Properties and phase transition of (Ti,Al)N thin films prepared by ion beam-assisted deposition

(Ti,Al)N layers thinner than 0.35 μm were deposited on the Ti or Al substrates with the aluminium or titanium ion beam-assisted deposition (IBAD) method. Directly after the implantation, phase mixing was observed on the top sample layer. Mainly a layer of c-Ti1−xAlxN was formed on the surface of both samples. Underneath, there was a c-TiN layer on the titanium substrate and a c-AlN layer on the aluminium substrate. After annealing at 450 °C for 48 h, the internal layer in the sample deposited on the Ti substrate decomposed, forming a structure containing a mixture of the c-TiN and c-AlN phases. Annealing the sample made on the Al substrate caused a transformation of the external layer into Ti2AlN. Aluminium deposition on the aluminium substrate and nitrogen implantation led to the formation of the c-AlN phase. The process of sample annealing caused a partial transformation of the cubic phase (c-AlN) into a thermodynamically stable hexagonal h-AlN phase. The top layer of all tested samples had a columnar structure. Annealing led to a change in the column density and height.