Effect of the ball mass to sample mass relation in the magnetic and structural properties of Fe0.6Mn0.1Al0.3alloys prepared by mechanical alloying

Abstract

Fe0.6Mn0.1Al0.3 samples were prepared by mechanical alloying (MA) using the 6:1, 9:1 and 12:1 ratios between the ball mass and powder mass (BM/PM) and milling times of 3, 6, 9 and 12 h. Balls of 10 and 20 mm diameter were used. X-ray diffraction (XRD) studies showed that the 6:1 and 9:1 samples present, for all milling times and balls of 20 mm, the three elements, and in some cases (9:1 and 12:1 relations) the formation of a bcc disordered Fe-Mn-Al phase. The 12:1 samples with 12 h milling present only the bcc disordered phase. Mossbauer spectra (MS) of the 6:1 samples were fitted with a narrow hyperfine field distribution (HFD) with ≈32.6 T mean field (typical for pure Fe). The 9:1 spectra were fitted with a HFD and an increasing paramagnetic site which, according to X-ray results, correspond to impure Fe and the paramagnetic alloy, respectively. For the 12:1 samples, the spectra were fitted in a similar way but, for 12 h, the HFD is broad. In this case the alloy is totally consolidated and presents ferromagnetic and paramagnetic sites. When balls of 10 mm diameter were used the bcc formation is accelerated.