a1 Department of Metallurgy, Indian Institute of Science, Bangalore 560012, India
a2 School of Materials Science and Engineering, The University of New South Wales, Sydney NSW 2052, Australia
a3 Department of Metallurgy, Indian Institute of Science, Bangalore 560012, India
a4 Department of Mechanical Engineering, Indian Institute of Science, Bangalore 560012, India
Nanoindentation experiments were carried out on a columnar ∼1.5-μm-thick TiN film on steel using a conical indenter with a 5-μm tip radius. Microstructural examination of the contact zone indicates that after initial elastic deformation, the deformation mechanism of the TiN is dominated by shear fracture at inter-columnar grain boundaries of the TiN film. A simple model is proposed whereby the applied load is partitioned between a deforming TiN annulus and a central expanding cavity in the steel substrate. It is possible to obtain a good fit to the experimental load–displacement curves with only one adjustable parameter, namely the inter-columnar shear fracture stress of the TiN film. The implication of results in the context of the performance of TiN films in service is also discussed.
(Received October 19 2003)
(Accepted May 18 2004)