Microstructure and mechanical properties of TiC---Al₂O₃ coatings

Abstract

The microstructure, phase distribution and hardness of TiC---Al₂O₃two-phase coatings prepared by high rate physical vapor deposition have been studied as functions of deposition temperature and feed composition. Structural analysis using X-ray diffraction shows that the coatings consist of α-Al₂O₃ and TiC (cubic) phases. Transmission and scanning electron microscopy have been used to study the distribution of the two phases in the coatings. The growth morphology is fine grained at low temperatures and becomes a dense columnar type at high temperatures of deposition. The microhardness shows a corresponding increase with deposition temperature. Details of the relationship between the microstructure, composition and hardness of the coatings are reported.