Structure and properties of lanthanum doped AlCrN coatings

Abstract AlCr(La)N coatings were grown through mid-frequency reactive magnetron sputtering on cemented carbide (YG8) and single-crystal silicon (111) wafer. The composition, microstructure and mechanical properties of the coatings deposited under different La target currents were evaluated. The concentration of La changed from 0 at.% to 7.73 at.% displaying a low rate of back-scattering compared to Al and Cr. La partly acted as a partial solid solution in the AlCrN lattice, whereas an increased amount of La was likely to be intergranular gathered, resulting in segregation at the grain boundaries and a grain size decrease. During this phenomenon, nc-AlCrLaN crystalline grains combined with a-La 2 O 3 /a-LaN were formed. The multilayer morphology appeared as the La target current increased. The friction coefficient of the AlCrLaN coating decreased due to the solid lubrication of La 2 O 3 . The AlCrLaN coating under the La target current of 1 A (La concentration 1.39 at.%) obtained the highest H/E ratio, H 3 /E ⁎2 ratio, abrasive resistance and adhesion strength.