Evaluation of Fracture Strength and Interfacial Strength of Sputtered TiN and AlN Films on Titanium Substrate.

Abstract

Titanium nitride (TiN) and aluminum nitride (AlN) films of 1-26μm thickness were deposited on pure titanium specimens by reactive RF magnetron sputtering method. Tensile tests were carried out for the specimens to evaluate the fracture strength of films and the interfacial fracture toughness between film and substrate. With increasing load the film was cracked repeatedly, and the partial delamination of the film started under the plastic deformation of substrate. The fracture strength of films σc were determined by the extrapolation method using the relationship between inverse of crack intervals and tensile stress of substrate. The σc of TiN and AlN films was almost the same irrespective of film thickness, but the σc of AlN film was small when the film thickness was 26μm. The interfacial fracture toughness Gc12 of both films increased with increasing film thickness, and the Gc12 of TiN film was larger than that of AlN film at the same film thickness.