The effect of Si addition on the microstructure and magnetic properties of Permalloy prepared by mechanical alloying method

In this paper, we report the preparation of nanostructured (Ni50Fe50)100−xSix and (Ni80Fe20)100−xSix powders prepared by the mechanical alloying method. Elemental maps using scanning electron microscopy as well as X-ray diffraction results showed that iron and silicon dissolved in the nickel lattice homogeneously and formed a face-centered cubic γ-(Ni (Fe–Si)) uniform solid solution after milling for 24 h. By increasing Si content up to 20 at.%, estimated crystallite sizes for Ni50Fe50 and Ni80Fe20 alloys were reduced from ∼35 and 46 nm to ∼9 and 17 nm, respectively. Up to 5 at.% Si, microstrain decreased due to dynamic and static recovery which were prevailing mechanisms due to high work hardening rate of powders. By increasing the Si content, saturation magnetization decreased and different rates of grain refinement resulted in dissimilar behavior of coercivity for two compositions. The maximum saturation magnetization (∼156 emu/g) and minimum coercivity (∼10 Oe) were achieved for the Ni50Fe50 and (Ni50Fe50)80Si20 alloys, respectively.