Microstructure and magnetic properties of mechanically alloyed FeSiBAlNi (Nb) high entropy alloys

●FeSiBAlNi(Nb) amorphous high entropy alloys (HEAs) were fabricated by the MA method.●Nb decreases GFA and enhances thermal stability and heat resisting properties.●FeSiBAlNi HEA shows the better soft magnetism than that of the FeSiBAlNiNb HEA.●FeSiBAlNi(Nb) HEAs show the better soft magnetism than that of their amorphous HEAs.●The existent mode of solid solution phases of the HEAs affects soft magnetism.

In this paper, the effects of milling duration and composition on the microstructure and magnetic properties of equi-atomic FeSiBAlNi and FeSiBAlNiNb high entropy alloys during mechanical alloying have been investigated using X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, transmission electron microscopy and alternating gradient magnetometry. The amorphous high entropy alloys have been successfully fabricated using the mechanical alloying method. The results show that the Nb addition prolongs the milling time for the formation of the fully FeSiBAlNi amorphous phase and decreases the glass forming ability. However, FeSiBAlNiNb amorphous high entropy alloy has the higher thermal stability and heat resisting properties. Moreover, the as-milled FeSiBAlNi(Nb) powders are soft-magnetic materials indicated by their low coercivity. The saturation magnetization of the as-milled FeSiBAlNi(Nb) powders decreases with prolonging of the milling time and shows the lowest value when the amorphous high entropy alloys are formed. It suggests that the as-milled products with solid solution phases show the better soft-magnetic properties than those with fully amorphous phases. The Nb addition does not improve the soft-magnetic properties of the FeSiBAlNi high entropy alloys. Rather, both amorphous high entropy alloys have similar soft-magnetic properties after a long milling time.