Influence of temperature on the magnetic properties of nanostructured Fe-49 wt.% Co-2 wt.% V alloy powder synthesized by mechanically milling pre-alloyed gas-atomized powder

Abstract

Abstract The magnetic properties of nanostructured Fe-49 wt.% Co-2 wt.% V alloy powder, synthesized by mechanically milling pre-alloyed gas-atomized powder, were investigated from cryogenic to high temperatures (60–900 K). At cryogenic temperatures, the as-milled nanostructured alloy powder exhibited stable magnetic properties. The decrease in MS was by a minuscule ∼2 %—from ∼212 ± 1 Am2/kg (at 300 K) to ∼217 ± 2 Am2/kg (at 60 K), and the increase in HCI was by a modest (∼8%)—from ∼6.1 kA/m (at 300 K) to ∼6.6 kA/m (at 60 K). At high temperatures (>300 K), both MS and HCI decreased. Annealing improved the soft-magnetic properties of the as-milled alloy powder. The annealed alloy powders retained their nanostructure—grain size ∼15–30 nm. The as-milled alloy annealed at 900 K showed the highest MS and the lowest HCI among all the other annealing temperatures—MS increased by ∼7%–∼225 ± 1 Am2/kg and the HCI decreased to ∼1.0 kA/m. The annealed nanostructured Fe-49 wt% Co-2 wt.% V alloy powder exhibited magnetic properties comparable to a few annealed nanostructured Fe- Co-based alloys. The annealed nanostructured alloy powder displayed fairly stable magnetic properties over a wide range of cryogenic temperatures. The annealed Fe-49 wt.% Co-2 wt.% V alloy powder is better suited for soft-magnetic applications than the as-milled powder, from ambient to cryogenic temperatures.