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

An approximately one monolayer thin amorphous Si3N4 tissue, that is formed during the deposition of the nc-(Al1-xTix)N/a-Si3N4 superhard nanocomposite coatings with their optimum structure and hardness, efficiently avoids the decomposition and softening of the fcc-(Al1-xTix) metastable solution to the titanium-rich fcc-(Ti1-deltaAldelta)N and the wurtzite h-(AlN) up to a temperature of 1100degreesC. In the absence of the Si3N4 skin, the decomposition and softening of (Al1-xTix)N occurs at about 900 to 900degreesC. (C) 2003 Elsevier B.V. All rights reserved.