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

摘要

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-AI 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.