Structure, microhardness and thermal conducting properties of the high-pressure high-temperature-treated Al–Ti–N materials

The w-AlN → rs-AlN polymorphic transition in Ti–Al–N system with low TiN content (3 mol %) was observed. The experimental data show that this transition is possible under 12 GPa pressure at 1773 K. The formation of rs-AlN phase in the resulting composite materials was confirmed by XRD. The obtained materials have intermediate physical and mechanical properties as compared to the undoped w-AlN and Ti_xAl_1−xN solid solution. They are found to have high Vickers hardness (31 GPa at a load of 50 g)—which is twice as hard as w-AlN. The thermal conductivity of the rs-AlN-containing Al–Ti–N materials was measured for the first time using the frequency separation (3ω) method and gave high thermal conductivity coefficients up to 100 W/m × K.