Magnetron Sputtering

Multi-element (CrHfNbTaTiVZr)N coatings were prepared through the magnetron sputtering of an equimolar CrHfNbTaTiVZr alloy target. This study determined the influences of N-2-to-total (N-2 + Ar) ratios (R-N) on the composition, structure, mechanical properties, and electrical performance of the coatings. Coating thickness decreased from 898 nm to 128 nm with increasing R-N from 0% to 100%. The alloy coating has bundles of fibrous structures with remarkable void boundaries. The coating changed from amorphous phase to face-centered cubic (FCC) phase with (111) preferred orientation, then to FCC phase with (200) preferred orientation, and finally to near-amorphous phase as R-N increased from 0% to 100%. The microstructure of the nitride coatings transformed from a columnar structure with rough faceted tops and void boundaries into a dense and small structure with smooth domed tops. The grain size of the nitride coatings also decreased with R-N. Accordingly, the electrical performance at high R-N was poor. The nitride coating deposited at R-N = 60% had the highest hardness of 16.6 GPa and the lowest friction coefficient of 0.52, owing to structural densification and grain refinement.