Electrically conducting ceramics based on $\rm Al$–$\rm AlN$–$\rm TiB_2$

The high-temperature conductivity of ceramics based on $\rm Al$–$\rm AlN$–$\rm TiB_2$ obtained by self-propagating high-temperature synthesis has been studied. The dependences of DC resistivity were measured in vacuum ($1$ Pa) by a four-point technique in a temperature range of $293$–$1273$ K. The evolution of the phase composition of the material upon heating was studied by time-resolved diffraction in real-time mode. The measurements show a “metallic” behavior of conductivity when the $\rm Al$–$\rm AlN$–$\rm TiB_2$ composite is heated, and there is also an abrupt change of resistivity in a temperature range of $870$–$970$ K that is linked with Al melting. In this case, the crystalline structure of ceramic phases does not undergo changes in the studied temperature range. The same temperature coefficient of resistance has been observed for all studied compositions up to the melting point of aluminum.