Synthesis of titanium – nickel intermetallides from mechanically activated powder mixtures

Synthesis products in mechanically activated powder mixtures of titanium and nickel of three compositions corresponding to double intermetallic compounds have been studied. The mechanical activation of the mixtures was carried out in a planetary mill at an intensity of 40 g and a processing time of 20 min. The synthesis was carried out in the thermal explosion mode by heating mechanically activated mixtures in a sealed reactor in an argon atmosphere at an average heating rate of 70$^\circ$C/min. The phase composition of the powder products after synthesis and additional annealing was studied by X-ray diffraction analysis, and the results were discussed using literature data on the temperature dependences of the Gibbs energy of intermetallic compounds. It has been found that, regardless of the elemental composition of the mixtures, the intermetallic compound TiNi$_3$, which has the highest negative Gibbs energy, is predominantly formed during synthesis. Therefore, a single-phase target product was obtained only from a mixture of composition corresponding to TiNi$_3$. Thermal explosion products in mixtures of the other two compositions are multiphase. After annealing, the phase composition does not change qualitatively, and the quantitative changes in the phase content are insignificant.