Effect of Annealing on the Crystal Structure and Magnetism of Mechanically Alloyed Fe50Co 50

Fe50Co50 powdered samples prepared by mechanical alloying (MA) method were annealed at 500 degrees C for 2 h (MA-annealed), and the X-ray diffraction (XRD), SEM-EDS, magnetization, and zero-field Co-59 NMR measurements were performed to investigate the annealing effects on the crystal structure and magnetic properties. The XRD patterns of the MA-annealed Fe50Co50 showed a bcc structure. However, it was not possible to distinguish between the A2 or B2-type structure. The values of lattice parameter decreased for MT <= 10 h and were close to the value of bulk annealed sample. The magnetization values increased after annealing. Furthermore, the NMR spectra of MA-annealed Fe50Co50 showed a peak centered at about 285 MHz, which was also observed in the bulk sample with a B2-type structure. These results suggest that mechanically alloyed Fe50Co50 powders undergo a structural change from the A2 to the B2-type bcc structure upon short annealing.