High pressure and high temperature stabilization of cubic AlN in Ti0.60Al0.40N

Abstract

In the present work, the decomposition of unstable arc evaporated Ti0.6Al0.4N at elevated temperatures and quasihydrostatic pressures has been studied both experimentally and by first-principles calculations. High pressure and high temperature (HPHT) treatment of the samples was realized using the multi anvil press and diamond anvil cell techniques. The products of the HPHT treatment of Ti0.6Al0.4N were investigated using x-ray diffractometry and transmission electron microscopy. Complimentary calculations show that both hydrostatic pressure and high temperature stabilize the cubic phase of AlN, which is one of the decomposition products of Ti0.6Al0.4N. This is in agreement with the experimental results which in addition suggest that the presence of Ti in the system serves to increase the stability region of the cubic c-AlN phase. The results are industrially important as they show that Ti0.6Al0.4N coatings on cutting inserts do not deteriorate faster under pressure due to the cubic AlN to hexagonal AlN transformation.