Correlation between soft magnetic properties and enthalpy relaxation for amorphous Fe-M-P (M = Cr, Mn, Ni, Mo) ternary alloys

Abstract

Annealing-induced changes in the coercive force ( H c), ac permeability (μ e), remanence ( B r) and reversible endothermic reactions have been measured for amorphous Fe-M-P (M = Cr, Mn, Ni or Mo) alloys with low T c, and the relationship between soft magnetic properties and enthalpy relaxation is discussed. Although the soft magnetic properties of the as-quenched alloys were improved upon high-temperature annealing, degradation of soft magnetic properties occurred with low-temperature annealing. The annealing-induced increase in H c at low temperature was about 30–60 mOe for Fe 74Cr 9P 17 and Fe 76Mo 7P 17 alloys, while the increase was much smaller for Fe 74Mn 9P 17 and Fe 33Ni 50P 17 alloys. By comparing the changes in the soft magnetic properties as functions of T a with those of reversible endothermic reactions, it is considered that the increase in H c and the decrease in μ e are due to low-temperature enthalpy relaxation resulting from local rearrangement of the metallic atoms of different species. It is also presumed that the generation of an internal stress field caused by the local rearrangement of metal-metal atoms brings about the increase in H c through an enhancement of the strain-magnetostriction interaction.