Fabrication and Characterization of Mono-sized Spherical Fe-based Metallic Glass Micro-particles

[(Fe0.5Co0.5)0.75B0.2Si0.05]96Nb4 metallic glass alloy particles with narrow size distribution and high sphericity were prepared in a Helium atmosphere by pulsated orifice ejection method (POEM). The analysis of these obtained particles was carried out by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and transmission electron microscope (TEM). The results show that the phase transitions of particles from the mixed phase consisting of the glassy phase and the crystalline phase to the fully glassy phase occur as the particle diameter is decreased. The particles obtained in the fully glassy phase have a diameter of less than 645 μm. The critical cooling rate for fully glassy phase is estimated to be in the range of 800-1100 K/s. No changes of the critical cooling rate occur in Ar or He atmosphere. Critical cooling rate measured in this method is definitely lower than that measured by time-temperature transformation diagram of bulk metallic alloy.