Title: Structural characterisation of the mechanically alloyed Fe57Co21Nb7B15 powders

Authors: Safia Alleg, Saida Souilah, Rachid Bensalem, Achour Younes, Joan Joseph Sunol

Addresses: Laboratoire de Magnetisme et Spectroscopie des Solides, Departement de Physique, Universite de Annaba, B.P. 12, 23000 Annaba, Algerie. ' Laboratoire de Magnetisme et Spectroscopie des Solides, Departement de Physique, Universite de Annaba, B.P. 12, 23000 Annaba, Algerie. ' Laboratoire de Magnetisme et Spectroscopie des Solides, Departement de Physique, Universite de Annaba, B.P. 12, 23000 Annaba, Algerie. ' Laboratoire de Magnetisme et Spectroscopie des Solides, Departement de Physique, Universite de Annaba, B.P. 12, 23000 Annaba, Algerie. ' Departamento de Fisica, Universitat de Girona, Campus Montilivi, Girona 17071, Spain

Abstract: X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were used to investigate the phase identification and the thermal behaviour of the mechanically alloyed Fe57Co21Nb7B15 powders. The diffusion of B into the Nb lattice leads, after 1 h of milling, to the formation of a bcc Nb(B) solid solution with a lattice parameter close to a = 0.3425 nm. The solid state reaction between Fe and B gives rise to the formation of Fe23B6 and Fe2B boride phases after 3 and 6 h of milling, respectively. On further milling (96 h), an amorphous matrix (∼80%), where nanocrystalline bcc α-Fe, bcc Nb(B), Fe2B and Fe3B phases were embedded, is obtained. The broad exothermic reaction in the DSC scans consists of several exothermic peaks and spreads over the entire temperature range 100-700°C. The enthalpy release at temperatures below 300°C can be attributed to recovery and strain relaxation. Crystallisation and grain growth are the dominating processes at high temperatures.

Keywords: nanostructured materials; mechanical alloying; amorphisation; X-ray diffraction; XRD; differential scanning calorimetry; DSC; nanotechnology; nanomaterials; phase identification; thermal behaviour; recovery; strain relaxation; crystallisation; grain growth; temperature.

DOI: 10.1504/IJNP.2010.035880

International Journal of Nanoparticles, 2010 Vol.3 No.3, pp.246 - 256

Published online: 07 Oct 2010 *

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