Effects of silicon content on the structure and properties of (AlCrMoTaTi)N coatings by reactive magnetron sputtering

Si-doped (AlCrMoTaTi)N coatings were deposited onto an Si substrate by radio-frequency magnetron sputtering of an AlCrMoTaTi alloy target under direct current bias in an N2/Ar atmosphere. The crystal, microstructural, mechanical, and electrical properties at different Si-target powers were investigated. As the Si content reached 7.51 at.%, the simple NaCl-type face-centered cubic structure of nitride was retained. Significant lattice decline and grain growth were observed in the nitride coatings. The microstructure of coatings transformed from loose columns with rough-faceted surface into dense ones with smooth-domed surface. The solubility of approximately 7.51 at.% Si content was demonstrated. Si incorporation significantly improved the mechanical properties of the coatings, but degraded their electrical properties. The hardness of the coatings increased from 20.7 GPa to 35.5 GPa, and the electrical resistivity increased from 793 μΩ cm to 3872 μΩ cm.