Effects of Processing Conditions of a Ball-Milled Fe65Co35 Soft Ferromagnetic Alloy on the Structural, Thermal, and Magnetic Properties

Abstract

The Fe₆₅Co₃₅ alloy is a well-known Fe-based soft ferromagnetic alloy with excellent soft magnetic properties, which make it a strong candidate to be used in technological applications. In the present work, synthesizing nanoscrystalline Fe₆₅Co₃₅ alloy by mechanical alloying is focused on, adding cyclohexane (C₆H₁₂) acting as a process control agent (PCA). PCAs are effective in favoring nanostructured alloys with uniform grain size. The production of this type of alloy is a promising approach to tune the magnetic hardness in Fe₆₅Co₃₅. Structural, thermal, morphological, and magnetic properties have been studied after milling for 10, 25, and 50 h with and without the PCA. In the structural analysis, it is shown that the cubic α-Fe(Co) phase is the predominant phase in all samples. The use of the PCA favors its nanocrystallinity; however, it slows Co diffusion into the Fe matrix. Thermal analysis detects an endothermic process between 525 and 575 °C in the samples milled with C₆H₁₂ only. This is associated with the transition of the residual Fe₃Co superlattice, to the stable α-Fe(Co). The effect of the residual Fe₃Co at room temperature on the magnetic properties is twofold, by decreasing the saturation magnetization of Fe₆₅Co₃₅ but increasing both remanent magnetization and coercivity.