Kinetic evaluation of combustion synthesis 3TiO2 + 7Al → 3TiAl + 2Al2O3 using non-isothermal DSC method

In situ process has been utilized to fabricate TiAl/Al2O3 composites, with thermodynamically compatible matrices and reinforcements being obtained, through displacement reaction between TiO2 and Al. However, the reaction involves intermediate steps between the starting and final materials, affecting the final phases and consequently the properties. In this paper, a model-free Kissinger-type method is applied to the non-isothermal differential scanning calorimetry (DSC) data to evaluate the reaction kinetics. The results reveal that the reaction between TiO2 and Al is driven by two competing modes: two-stage liquid combustion, and one-stage solid combustion. Following solid combustion mode, the metastable fcc-TiAl, confirmed by TEM investigation, is formed as precursor for the final ordered γ-TiAl.