"Magnetic characterization of the mechanically induced thermite reaction between Fe2O3 and Al"

LAURA CRISTINA DAMONTE; CUADRADO- LABORDE, CHRISTIAN; MENDOZA ZELIS, LUIS; SOCOLOVSKY, LEANDRO M.; TORRIANI, IRIS

PHYSICA B - CONDENSED MATTER

Elsevier

Año: 2004 vol. 354 p. 125 - 128

0921-4526

We have investigated the mechanically-induced self-propagating reaction (MSR) between hematite (Fe2O3) and aluminium. In this reaction the final phases, Al2O3 and Fe, are formed by an in situ chemical reaction. The experimental techniques used to characterize the evolution of the system with milling time have been: X-ray difractometry (XRD), Magnetometry (RT and 5 K) and Mössbauer Spectroscopy (MS) (RT and 77 K.) After reaction, Fe particles of nanometer size in a cristaline Al2O3 matrix have been formed. At longer milling times, a rather wide particle-size distribution, around 20 nm, was observed by XRD. MS were constituted of both paramagnetic (PM) and ferromagnetic (FM) contributions. PM contribution was associated with small grains of super PM Fe and hercynite (FeAl2O4), whereas the FM component was associated to larger iron grains (i.e. > 20 nm). Saturation magnetization, coercivity field and remanent magnetization rapidly reached a stationary value with milling time. A correlation between the microestructural characteristics of the sample and its magnetic properties before and after reaction is described. © 2001 Elsevier Science. All rights reserved