Preparation and characterisation of aluminium nitride–titanium nitride composites

Aluminium nitride–titanium nitride (AlN–TiN) composites were prepared to increase the fracture toughness of AlN-based materials. Two methods were used to achieve particle-reinforced materials; TiN (0.3–3.4 vol.%) was formed in-situ or TiN particles (0–21 vol.%) were added. The resulting composites were dense and homogeneous, even at high TiN content. The Vickers hardness and Youngʹs modulus increased when adding 21 vol.% TiN, about 8 and 5%, respectively. SENB measurements showed a 33% increase in fracture toughness when 21 vol.% TiN was added. The toughening mechanism was mainly crack deflection around TiN grains. The fracture toughness was also calculated using various models based on Vickers indentation. The different models underestimated the KIC values compared to the SENB method. The electrical resistivity for materials with low TiN content was high, 108–1014 Ω cm. In the 21 vol.% TiN material the percolation limit of TiN was reached and the resistivity dropped to 10−1–10−2 Ω cm.