Study on reaction mechanisms of iron matrix compositesreinforced with in situ Al2O3 particles reacted byAl-Fe2O3-Fe system

Abstract

Iron matrix composites reinforced with Al2O3 particles were fabricated in situ through exothermic dispersive (XD) reaction from a powder mix of pure elements Fe, Al and Fe2O3. The fabrication and reaction mechanisms were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS) and differential scanning calorimetry (DSC) analysis. The reaction between Al and Fe2O3 was found to occur in three steps. Their activation energies are 203.8 kJ/mol, 1100.9 kJ/mol and 380 kJ/mol, respectively. DSC analysis shows that the reaction peak shifts to a higher temperature with an increase in the heating rate. When the heating rate is 10 K/min, the rates of the three reactions exhibit a similar trend, i.e., the reaction rate is very slow at the start, and then it increases rapidly, finally it becomes slow again. Their reaction times are 456, 672 and 650 s, respectively.