Thermal stability of magnetic properties of nanocrystalline (Fe0.7Co0.3)88Hf4Mo2Zr1B4Cu1 alloy with induced magnetic anisotropy

Abstract

The effect of nanocrystallizing annealing in the presence of an ac magnetic field (magnetic heat treatment) and tensile stresses (thermomechanical treatment), as well as in the presence of both tensile stresses and an ac magnetic field (complex thermomechanical magnetic treatment) on the magnetic properties of the nanocrystalline (Fe_0.7Co_0.3)₈₈Hf₄Mo₂Zr₁B₄Cu₁ alloy and their thermal stability has been studied. It has been found that the nanocrystallization of the studied (Fe_0.7Co_0.3)₈₈Hf₄Mo₂Zr₁B₄Cu₁ alloy in the course of magnetic heat treatment, thermomechanical treatment, and thermomechanical magnetic treatment at low tensile stresses (6–30 MPa) leads to about a threefold decrease in the coercive force, but does not ensure the thermal stability of magnetic properties at high temperatures. In nanocrystallization, in the course of thermomechanical treatment at 620°С for 20 min under tensile stresses σ = 250 MPa has been found to be optimum for the high-temperature application (up to 550°С) of the studied alloy.