球形铁基金属玻璃单分散粒子的制备及评价

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

利用脉冲小孔法在He气氛下制备出了球形粒径可控的[（Fe0.5Co0.5）0.75B0.2Si0.05]96Nb4金属玻璃单分散微粒子,这些粒子具有粒径均匀和圆球度高等优良特点.通过XRD、DSC以及TEM对所获得的粒子进行了检测分析,结果表明随着粒径尺寸的减小,微粒子的微观结构从混合相逐渐向全金属玻璃相转变,制备的粒子均为全玻璃相,临界尺寸小于645μm.通过冷却速率的计算,得到全玻璃相微粒子的临界冷却速率为800~1100 K/s,该速度与环境气氛的改变无关,并且该计算值低于同成分的大块金属玻璃合金TTT曲线的测量值.

[（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 change of the critical cooling rate occurs 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.