Influence of mechanical alloying conditions on amorphous phase formation in Fe67B33

Mechanical alloying of Fe67B33 mixture was carried out in a planetary ball mill. Variable milling parameters were a balls size, a milling atmosphere (Ar, He) and a filling ratio. Powders were characterized by X-ray diffraction analysis, electron scanning microscopy (SEM) and differential scanning calorimetry (DSC). It was found that balls temperature strongly affects the amorphous phase quantity: the use of atmosphere with higher thermal conductivity (He) and small balls noticeably increases the amorphous phase output. It was revealed by SEM that considerable part of boron particles survives in the course of the milling and their presence can be responsible for a broad exothermic effect on the DSC curves. The maximal volume fraction of amorphous phase was about 77% and its composition was evaluated as 20/22 at.% B.

► Mechanical alloying of Fe67B33 mixture.
► The amorphous phase formation depends on balls temperature.
► Considerable part of unreacted boron is detected by SEM.
► Maximal volume fraction of amorphous phase was about 77%.
► Amorphous phase composition was evaluated as 20/22 at.% B.