Effect of rapid solidification in Mn2FeSi alloy formation and its physical properties

The structure and magnetic properties of Mn ₂ FeSi alloy as a prospective Heusler material are studied from the viewpoint of the rapid solidification technology used for its preparation. The planar flow casting leads due to fast cooling of the melted material to formation of ribbons with different structural and physical properties. In present study, the crystalline ribbon-type samples are produced and subjected to detail analysis using electron microscopy, positron annihilation spectroscopy, X-ray diffraction, as well as magnetic and Mössbauer measurements. It is shown that the as-prepared Mn ₂FeSi ribbon is paramagnetic at room temperature and adopts a cubic structure with lattice parameter of 0.567 nm and Néel temperature of antiferromagnetic/paramagnetic transition around 45 K. The presence of other phase(s) observed at low temperatures is reflected also in changes of the structural and physical properties after sample annealing at 773 K for 100 h. The results of microstructure, magnetic, and phase composition observations are completed by the positron life time measurements suggesting single vacancies as the main defects in which the positrons are trapped.