Structural, microstructural and Mössbauer studies of nanocrystalline Fe_100-x Al_x powders elaborated by mechanical alloying

¹ LMMC, M’hamed Bougara University, Boumerdes, 35000, Algeria
² Nuclear Research Center of Algiers, 2 Bd Frantz Fanon, BP 399 Alger-Gare, Algiers, Algeria
³ Nuclear Research Centre of Draria, BP 43, Algiers, Algeria

^a e-mail: nadia.boukherroub@yahoo.fr

Abstract

Nanocrystalline Fe_100-xAl_x powders (x= 25, 30, 34 and 40 at %) were prepared by the mechanical alloying process using a vario-planetary high-energy ball mill for a milling time of 35 h. The formation and physical properties of the alloys were investigated as a function of Al content by means of X-ray diffraction, scanning electron microscopy (SEM), energy dispersive X-ray and Mössbauer spectroscopy. For all Fe_100-xAl_x samples, the complete formation of bcc phase was observed after 35 h of milling. As Al content increases, the lattice parameter increases, whereas the grain size decreases from 106 to 12 nm. The powder particle morphology for different compositions was observed by SEM. The Mössbauer spectra were adjusted with a singlet line and a sextet containing two components. The singlet was attributed to the formation of paramagnetic A2 disordered structure rich with Al. About the sextet, the first component indicated the formation of Fe clusters/ Fe-rich phases; however, the second component is characteristic of disordered ferromagnetic phase.