An investigation of the relationship between heat treatment and microstructure in (TiAlV)N and (TiAl)N ceramic films

(TiAl)N and (TiAlV)N films coated on M2 high-speed tool steel were heat-treated in an argon atmosphere at temperatures of 700°C, 800°C and 900°C for 3 h. The structural and mechanical properties of the ceramic films were examined by microindentation hardness testing, X-ray diffraction (XRD) and scanning electron microscopy. Annealing at elevated temperatures led to a decrease in the hardness of the ceramic films. The magnitude of this hardness change became larger with increasing annealing temperature. Elevated temperature anneals also modified the distribution of elements in the ceramic films. XRD data show that phase transformations take place in the structure. These transformations resulted in a decrease in the hardness, residual stress and spacing between the planes of the film. The surface topography was not affected by the heat treatment.