Correlation between structural parameters and magnetic properties of ball milled nano-crystalline Fe–Co–Si powders

• Magnetic properties can be improved by reducing the grain size up to the nanometer.
• Increasing the Si content increases the reduction rate of coercivity.
• Addition of Si to the Fe–35%Co powders leads to the finer crystallite sizes.

The main aim of this research is to fabricate the nano-crystalline Fe–Co–Si alloy with superior magnetic properties to be used in producing soft magnetic composites. The alloy powders were prepared by using a planetary ball mill. Morphological, structural and magnetic evolutions during milling were analyzed by scanning electron microscopy coupled with Energy-dispersive X-ray microanalyzer, X-ray diffractometer and vibrating sample magnetometer. The results confirm the production of the Fe(Co) and Fe(Co, Si) solid solutions after milling. Increasing the milling time did lead to smaller crystallite sizes and lattice parameters, but larger amounts of micro-strain and dislocation density. The magnetic measurements indicate that higher amounts of Si lead to lower values of saturation magnetization. The variations of coercivity could be attributed to the introduction of dislocations and reduction of crystallite size as a function of milling time.

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