Structural and Magnetic Properties of Inverse-Heusler MnFeSi Alloy Powder Prepared by Ball Milling.

Ternary MnFeSi alloy was synthesized from pure elemental powders by mechanical alloying, using a high-energy planetary ball mill. The formation of an inverse-Heusler phase after 168 h of milling and subsequent annealing at 1173 K for 1.5 h was confirmed by X-ray diffraction. The diffractogram analysis yielded XA structure and the lattice parameter 0.5677 nm in a good agreement with the theoretically obtained value of 0.560 nm. The final powder was formed by particles of irregular shape and median diameter D50 of 3.8 μm and their agglomerates. The chemical analysis resulted in the mean composition of 49.0 at.% Mn, 25.6 at.% Fe and 25.4 at.% Si. At room temperature, the prepared samples featured a heterogeneous magnetic structure consisting of dominant paramagnetic phase confirmed by Mössbauer spectrometry and a weak ferro-/ferrimagnetic contribution detected by magnetization curves. From the field-cooled and zero-field-cooled curves the Néel temperature of 67 K was determined.