The effect of frequency of electromagnetic vibrations on vibrational motion in Fe-Co-B-Si-Nb bulk metallic glasses

The method for producing Fe-Co-B-Si-Nb bulk metallic glasses using electromagnetic vibrations is effective in forming the metallic glass phase. The purpose of this study was to investigate the effects of the frequency of electromagnetic vibrations on the vibrational motion in Fe-Co-B-Si-Nb bulk metallic glasses. The amplitudes of the electromagnetic vibrations at 5 kHz were calculated to be on the order of micrometers, but those at higher frequencies were on the order of nanometers. It was found that the nanometer-sized amplitudes resulted in the disappearance of the increased cooling rate caused by electromagnetic vibrations observed at lower frequencies. When particles in the sample have lower electric resistance than the molten sample, these particles are considered to vibrate vigorously in the molten sample by Lorentz force because the electric current concentrates in those. It is suggested that this phenomenon is the reason electromagnetic vibrations decrease the number of crystal nuclei.