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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