Kinetics of Fe2O3-Al reaction prior to mechanochemical synthesis of Fe3Al-Al2O3 nanocomposite powder using thermal analysis

Abstract

The effect of ball milling on kinetics of the thermite reaction of 3Fe2O3 + 8Al powder mixture to synthesize<br />Fe3Al-Al2O3 nanocomposite was investigated using differential thermal analysis. A model-free method<br />was applied to the non-isothermal differential calorimetry (DSC) data to evaluate the reaction kinetics<br />according to the Starink method. The activation energy of the thermite reaction in the Fe2O3-Al system<br />in ball milled 3Fe2O3 + 8Al powder mixture was determined to be 97 kJ/mole, which is smaller than<br />that for non-milled powder mixture indicating the change of reaction mechanisms. The change in the<br />reaction mechanism could be resulted from the formation of short-circuit diffusion paths occurring in<br />the precursors during milling. The change in the reaction mechanism of such nanostructured 3Fe2O3 +<br />8Al powder mixture could be reason of the formation of desired phases (Fe3Al and Al2O3), which such<br />stoichiometric phases cannot be achieved by conventional molten state thermite reaction.