Combustion Peculiarities in the 2Co–Ti–Al System and Properties of the Half-Metallic Ferromagnetic Heusler Alloy Co₂TiAl

Combustion in the 2Co–Ti–Al system is observed by high-speed video recording. It is established that combustion occurs in the frontal mode, and the process parameters are determined. The maximum rate of the increase in the combustion temperature from the moment of initiation to the maximum value reached is 2.7 × 10⁴ K/s. The front propagation velocity calculated from the video recording is 9.4 cm/s. The microhotspot mode of combustion of the reaction composition is found. The temperature dependencies of the electrical resistivity and magnetic moment of the single-phase Co₂TiAl product synthesized in the combustion mode are measured. For the synthesized Co₂TiAl sample, the Curie temperature is T_C = 120 ± 5 K and the electrical resistivity at room temperature is 1.35 μOhm m. It is shown that the electrical and magnetic properties of the Co₂TiAl alloy obtained in the combustion mode are similar to those of alloys obtained by arc melting.