Electric-discharge sintering of TiN-AlN nanocomposites

The structurization and properties of TiN-AlN and TiN-AlN-Y2O3 nanocomposites consolidated by electric-discharge sintering are examined. TiN-AlN composites with a relative density of about 98 to 99% are produced. Their structure is not homogenous and consists of TiN and AlN grains of about 200 nm in size. There are also large spherical grains of titanium nitride of 2 to 10 µm. This effect is probably caused by microdischarges between particles of the conducting phase and subsequent meltback of the interacting surfaces. The effect of yttrium oxide additives on the material structure and properties is investigated. It is shown that TiN-AlN composites consolidated by electric-discharge sintering have high hardness (HV ∼ 25 GPa) and fracture toughness (K1c ∼ 6 MPa · m1/2).