Thermal stability and machining performance of arc evaporated Ti1-xAlxN hard PVD coatings with x=0.5 – 0.73 ratios using an integrative approach

Abstract

Incorporating Al into TiN-based coatings plays a key role in enhancing their mechanical properties and thermal stability which are the crucial properties for cutting tool applications. In this paper, we study the effect of different Al contents on the mechanical and thermal properties and consequent machining performance using an integrative approach. The results show that heat treatment of the Ti1-xAlxN coating decomposes them into their substituents, which is accompanied by the formation of c-AlN and c-TiN domains. The coherency strain between these domains results in increased hardness values under temperatures up to ~900–1000 °C. This growth was found to be substantial in cases with a single-phase cubic structure. In the coating sample with lower Al contents, where a cubic structure is present, the machining performance tended to be superior mainly due to improved adhesion to the substrate, higher hardness, and compressive residual stress.