Characterization on Microstructure Homogeneity of θ-Al2O3 Powder Systems During Phase Transformation

The traditional differential thermal analysis (DTA) techniques are employed to evaluate the kinetic behavior induced by the inter-particle relationships in a nano-particle θ-Al2O3 powder system during θ- to α- phase transformation. Discrepancies in homogeneity and inter-particle distance of the powder system may result in the diagnostic DTA profiles which can be use to evaluate the characteristics of the powder system as well as the formed α-Al2O3 particles. Based on the acknowledgement, a quasi-homogeneous transformation shows that a duration of 90 seconds is needed for one θ-crystallite to transform into one α-nucleus with a heating rate of 10 oC min-1 and fabrication of the high phase-pure and mono-sized α-Al2O3 powders is obtained.