Thermal stability of the nanocrystalline Fe-8P (wt.%) powder produced by ball milling

GRAPHICAL ABSTRACT

ABSTRACT

The thermal stability of Fe-8P (wt.%) ball milled powders was investigated by differential scanning calorimetry X-ray diffraction and ⁵⁷Fe Mössbauer spectrometry. The effect of structural disorder is evidenced in the DSC thermogram by the presence of a large exothermic reaction consists of several overlapping peaks and spread over the temperature range (150-700)°C. The result of the Rietveld refinement of the XRD patterns indicates that during the annealing of the powders up to 210°C, three phases are observed: α-Fe(P), solid solution Fe₃P and FeP phosphides. The Mössbauer spectra analyses show that the paramagnetic FeP phosphide phase is the only product after the annealing (∼ 2%). The annealing at 450°C leads to a mixture of α-Fe(P) solid solution, Fe3P nanophase and a small amount of a paramagnetic FexP (1 < x < 2) phosphide phase (∼ 3%) in addition to iron oxides.

KEYWORDS:

• Fe-P alloys
• ball milling
• annealing
• DSC
• rietveld
• mössbauer

Acknowledgements

This work was supported by the Ministère de l'Enseignement Supérieur et de la Recherche Scientifique, Algérie. The authors are very grateful to A. M. Mercier from the Institut des Molécules et Matériaux du Mans, IMMM UMR CNRS 6283, Université du Maine Le Mans, France for performing X-ray diffraction measurements and to the Spanish MAT2006-13925-C02-02 support.