Mössbauer spectroscopy study of the disordering process of Fe-rich FeAlSi alloys

Abstract

In this work we study systematically the influence of different Al/Si ratios on the magnetic and structural properties of mechanically disordered powder Fe75Al25−xSix, Fe70Al30−xSix and Fe60Al40−xSix alloys by means of Mossbauer spectroscopy and X-ray diffraction measurements. In order to obtain different stages of disorder the alloys were deformed by ball milling annealed (ordered) alloys during different number of hours. X-ray and Mossbauer data show that mechanical deformation induces the disordered A2 structure in these alloys. The results indicate that addition of Si to binary Fe–Al alloys makes the disordering more difficult. The study of the hyperfine fields indicates that depending on the Fe content the magnetic behaviour of these ternary alloys varies. For Fe75Al25−xSix series, the alloys have different magnetic behaviours with deformation depending on the Si content. The magnetization of the alloys with high Si content decreases with deformation, as it happens to binary Fe75Si25 and the magnetization of the alloys with low Si content increases with deformation, as it happens to binary Fe75Al25. For Fe70Al30−xSix series the mean hyperfine fields show that there are two different stages with the disordering, in a first stage the mean hyperfine fields decrease and in the second stage they increase. Finally, for Fe60Al40−xSix alloys there is a magnetic transition, from a paramagnetic ordered state to a magneticdisordered state.