Reactivity of the Ti-Al system: Experimental study and molecular dynamics simulations

The reactivity of the Ti-Al system was investigated experimentally in the case of reactive laminated particles produced by high energy ball milling. The ignition temperature for a self-sustaining reaction was measured as a function of the heating rate. By means of the Kissinger analysis, two activation energies were evaluated. The first one is associated with the solid-state transformation at the interface below the melting point of Al. The second one corresponds to the exothermic dissolution of Ti into Al liquid together with the formation of TiAl 3. A complementary microscopic approach was developed in order to detect all elemental processes associated with the reactivity of the Ti-Al system in composite materials. Above the melting temperature of Al, the exothermic dissolution of Ti into the liquid layer starts and induces a self-sustaining behavior until the reaction is complete. The dissolution step is limited by the low solubility of Ti in Al. The formation of the intermetallic compound TiAl 3 was observed. The microscopic analysis of the dissolution at the interface explains some specific features of reactive particles.