Spherical indentation damage in TiC–Ni3Al composites

Advanced cermets based on titanium carbide (TiC), with a ductile nickel aluminide (Ni3Al) binder, have shown significant promise for use in a variety of demanding wear environments, due to a combination of high strength and good corrosion behaviour. In the present study, TiC–Ni3Al composites were produced by melt infiltration, using aqueous slip cast TiC preforms, and Ni3Al binder contents from 10 to 50 vol. %. These samples were subjected to spherical indentation testing, with applied loads from 250 to 2000 N, using WC–Co spheres ranging in diameter from 1.19 to 2.38 mm. Indentation stress-strain curves were determined and compared to the calculated elastic (i.e. Hertzian) response. The bonded interface method was used to examine the subsurface damage of the cermets after indentation. Significant deformation of the binder and the eventual fracture of TiC grains were observed. The nature of the quasi-plasticity of TiC–Ni3Al, and the affect of binder content on surface and subsurface deformation, are discussed.

► The spherical contact damage behaviour of TiC–Ni3Al cermets has been assessed. ► A wide range of Ni3Al binder contents (10 to 50 vol. %) was investigated. ► Comparison was made to classic Hertzian contact mechanics. ► The cermets exhibited a non-linear, ‘quasi-plastic’ indentation response. ► Sub-surface damage was also assessed using the bonded interface method.