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【正文】 . The results show that the αAl2O3 seeds and the mixture of αAl2O3 and ammonium nitrate can lower the phase transformation temperature of αAl2O3 to different extents while the particles obtained agglomerate heavily. AT has great potential synergistic effects on the phase transformation of alumina and reduces the phase transformation temperature of αAl2O3 and the trends of neckingformation between particles. Therefore the dispersion of powder particles is improved significantly. 來源數(shù)據(jù)庫：Springerlink⑥ 題 名：Microstructurecontrolled effects on temperature reduction of αAl2O3 crystallite formation作 者：RungJeYang FuSuYen ShenMinLin文獻源：Copyright 169。 2007 Elsevier . All rights reserved摘 要：The interparticle relationship effects on a temperature reduction and simultaneity of αcrystallite formation during θ to αphase transformation were examined using DTA, XRD, and TEM techniques. Three powder systems derived from the same θpowder of average crystallite size nm were prepared, with the intention of creating different microstructure for each powder systems as: (1) asreceived, (2) pretreated by homogenization with a mechanical stirring acpanied by pH adjustment for dispersion, and (3) homogenized and additionally uniaxialpressed to pacts with higher bulk density. Activation energies of θcrystallite growth occurring in the three powder systems were also obtained based on an isothermal model of grain growth rate equation. It is found that the temperature reduction characteristics can be related to the homogeneity as well as the inter θAl2O3 crystallite distances behaved by the θcrystallites. Higher homogeneity and shorter intercrystallite distance for the θpowder systems may favor the αcrystallite formation at lower temperatures over a shorter duration of phase transformation. Furthermore, activation energies of θcrystallite growth can be reduced. And αAl2O3powders fabricated can be monosized and free of vermicular growth.來源數(shù)據(jù)庫：Elsevier SD9 / 9
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