Effects of mechanical treatment on phase transformation and sintering of nano-sized γ-Fe2O3 powder

The effects of mechanical treatment on the phase transformation and sintering of nano-sized γ-Fe2O3 powder were studied. γ-Fe2O3 powder was obtained by calcining iron tartrates at 300 °C. The mechanical treatment increased the contact areas in theγ-Fe2O3 powder, which acted as nucleation sites for the γ→α-Fe2O3 phase transformation, and resulted in lowering the transformation temperature. The greater surface area and fine equiaxed particle of the milled powder thus obtained were due to the vermicular microstructure development being inhibited. Consequently, the samples with mechanical treatment after sintering developed a uniform fine-grained microstructure.