Impacts of powder size on amorphous-crystalline transition behaviours in gas atomized Fe-rich alloy powders

Abstract

The present research is focused on the development of Fe-based bulk metallic glassy alloy powders by gas atomization (GA) technique, for their utilization in additive manufacturing. The pre-alloyed ingots are gas atomized under nitrogen gas pressure, producing the powders with a wide size range of 1–300 μm. After sieving analysis, it was found that 50 and 90 % of powders were below the 47 and 91 μm size ranges, respectively. Scanning electron microscopy (SEM) reveals high sphericity, smooth surface finish, and satellite-free outer surface characteristics in the developed GA powders. The finer powders (< 50 μm size) have been achieved with more tap density relative to apparent density compared to coarser powders (>50 μm size). The powders below the 63 μm size range are examined as fully amorphous structures through an X-ray diffraction (XRD) pattern. The thermograms also explain high amorphicity (~ 90 %) for these powders (< 63 μm size), evaluated by differential scanning calorimetry (DSC). The soft magnetic properties are obtained with an effective variation with the change of powder particle size. The developed amorphous powders have the potential for the additive manufacturing of soft magnetic machine components.