Avoiding the high-temperature decomposition and softening of (Al1-xTix)N coatings by the formation of stable superhard nc-(Al1-xTix)N/a-Si3N4 nanocomposite

Abstract An approximately one monolayer thin amorphous Si 3 N 4 tissue, that is formed during the deposition of the nc-(Al 1− x Ti x )N/a-Si 3 N 4 superhard nanocomposite coatings with their optimum structure and hardness, efficiently avoids the decomposition and softening of the fcc-(Al 1− x Ti x ) metastable solution to the titanium-rich fcc-(Ti 1− δ Al δ )N and the wurtzite h-(AlN) up to a temperature of 1100 °C. In the absence of the Si 3 N 4 skin, the decomposition and softening of (Al 1− x Ti x )N occurs at about 800 to 900 °C.