Structural characterization of nanostructured Fe-8P powder mixture

Nanostructured Fe-8P (wt%) powder mixture was prepared by high energy ball milling in a planetary ball mill (Fritsch P7) under argon atmosphere. The morphology of the particles, the phase identification and the alloying evolution process as a function of milling time are studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fe-57 Mossbauer spectrometry (MS), respectively. Refinement based on Rietveld method of the XRD patterns and the Mossbauer spectra analysis show that the FexP (1 < x < 2) and Fe(2)p phosphide phases are the main product after 3 h of milling (similar to 10%). From the XRD Rietveld refinement, it is observed that the Fe(2)p phase disappears completely after 12 h of milling, while the Fe(3)p nanophase appears after 9 h and remains for larger milling duration. The lattice structure distortion is evidenced by the lattice parameter changes of the milled products. A two structure state of the alpha-Fe(P) solid solution: alpha-Fe-1 and alpha-Fe-2 is confirmed by both the XRD and MS measurements. After milling for 21 h, a mixture of a disordered two phase alpha-Fe(P) solid solution, Fe3P nanophase and a small amount of a paramagnetic FeP phosphide phase (similar to 2%) is obtained.