Magnetic and structural study of mechanically alloyed Fe0.7-xMnxAl0.3

In this work the magnetic and structural properties of the Fe0.7-xMnxAl0.3 (0.00 less than or equal to x less than or equal to 0.30) alloy system, pre pared by mechanical alloying are reported. The study was carried out, using X-ray diffraction (XRD), Mossbauer spectroscopy (MS) and vibrating sample magnetometry (VSM), in samples prepared by milling for 24, 48, 72 and 84 ho urs pure elements powders. X-ray data showed that, after milling, all the s amples had a b.c.c. structure. The exception are those with x = 0.30, mille d for 72 and 84 hours, which presented a mixture of b.c.c. and f.c.c. phase s. The lattice parameters were, for each composition, nearly independent of the milling lime and increase with x. The mean hyperfine fields of the dif ferent alloys, calculated from the fits of the Mossbauer spectra to a hyper fine field distribution (HFD), decreased monotonically with the increase of the Mn content and increased with the milling time. Similar results were o btained for the saturation magnetization dependence on the Mn content and m illing times. These results allow to conclude that the increase in the Mn c ontent produces a small lattice expansion and a weakening of the ferromagne tic character of the system. In contrast with this, the induction of disord er with the milling time enhances the ferromagnetic character of the sample s.