Influence of N₂ Partial Pressure on Structure and Mechanical Properties of TiAlN/Al₂O₃ Multilayers

TiAlN/Al₂O₃ multilayers with different Ar/N₂ ratios were deposited on Si substrates in different N₂ partial pressure by magnetron sputtering. The crystalline and multilayer structures of the multilayers were determined by a glancing angle X-ray diffractometer (XRD). A nanoindenter was used to evaluate the hardness, the elastic modulus and scratch scan of the multilayers. The chemical bonding was investigated by a X-ray Photoelectron Spectroscopy (XPS). The maximum hardness (36.3 GPa) and elastic modulus (466 GPa) of the multilayers was obtained when Ar/N₂ ratio was 18:1. The TiAlN/Al₂O₃ multilayers were crystallized with orientation in the (111) and (311) crystallographic planes. The multilayers displayed stably plastic recovery in different Ar/N₂ ratios. The scratch scan and post scan surface profiles of TiAlN/Al₂O₃ multilayers showed the highest critical fracture load (L_c) of 53 mN for the multilayer of Ar/N₂ = 18:1. It indicated that the multilayer had better practical adhesion strength and fracture resistance.