Structure and Magnetic Properties of a Medium-Entropy Fe46Co34Ni20 Alloy Powder
The nanocrystalline/nanoscale ternary FeCoNi alloys are known to have an excellent combination of soft-magnetic properties and thermal stability and they find applications in various miniaturized devices, e.g. sensors and actuators. A medium-entropy nanocrystalline Fe46Co34Ni20 alloy was synthesized by mechanical alloying. The x-ray diffraction and scanning electron microscopy were adopted for their structural characterization at ambient temperature. The alloy powder was comprised of two phases: an f.c.c. phase (γ) and a b.c.c. phase (α-Fe). The powder particles were irregularly shaped and, the mean and D90 of the powder particles was ~5 μm and ~10 μm, respectively. The grain size was less than ~10 nm. The intrinsic coercivity and saturation magnetization of the alloy powder was ~3 kA/m and ~164 Am2/kg, respectively. The nanocrystalline alloy powder exhibited superior soft-magnetic properties—magnetization increased by ~24% and the coercivity decreased by ~16 times—as compared to the nanoparticles of a similar composition, synthesized by chemical methods. Thermal treatment at 840 K resulted in an improvement in the soft-magnetic properties of the mechanically alloyed powder—saturation magnetization increased by ~13% and intrinsic coercivity decreased by ~33%.
KeywordsFe–Co–Ni ternary alloys Mechanical alloying Magnetic properties
The authors thank the College of Engineering and Computer Science and the Institute of Advanced Vehicle Systems at the University of Michigan in Dearborn for the financial (Grant# U052349) and infrastructural support to conduct the experimental work.
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