Evaluation of relaxation process in FeMo14C15B6Erx (x = 0–2) bulk metallic glass by valence electron energy loss spectroscopy

Abstract

Relaxation processes during heating of both ribbon and bulk FeMo14C15B6Erx(x = 0∼2) metallic glasses were examined using valence electron energy loss spectroscopy (VEELS). The plasmon energy was decreased with increasing temperature due to thermal expansion and chemical reordering in the glasses. The chemical reordering stimulates a specific solute cluster formation; M23(CB)6 solute clusters began to form above about 200 °C in both ribbon and bulk FeMo14C15B6Erx (x = 0, 0.5, 1) metallic glasses. The M23(CB)6 solute clusters were only formed above 400 °C in the ribbon FeMo14C15B6Er2 metallic glass, indicating inhibition of the M23(CB)6 formation occurred owing to the Er-(C, B) complexes/clusters formation. The Er-(C, B) complexes/clusters were formed in the cooling process of the sample fabrication. In contrast to the ribbon sample, the M23(CB)6 formation did not occur in the bulk FeMo14C15B6Er2 metallic glass during heating. The amount of the Er-(C, B) complexes/clusters in the bulk sample was larger than that in the ribbon sample because of the slow cooling rate in the bulk sample fabrication. Because the solute carbon and boron atoms were mostly consumed by forming Er-(C, B) complexes/clusters in the bulk FeMo14C15B6Er2 metallic glass, the M23(CB)6 formation was suppressed.