Thermal Stability of Field- and Stress-Induced Anisotropy in Nanocrystalline Fe-Based and Amorphous Co-Based Alloys

Abstract

Thermal stability of induced magnetic anisotropy (IMA) was studied in a course of subsequent annealings without any external effects for already field- or stress-annealed specimens of the nanocrystalline Fe73.5Cu1Nb3Si13.5B9 and amorphous Fe3Co67Cr3Si15B12 alloys. For these alloys the dependence of IMA thermal stability on the magnitude of the IMA constant (Ku) and temperature of stress-annealing was investigated. For the nanocrystalline alloy thermal stability of field- and stress-induced anisotropy with identical Ku was compared. It was shown that nanocrystalline specimens with identical Ku values after field- or stress-annealing have identical thermal stability of IMA. This can point to a similarity of the mechanisms of IMA formation after field- or stress-annealings. Thermal stability of stress-induced anisotropy in the nanocrystalline alloy with Ku value less than 1000 J/m3 and the amorphous alloy with Ku less than 100 J/m3 depends on the value of Ku. For both stress-annealed nanocrystalline and amorphous alloys magnetic anisotropy induced at higher temperatures is more stable because more long-range and energy-taking processes take place at these temperatures.