Journal of Advanced Materials in Engineering (Esteghlal)

Cobalt-based amorphous alloys attracted the attention of many researchers to carry out fundamental research for their application in electronics, sensors and magnetic memory due to their special magnetic properties including close to zero Magnetostriction, magnetic permeability and high saturation magnetization. The purpose of this study is the  formation and evaluation of microstructure and magnetic properties of cobalt-based amorphous alloy produced by melt spinning and mechanical alloying. The final compositions produced by both methods were studied by scanning electron microscopy, X-ray diffraction and vibrating magnetoresistance. The results showed that compound produced by chill block melt spinning has a better magnetic properties.

In the present study, the mechanical alloying process was used to produce the Ni-Nb-Si amorphous alloy. X-ray diffraction (XRD)analysis and high-resolution transmission electron microscopy (HRTEM) were used to approve the amorphous phase formation after 12 hours of mechanical alloying. The results obtained from the SEM morphological images of powder particles during mechanical alloying showed that increasing the milling time caused the reduction  of the powder particles size and uniformity in the shape of the particles. Enhancing the embrittlement and fracturing rate caused brittleness and the  increase in the  failure rate; these were followed by a decrease in the powder particle size to 1-5μm. Cold welding and flattening of the pure elemental powders after mechanical alloying for 2 hours formed a lamellar structure of the alternative layers of different elements lying over each other. SEM image of cross-section of powder particles showed that by increasing the milling time, the interlamellar spacing was decreased, the elements were distributed more uniformly, and finally, a uniform structure of theamorphous phase was completed.