Structure and mechanical properties of multi-principal-element (AlCrNbSiTi)N hard coating

Multi-principal-element nitride (MPEN) has great potential in the application of cutting tool protective coatings. However, the investigation of the nanostructured MPEN coatings is still insufficient. In this paper, we study (AlCrNbSiTi)N MPEN coatings deposited at various bias voltages ranging from −50 to −200 V, using RF magnetron sputtering technique. The microstructure and mechanical performance e of the coatings are systematically investigated. The results show that the (AlCrNbSiTi)N coating forms an FCC crystal structure and exhibits columnar grains. In the elongated grain, there exists a nanocomposite structure with (AlCrNbTi)N nanograins surrounded with crystallized Si3N4 interfaces. The mechanical performance and wear resistance of the coating is enhanced first and then degraded with the increasing bias voltage. The coating deposited at −150 V exhibits the highest hardness and elastic modulus of 39.8 and 436.7 GPa, respectively, and has the lowest wear rate of 6.7 × 10−6 mm3·N−1·m. These results show that the (AlCrNbSiTi)N coating is a competitive candidate for protective coating applications.